I like the length of those rods, but Im going a different route if possible. I don't like the idea of cutting the journals since it will reduce the amount of overlap between the main and rod journals, other part is budget, we'll see where that goes. In the beginning stages of accessory drive mock up and will be working on turbo hot side mock up in the near future. The buick V6 rods are almost a direct fit, but too much offset. Im going to contact K1, Eagle, or Molnar to find out what options I have.
SleevePAPA ; Your chassis looks vary well done. Good looking car!
“I don't like the idea cutting the journals since it will reduce the amount of overlap between the main and rod journals,” I see this as a concern on these forum . But NASCAR is down to 1 7/8 inch rod journals at 100 + HP per rod. I'll be lucky to make 75 or 80 HP per cylinder. http://www.ebay.com/itm/Set...AOSwPe1UFzFD&vxp=mtr They are 6.200" long, 1.976" on the big end without bearing, for the 1.850" crank journals, .805" wide, with a .787" diameter wrist pin size. These have 3/8" rod bolts. Weight: 530 grams. NHRA pro stock is going smaller and smaller also in the search for lightness. I know billet V forged. Nope. Now cost, OK, the crank guy said $500 for the work. Another shop to balance it $190. So if I saved that and spent it on custom rods...
PS; The motor heads around here don't like Eagle rods.
SleevePAPA ; Your chassis looks vary well done. Good looking car!
“I don't like the idea cutting the journals since it will reduce the amount of overlap between the main and rod journals,” I see this as a concern on these forum . But NASCAR is down to 1 7/8 inch rod journals at 100 + HP per rod. I'll be lucky to make 75 or 80 HP per cylinder. http://www.ebay.com/itm/Set...AOSwPe1UFzFD&vxp=mtr They are 6.200" long, 1.976" on the big end without bearing, for the 1.850" crank journals, .805" wide, with a .787" diameter wrist pin size. These have 3/8" rod bolts. Weight: 530 grams. NHRA pro stock is going smaller and smaller also in the search for lightness. I know billet V forged. Nope. Now cost, OK, the crank guy said $500 for the work. Another shop to balance it $190. So if I saved that and spent it on custom rods...
PS; The motor heads around here don't like Eagle rods.
If the budget allows for forged rods and pistons, I plan to push the s366 to its limit, likely into the 600hp range at the wheel. The eagle rods with arp 2000 bolts are rated to 1500hp, that's all I know about those. Im considering K1 rods since they are a bit wider and would be within the sideplay limits of the journal. I still need to call them, but there are other irons in the fire right now. I remember someone finding the minimum size rod journals, it may have been Joseph Upson. Pauter has made a set for the LZ9, but they are $$$$. Im interested in what you find for the true stroke, deck height, and rod lenth, as data is varied from person to person.
“likely into the 600hp range at the wheel.” That's a big number. I will be very interested in how she holds up. Have you posted more details on the engine build beyond Facebook?
“likely into the 600hp range at the wheel.” That's a big number. I will be very interested in how she holds up. Have you posted more details on the engine build beyond Facebook?
I opened up a build thread on turbobuick.com, but not many people took interest. The LC2 is proven to hold big power and not many people care about a non LS engine swap, so that's why I opened a page on FB, it's public so you can click all the pics for details.
Mars ran 10.56 @130mph with the turbo LZ9, cam swap and springs were the only internal engine mods. Was in a 3rd Gen Camaro, been running in the 400hp range for the last 3 years, keeping the car in te 11's for bracket racing. The GN is a bit heavier so the LZ9 will need a bit more to run consistant 10's, that's where ill be happy......for now.
Let me know what you find out for the limits of the rod journal, I looked at some of those carrillo rods.
The mold lines say that this is a forged non twist crank. Great stuff!
Oil squirters on all 6 cylinders. Help keep pistons cool when you increase the power.
You can see the light gleam off of all the little chamfers I spent the day making. I also removed all the flashing in the oil drain back holes and smoothed around the tops of them. I prefer this tool to debur the bolt holes.
On the bottom I also removed all the flashing from the oil drain back holes and smoothed around the outlets of them as well . All edges chamferd. And the inside of the block skirts are sanded smooth. I wanted to get some of this work done before we start to handle it, in and out of the hot tank, or on and off the granite plate, or move it to places to get work done.
I'm not done with the block so I may not be ready to check the dimensions this week.
Dobey; I'm sorry I didn't respond to your questions I must of mist it but I was just going over this thread.
“Are you trying to spin the thing to 10K RPM?” Not 10K but I think I can push it to 85 or even 9K. I got the titanium valves for less then stainless steel valves and they have never been run. The exhaust were installed. Then at the end of the season removed and sold. Two of the intakes have what looks like water spots on them however I can't feel them or measure a difference. Besides I only need 6.
“I'm kind of afraid to ask what the cam specs you're planning to use are.” I haven't selected a cam yet because it will depend on what I can do for the bottom end. It will be an, off the shelf, “drag/circle track” type grind I expect.
“You're talking about getting peak N/A power, but with a budget, and then go on to talk about custom grind crank and solid roller valve train. I'm a bit confused.” I hope to make it a “budget build” by searching the internet high and low for brand name, off the self, parts at the best price I can find. I may need to do some small modes myself. Like narrow the big end of the rods or change the valve notches. I also will keep my build sorta flexible so if I find something that's a little different than my original plan. Like the titanium valves for less than stainless. And the pistons, a race teem had opened the box, put them in inventory, then later sold them unused. The engine was “new”. GM was putting it on the test stand when they dropped it on the floor. The coolant crossover and pump were broke off so The dismantler sent used ones along. It was in storage various places for 9 years when I got it. 06 f40 trans have a 10% chance of rattling in neutral so GM sold them for next to nothing. Most “new” F40s you see are these. A roll of the dice. But maybe the best torque handling transverse manual trans. You can get a LSD for them. But I would like to be closer to a 4.10 final drive. Like my old M19.
The heads look good also, rockers are 1.7:1. I'll have to change them out for something adjustable. However I don't have a solid plain yet. Modify a set of full rollers (tips roll) to work. Stay tuned for that.
I would suggest checking out some info on ls1tech on the factory rockers. I seem to recall people losing valvetrain stability when going to adjustable rollers. The added inertia of a roller tip bearing mass and decreased stiffness of the aluminum body are big disadvantages vs the cast steal shaft mounted and optimized shape of the factory pieces.
OK. So not exactly a "budget build," but more like "patience and getting lucky with buying parts cheap" build. You might save some cash here and there, but if anyone else wanted to do a similar build, will likely cost a bit more.
What ECU are you planning to use? I think the factory ECU will only let you map stuff up to about 8200 RPM, so if you want to go higher than that, you might want to look at going with an aftermarket like AEM or Haltech.
I think you probably got the same set of Ti valves that I got for my LS build. Be careful, as they have longer stems than stock LS valves. Wasn't made apparent when I bought mine, but at least they were cheap enough I don't feel terrible about it, and can probably sell them off easily enough. I measured the difference in spring height with them, and not sure I'd go with getting new grooves cut to make them the right length. Anyway, just a bit of warning there.
I think there's a Saab version of the F40 that has a 3.92 final drive, but information on this stuff is very hard to find.
Xnke on 60v6 forum found the lift limit of the stock rockers, which is .545 before the contact patch is on the edge of the valve stem.
Good luck finding a cam with the larger journals, comp wont even touch it. Schneider maybe. But if you find someone who will grind a cam to fit the larger LZ journals and not cost a small fortune, let me know, i'll sell the brand new WOT Tech turbo grind and bearing spacers.
FieroWannaBe; Thanks for the info. I had not heard that but thous were part of my concerns. And getting it all under the valve covers, I assume they're using “nuts and studs” for the adjustment? I have some china rockers on a slow boat from Cali. Should be here tomorrow. China because they are just a test. Stainless steel, 1.7:1, LS, pedestal mount, with the adjustment bolt that bears on the push rod. I will need to make pedestals that fit the 3900. and I'm not sure of the geometry of the rocker body. Pictures soon. $108 for china or $800 to $1000 or more for US. Something is wrong. I know all china bearings are total junk, but can I make something like this work. That's the fun part! Then switch to the good stuff with similar mods.
Dobey; Don't let the logical side of my brain hear you say that.
To myself; It is a budget build. Yes definitely, definitely!
sleevePAPA “Good luck finding a cam with the larger journals, comp wont even touch it. Schneider maybe. But if you find someone who will grind a cam to fit the larger LZ journals and not cost a small fortune, let me know, i'll sell the brand new WOT Tech turbo grind and bearing spacers.”
A poster on one of these forums said he asked comp for a 3400 cam with large journals and they said yes they could but he didn't make the perches. So... I have no solid plan “yet” for the cam but... I may get 1st gen. Roller and shrink sleeves on it, then finish turn and polish to size. I might run a drive off the cam thru the timing cover for a position wheel. So the reason for the remote pump. Subject to change at any given moment.
FieroWannaBe; Thanks for the info. I had not heard that but thous were part of my concerns. And getting it all under the valve covers, I assume they're using “nuts and studs” for the adjustment? I have some china rockers on a slow boat from Cali. Should be here tomorrow. China because they are just a test. Stainless steel, 1.7:1, LS, pedestal mount, with the adjustment bolt that bears on the push rod. I will need to make pedestals that fit the 3900. and I'm not sure of the geometry of the rocker body. Pictures soon. $108 for china or $800 to $1000 or more for US. Something is wrong. I know all china bearings are total junk, but can I make something like this work. That's the fun part! Then switch to the good stuff with similar mods.
I have a set of rockers on the way for my LX9 (non VVT 3500) that I'm going to try, mine are 1.8:1 though... got lift? hopefully I don't end up with piston to valve clearance issues. we'll see. got a link or a part number for the rockers you're going to try?
FieroWannaBe; Thanks for the info. I had not heard that but thous were part of my concerns. And getting it all under the valve covers, I assume they're using “nuts and studs” for the adjustment? I have some china rockers on a slow boat from Cali. Should be here tomorrow. China because they are just a test. Stainless steel, 1.7:1, LS, pedestal mount, with the adjustment bolt that bears on the push rod. I will need to make pedestals that fit the 3900. and I'm not sure of the geometry of the rocker body. Pictures soon. $108 for china or $800 to $1000 or more for US. Something is wrong. I know all china bearings are total junk, but can I make something like this work. That's the fun part! Then switch to the good stuff with similar mods.
$800-$1000+ for rockers from the US? Where the heck are you shopping? My Harland Sharps for my LS4 were only ~$400. If you're looking for a "budget" option, and the V6 rocker bearings are the same size as the LSx rockers, you could get a trunion upgrade kit from Comp or whomever. It's less than $200, and fixes the weak spot of the stock rockers.
If you want true rollers and can use the LSx rockers, there are plenty of options in the $300-$500 range.
$800-$1000+ for rockers from the US? Where the heck are you shopping? My Harland Sharps for my LS4 were only ~$400. If you're looking for a "budget" option, and the V6 rocker bearings are the same size as the LSx rockers, you could get a trunion upgrade kit from Comp or whomever. It's less than $200, and fixes the weak spot of the stock rockers.
If you want true rollers and can use the LSx rockers, there are plenty of options in the $300-$500 range.
your pushrods probably don't adjust on the pushrod end, and are probably aluminum. personally, I would prefer a steel rocker to aluminum, less flex, and way stronger.
Originally posted by ericjon262: your pushrods probably don't adjust on the pushrod end, and are probably aluminum. personally, I would prefer a steel rocker to aluminum, less flex, and way stronger.
I'm not going solid roller, so they don't adjust, but the adjustable ones weren't that much more expensive. The HS rockers have a very good track record. If I wanted to go with steel, I would have probably just stayed with factory and did the trunion upgrade.
Originally posted by dobey: I'm not going solid roller, so they don't adjust, but the adjustable ones weren't that much more expensive. The HS rockers have a very good track record. If I wanted to go with steel, I would have probably just stayed with factory and did the trunion upgrade.
I haven't looked into the adjustable variety all that much, I just did a quick once over on summit to see what might work in the realm of full roller rockers. the rockers I ordered were about $400 for a set of 16. hopefully they will work, if not, summit is pretty good about returns...
Dobey; Don't let the logical side of my brain hear you say that.
To myself; It is a budget build. Yes definitely, definitely!
sleevePAPA “Good luck finding a cam with the larger journals, comp wont even touch it. Schneider maybe. But if you find someone who will grind a cam to fit the larger LZ journals and not cost a small fortune, let me know, i'll sell the brand new WOT Tech turbo grind and bearing spacers.”
A poster on one of these forums said he asked comp for a 3400 cam with large journals and they said yes they could but he didn't make the perches. So... I have no solid plan “yet” for the cam but... I may get 1st gen. Roller and shrink sleeves on it, then finish turn and polish to size. I might run a drive off the cam thru the timing cover for a position wheel. So the reason for the remote pump. Subject to change at any given moment.
I guess it depends on who they talked to. Talking to one of the salesman over email, they wouldn't budge after I told them what engine I was using, regardless if it needed to be VVT or not. Then I called the tech line and they said it would be a custom billet and couldn't manufacture the 3400 cam with larger journals. I hope you get further than I did, though.
Also, I looked into those nascar rods, I'll go that route but it seems I can only find rods that have the Honda size journal(1.88), a BE of 2.01". Where can I find the chevy journal rods with the 2.100 journal size?
If the bearing dimensions are the same on the V6 rockers as on the LS rockers, then you can probably use the shafts from the V6. I don't know what the quality of the bearings on those is, but I can tell you that the common failure point on the stock LSx rockers in high lift applications is the bearings, which is why the trunion upgrade from Comp/etc… exists. If your new rockers have the same parts that are used in the trunion upgrade kit, you might have gotten a decent bargain there, assuming the rockers themselves aren't made from bad steel.
The bearing for the V6 rocker is .812 (13/16) OD the new ones are .875 (7/8). So no crossover there. But what is the OD of the bearings in Comps up grad kit??? Or in an LS rocker ? They do clear the LIM, but just. The valve cover rail will make adjustments difficult. I would like an adjustable pedestal mounted rocker so a phone call to Comp, about there up grad kit, may be in the future. Can I get it for just one at first ?
Originally posted by fierogt4e: The bearing for the V6 rocker is .812 (13/16) OD the new ones are .875 (7/8). So no crossover there. But what is the OD of the bearings in Comps up grad kit??? Or in an LS rocker ? They do clear the LIM, but just. The valve cover rail will make adjustments difficult. I would like an adjustable pedestal mounted rocker so a phone call to Comp, about there up grad kit, may be in the future. Can I get it for just one at first ?
The upgrade kit is for the LS rockers, and I think is the same hardware they use in their full LS rockers, so probably 0.875 too. Measure the shaft instead. The bearing OD might be larger for the LS, but if the ID is the same (ie, the shaft diameter is the same), then the shafts should be usable in the LS rockers.
I don't know if you can buy a set for a single rocker, but it's possible. Check their web site or call them.
Exoticse; I showed my son your post. He dose all the recording, editing and posting of the videos. We thank you Maybe Sunday we can get the 1st one up of the engine.
SleevePAPA; This should show you a wide rang of rods. All 6.125 C to C, 2.100 BE. Look for .927 SE so you can use ls pistons.
Here is my first look at rod length, piston compression height, and stroke combinations. (Info has changed so math may be off.) I'm looking for good info everywhere.
3900. crank, rod, and pistons
stock cylinder head deck height 8.818” 224mm stock stroke 3.307” 84mm stock bore 3.8976” 99mm stock compression height 1.337 stock rods 5.827” 148mm stock head gasket (measured at .065) .055” .6560ci stock cylinder head volume 36.cc 2.1968ci piston dish, custom 15.cc 0.9153ci total combustion volume 3.7681ci one cylinder volume, stock 39.4442ci
rod length / compression height / rod to stroke ratio
5.7” rod + 1.395 c. h. = 3.447 stroke* 1.653 rr low end only 5.827 rod + 1.337 c. h. = 3.307 stroke stock 1.762 rr 6” rod + 1.165 c. h. = 3.307 stroke no rod? Turn journal? 1.812 rr best 6” rod + 1.110 c. h. = 3.416 stroke OK 1.756 rr 6” rod + 1.095 c. h. = 3.447 stroke*# OK 1.740 rr OK 6.125” rod + 1.053 c. h. = 3.280 stroke 1.867 rr 6.125” rod + 1.073 c. h. = 3.240 stroke**## 1.890 rr, high rev.s no low end 302ci Chevy
* A 3900 crank with the journal turned down to 2.100” and offset to the max stroke, less a .005” clean up is 3.447”.
** A 3500 crank with the journal turned down to 2.000” and offset to the max stroke, less a .005” clean up is 3.240”. This is a good way to reduce rod journal weight for higher rev.s. Strength is the question. Small lighter journal = smaller light rod end =less counter weight = faster spin up
# One cylinder W. 3.905 LS bore = 41.3043ci. 12.9 compression 4.01L
## One cylinder W. 3.905 LS bore = 38.8240 ci. 11.3 compression 3.77L
--- So this is just how I started. Then I ran them on Desktop Dyno. To see how they looked
I was looking at the 6.125" rod along with the 3.905" bore pistons from carrillo. A CH of 1.035" and 18cc dish volume.
That will put the compression at 10.96 with the piston in the hole .0045"
A bit more compression than I wanted for boost, but it has been done. That's about the best combination I could find so far, I wish they were offered with a larger dish. Looks like a nice meaty top land, though.
*edit* Found a set from wiseco with a 1.050" CH, and a 30cc dish, 3.903" bore. That will put the SCR in the 9.72:1 range, pistons out of the hole 0.0105" and a quench of 0.041". Seems to be the best off the shelf option as of right now.
Are those specs from the net findings, or have you measured?
SleevePAPA; “Are those specs from the net findings, or have you measured?”
Most are from the net but I am trying to confirm the ones I need. My stock rods are 5.827” The wrist pins are all offset to the major thrust side .0315in (.8mm). stock used head gasket measured at .065”. Over all. Steel parts only .008, .008, .037 The plastic embossing is on both sides of the outer shims. The stock compression height is 1.305 on this one.
I misunderstood the Cometic site so I took a second look to see how everyone was getting a .051” thick gasket. OK now I see.
The block is ready to hot tank. Then take to work for measuring.
After I decided on a piston I Got a price from the big 3. Then took the part number and put it in a search engine. (Bing) and found them at a $225 savings. nothing on the first page helped. It took some time to find a good price on the rods ($60 off) but a friend hasn't picked up the C-10 parts yet so I'll keep looking till he pays.
SleevePAPA; “Are those specs from the net findings, or have you measured?”
Most are from the net but I am trying to confirm the ones I need. My stock rods are 5.827” The wrist pins are all offset to the major thrust side .0315in (.8mm). stock used head gasket measured at .065”. Over all. Steel parts only .008, .008, .037 The plastic embossing is on both sides of the outer shims. The stock compression height is 1.305 on this one.
I misunderstood the Cometic site so I took a second look to see how everyone was getting a .051” thick gasket. OK now I see.
The block is ready to hot tank. Then take to work for measuring.
After I decided on a piston I Got a price from the big 3. Then took the part number and put it in a search engine. (Bing) and found them at a $225 savings. nothing on the first page helped. It took some time to find a good price on the rods ($60 off) but a friend hasn't picked up the C-10 parts yet so I'll keep looking till he pays.
Did you measure the fire ring on the headgasket, or just the edges? Which rods are you going with?
Im still on the fence about turning the crank down that far for a 2.100" Journal, especially since I would like to see 600+ whp from this build.
First, thanks for answering all my questions, I get the feeling you know what your are doing so I hope you don't mind if I ask some more?
I've been following Joseph's build since 2007, mainly from the v6z24.com site. He had a lot of issues with the engine and it only put down low 300's to the wheel. He has been working through the issues but doesn't seem to follow up much anymore. So no real numbers to base my power estimate from. Mars, however, managed to make enough power to put down a 10.56 @ 130mph with a cam only short block. Heads have never been off, but power estimates around the 550 mark.
Mrtohil had a great build going, but IIRC, he passed away before the build was complete and running. Great information produced while he was machining the engine.
Im looking at the Lunati rods, rated for 800hp, and Wiseco pistons right now. Im wondering if you may have some input?
Anyway:
6.125" C2C Rod 2.100" BE, .927 pin 655 grams, but expect lighter to machine for .860" BE width, give or take.
3.903" forged piston 1.050" CH 30cc dish
With this combo, the pistons will be proud of the deck about 0.0105" DCR of 9.4:1 0.055 Quench most likely will need to clearance for the valves
Do you forsee any issues with the combination, mainly the pistons proud of the deck?
Originally posted by sleevePAPA: 6.125" C2C Rod 2.100" BE, .927 pin 655 grams, but expect lighter to machine for .860" BE width, give or take.
3.903" forged piston 1.050" CH 30cc dish
With this combo, the pistons will be proud of the deck about 0.0105" DCR of 9.4:1 0.055 Quench most likely will need to clearance for the valves
Do you forsee any issues with the combination, mainly the pistons proud of the deck?
Have you had the deck height measured to be certain about rod length and compression height? How far down is the top ring on that piston? If the top ring is going to get close to the deck, I'd be a little concerned. If top ring is down far enough, cam timing won't result in piston/valve contact, and compressed gasket thickness is ~0.050, I'd think you'd generally be OK though.
I have 6.300 Lunati rods and domed 1.321 CH Wisecos (drop-in replacement for stock bottom engines) for my LSx build. This puts them 0.008" out of the deck on my build. I'm not going for turbo though, and am going for ~11:1 CR.
Have you had the deck height measured to be certain about rod length and compression height? How far down is the top ring on that piston? If the top ring is going to get close to the deck, I'd be a little concerned. If top ring is down far enough, cam timing won't result in piston/valve contact, and compressed gasket thickness is ~0.050, I'd think you'd generally be OK though.
I have 6.300 Lunati rods and domed 1.321 CH Wisecos (drop-in replacement for stock bottom engines) for my LSx build. This puts them 0.008" out of the deck on my build. I'm not going for turbo though, and am going for ~11:1 CR.
Personally, no. I'm only going off what people have found in their own research, which is 8.818" The piston set I'm looking at is wiseco K449x3903, nitrous/turbo pistons. They don't show any figures for top land thickness, but being a turbo/nitrous slug, it probably has a thicker than normal top land. But I will verify eventually.
Compressed gasket thickness has been verified by the OP, at .065" measured at the ring land. I have my engine mocked up for building the hotside and came up with .066" with feeler gauges. I think the cometics are .051", to add to the confusion.
Originally posted by sleevePAPA: Personally, no. I'm only going off what people have found in their own research, which is 8.818" The piston set I'm looking at is wiseco K449x3903, nitrous/turbo pistons. They don't show any figures for top land thickness, but being a turbo/nitrous slug, it probably has a thicker than normal top land. But I will verify eventually.
Compressed gasket thickness has been verified by the OP, at .065" measured at the ring land. I have my engine mocked up for building the hotside and came up with .066" with feeler gauges. I think the cometics are .051", to add to the confusion.
If you can, I'd suggest getting the main bore checked and deck height measured, before getting the rods and pistons. Make sure it's all square. If you need to take material off the decks to square things up, it'll change the dimensions. The stock measurement is usually +/- 0.005 or something like that. So if your block is slightly taller, the pistons will be back in a bit, and if less, they might be out a bit more. If the measurement you're using is correct, and your math is right (I haven't checked it), then 0.010 out of the deck sounds like it would be fine, assuming it doesn't bring the ring up too close to the edge. So I'd say call Wiseco to get the ring land measurement, and get your block measured and checked, and plug in the right numbers to verify it will be good, before clicking on the buy button.
As for the gaskets, Cometic will make you custom gaskets that will compress to any reasonable thickness with any reasonable bore size. Pricing is not much more than their shelf gaskets either.
If you can, I'd suggest getting the main bore checked and deck height measured, before getting the rods and pistons. Make sure it's all square. If you need to take material off the decks to square things up, it'll change the dimensions. The stock measurement is usually +/- 0.005 or something like that. So if your block is slightly taller, the pistons will be back in a bit, and if less, they might be out a bit more. If the measurement you're using is correct, and your math is right (I haven't checked it), then 0.010 out of the deck sounds like it would be fine, assuming it doesn't bring the ring up too close to the edge. So I'd say call Wiseco to get the ring land measurement, and get your block measured and checked, and plug in the right numbers to verify it will be good, before clicking on the buy button.
As for the gaskets, Cometic will make you custom gaskets that will compress to any reasonable thickness with any reasonable bore size. Pricing is not much more than their shelf gaskets either.
OEM MLS gaskets will do just fine. Just so happens that LS engines in general have roughly 0.008-0.009" piston protrusion from what I've been finding. So that's good news. But I will make sure to measure twice before I commit to a combination. Thanks Dobey. Maybe the OP can use some of this data?
SleevePAPA; I try not to suggest to any body how to build there engine or to assess there build. We're building two very different monsters out of the same engine. I am talking about what I am building and why. And passing on some info that may help others because hot rodding these little motors is not often done.
I plane to go with “of the self” piston and rods then adjust the stroke to fit. Yes that's backwards. I will be turning the crank down a 1/4” so a slight change in the stroke is no additional expense. I had my block at work Monday but couldn't get help on the CMM to check all the numbers. Seeing if the cylinders have been moved outward 1.5mm is bothering me also. I may have to do it my self with micrometers but that cant tell me if the cylinders are shifted outward.
The following say what I believe, better than I can say it, about why I'm using the longer rods. Some readers may not know.
Collected from others; (Pros, or not) Whatever you do don't confuse race engines with street engines. They are two very different critters. Different rod combos are done to find 5-10 hp. Your car will change that much on the street depending if it's 85 or 65 degrees out. Most enthusiasts are limited by budget. Long rod combos are used less, so they generally cost more. If you can find some for a usable price then I'd say go for it. Else stick with the stock length. --- On paper, a longer rod, netting a higher rod/stroke ratio, is supposed to allow you to rev the engine higher at a safe level. This is because less force is being applied as a result of piston thrust (side loading) on the cylinder walls. also, the rod bearings will be taking less of a beating due to "better" attack angles on the power stroke which is likely the biggest worry, in my opinion, when wanting to rev a motor - spinning rod bearings. Also, from another perspective with the longer rod, its going to dwell at TDC longer which means its going to sit at peak cylinder pressure longer than a short rod. I could see that as a good thing and a bad thing. The good - power loading. It will hold peak cylinder pressure longer which could mean more power. The bad - If you have a hot motor, sitting at peak cylinder pressures is going to create more heat which induces hot spots which in turn increases the likelihood of pre-ignition.
--- I guess If I had to choose I'd say use a long rod, especially if the cost difference was slight (which it usually is with today's huge imported parts market). The longer rod will provide better geometry (create less rod angularity) which theoretically will reduce mechanical losses. The longer rod may also help reduce piston weight by making for a more stable piston with a reduced skirt length. The dwell change is very slight, arguably insignificant with a wide array of common rod to stroke ratios. And finally, the ring pack may be squeezed a little at a 1.15" compression height but it is surely a usable distance since C.H.'s of 1.0" are commonly used, even though the wrist pin interferes with the oil ring. There shouldn't be anything too serious to worry about with a long rod. ------------------ Sincerely George
[This message has been edited by fierogt4e (edited 07-13-2016).]
Thanks for the insight! I've crunched a lot of numbers trying to find a combo that would work well with the stock stroke, as a feel more comfortable with it as it is. So the 6.125" rod seems to be the best match, with a OTS 1.035 slug, and with a 1.050 CH slug. The 1.050 slug seems to be the better option considering the quench distance may fall within .050", and the dish size will yield about a 9.4:1 DCR.
I'll go back to being a spectator now, thanks again! Looking forward to more updates...
back to the subject of rocker arms, the 3500 and 3900 use a simlar pedestal mount rocker, and no guideplates are available. I came up with this to replace the pedestal and act as a guide.
12 would be required, as they don't link to the other valves, along with conversion studs. the LX9 rocker bolts thread into the head about 25mm(~1") the longest off the shelf M8x1.25 to 3/8" stud I've come across is about 20mm (~.800"), personally, I want the most thread engagement that I can get with mine, so I'm planning to have ARP make a set for me. there are 5/16" conversion studs available, but there aren't nearly as many rockers available in 5/16", and nothing I really liked was available in 5/16"
hopefully I don't end up with piston to valve clearance issues. we'll see. got a link or a part number for the rockers you're going to try?
