well it's has been a month of hard work but the 3L duke lives. anyone interested in building one here is what i have used and what i have done to the little engine that a month ago couldn't and now she can go. ok i started out with a 1984 non roller 2.5L that a bought for $50 and striped it apart and took the heads block and manifolds to my machineist. he started out with a boring the block 60 over and shaving the block .001 then i bought a 153 crank and had it resized for sbc forged rods and pistons the head was port and polished shaved .004, valves triple cut and maifold ports where matched. i bought the cam and lifters and stiffer springs from the fiero store. i but the engine together in one sat and had it in the car on sunday. then all the truble started i had a blot broke off where the starter mounts got that fixed then i had put the distubter in backwords took it to my freinds shop and they fixed that because i have no idea what was wrong then i bent a push rodfixed it. took the car for a spin and puched a push rob through a rocker arm fixed that and went for a drive nothing broke. having drove it yeasterday for a few hours letting everything set i can only say wow if realy goes good. i still have to regap the spark plugs (at 40 should be at 60 im told) and fix the ics but thats it

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86 coupe 3.0L P&P shaved, 4 cyl 5 speed
full Body kit ASA Rims
hood and light mods

Thanks for the info! Have you taken it to the dyno yet? Makes me want to build up my 84 duke that is sitting in my garage. is there a reason why you did not use like a 85/86 block? did you have it internaly balanced?

Kyle

yeah i did not like the roller lifter because i was told that i could get a better cam for the non roller i had the crank balanced to it was a fun project that only cost about $2000 Can i guess i would have to add everything up but it was not that bad i was told i shoud have about 150Hp to the wheels and about 180 ft/lbs of tourge

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86 coupe 3.0L P&P shaved, 4 cyl 5 speed
full Body kit ASA Rims
hood and light mods

This is what I like to hear, long live the big duke.

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The Iron Duke Resource Site

Sig design by MinnGreenGT

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For you Dash!!!! Could you put a list of all the parts/items/machine work you have done along with what costs you can remember and email it to me?

TIA

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87 2M4 5 spd Daily Driver Project with working A/C!
86 SE Needs every thing but a Motor & Sunroof Seal!!! Now for Sale! $750.00
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Web Master
Central Florida Fieros
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So the 153 crank nets you a 3 Liter when using the 2.5L block? if thats the case i think i should build an Iron Duke for my indy and sell the 3.4L!! woo hoo!

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Email: adriantalliss@email.com
1984 Indy Fiero 4spd 3.4L
-Est 220hp @ 5000rpm / 230 tq @4500rpm, centerforce II clutch, 390cfm 4bbl holley, crane h272 cam, Edelbrock Torker II intake, 9 to 1 comp, minor head porting,headers, true 2" mandrel dual Supertrapp exhaust, factory 4.10 4 spd, 17x7 white Konig Ziege FR 205/40R17 RR 235/45R17. All interior leather changed to white, custom built adj aluminum rear wing, aftermarket gauges, corvette MBC upgrade, Held coilover kit, 2 inch drop front and back.

[This message has been edited by donk316 (edited 08-06-2003).]

quote Originally posted by donk316: if thats the case i think i should build an Iron Duke for my indy and sell the 3.4L!! woo hoo!

how much do you want for it?

I would have used a truck duke block or and older duke, they're much stronger than the fiero block

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--Adam--
1987 Blue GT 5-speed
IM AOL: FieroGT5speed

[This message has been edited by GTFiero1 (edited 08-06-2003).]

Good work, I'd like to do something like that someday. I have question for you does the 3L used in the mercruiser inboards bolt to the fiero trany or would it bolt to a regular sbc trany?

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'69 AMC Ambassador sst 2dr hardtop 390ci 3 spd B&m shift kit-the cruiser(315hp/427ftlbs)
'86 Fiero GT 4spd, aluminum head 3.1, vented rear brakes, Cavalier seats-got a T3 turbo just need some time
'93 Cavalier Z24 5 spd (engine donor)-parting out
'82 Yamaha Heritage Special 400cc 6 spd, hi-flo exhaust and air filters-For Sale to buy more Fiero stuff

that part i don't know i had a good freind of mine figure all that out i was kinda the check book but i think the only thing i changed was the flywheel but i could ask for you

Get us a complete parts and modifications list so that those of us whoc would like to stick with the duke can consider this as well.

I need to know which crank, and how to find one, and what rods and pistons to use. As for the overbore, I would stick with just enough to clean up the cylinder walls. I may even have a source for a block so this may be doable.

Just the displacement increase alone should be good for over 150ft/lbs of torque and at least 110hp. I know the hp sounds low, but remember we are talking 5000rpm max here, if the crank is stronger than the stck crank, and has full counterweights it may be good fo a few hundred more. As for the torque, it may end up closer to 160 or even more since the longer stroke will produce proportionally more torque than just the displacement increase. This could be a brutal car to launch, probably very quick in the bottom end.

I want one.

Ira

[This message has been edited by Monza76 (edited 08-09-2003).]

I want to something to my motor this winter, I have a roller block though, but I want to do something like you did Dasher. I was thinking of getting a S-10 block and do that up. Would the 153 crank bolt up to an auto?

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Outstanding job. Any idea on the torque output?

The valve problems could be weak parts but there are other things to watch out for.

You might be having problems with rockers and push rods because you seem to have not done anything to make up for the shaved head and block. You dropped the whole valve train and head .005. That could be over compressing the system, especially if you have a cam with more lift.

You could also be binding up the valve springs. I would check carefully for either problem.

Unless you fix that you will probably break more valve parts.

The "easiest" thing I can think of to make up for a slight shaving is cut washers from shim stock and run the rocker bolts thru them into the head. that will slightly raise the pivots so you stop over compressing the valve train.

thanks orge i think i have figured out the push rod problem i have a buddy of mine figure out how long they had to be with an ajustable push rob then i found some that where the right length. note they a not stock fiero pushrods good call orge. i think the crank would work with an auto tranny but i don;t seee the piont of doing all that engine work if your going to still run a auto. with an auto you can put anything in the 4 cly is fun but a 3.8 or a 4.9 would be much better

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86 coupe 3.0L P&P shaved, 4 cyl 5 speed
full Body kit ASA Rims
hood and light mods

Interesting fix on the pushrods. If you know... What were the replacements from in case anyone else needs them. (Note for others... These will only work in the setup listed above. different amounts of shaving would require different p-rods or other methods of restoring the valve train geometry. If you shave 20 thousandths total, just use a FelPro Head saver shim.)

If the cank takes standard Fiero flywheels then it should work with any transmission that could normally be used in Fiero.

Assuming the TC is properly matched to the new configuration... (That isn't always easy.) Running an automatic would actually increase torque to the wheels even more. For this reason and others Automatics are usually prefered for drag racing.

This would probably be a good candidate for the 4T60. The 4T60 allows deep gears and still gets decent fuel economy.

Nice job, Dasher! I always wondered what a Chevy/Pontiac hybrid Duke could do.

quote Originally posted by RockChip: ...does the 3L used in the mercruiser inboards bolt to the fiero trany or would it bolt to a regular sbc trany?

Since nobody has answered this, I will.
The Mercruiser uses a Chevy bolt pattern. At least our old one had a Chevy pattern. Ours was 153 C.I./120 HP. The head was not crossflow, either.

I also looked at GM Powertrain's web site. The marine version of the Duke also looks to have a Chevy bellhousing pattern.

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Raydar

88 3.4 coupe. 17s, cut springs 'n all.

[This message has been edited by Raydar (edited 08-10-2003).]

He didn't use the marine engine.

Just the crank from it far as I can tell.

That means the bell housing doesn't change. If the crank accepts the same flywheels then any Fiero L4 transmission will work.

As much as I hate to bring bad news, its a 2.7L (its not BAD news, just alittle dissapointing) but anyway, the The 153 crank witch is 3.25" will net you a 2.7L given a 4" bore. However, with the mercruiser crank you will have essentially the same engine as the mercruiser, therefore 3.0L. And again as its been stated, the mercruiser engine can be used interchangeably with a regular Small Block Chevy. Same crank output and bellhousing. The crank would have to have its rear flange machined down and re drilled for the FWD flexplate, OR, make a custom flexplate. (witch I dont think would work)

As long as the crank has 2 counterweights for every cylender, (like on the SD4's and Mercruiser 3.0's) I think the Iron duke could push some respectable numbers. I have not seen the 153 crank so Im not sure if they have the two counterweights per cyl or not. But in my own theory, I believe the crank was the absolute weakest part of the duke.

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84 Indy fiero Quad 4 HO (almost done!!)
85 2m? Getting parted out soon
Silver 88 GT, Newest addiction.