It took some time sorting out my installation mistakes (under-torquing) and manufacturing defects, (warped parts from Edelbrock and Mr. Gasket), but it is now running and very well at that.

The basic equipment changes are as follows.

Holley 2300 2 barrel carb, 350 cfm, (flat track racing model)
Edelbrock Torker II intake
14" K&N with a 1.5" riser for direct air flow.
MSD ignition with MSD Blaster coil
Taylor 8 mm wires and Delco sparks.
78 Amp alternator (home town re-build)
Mallory bypass fuel regulator
stock engine internals except for mild exhaust porting
stock 2.8 fuel pump
ported manifolds
re-built Y pipe
Thermo-tec black pipe wrapping
2.5" mandrell bent exhaust
CATCO hiflow CAT
Moroso racing muffler w/ single exhaust

The cosmetic/functional body stuff includes a 5" scoop, (it really works) 5" wing stands, and recessed lights. Here is the only pic of the current car. (it has primer on the stands) #11 on this thread
https://www.fiero.nl/forum/Forum1/HTML/042593.html

Now for the driving of it.

The car is still not a tire burner. The Goodrich T/A's dig right in, but a hard shift into second shows substantial wheel spin.

The torque is amazing. It will idle smoothly at 300 rpm!!! I set it to 750 to keep up the lubrication.

The pull is strong from 500 right thru to red line. The 1" conversion spacer on top of the dual plane intake gives the extra oomph over 5000 rpm. The dual plane intake gives the oomph down low.

The sound is unlike any 2.8 I have heard. It is very low, and sounds not unlike the big carb'd Porsches or a V8 Vette. The resonance makes the car be noticed even though it is not the loudest car around. We are talking just below window shaking volume, but the same kind of wavelengths. Sort of like cranking Led Zepplin's Hearbreaker.

It definitely does not sound like a ricer with a f*rt can tied to his bumper

The speed at which Tach needle goes up to red line in 1st, lets me know that I have a faster car under me. It has not been to the track, but by the end of July, the London Fiero crowd will be out and we will get it timed.

Stock it was 15.474. I don't know if it will break 15.0 but we'll give it a shot.

Altogether, the carb mod was a good one. The power band is smooth and strong. It starts good, and the torque comes on evenly... and.... I have no "Check Engine" light to worry about again .

For the guys doing carb conversions, I hope this gives you some good info. and a little inspiration. And remember .... we don' need no steenking ECM

Arn

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Arn Brown,

Nicely done! Even though I'll never go back to carbs, a big fat + for you!

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you go Arn.

[This message has been edited by Master Tuner Akimoto (edited 06-24-2004).]

Thanks Master Tuner. You are an inspiration for all us carb guys.

Arn

Cool. sound like you made a good choice. Any pics?

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-Chris - Custom Gun Metal 86 GT 3.4 5spd

"It's too low, too rough, too loud, drinks gas, it's totally impractical, but damn good lookin. In other words, It's almost perfect!"
Build up tread or MODS w/ Pics

Not yet.

I have the old fashioned camera.

I hate developing with only half a roll

Arn

I love having a carb'd engine. As you say the power from idle to redline is so much better.

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Happiness isn't around the corner...
Happiness IS the corner.

Great it is working well. Nice work. I wonder how much inprovement must be contributed to all the other mods besides the carb. You did a lot apparently all at once. Porting the exhaust manifolds alone can be a big improvement yet you also have a hi-flow cat and a free flowing muffler and a K&N filter.

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Red 88 GT T-Top 3800 INTERCOOLED SUPERCHARGED
White 88 GT Stock
Please give me a rating if you appreciate my contribution.
History of Skitimes Car

I too prefer carbs for the simplicity. If i do and engine conversion again, it will be prob a carbed 4.3. or 3.4. Congrats on getting rid of all the electronic junk.

Here is how I figured it, Skitime, based on what I have been told.

The improvement in flow in the intake is no help if the engine is constipated.

So, porting the manifolds, porting the Y, and adding the 2.5" pipe, adds potentially 6-12 hp, (depending on who you are listening to) with a stock plenum. The carb gives more air.

In other words, I do not believe the stock plenum can supply enough gas to the renovated exhaust to reach it's full capacity.

Enter the carb. The carbs, whether the 390 cfm or the 350 cfm flow alot better than even a ported plenum. The Edelbrock intake with it's patented runner system, on their website gives another 20 ft/lbs of torque over a stock GM carb intake. Hence the carb on a really good intake, coupled with
a free flow exhaust, will cause the stock heads to max out.

And that is, as far as I know, my limitation. My heads are stock. Any improvement to them in the future will optimize net gains from any new mods with lots of air flow happening.

I am going to run the stock engine this year and see what it will do. When I can determine the real difference between the stock MPFI setup and Holley/Edelbrock setup, then I'll carefully proceed with valve work and maybe cam work.

In short, if I had left the stock plenum in place, I believe the porting work on the manifolds would have netted not more than about 10 hp, and possibly as little as 6.

Arn

quote Originally posted by Arns85GT: Holley 2300 2 barrel carb, 350 cfm, (flat track racing model) CATCO hiflow CAT

Can you run a those two together without the cat having a "melt-down"?

Ed

Ed, there is no problem.

The CAT has 2.5" inlet sizes and has volumetric and flow capacity for a 5 litre V8.

There are 2 reasons for the CAT, and the first is emissions this fall.

The second is that the Moroso racing muffler is 95 DB and I wanted to tame it a little. Glad I did too. The combination sounds so sweet

Arn

Arn,
Congrats on getting it sorted out!!!

Those who say a carbed motor will not pull cleanly from the bottom of the range to top have not driven one set up properly. My carbed 3.4 pulls hard all they way from 800 to 5500 rpm and the sound is different from an injected motor, deeper with lots more growl.

Welcome to the club

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85 GT 4-speed
3.4 pushrod, 390 Holley carb, Edlebrock intake, MSD 6A ignition. 04 Gran Prix exhaust tips, Ported manifolds and lots more to go.
Richey

Good to hear its running well. I had to crank Heartbreaker to see if that was how I remember it sounding. Hope you pass the E-test... enjoy the better gas mileage too

Brad

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Sad to say but I am no longer a member of the carbed brotherhood. It was a blast though! Wait till you see what Ive done...<giddy>

Should be done in 3 to 4 weeks then its "omg, wtf is that?" time.

Heres a tuning note for all the carbd guys. Regarding the 390 Holley 4bbl, you can easily jet it down 1 to 3 sizes to gain a little more mpg, hp and throttle response. I was running 49's and sure i could goto 47. Factory jets are 51(?) I also installed one step lighter spring on the secondaries and could have used one step less aggresive accelerator cam, now this is on a 3.4 with a h272 cam.

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Calgary - August 1, 2004 Fiero Fiesta
1984 Indy Fiero 3.4/3100 Hybrid NA
*ALL THROTTLE AND NO BOTTLE*
http://www.gmpcm.com/ Killer ECM/ PCM tuning software and information

[This message has been edited by donk316 (edited 06-24-2004).]

quote Originally posted by BtotheB: enjoy the better gas mileage too Brad

HMM... I was getting an average of 17mpg with my stock 2.8L F/I engine, With a 3.4L and a 4bbl carb I'm getting about 19mpg. (This is "city" driving, I haven't taken it on a long highway cruise yet. Also driving easy as the engine is still being broke in. ) So yes I will enjoy the better milegae.
Also I don't need to have it emission tested, It's exempt !

[This message has been edited by Oreif (edited 06-24-2004).]

thanks for sharing, I've been considering this myself, +

quote Originally posted by donk316: Heres a tuning note for all the carbd guys. Regarding the 390 Holley 4bbl, you can easily jet it down 1 to 3 sizes to gain a little more mpg, hp and throttle response. I was running 49's and sure i could goto 47. Factory jets are 51(?) I also installed one step lighter spring on the secondaries and could have used one step less aggresive accelerator cam, now this is on a 3.4 with a h272 cam.

I also arrived at basically the same settings through trial and error.
#49 main jets but I am running the short yellow spring for my secondaries (I have no bog or surge)
I did switch to 8.5 power vlave after driving the car with a vacuum guage hooked up and discovering that at cruise speeds I never fell below 11 Hg. Installing the 8.5 helped to eliminate a dead spot I had that I suspected was a lean surge condition. I could probably get by with a 9.5 and not lose any MPG.
My accel pump cam is stock. 3.4 with a H260 cam

in a few months ill be in the carbed club...carbed and juiced giddy-up. I gotta get the intake and carb yet, anyone gottem for sale?

How'd you set it up with the stock 2.8 fuel pump?

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Carbed 2.9 engine build in progress. forged pistons, crane cam, fully balanced, ARP bolts, double roller timing chain and more
--Adam--
IM AOL: FieroGT5speed

I started out with the 390 ,#49 jets, short yellow spring, and I never got a chance to really test it.

The float valve stuck on the secondaries side and the ghyser hit the manifold and poof.

When I went at the fire repair, talking to a local speed shop that deals in carbs, they advised me that the 2 barrel would perform as well as the 4 barrel on the 2.8, be more flexible, and give better action out of the hole, (streetlight to streetlight).

So I went to the flat track 2300 Holley. The bowl is center hung, stock, I have no choke, (it starts fine anyway) and from what I can see, the size is pretty much a perfect match to the 2.8.

I expect the 3.4's need a bit more, but there is some wisdom in having a carb with only 1 throttle screw, and 2 idle screws to adjust I just don't have the complications of a secondary system, choke mechanism and the spring/vacuum system. I have more air from idle. If I had the bucks, I would be tempted to try the 4150 with mechanical secondaries. I know they are a little more tricky to handle the accelerator, but they are a thrill to drive.

Arn

Arn - Not too many ppl attempt to modify the existing 2.8 because they rather swap to another V6 at the same time. That's great that the likes of you and Oreif and others keep the 2.8 going. I think it's a preference that anyone can attempt. Keep up the sharing, it's great. Thx.

quote Originally posted by GTFiero1: How'd you set it up with the stock 2.8 fuel pump?

Mallory makes a racing fuel regulator for their high output pumps.

It takes 60 psi down to as low as 3 psi up to 15 psi.

It is a bypass style so your pump runs easy and you can adjust your fuel pressure with nothing but a 3/4" wrench and your fingers. I put a liquid filled fuel pressure guage on the carburetor side of the regulator and I try to keep it as close to 6 psi as possible.

The 2.8 fuel pump is really good once you step the pressure down. It has lots of volume and you will never starve even an SBC. The Mallory fuel regulator can be seen here

http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=1472&prmenbr=361

Arn

I carbed mine about 8 years ago and am happy with it also

I am thinking about going to a carb. I am taking mechanical engineering and i work at a machine shop and would like to make a custom intake to feed three 2bbl carbs to my 3100 V6 (fiero 2.8 top end) Any thoughts any ideas on what carbs whould work and where i can get them and prices. I guess some racing crabs/fule injection can get expencive and be a disastor. Thoughts?

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quote Originally posted by Arns85GT: Mallory makes a racing fuel regulator for their high output pumps. It takes 60 psi down to as low as 3 psi up to 15 psi. It is a bypass style so your pump runs easy and you can adjust your fuel pressure with nothing but a 3/4" wrench and your fingers. I put a liquid filled fuel pressure guage on the carburetor side of the regulator and I try to keep it as close to 6 psi as possible. The 2.8 fuel pump is really good once you step the pressure down. It has lots of volume and you will never starve even an SBC. The Mallory fuel regulator can be seen here http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=1472&prmenbr=361 Arn

which version of them did you use? thanks

to GTFiero1, I used the gas one, third on the list. $74.99

to WS63100FIEROGT, the 3 carb idea is great, however, you are talking about stuff done in the 60's and in later years, most didn't keep up the style. Your main problem is creating too much available air and ruining your vacuum at low rpm. In other words, the style you are contemplating is made for a screamer.

The 350 cfm I am using is about ideal for a 2.8. Your 3.1 is not too different and I expect 390 cfm is pretty close for the engine for optimum performance. Oreif uses the 390 on his 3.4.

But to answer your question, I can't recommend 3 carbs that would total somewhere under 450 cfm. and that is what you need. Too much carb will just result in poor performance at the streetable end of the rpms. In fact, I could have bought the 500 cfm 2300 Holley and my information is that it would be a poor choice for mine for the above reasons. That is also the reason I am not running an Edelbrock carb. They're just too big.

Of course if you are running speedway style racing and need all your action at 6,000+ rpm, that's another story. But those engines don't idle worth a d**m.

Arn

quote Originally posted by WS63100FIEROGT: I am thinking about going to a carb. I am taking mechanical engineering and i work at a machine shop and would like to make a custom intake to feed three 2bbl carbs to my 3100 V6 (fiero 2.8 top end) Any thoughts any ideas on what carbs whould work and where i can get them and prices. I guess some racing crabs/fule injection can get expencive and be a disastor. Thoughts?

It would be better if you went with 3 Weber 34-ICT 150cfm 1-bbl carbs and hooked them up like the 67 Pontiac tri-power where the center carb was the primary and the other 2 carbs were the secondaries. Since carbs pass air and fuel, It's not like a fuel injection system where if you have a slightly over size throttle body, the system compensates for it. Over-carb'ing will cause a lot of bog and poor performance.
The Weber 34-ICT's can be bought for about $195 each. ( ICH's if you want to add a choke and they are the same price.)
http://www.weber-carburetors.com/Weber/weberpartscarb.asp

Good old Weber

The question I have is not the top end, for which 450 cfm triple carb setup would do great, but the 150 primary.

I was told that the strength of the 2 barrell is having more air in the lower rpms and developing more torque.

If the 3 Webers come on with primary/secondary sequencing, is it possible to put a larger middle carb? I think Chrysler did that in some cars. Maybe more like 200 cfm on the primary side?

Any thoughts?

Arn

Its good to see you're happy with your carb and all those other great mods you've done! WS63100FIEROGT where are you taking mechanical engineering?