fierosound:Still working making it run/drive as good as it looks. Not fully broken in, so don't ask for dyno or 1/4 mile times.
Starts OK, idles like crap, cruises good, WOT is terrible - falls on it's face. TERRIBLE mileage - you can watch the fuel gauge needle move as you drive. Loud as hell, handles like crap, and can't get ECM to control TCC properly. Makes me feel sick to over how much went into this, and often wish I never bought it - since it wasn't really what I THOUGHT I was getting. Thanks Chester...
Yeah, I'm beginning to understand how Chester came up with the name The Dirty Rat. If you want to see some of the problems I had with my 4t60 TCC, check https://www.fiero.nl/forum/Forum1/HTML/052684.html
[This message has been edited by 30+mpg (edited 12-06-2008).]
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10:26 PM
Dec 8th, 2008
fierosound Member
Posts: 15190 From: Calgary, Canada Registered: Nov 1999
... The stock cruise control parts (vacuum canister, diaphram, solenoid etc) were removed and a less bulky Delco electronic cruise unit was installed below the air cleaner.
Still haven't fixed the head, but I thought I'd post this today...
I needed room to mount the air cleaner where the cruise control vacuum canister, solenoid etc were. So I switched to the much more compact Delco electronic cruise module used after 1996 on many GM cars.
As I said earlier, the Edelbrock AVS 500cfm is too damn big, and it's the smallest they make. Idle is not bad but could be better, part throttle driving is pretty good but WOT is terrible. The engine doesn't draw enough air to open the secondary air valve and pull the fuel properly.
Even though it's listed as a 500cfm, mechanically it looks identical to the 600cfm - the primary difference being the jet sizes. Specifically, we're looking at the throttle bores and venturi diameters. Smaller primaries and smaller secondaries are what's needed because at 3.3L displacement, the engine will only ever draw about 400cfm.
The Edelbrocks are a clone of the Carter Super-Quad AFB /AVS series of carburetors and are physically identical. Well, Carter DID make a 400cfm carb - the AFB 9400/9410 and it had smaller venturis and bores compared to the Edelbrock 500cfm. This makes it perfect for the 3.3L SD4.
Unfortunately, Carter hasn't made any for 20 years and since they were only made as a replacement carb for the GM 231 V6, they are very rare. A rebuilt one just sold on eBay 2 weeks earlier for $350 - darn!! And emailing all the carb rebuilders came up with nothing.
As luck would have it, I finally DID find a brand new, in the box Carter AFB 9410 400cfm from The Carb Shop. http://www.thecarburetorshop.com
It was likely the last and ONLY new one in existence and I paid dearly for it. It seems nothing is cheap with an SD4!
Unfortunately, it doesn't have the nice polished finish of the Edelbrock.
The smaller primary venturies would produce faster air velocity at idle and would greatly improve that function. And smaller secondaries are what's needed because at 3.3L displacement, the engine will only ever draw about 400cfm.
Here's a comparison of the throttle bores back-to-back (secondaries in middle). The primary bores are the same, but the secondaries are very different.
Carter 1-7/16" 400cfm on Left - Right is 500cfm 1-11/16" Edelbrock
Here's a comparison of the venturies back-to-back (secondaries in middle). The primary venturi on the 400 is slightly smaller, and the booster is a different shape. But here again, the bigger difference is in the secondary's primary venturi size.
Carter 1-1/4" 400cfm on Left - Right is 500cfm 1-9/16" Edelbrock
Because the Carter and Edelbrock are physically identical, installation requires nothing more than swapping carbs. All the lines and throttle linkages connected as before without modification.
... to be continued
[This message has been edited by fierosound (edited 01-11-2009).]
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04:19 PM
TennT Member
Posts: 1523 From: Humboldt, Tenn Registered: Nov 2002
Weren't the booster venturis the main difference on the 500 cfm and the 600 Edelbrocks? Holley used to make a 450 Economaster spreadbore, IIRC. No matter, you got your carb. tg
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05:51 PM
30+mpg Member
Posts: 4056 From: Russellville, AR Registered: Feb 2002
Weren't the booster venturis the main difference on the 500 cfm and the 600 Edelbrocks? Holley used to make a 450 Economaster spreadbore, IIRC.
I didn't physically compare venturis between the 500 and 600, but according to Edelbrock's chart they are the same diameter bores and venturis - perhaps a different shape venturi??
I'm pretty limited here. A Holley won't fit the engine bay, a spreadbore won't fit the manifold without an adapter which then makes it too tall below the decklid.
[This message has been edited by fierosound (edited 12-11-2008).]
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07:47 PM
Dec 15th, 2008
TennT Member
Posts: 1523 From: Humboldt, Tenn Registered: Nov 2002
I've repaired the spark plug hole on Sunday and need 24 hours for the sealent on the insert to cure. Everything looks good and I will likely be starting the engine in the next day or two.
I have installed the 400cfm Carter 9410 Super-Quad 4-barrel carburetor (designed for GM 3.8L V6 engines). This replaces the Edelbrock 500cfm which was just too big for this 3.3L SD4 engine.
I installed a divider plate in the intake manifold. This will increase the vacuum signal to the carb by changing it from an “open plenum” to a “divided plenum” and should make low RMP throttle response crisper.
With the divider, you also require a base gasket with the divider down the center as well.
Here’s the carb installed. There’s to easy way to get a highly polished finish like the Edelbrocks (they have a 10 step process), so I painted the main body aluminum and the upper portion gloss black (basically the reverse of marine carbs). The paint will seal the pores of the aluminum so the carb won’t get stained from gas, oil and engine grime. It looks pretty good.
I have set the idle speed and mixtures and check and adjust the throttle response. The carb seems to be working well. I have a steady 1000rpm idle, seems smoother than before too. When blipping the throttle you can see the the secondary air valve open and fuel from the nozzles shooting in. I think this will be a BIG "night & day" improvement in driveability.
I think because the Edelbrock 500cfm was too big the secondaries never opened up properly AND it basically ran as a 2bbl that was too small at the upper RPM band and so the engine leaned out as the RPM went up. Shouldn't have that problem now.
I was able to get it out for a short test drive and it's quite driveable with the new Carter carb. It drove well and I could DEFINITELY feel this carbuetor WAS working much better than the Edelbrock, but I won't be able to fine tune for WOT performance and such until later once all the snow is gone.
[This message has been edited by fierosound (edited 01-21-2009).]
You have done a great job rebuilding the car. Thanks for posting your build thread its very helpfull and inspirational, so that I get to work on my own car. I wish I could give you another plus.
Keep up the great work and please continue to post
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01:46 PM
Feb 11th, 2009
fierosound Member
Posts: 15190 From: Calgary, Canada Registered: Nov 1999
I have it driveable and it feels pretty good with the new carb, but fine tuning can't be done until all the roads are clear and the weather is warmer a couple of months from now.
Official "Public Unveiling" of my Indy is coming up at World of Wheels Feb. 20-22 in Calgary. I'm curious/nervous about the response, but I know people/kids were waving (favorably, thumbs up, etc) when I drove down the street with the thing, so I think people will be "wow'd". I know virtually nobody has ever seen a Fiero Pace Car in this city, so I expect a lot of questions.
Our Club is putting in 6 cars in total, including a second all stock Indy next to mine, my 3.4L supercharged 87 GT, a blue 87 GT, burgandy 87 2M4 and red 85 GT.
I have installed the 400cfm Carter 9410 Super-Quad 4-barrel carburetor (designed for GM 3.8L V6 engines). This replaces the Edelbrock 500cfm which was just too big for this 3.3L SD4 engine.
I installed a divider plate in the intake manifold. This will increase the vacuum signal to the carb by changing it from an “open plenum” to a “divided plenum” and should make low RMP throttle response crisper.
[
Cut a little notch out of the divider plate to balance it
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12:36 PM
Kento Member
Posts: 4218 From: Beautifull Winston Salem NC Registered: Jun 2003
You have done a great job rebuilding the car. Thanks for posting your build thread its very helpfull and inspirational, so that I get to work on my own car. I wish I could give you another plus.
Keep up the great work and please continue to post
There's a head and a couple of these intakes on eBay. They'll fit a stock 2.5 Iron Duke engine.
I am bidding on both of those intakes currently for my Super Duty head.
Three things though.
1) the intakes don't fit a stock head, only a super duty head.
2) The heads don't fit a stock block without machining. The heads are setup for 1/2" head studs, whereas stock Iron Duke studs are 11mm.
3) That head is pretty much at the end of its useable life. It has .170" machined off of it already. There's no more material left to do a clean up cut on the deck surface. Its milled so far one of the bolt holes is actually protruding into the deck surface now. Aluminum castings can be welded on (unlike iron), and there are even hard aluminum filler rods used specifically for repairing the deck surfaces of cylinder heads, but it would be in the neighborhood of $1500 worth of head work to restore some deck material.
From an email I received from the guy doing my SD head:
quote
".170 is huge the head you have is only cut .100 and as far as welding the deck yes it is possible if you have a huge pocket book and they don't make them or cant find them anymore. Not really an option.
