Replacement carb

[page62]

As I work on my list of "to do" projects, it seems a carb is well up there. Among other things, when I press the throttle to the floor, the car hesitates . . . bad!

My car is staying pretty much stock, so I'd like to put another Q-Jet on there. So far, my choices seem to be:
Edelbrock Q-Jet
Edelbrock Q-Jet -- rebuilt ($100 less)
Jet Performance Stage I Q-Jet
Local auto parts store rebuilt carb

Whaddya y'all think?

 

[Hijinx]

Why not go with their Stage II? They build it to your engine specs. That is what I am planning to do on my '73. I have heard good things about them. The Stage II will give you more go for the money. You can get them to do it on your carb for around $250 or just buy a JET Stage II carb from Summit or Jegs (cant remember which) for $350. Not sure which I plan to do yet, but its high on my list as well.

 

[jsimpson]

Actually, I woould have voted for a rebuild by The Carburetor Shop if it were one of the choices!

 

[69MyWay]

Hey, I don't see fuel injection on the list!:eek

I think Hijinx is giving some good advise there. Carbs are usually the subject of much frustratiobn and ad on these forums.

I think where most people goof up is not matching a carb to the car, and the driving characteristics of the owner. The Edelbrock Performer is just plain purrrrty. They work fair, and typically take a stroke of genius or luck to dial them in the first time.

The Q-jet direct replacement makes the most sense. However, if you have mods done to the engine, chances are it won't be right either. Plus Q-jest is also difficult to dial in if needed (metering rods, etc).

Getting one from a local autoparts store is okay for a stock engine, but then again it may simply be a generic equivelent and never run quite right.

For the performance oriented, the Demon, Street Avenger, etc. etc. over a wide range of performance and quick change tuning.

If it is all stock, go with the most direct stock replacment, do the idle set tuning, slap the air cleaner back on and enjoy the car.

If performance minded, take your time and match to the overall package for best results.

Did I mention fuel injection? Actually, you can get a used TPI manifold from a 85-92 Camaro, or 85-91 Vette for around $100 to $250, a wire harness for about $250 and $100 chip. After some other messing around with fuel lines, etc. You can be running C4 performance and technology and leave the old carb tuning in the dust. Plus, you may get an extra mile or two per gallon, instant cold starts, and the ewwwww, aaaaaaa, factor when you pop the hood at a show.

 

[jsimpson]

Oh yes, I replaced my Q-jet with TPI; there's no doubt in my mind that is what I'd do all over again if I had another C-1,2, or 3.
"A mile per gallon or 2"?? I'm getting about 20 mpg with my TPI 78 and a huge increase in low end torque - power where I need it every day rather than up in the top rpm's where I hardly ever get a chance to use it!

 

[Hijinx]

Chris & Jsimpson,
Is there a good source of info for this conversion? I know it will match up and work, but I have not seen any text on actually doing the conversion. Chris, I know you went the Edelbrock path, but I would like the looks of a later model "long top" runner based TPI. I am even willing to buy a book on it. Where can I find this?

 

[jsimpson]

Order the instruction booklet for the wiring kit from Painless Performance Products. It gives all parts and part numbers needed.

 

[rpounds]

Since you are wanting to keep your vette "pretty much stock", I would go with a rebuild of your current carb. However, I would make sure to take it to someone that has above average knowledge of Q-jets. Back in the late seventies, I had a '67 El Camino SS-396 with a Q-jet. I took the carb to a local yocal to have it rebuilt . . . all he really did for me was swap one set of problems for another. Someone told me about a fellow who really knew his Rochester's . . . so off the carb came and over to this new contact. He took a while to get it back to me, but when I bolted it on, it was perfect . . . the guy really knew what he was doing . . . it made a big difference.

Just my $.02

 

[69MyWay]

Chris & Jsimpson,
Is there a good source of info for this conversion? I know it will match up and work, but I have not seen any text on actually doing the conversion. Chris, I know you went the Edelbrock path, but I would like the looks of a later model "long top" runner based TPI. I am even willing to buy a book on it. Where can I find this?

Feel free to pick my brain about the conversion all you like. Just ask me whatever. You will find that the wire harness kits from painless do come with decent instructions. They run on a more basic system so many of the stock inputs are not used.

I have seen people get away under $500 running and driving on TPI systems where they got good deals on the manifolds then did the install themselves.

You end up installing the computer (it fits great behind the passenger dash pad). It has to be hooked to power, ground, and ignition power. You then simply plug all the other connectors from the computer to the sensors on the harness. You plumb an extra 3/8" high pressure fuel line down the car and run two wires back to an inline high pressur pump. The rest is just bolting the hardware on, finding a nice looking air cleaner, and polishing the runners and upper intake to look good.

With the basic TPI, you get a generic chip burned to match your cam, compression, exhaust, gear ratio, etc. and you are off and running.

 

[jsimpson]

I used the emissions line for the return line - no problems. I also had my chip burned for EGR delete and elimianated all of my EGR plumbing. Now if only I could find a TPI system for my big block that works as well as this one for under a thousand!

 

[Hijinx]

OK, I'll Bite

Alright, I'm on board for the TPI. Now, which model do I look for? Sounds like late 80's off a Vette or more probably a Camaro? What I read between the lines, is get the intake and such, get the ECM and get the wiring from Painless. This provides the cleanest setup? Should go well with the new hood. Of course, I'll be sleeping in it for a while!

 

[69MyWay]

You can use any intake from a 305 or 350. The center bolt holes will be different on the 87 and new TPI manifolds. No worries. You can slot them out and use a nice high quality washer to fill the gap. I have done it several times with no failures.

You will want 350 injectors. If you already have a 350 manifold, then no worries. You can cross referrence the part number on the injector with your G.M. parts counter to ensure you have 350 injectors. If not, you can get a brand new set from Accel and others very reasonable.

Painless is one of many companies that makes a harness. Street and Performance also make them as well as many more. The one difference is you can call up Summit and order both the harness and new injectors if needed. I would say that www.streetandperformance has the best customer service and support. However, they charge a little more for the EFI conversion parts.

The provider of the harness will instruct you which computer box you need to make it run. You can go to the bone yard and pick up a computer as long as it has the correct service number. Then, the chip is up to you, your budget, and your mods on the engine.

 

[Hijinx]

OK, I have a line on two TPI setups

1. From an 88 Camaro IROC-Z - Complete in great shape. I can get this for $600 - $800. Still haggling over the price

2. From an 86 Vette - Complete with Painless wiring harness. I can get this for $800

Should I continue to shop around or is the second item with the included Painless harness worth the money?

Need to know pretty soon.

 

[Hijinx]

Oops, forgot. Actually, no throttle body or injectors on the Vette setup. Here is what it has;FEATURES:

1. Painless wiring harness # 60102 "GM 86-89 TPI Mass Air Standard Harness" brand new in the box along with warranty card and instructions.
2. Ported, dipped, cleaned and painted manifold. (see pictures) TPI setup off of 1986 corvette.

3. Runners and plenum. The guy I bought it from started to port and polish the plenum and runners. I had the manifold professionally done by http://www.precisionengine.com/ here in Houston. The plenum and runners need finishing. They are not siamesed. The plenum has had a great deal of time spent on it to sand it down…it needs finishing.

4. Mass air flow. The screen has been taken out but the fins will need to be cut down for added CFM.

5. ECM ... I don't program these but will include my programmers 411 and he can tweak it for you. He's very reasonable. Here's what it has right now. Cold start disabled, VATS disabled. What you have is ARAP base file (1989 vette with auto trans), fans on at 200, no EGR code, kept VSS, a little less timing because of the iron heads and taller gear I was going to use, delayed TCC lockup (to 47mph vs 40), and a little more acceleration enrichment (pump shot) because of the larger cam (It was a 178 cam). The fans are set to "normally open”.

6. New TB gasket set. Needs orversized runner gaskets from TPIS.

7. Does not include 52mm TB or injectors. I kept those for another project.

 

[69MyWay]

Keep working it. The 86 Vette is your best bet as it already has the puter and harness. However, I would prefer to see you run a speed density (no mass air flow). In the end, it really does not matter if you get a good deal one way or the other.


I have a TPI manifold off a 1988 5.7 IROC, but it needs one set of runners, injectors, and a tb. So, otherwise, it is basically worthless. You need to keep searching. I have seen ready to go manifolds at car shows for $250 OBO.


I notice my link to street and performance is not working.

You can call them at (501) 394-5711. Ask to speak to Mark and see if he knows of any complete systems for good deals.

 

[jsimpson]

I'd take the one from the 86 Vette. Vette TPI's have the fuel inlet on the passenger side. Camaros have the fuel inlet on the driver's side - messier plumbing. The painless wiring kit alone is worth $250. Also bear in mind that you can easily convert a MAF TPI to MAP, so that's not an issue. The ECM which is specified in the Painless manual, will have to have a newly burned chip anyway, so source one from a V-6. The junkyards don't know they're the same as the V-8 units, so they sell them for a lot less!

 

[Hijinx]

Chris,
The IROC deal has everything. The only thing I would want to get is the Painless harness. Its basically complete. If I could get it for $600, should I? Is there a dollar amount I should not go over?

 

[Hijinx]

But is the Vette setup worth $800 without the throttle body or injectors?

 

[jsimpson]

Probably not, and I would offer considerably less. A complete unit can be had regularly for $350 to $500 at auto flea markets. But remember that you need either new injectors or cleaned and matched injectors anyway. As for throttle bodies, that should be an easy find with all the people going to aftermarket bigger throttle bodies! I did my entire installation for under a thousand, and I didn't get a bargain on my injector at $500. I also sprung for all new sensors and IAC, which weren't cheap!

 

[Hijinx]

OK, called Chris' friend, although I could not talk to him directly. Their cost is from $2600 to $3800 based upon how you get it (plain, polished, chromed, etc...)

Sounds like I need to shop around for the Vette version, due to fuel line routing. Expectations would be to find a unit for around $500 complete and expect to replace the injectors. Definately need to consider getting the Painless wiring harness.

Is that about right?