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GTA TECH Want to discuss technical topics about your GTA.... engine tuning, mechanical upgrades, problem areas, etc.? Then post it HERE!

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Old 03-29-2005   #1
Urr Force
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A couple of engine questions from the new guy...

Hey everyone, I'm pretty new to the site, and the GTA world. I've been asking this question around here but let me ask you guys. I've already decided to replace the 1987 305 TPI with a 350 short block and re use the TPI. My question is which heads should I use?? I know some will go all out and say AFR, and Edelbrock, and Vortec. But for the money, and for use with the later style base. Which heads are are sure bet......(would prefer experienced opinion). Also (and I know this has been beat into the ground) but what is the REAL deal with swapping to a stout carb/intake setup?? Anyone done this swap and been pleased with it?? THanks
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Old 03-29-2005   #2
FearThisGTA
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GTA Year: 1991
GTA Engine: 350 TPI Automatic
Re: A couple of engine questions from the new guy...

1rst the head question the Vortec heads are your best bang for the buck.But in order to reuse the TPI system you will have to buy a new base manifold that will work with it. "IF" it were me I would look for a set of used vette alum heads form the vette TPI's from 86-91(Or the ZZ4 heads), OR go with the World or Dart iron heads BUT get them bare. Reason being is b/c then you can pick out what valves and get the matching springs to go with your cam you decide to run.

Ok the carb and intake setup. Yeah you can do it you are gonna need extra stuff, like something to lock up the converter and a new distributor that is not require a computer,ie the old HEI distributors are a reliable source. IMHO, you will be under the hood all the time tuning that carb, b/c no matter how many times you adjust it it will change again, where F.I. is there and no need for adjusting all the time. Plus the F.I has alot more driveablity to it campared to the carb's. Good luck.
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1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
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Old 03-29-2005   #3
MunsonGTA
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GTA Year: 1987
GTA Engine: Custom
Re: A couple of engine questions from the new guy...

don't go carb, stick to efi. It's much better for tuning, gas milage and usually reliability. As for the heads, I run modified 113 vette heads from an 89 vette on my car. They'll bolt right onto a 350 short block and work great. They have a little smaller combustion chamber then stock also so they'll raise your compression ratio a little. And they're aluminum so you'll get a decent weight reduction. Then when you have the extra money you could get them ported or have some machine work done so you can run larger valves. Mine are fully ported and polished, bigger valves machined in, manley stainless race valves, springs good to .550 lift, pushrod guides.
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87 GTA: Forged 408 LSX short block, TEA stage 2 cnc ported 243 heads, BTR Stage 3 stroker cam, Fast 102 intake, NW 102 TB, Longtube headers, custom 411 ECM, custom harness, custom tuned, Performabuilt stage 2 4l60E with PTC 2800 stall, 9 bolt rear with 3.70 gears and TAP girdle.

11.16 at 123 mph.
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Old 03-29-2005   #4
Urr Force
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Re: A couple of engine questions from the new guy...

ok cool, I have a set of 487X heads from the 71 72 LT1's would those work alirght?? Don't get me wrong guys I like the TPI but I look at the whole picture ya know?? TPI is a bit pricey to work with, and get any decent numbers. I know carbs a little better, and are better at working on them. I don't know, I figure with a decent edelbrock intake, and an edelbrock or demon carb, I have all the rest such as HEI, and other parts. I don't know, just considering it.
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Old 03-30-2005   #5
Fred91GTA
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Re: A couple of engine questions from the new guy...

487 heads? If I'm not mistaken, those have the 76 cc chambers in them, right? Most heads from that era were smogger heads so they mostly came in combustion chamber sizes of 72cc and greater. The stock iron L98 heads have 64cc chambers. You have a 305 so your heads have a 58cc chamber. If you put those 487s on a stock short block, you'll have much lower compression. Something around the neighborhood of like 8.4 - 8.8:1. Maybe even lower. The drop in power from the loss in compression would probably be more than the power gained from the better head given the same compression. Have them milled down to 58cc to maintain your correct compression ratio which should be 9.3:1. If you're bent on using those heads, you could use some flattop or domed pistons to bump up compression.

As said above, try shooting for a set of 113 heads. Those things are good to about 350HP untouched I believe. However, they do not have provisions for an EGR so if you want to keep EGR, you'll need to plumb it from another source such as a primary header pipe. As for TPI, if emissions are not a real concern for you, trash the stock TPI and go with a Holley Stealth Ram. I am also a firm believer in EFI. Carbs are good, but you can't beat fuel injection for driveability.
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Old 03-30-2005   #6
MunsonGTA
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GTA Year: 1987
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Re: A couple of engine questions from the new guy...

I'm with fred, stick to the efi. You'll like it alot better in the long run. As he stated, if you aren't restricted with echeck then ditch the LTR setup for something else. There are others out there such as the stealthram that I run on my car, the superram, miniram, converted lt1 intake. All have difference prices and perform different. I know here in the state of ohio, since the camaro and firebirds are no longer being made, we can register our cars as collector cars. This makes the car emissions exempt and you no longer have to deal with echeck. The collector plates are the same price as normal. Your state might be different but I know that's how it works here in ohio.

You can usually find a set of 113 heads on ebay or thirdgen.org classifieds. I usually see sets go for 150-400 dollars. Are you going to be using an 87+ roller block with a 1 piece rear main or an earlier block?
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87 GTA: Forged 408 LSX short block, TEA stage 2 cnc ported 243 heads, BTR Stage 3 stroker cam, Fast 102 intake, NW 102 TB, Longtube headers, custom 411 ECM, custom harness, custom tuned, Performabuilt stage 2 4l60E with PTC 2800 stall, 9 bolt rear with 3.70 gears and TAP girdle.

11.16 at 123 mph.
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Old 03-30-2005   #7
Urr Force
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Re: A couple of engine questions from the new guy...

I'm gonna be using an 84 4 bolt motor. It's has flat top speed pro pistons. I was looking at the scoggin dickey package where you get the modified vortec heads, and they give you a GM parts TPI base for the heads and everything you need to install for like 1200 bucks. I guess I can be more patient and work with TPI parts. After all they pretty much are a big part of the GTA image right?? With that said can you guys tell me EXACTLY what I need to change if I swap to the 350 TPI. If I can get a no bulls#!t to-do list, than I'll definately be game for TPI.
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Old 03-30-2005   #8
MunsonGTA
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GTA Year: 1987
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Re: A couple of engine questions from the new guy...

if you currently have a 305 tpi all you'll need are some 22 or 24 lb injectors and maybe a custom chip. You'll most likely need the custom chip anyways if you plan to mod the engine.
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87 GTA: Forged 408 LSX short block, TEA stage 2 cnc ported 243 heads, BTR Stage 3 stroker cam, Fast 102 intake, NW 102 TB, Longtube headers, custom 411 ECM, custom harness, custom tuned, Performabuilt stage 2 4l60E with PTC 2800 stall, 9 bolt rear with 3.70 gears and TAP girdle.

11.16 at 123 mph.
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Old 03-30-2005   #9
Urr Force
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Re: A couple of engine questions from the new guy...

Quote:
Originally Posted by MunsonGTA
if you currently have a 305 tpi all you'll need are some 22 or 24 lb injectors and maybe a custom chip. You'll most likely need the custom chip anyways if you plan to mod the engine.
what about knock sensor??
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Old 03-31-2005   #10
MunsonGTA
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GTA Year: 1987
GTA Engine: Custom
Re: A couple of engine questions from the new guy...

i don't know if you need the 350 knock sensor or not. One of the other guys might know. I also don't know if the intake will bolt right onto the older style block since it's from a newer style engine. You might have to have the holes machined for it, which shouldn't cost much.
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87 GTA: Forged 408 LSX short block, TEA stage 2 cnc ported 243 heads, BTR Stage 3 stroker cam, Fast 102 intake, NW 102 TB, Longtube headers, custom 411 ECM, custom harness, custom tuned, Performabuilt stage 2 4l60E with PTC 2800 stall, 9 bolt rear with 3.70 gears and TAP girdle.

11.16 at 123 mph.
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Old 03-31-2005   #11
Urr Force
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Re: A couple of engine questions from the new guy...

Quote:
Originally Posted by MunsonGTA
i don't know if you need the 350 knock sensor or not. One of the other guys might know. I also don't know if the intake will bolt right onto the older style block since it's from a newer style engine. You might have to have the holes machined for it, which shouldn't cost much.
yeah I know the intake won't bolt right up. I've heard it's easy to do.
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Old 03-31-2005   #12
Fred91GTA
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Re: A couple of engine questions from the new guy...

Not sure about the knock sensor either, but I'd get a new one if I were you. If it goes out, then it'll be a pain in the ass when the Service Engine Soon Light comes on. I know I've had to replace mine in the past. Also, if you're getting aftermarket heads, the intake manifold won't have to have it's center bolt holes enlarged for a 90 degree angle. Just get heads with the late model 72cc angle in them. I am about 80% sure though that the 113 heads have the older intake bolt pattern. Also, check all your TPI wiring. Most times, SES lights are caused by faulty wiring to the sensors. These cars are going on 18+ years-old now, and I'm willing to bet some of that wiring has seen some wear. Especially the wiring in the engine compartment.

The Vortec head package is a good idea, and I actually considered it myself awhile back. However, the added cost of a dedicated Vortec manifold kinda turned me off. Also, if you do have high compression pistons in the shortblock already, double check the compression of the engine with the Vortecs. Don't go too high. Vortecs are still made of iron.
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Old 03-31-2005   #13
Urr Force
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Re: A couple of engine questions from the new guy...

Quote:
Originally Posted by Fred91GTA
Not sure about the knock sensor either, but I'd get a new one if I were you. If it goes out, then it'll be a pain in the ass when the Service Engine Soon Light comes on. I know I've had to replace mine in the past. Also, if you're getting aftermarket heads, the intake manifold won't have to have it's center bolt holes enlarged for a 90 degree angle. Just get heads with the late model 72cc angle in them. I am about 80% sure though that the 113 heads have the older intake bolt pattern. Also, check all your TPI wiring. Most times, SES lights are caused by faulty wiring to the sensors. These cars are going on 18+ years-old now, and I'm willing to bet some of that wiring has seen some wear. Especially the wiring in the engine compartment.

The Vortec head package is a good idea, and I actually considered it myself awhile back. However, the added cost of a dedicated Vortec manifold kinda turned me off. Also, if you do have high compression pistons in the shortblock already, double check the compression of the engine with the Vortecs. Don't go too high. Vortecs are still made of iron.
ok I see what your saying.........since I was gonna have the engine out, I was gonna try and pop for a painless wiring harness and put that in while the motor's out.

Last edited by Urr Force; 03-31-2005 at 06:21 PM.
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Old 04-26-2005   #14
Kenwood
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Re: A couple of engine questions from the new guy...

Nothing about a painless harness is painless>>>Stay away..nuff said..

113 vette castings were LATE year tpi vette heads...alum LATE MANIFOLD...

I actually have a set im debating getting rid of...BUT the problem with the 113 vette heads was that the EGR had to be run externally...thats why aftermarket manifolds have those oval plugs in the back...On the vette the egr released out the manifold and dumps into the exhaust manifold>>>instead of through a port in the head...

so your option is to delete the egr system Or weld a bung to your headders>>>or drill/tap manifolds for EGR..

as far as them going for 150 bucks...LOL those are usually the early vette aluminum heads which are POFS... typically 250ish-500 range depending on condition and mileage....BEWARE as scammer will try to sell early castings as 113>>big difference between the 2 for sure..

Last edited by Kenwood; 04-26-2005 at 09:36 PM.
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Old 04-27-2005   #15
MunsonGTA
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GTA Year: 1987
GTA Engine: Custom
Re: A couple of engine questions from the new guy...

i have the 89 113 heads and they are badass. They are also really modified. I do see alot of sets going for between 250-500 bucks, most of the time the heads are complete. Thirdgen.org usually has a set for sale almost everyday.
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87 GTA: Forged 408 LSX short block, TEA stage 2 cnc ported 243 heads, BTR Stage 3 stroker cam, Fast 102 intake, NW 102 TB, Longtube headers, custom 411 ECM, custom harness, custom tuned, Performabuilt stage 2 4l60E with PTC 2800 stall, 9 bolt rear with 3.70 gears and TAP girdle.

11.16 at 123 mph.
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