I need to get an extra set of heads for my 91' GTA and I'm still kinda new to the TPI set up. Well I found a set of center bolt TBI heads on a early 90s Caprice wagon in a local JY and just would like to know if they would fit on my car before I decide to go and pull them.

 

They would work but they would flow like crap and you won't make any power after 4000rpms unless you ported and polished them a good bit. However, if you decide to run them, you will have the most low end torque out of anyone on here.....hahaha.

 

Then that might actually work out for me I already plan on porting and polishing them along with adding bigger valves. If I can get some low end torque that would be good too cause I'll be using them for when I turbo the T/A and maybe it could make up for the turbo lag.

 

350 rwtq
150 hp.

 

Ok this is what I'm looking at doing I have a 91' GTA with a 305 tpi that I'm building a twin turbo set up for and since I have a broken bolt on one of the heads that are currently on my car I have decided that I'm going to just change the heads all together. I was told that if I put 350 heads on the car that should lower my compression to right about where I want it. I was goignt o pull the heads off of an Irock I found in a JY but by the time I went back it was already crushed, but I found the caprice while I was out there.

I plan on porting and polishing the heads along with bigger valves and putting new roller rockers and lifters. Besides that I plan on changing the cam. I'm also going to be using two super 60 turbos off of the mustang svos with two S13 sylvia intercoolers and bovs. I already have a bbs twin 58mm throttle body with the plenum ported to match along with a bbs adjustable fuel pressure regulator and venom 32lbs. injectors and I am getting a holley 255lph fuel pump.



Now my question is how well would these heads work with what I'm trying to do?

 

I have also found a set of 305 HO heads in another JY I don't know if I could get them as cheap as the TBI ones, but would it be wiser to use these.

 

i have a similar question
i'm taking a tpi setp off of an 86 trans am and putting it on an 89 formula with a tbi 305
will the tbi heads work with the tpi's intake or should i grab the heads off of the trans am too?
and if they will both work what are the pros and cons of both?

 

I guess this is a forum of questions, and mine is, can I use a set of old 283 heads I have on my '85 T/A? It's the first year they used TPI, I think...

 

From what I've been told you should be able to use the tpi heads with the tbi inatake manifold. As far as pros and cons I'm still in the learning process myself.



I think you would need a diffent base for a older style head, I know there are companies who make them I just haven't looked into it since I plan on using the newer style heads. I could be wrong but again I'm just going off of what I've been told.

 

If your T/A is a 85 TPI then it should have sidemount heads already, if so then ya 283 heads would bolt onto it fine

 

86 TPI should still have the perimater/sidemount heads, you would have to modify the two center bolt hole's on your intake to make the swirl ports fit, if you can get the 86 TPI heads (416's I beleive) cheap I'd just use them, the stock TBI heads off your 89 formula arnt all that great.

Putting them swirl ports under a TPI will give you the greatest tow truck motor you could posibly make that will never be put into a truck

Also both 89 TBI and 86 TPI have prolly the worst cam's ever, ya might wanna upgrade that wile you have it all apart.

LG4/L03 #14088841
Int/Exh 177/194 Lift .350/.385

1986 TPI Flat Tappet #14094097
Int/Exh 178/194 Lift .350/.385

 

If you are building a twin turbo car......look into getting some good heads or you will just boost sack and make no hp. Look into some L98s, GM Bowtie heads, or vortec heads(great head for the price)

 

I'll be on the look out then for some L98s at the jy then, cause I can get them for $50 for the pair. I almost picked a set up last week but they had crushed the car before I could get them.

 

I'll be on the look out then for some L98s at the jy then, cause I can get them for $50 for the pair. I almost picked a set up last week but they had crushed the car before I could get them.

 

swirl ports?
i'm new to all of this engine modification stuff
so if i use this tpi setup in place of the tbi with the tbi heads i'll get really good low end torque?

what's the easiest thing to do just swap the tpi heads for the tbi heads?
and does that take any modification?

 

I'd use the TPI heads from your donor car personaly. Swirlports are what your stock TBI heads are and midify'n your TPI intake to mount the centerbolt heads can be trouble if you are not very mechanicaly inclined.

I'd also slip in a used LT1/LT4 cam from a F-Body/Vette wile I had it all apart anyway's, would have to pull the rad to side it in/out. It is a tight fit though.

I'd stay away from the B-Body LT1 cam, its not worth the labour to put it in the car in my opinion

 

My TPI is an '85, no ****, recaro interior, anniversary rims and all. I've never pulled the valve covers, but I really don't know if they are "center bolts", since they clamp down like any other small block cover, so I'd guess I can do it and tack on some compression, and do some good math to match the cam, some serious programming could make a sweet 3.27 BW posi cruiser with a nice bottom end, ya think? Nice pick up with good highway mileage? Sweet car to pick up chicks on interstate road trips, maybe... By the way, is this model rare by chance? How many black and gold '85 T/As were made anyway?

 

This is a center bolt valve cover, note the bolts in the center


This a perimiter bolt valve cover, note the bolts on the side

 

appreciate the pics!!!

 

can i bolt my tpi intake directly to my tbi heads?

 

Valves larger than 1.94/1.5(stock on 350's) won't clear the bore size of a 305. Yes, 350 heads have larger combustion chambers, so it will drop your compression, but why are you even thinking of running TT's on stock cast pistons?
- note to all, if you want performance, stay away from swirl-port TBI junk. Less hp, less throttle response, and less mid-range performance.