Hi, I have a 1990 Trans Am with a 5.0 TPI automatic and was looking to get a little more from it. I've read some articles about certain upgrades and several pointed me towards new runners, intake manifold, camshafts, and littler things like plug wires, airfoil, and distibutor caps and rotors. When installing large bore runners, such as the ones from TPIS, what all else must be done to the intake, or can you upgrade the runners by themselves? Is installing an intake manifold a huge deal or can it be managed by someone who has somewhat of an idea of what he's doing over a week or so of work? And lastly, what all is involved to change camshafts?
Responses would be greatly appreciated, Thanks!

 

Do some searching around a little on the subject, someone just posted a really good response (i think it was this board) about doing a cam swap. Make sure you consider as well a full exhaust (headers and cat back) a cold air intake, 1.6RR do 3.73's or 3.42's in the rear since its an automatic, SFC's and maybe some other suspension mods, doing the exhaust and CAI is probably a good place to start, then gears and see what your at.

 

i was gonna keep my 305 but i'm not gonna waste my time,just gonan swap in a 350. may want to look into that. but if not look into basic bolt ons

 

I read something about installing 1.6 rocker arms that you also have to machine something on the heads to make it fit. Is that true? And is there a big difference between 1.5 and 1.6 ?

 

yeah you get mor lift with the 1.6 and if they are roller theres less friction so u get some gains there

 

they say on a stock L98, 1.6 rockers are worth 15hp over 1.5's stockers. reduced friction of the aftermarket roller rockers with extra lift provided by the increased ratio are what gives you the performance boost.

for a auto TPI 305...

what ur gonna want to do is look into a bigger cam than that peanut cam. something not too big since you still have stock heads. combined that cam with some TPI bolt ons, like base and runners. you gonna wanna match the runners to the base opening, and match the top of the runners to the plenum. that makes air flow transistion good. then add some tunning work.. adjustable fuel pressure regulator would help alot to get a rough tune. depends on how big the cam is.. but you dont need anything radical to get decent performance

get good exhaust system... headers back

then look to add some good gears.. 3.23-3.42's for sure. then get a good torque converter... 2800stall is nice, thats what i'm runnin on my 350.

those mods alone will wake that car up. gears and converter will net your biggest gains

 

gears on my 305TPI auto lowered my 1/4 mile time by half a second and increased my mph by 3.
15.7 @ 86 with the Auto and 3.23 gears
15.2 @ 89 with the Auto and 3.73 gears

I put a 5 speed and 4.10 gears with a Holley Stealth Ram and the ET stayed the same but MPH went up to 91.5mph.
The HSR took away some torque from my 305, which I felt right away.
heads and cam should wake up the 305, but imho, it's not worth putting money into a 305 when you can pick up a 350 for a couple of hundred dollars.

I put the HSR on my 305 since I had it in the garage and I'll be going with a 350 or 400 sometime this year.

 

I'd start with some gears. Just finished putting the 3.42's in my 91 formula 305 and there is a day and night difference. Going to the track next week to see how well they worked out but I'm hoping for high 14's. Ran a 15.5 before the gear swap.

 

The first mod I'd do would be headers and exhaust . I went from 14.8 bone stock to 14.2's. Intake mods didn't do much with the stock heads and cam.

 

Ok, from what I've gathered, gears and headres w/ exhaust sound like a good place to start. I got a quote from Jet Hot for the Hooker 2055 headres for $725, but money is kinda nonexistent for me right now so im going to have to hold off on that. But what about gears? Which brand ? How much? For mild performance what would be the best choice? And most importantly, how hard of an install?

Thanks.

 

Rear diff. work requires a little experience or patience. I would use a 3.42 gear if you plan on keeping it on the road in highway situations so youre not screaming down the interstate in the rpms at 80mph. If this is going to stay at the track and around town only, then 3.73s should be alright.

 

see the sig for more ideas.

 

I dont hate on the 305, unless your going to rebuild it :-) than go 350:-)

If u have one in good shape heres what I recommend.

Its pretty much the same as everyone else.

Cars that dont have the good 3:23 or 3:27 from the factory should get to that at a minimum. 3:42 or 3:73 is okay too(3:73 if u ever swap to 350 might end up hurting ya depends on the whole combo)

Get that done.

Go with a quality shift kit like Trans GO.

Do an exhaust. Get some headers/catback, even before u do the intake side on a 305.

For a cheapie mod with results, port your own base and plenum yourself, I would think you will see a lot more bang for your buck there, than to spend $400 on a aftermarket base(again talking 305)

Runners and the like, hit the classifieds.

The biggest bang for the buck would prolly be learning to do yourown tuning.

Many of us have picked up 2-3 mph and a couple to half a sec. in the qrtr with it. We have a great DIY PROM board here.

later
Jeremy

 

PM Don 88. His 305 had to be a low 14 sec car with stock manifolds and peanut cam. I think he had all of the bolt ons with a stock prom and advanced timing. I bet with a converter,headers and tuning it would have run 13s easily.

 

Thanks alot for the posts. Helped me out a bunch!

 

see sig also

 

Do all the mods you can without doing anything to the 305 itself. Make sure all the parts you use will work for a larger motor so if and when you decide to put a 350,383, or so on in your car, you won't have wasted any money on the small motor. So basically exaust, intake, pulley, gears..... and so on

 

I have to agree with some of what has been suggested. The best bang for your buck you are going to get starting from a stock motor will be exhaust. A good set of headers (I had good experience with the edelbrocks), a high flow converter and a 3" cat-back system will help a ton, and can be done for under $800. Most of the aftermarket TPI parts, at least in my past experience, are intended mostly for 350 motors or highly tricked-out 305s. The TPI intake system GM engineered was pretty effective, especially for the 305s since the identical intake is used for 350s, including the Vettes. Where most of the restriction comes in on the exhaust side.

If you do decide to go with the intake side, I would get a base and runners together, you have to take the whole damn thing appart anyway, might as well replace them both at once! The other option would be new heads, but on a stock motor, you really need more aftermarket parts to take full advantage of spending $1000+ on decent heads.