For all you die hard chevy guys... need some advice please! - Tilted Forum Project Discussion Community

KrazyKracka · 07-06-2006, 07:07 AM

Ok I recently picked up a 1985 Trans Am, and it's in very good condition, but I'm changing out the original 305ci V8 for a 350ci V8. I'm curious as to what kind of camshaft I should run in the vehicle. Is there a cam out there that will give me around 300-320 Rear wheel HP and still work properly with the factory Tuned Port Injection? The engine I have here has been completely overhauled, and it runs cylinder heads with approximately 165CC intake runners, and 58CC combustion chamber size, netting me somewhere in the area of 9.7-10.0:1 compression ratio. I was looking at a camshaft with a duration of about 224/234 degrees duration, and .465"/.488" lift, intake/exhaust respectively, but I fear that the loss of vacuum will not bode well with the ECM. I really really really do not want to switch to a carburetor. Sooooo, if anyone could give me some advice, I would appreciate it. Thanks!

Scorps · 07-06-2006, 04:27 PM

I'm a carb guy so I have idea how different cams will react with a TPI...Carbs can be better if tuned right

KrazyKracka · 07-06-2006, 05:29 PM

Can't switch to carb here, due to emissions regulations. I have to keep all my smog equipment as well. It makes everything a pain!

BigTruck1956 · 07-06-2006, 05:34 PM

You would probably be fine with a duration that high. You would probably won't notice any vacuum issues, although you might want to look into getting a camshaft with a ecm chip designed for it, or maybe just a performance chip designed for a higher duration cam. Is it auto or standard? Your specified duration is nearing the point where your stock torque converter will not work properly. What are you setting the car up for? If its a daily driver then i dont know if you want to put that hot of a cam into it. You're basically moving the power band to 3000-6500 rpm. If you think youre going to spend the majority of your driving within that range, then go for it. Otherwise I would step down on the cam a little and try to squeeze power from somewhere else, like the heads for example.
On a side note, my buddy did this conversion on his non-trans am carbureated firebird. He just put in a factory GM stock crate 350, and the difference was very noticible.
good luck.

edit: just read your new post. With a duration that high, you definately will not pass an emissions test...

KrazyKracka · 07-07-2006, 04:41 AM

The car is an automatic, but I do have a 2400RPM stall torque converter for it, lockup variety to work with the overdrive transmission. The car will be driven daily, or nice days, and see occasional drag strip use, so I guess I need to keep the powerband where it is from the factory, which is 1500-4500 RPM. What can I do to make some horses there?

My 'emissions' test, isn't a sniffer, so that doesn't matter. What DOES matter is that the catalytic converter and all factory smog equipment are still on the vehicle, and have to function properly. That's all.

07-06-2006, 07:07 AM	#1 (permalink)
KrazyKracka Crazy Location: PA	For all you die hard chevy guys... need some advice please! Ok I recently picked up a 1985 Trans Am, and it's in very good condition, but I'm changing out the original 305ci V8 for a 350ci V8. I'm curious as to what kind of camshaft I should run in the vehicle. Is there a cam out there that will give me around 300-320 Rear wheel HP and still work properly with the factory Tuned Port Injection? The engine I have here has been completely overhauled, and it runs cylinder heads with approximately 165CC intake runners, and 58CC combustion chamber size, netting me somewhere in the area of 9.7-10.0:1 compression ratio. I was looking at a camshaft with a duration of about 224/234 degrees duration, and .465"/.488" lift, intake/exhaust respectively, but I fear that the loss of vacuum will not bode well with the ECM. I really really really do not want to switch to a carburetor. Sooooo, if anyone could give me some advice, I would appreciate it. Thanks!

07-06-2006, 04:27 PM	#2 (permalink)
Scorps Lost!! Location: Kingston, Ontario	I'm a carb guy so I have idea how different cams will react with a TPI...Carbs can be better if tuned right __________________ A.K.A. PainTrain

07-06-2006, 05:34 PM	#4 (permalink)
BigTruck1956 Psycho Location: norcal	You would probably be fine with a duration that high. You would probably won't notice any vacuum issues, although you might want to look into getting a camshaft with a ecm chip designed for it, or maybe just a performance chip designed for a higher duration cam. Is it auto or standard? Your specified duration is nearing the point where your stock torque converter will not work properly. What are you setting the car up for? If its a daily driver then i dont know if you want to put that hot of a cam into it. You're basically moving the power band to 3000-6500 rpm. If you think youre going to spend the majority of your driving within that range, then go for it. Otherwise I would step down on the cam a little and try to squeeze power from somewhere else, like the heads for example. On a side note, my buddy did this conversion on his non-trans am carbureated firebird. He just put in a factory GM stock crate 350, and the difference was very noticible. good luck. edit: just read your new post. With a duration that high, you definately will not pass an emissions test... __________________ so much to do, so little time.....at least i aint bored. Last edited by BigTruck1956; 07-06-2006 at 05:36 PM..

07-07-2006, 04:41 AM	#5 (permalink)
KrazyKracka Crazy Location: PA	The car is an automatic, but I do have a 2400RPM stall torque converter for it, lockup variety to work with the overdrive transmission. The car will be driven daily, or nice days, and see occasional drag strip use, so I guess I need to keep the powerband where it is from the factory, which is 1500-4500 RPM. What can I do to make some horses there? My 'emissions' test, isn't a sniffer, so that doesn't matter. What DOES matter is that the catalytic converter and all factory smog equipment are still on the vehicle, and have to function properly. That's all. Last edited by KrazyKracka; 07-07-2006 at 04:44 AM.. Reason: Automerged Doublepost

07-06-2006, 05:29 PM	#3 (permalink)
KrazyKracka Crazy Location: PA	Can't switch to carb here, due to emissions regulations. I have to keep all my smog equipment as well. It makes everything a pain!