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1986 TPI 305 to 350 Swap

6K views 7 replies 3 participants last post by  Redlined 
#1 ·
Ok, so here is the deal. I would like to swap a hot modded 350 into my 1986 Trans Am. It currently has TPI with a 305. Motor is still good. The car only has 65k on it. But, as always, I want more power. My motor is your basic 4 bolt main 350, .30 over, hot cam (sorry, dont remember the specs, runs better on premium, by alot), Scat crank, stage 2 I Beam rods, Kieth Black flattop pistons, cast heads.

My question is this: Can I throw this motor (sans the Weiand manifold...) under my TPI? Will the computer adjust itself for me? Will the distributor work in this motor? I DO NOT have centerbolt valve covers on this stock motor in the car. And the angle appears to be the older style on the heads. I think I remember reading somewhere that they made TPI's in the early years that would bolt to any standard small block... Do I have this said settup?

Im not running a roller cam in my "hot" 350. Will that cause any issues? I know Ill have to remove my Pete Jackson gear to gear timing set. Probably throw a double roller in it... Is there anything else Ill need? I have pics of the motor if needed (both).
 
#2 ·
well id like to see pics....but just to look at them.Lol
 
#3 ·
Ok, so here is the deal. I would like to swap a hot modded 350 into my 1986 Trans Am. It currently has TPI with a 305. Motor is still good. The car only has 65k on it. But, as always, I want more power. My motor is your basic 4 bolt main 350, .30 over, hot cam (sorry, dont remember the specs, runs better on premium, by alot), Scat crank, stage 2 I Beam rods, Kieth Black flattop pistons, cast heads.

My question is this: Can I throw this motor (sans the Weiand manifold...) under my TPI?
Yes
Will the computer adjust itself for me?
Not really. The only "adjustment" it will do is either pull back timing or leave timing alone based on if it "hears" detonation.
Will the distributor work in this motor?
Yes
I DO NOT have centerbolt valve covers on this stock motor in the car. And the angle appears to be the older style on the heads. I think I remember reading somewhere that they made TPI's in the early years that would bolt to any standard small block... Do I have this said settup?
You have a pre-87 TPI car. It should bolt right up.

Im not running a roller cam in my "hot" 350. Will that cause any issues?
No
I know Ill have to remove my Pete Jackson gear to gear timing set. Probably throw a double roller in it...
Why? You could still run the gear drive.
Is there anything else Ill need? I have pics of the motor if needed (both).
Basically you are simply going to be swapping long-blocks under your TPI manifold. It is plug and play and it should fire right up. I would strongly suggest getting an adjustable fuel pressure regulator, and crank that puppy up. I would imagine that the car will run lean if you leave the setup exactly as it was for the 305. I would contact Alvin from pcmforless.com and tell him what you are up to. He can burn you a new chip. Tell him stock 305TPI injectors feeding 350 cubes with a hotter cam. Make him de-sensitise the knock sensor, adjust the fan turn-on temps, etc... He will hook you up. You are going to want to gut your catalytic converter too. That tiny 305 exhaust is now going to have a hot 350 in there, and you don't want it to be chocked up on initial startup.
 
#4 ·
Perfect! Thank you Joelster. From what I understand, the gear to gear will mess with the knock sensor and cause the timing to be messed up or the pcm to shut the motor down. I dont know much about it, just what I heard. Fortunately, where I live, I have no need to worry about IMing my car. So the Cat's were gone right when I got it. And its running stock 3inch piping. So, that should be ok to start with.

Another thing I would like to do away with is the AIR system. Ive read that I should be able to ditch it with zero issues. Any ideas? I want a stripped down, yet badass version of TPI. Im not looking to make 600 hp or anything (yet, lol), so Id like to keep the TPI as long as possible. I am very pleased to hear that my motor will bolt right up underneith my TPI. That rocks.

Once I get started with the wrenching, I will get ahold of Alvin. That way its in the mail and here by the time Im done swapping. Also, I am going to go to headers. Ive been curious about Edelbrock's new TiTec Shortys. Any word on em? Otherwise Ill go with some good ol Hookers. From what I understand, Ill need to go with shortys, since full lengths wont fit, or some jibber jabber.

Once I get there, Ill start a thread and add all the tech tips I have recieved. Thank you for your help, i really appreciate.
 
#5 ·
Perfect! Thank you Joelster. From what I understand, the gear to gear will mess with the knock sensor and cause the timing to be messed up or the pcm to shut the motor down. I dont know much about it, just what I heard. Fortunately, where I live, I have no need to worry about IMing my car. So the Cat's were gone right when I got it. And its running stock 3inch piping. So, that should be ok to start with.
The pcm won't shut the motor down because of noise, but it may pull timing out. I have never heard of a gear drive causing this, but honestly, not many people run them with EFI motors so who knows. Roller rockers are notorious for causing "false knock" though. There is a way to de-sensitise the knock sensor with a resistor, but I don't remember what the resistance is off-hand. Alvin can just program it out for you when he burns you a chip.

Another thing I would like to do away with is the AIR system. Ive read that I should be able to ditch it with zero issues. Any ideas? I want a stripped down, yet badass version of TPI. Im not looking to make 600 hp or anything (yet, lol), so Id like to keep the TPI as long as possible. I am very pleased to hear that my motor will bolt right up underneith my TPI. That rocks.
Ditch the AIR.

Once I get started with the wrenching, I will get ahold of Alvin. That way its in the mail and here by the time Im done swapping. Also, I am going to go to headers. Ive been curious about Edelbrock's new TiTec Shortys. Any word on em? Otherwise Ill go with some good ol Hookers. From what I understand, Ill need to go with shortys, since full lengths wont fit, or some jibber jabber.

Once I get there, Ill start a thread and add all the tech tips I have recieved. Thank you for your help, i really appreciate.
I am sure that there are full lengths that will fit, but then you'll need a different cat-back system. I know several guys with nasty small-blocks in 3rd gens and they all run long-tubes. For the money running long-tubes should be a no-brainer.

Keep in mind that a TPI induction system is done at about 5200rpm. It simply won't flow enough air to satisfy a motor that wants to spin higher than that. If you have a nasty cam that peaks above that, the performance will be compromised.
 
#6 ·
Thank you for the information. That will be more than enough to get me started. Ill be on the lookout for good ceramicoated longtubes. That is the way Id rather go. I was just under the impression that I wouldnt have any room for em. So that is a plus to know that I can. I think, just to avoid problems, Im going to just throw in a double roller timing set. No reason to make it more difficult than it needs to be...
 
#7 ·
There is a dirt cheap way to disable the knock sensor. I will describe how you do it for a 4th gen LT1 car. You go to your local Radio Shack and you buy a 3900ohm resistor, they usually come in packs of ten for like 2 or 3 bucks. You find the wire leading to the knock sensor, and you cut it. Then you run the wire into one end of the 3900ohm resistor, and the other end you connect to a ground. When you turn the key on the PCM will see 3900ohms of resistance from the knock sensor wire and assume that it is functioning perfectly and not hearing any knock. That is the resistance that a 4th gen LT1 knock sensor has during key-on operation with no knock detected. Once it "hears" knock the resistance changes, and the PCM adjusts the timing accordingly.

I don't remember what the resistance is for a 3rd gen 305TPI car though, or what wire to snip. I'll try to dig for it. That way you could keep the gear drive with no worries.
 
#8 ·
Cool man, I appreciate it. Oh, and I wont need any cat back system, since I dont have IM to worry about. I ditched that a long time ago...
 
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