TBI swap question

[Ackattack]

I going to be swapping a TBI 350 into my 69 real soon here. I think I have a handle on most things.

My one undecided thought was about the exhaust system.

I can use the original 69 exhaust manifolds with the fairly new hooker dual exhaust system I have on the truck now. Its a little louder than I want, and I don't think its sealing real well at the manifolds. I'd also have to add a O2 bung, but that's not a real big deal.

The other option is to use the exhaust manifolds and exhaust system off of the 91 donor truck. The exhaust system appears to be relatively new and is much quieter. The cat has already been removed by the previous owner (probably when it was replaced). I would have to modify it a little since the donor truck is a LWB, and my 69 is a SWB, then I'd have to fit it up and around the trailing arms too. My one big concern with this option is the clutch linkage. My 69 has a 4speed, and the clutch linkage attaches to the engine block very close to where the TBI exhaust manifold collector is. Is this going to be an interference? Will it even work? Does the "newer" engine even have the mounting holes for the clutch linkage? I haven't checked, but I assume it does since it's still a genI sbc (but of course its a later roller engine...so maybe not).

I also like the design of the TBI manifolds since the since the spark plug wires don't have to run around and under the manifolds, but rather are on top of the manifolds.

[OJ1988]

You might want to check the block for clutch provision first. Some of the later models lacked these.

If it were me, I would stick with exhaust on the 69, seems like that would be easier than swapping the later model exhuast over.

Does your exhaust have an h pipe? If not they can mellow the sound a little bit.

[coop34]

Make sure to get the O2 bung welded in as close to the manifolds as possible. Mine was put in too far downstream and doesn't get hot enough to operate correctly.

[MARKDTN]

I think you will want to stay with the center dump manifolds. You could also use C4 (84-91 or 92-96) Corvette manifolds. They are center dump and true 2 1/2". I think the later TBI manifolds may interfere with something. At a minimum I doubt the whole system would just bolt into the earlier truck without some modification.

[coop34]

I tried 2 or 3 different stock manifolds including the donor 90 silverado manifolds. None of them fit. I ended up going with the original rams horns because I knew there wouldn't be any fitment issues with those.

[hugger6933]

My 68 has tbi truck manifolds on it but it is an auto. Coop, have you tired a heated o2? you can get one with three wires [hot ground and ecm feed] also on the roller a lot of tbi's were NOT roller engines. Infact I have not been into any or very few I can't remember. Most of the rollers came in 96 when the vortec haeds came out

[Ackattack]

Originally Posted by hugger6933

My 68 has tbi truck manifolds on it but it is an auto. Coop, have you tired a heated o2? you can get one with three wires [hot ground and ecm feed] also on the roller a lot of tbi's were NOT roller engines. Infact I have not been into any or very few I can't remember. Most of the rollers came in 96 when the vortec haeds came out

Oh, I thought all 88+ were roller engines

[coop34]

Hugger: Yes, I am going to fix my O2 situation with a heated one.

[sean1969c10]

Usually cars got the rollers and trucks were flat tappet. I know there are exceptions to these rules but this is the norm. I would guess the 69 truck center dump manifolds would flow much better than the TBI truck manifolds.