TBIThrottle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.
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As I had said in another post I am thinking of doing a 350TPI swap into my firebird that currently has a 305TBI. I am new to the 3rd Gen F Body's and as I read posts on this forum I see that people are replacing the shortblocks on these 305TBI's with 350's and 383's. Can you use any of the older small blocks for that? And what about the heads, will the TBI intake and throttle body bolt up to aftermarket SBC heads?
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it will, but you would have to modify the inner 4 bolt holes for aftermarket or pre 1987 heads IIRC. I would ditch the intake for a dual plane with an adapter plate, the factory intake is junk.
Ok, that's cool about the block. I would be using a pretty strong motor. Isn't there aftermarket intakes and throttle body's for that motor? Can you explain more about modifying the 4 holes?
you can use just about any block IIRC, but I would go with a 87 and up block because they are all one peice rear main seal and will all have ports for knock sensors and all that jazz because there was no carb smallblock after 1986.
The center bolts on 87+ smallblocks with iron heads have a different bolt angle, 86 and earlier was 90* to the mating surface and 87 and up was 72* , why, I don't know, but you would have to grind down the ledge the bolt face sits on and re drill it to 90*. why don't you want to get and aftermarket intake, but you are looking at aftermarket heads, the intake sucks, and a new one is only $150-300 brand new, even less used.
I do want to get an aftermarket intake. I asked if there were alot of aftermarket intakes. So do the TBI motors have knock sensors then? Are internals different in the 87 and newer blocks then in the older small blocks? Do these motors also use a standard style distributor, like an HEI? I've built alot of SBC's and a few carbureted LS1's, so I'm pretty new to fuel injection builds.
Yeah, i think they pretty much all have KS. at least for the generation 1 blocks, I'm not too sure about the later style blocks. 87 and up should have a roller cam setup among other things. I've heard that you can use the big hat style dizzies that used to come on the 86' and back blocks(computer controlled, I think) but the gear needs to be changed to the one that is on the roller dizzy so it doesn't get all chewed up.
you can use any gen 1 smallblock intake, if you keep the swirl ports or any other 87+ iron heads, you'll have to get adapter bushings for the center boltholes, I would stay away from airgaps with a TBI motor, I also reccomend running a good dual plane manifold.
the crankshafts in the 87+ blocks have a 1 piece rear main seal and cannot be put into a older block, but the older cranks can be adapted to go into the newer blocks.
osirus brings up a good point about roller camshafts, most 87+ should have provisions for a factory roller cam, if you're going to use your original 305 block, it should be a roller cam, if your going to use a different block, check in the lifter valley for 3 raised bumps, the should be drilled and tapped , if the are then all the rest of the valvetrain parts off of your 305 can be transfered to the different block.
What I would really like to do is put in a well built 383(11:1, roller cam, good heads). That's my plan wether I go with TBI or TPI. I just figured that if you could build an old style motor and then put a performance TBI and intake on it, then I wouldn't have to change the wiring and it would be a somewhat basic swap. So you guys would recommend using an 87 and up block then for what I want to do? Is there alot of stroker kits and aftermarket heads and cams for the 87 and up blocks? And if I could get your opinion on this, for what I want to do, is there any real reason to switch to TPI?
it really depends on how you switch to TPI, if you go stealth ram, you could build a pretty hot motor, but it's much more expensive esp if you already have a TBI setup. I would never build a car with a TPI like the factory did unless it was going in a truck. also, I wouldn't run 11:1 compression. it gets out of pump gas terretory,
I know I'll be out of pump gas territory, that's no prob. I'm only going to drive it on Satuday nights and the occasional pass at the drag strip. So I can use a carbureted intake manifold for the TBI setup? Where can I get a throttle body unit that would support roughly 450 HP? Im trying not to be repetitive but it seems like everything has a slight technicality and I don't want to order parts that won't go together.
