Hi! First time poster.

So I have an 88 Formula with the 190 hp TPI 305. Despite all the good reasons for keeping the 305 setup with TPI, I would like to convert to carburetor. I have a complete 1984 ram air assembly from the air cleaner up to the hood flap and grate.

My question is: Will an 84 305 intake manifold match up to an 88 305? And for that matter, would it match up to a LT1/LT4 block/heads? An LS motor?

Thanks for your thoughts!

 

84 sbc intake will need the center 4 bolt holes elongated to match the different bolt angles in the 1988 heads. They changed in 1987.
Lt1, lt4 as in a gen2 sbc? No, every intake to head bolt is in a different place than a gen1. Gen5? Nope extra completely different.
lsx gen3/4, nope, nothing is the same.
I'm not sure what you're thinking of doing other than taking a 84 intake and carb and putting it on a 88. That's the only plausible way to use the 84 air induction setup.

 

Thanks for your thoughts Aliceempire! I am probably one of the less skilled forum members. Although in my high school years (a million years ago) I successfully single handedly swapped the intake manifold, heads and oil sump from a blown 455 stage 1 to a donor 455 block.

I am not looking to impress anyone on the track with my formula. I would like to eventually have in the ballpark of 300 hp to liven up weekend tooling around. In my case a large part of the joy of owning the formula would come from the auditory experience. I am admittedly old school. The two things I miss the most are 1) the burble of true dual exhaust (the lower the better) and 2) the moan of a carburetor sucking air when its pedal to the metal.

I have read over and over that the 305 is not the best path toward hp. The LS series sounds like a great payoff in hp and decent mpg. Seems like the prudent thing to do is convert my 305 to carb and see how that goes - possibly improve the exhaust system too. Try to enjoy it like that for awhile before jumping in too deep.

The only problem with this plan is whether it would ever be able to upgrade without giving up the functional cowl induction. From what I read the LS is over an inch shorter than the sbc. Are there aftermarket intake manifolds that could account for the difference in height? Adapter plates that could mount a carb a little higher? Special engine mounts?

 

If all you want is 300hp then building a 350 or even the 305 up to that is no problem. WAY cheaper and more straightforward than an LS swap.

 

As stated just above this, an lsx swap isn't needed for 300hp. If you're going carb then the 'gas mileage' aspect of a ls goes away. So does the easy start and drivablity typically noted on street ls builds. Not that a carb is all bad but my thinking is, why take modern tech and dumb it down.

You want 300hp and use of the cowl induction (barring any conversation on whether or not that cowl adds any gogo juice), well that's easy enough with a sbc 350 and a quadrajet. The air intake is easiest to reuse going on the application was originally from, so a qjet and a similar height manifold to the 305s original. GOOD exhaust, decent heads, relatively small cam, properly set up and tuned will grant you what you want. Doable with a 305 too but a bit more effort, more money and still less torque. Mostly ez pz.

 

Also the 1984 Carburetor (Rochester Quadra-Jet) will not mate/ fit to the 1988 TBI (Throttle-Body Injection) Intake-manifold.

There were no Carburetors being used in 1988... so no Four-Barrel Spead-Bore Carburetor Intake-Manifolds either.
The TBI Intake-Manifold is designed similarly to a Two-Barrel Carburetor Intake-Manifold.
No way these two (1984 and 1988 Designs) are going to fit together.

Also as already mentioned, the Intake-Manifold Bolt-Angle is different for the 4 center-most Bolts (between 1984 and 1988).

 

I also agree that keeping a Gen-I SBC (305 or 350), would be the better route to take for only 300 HP.


It is far less expensive, less time consuming, and requires far less Parts changes.

 

Really appreciate the input! I plan to keep this car until I drop dead - hopefully of natural causes. It is my reward for 2-3 decades of driving boring daily drivers and concentrating on raising a family. The 305 certainly beats a minivan - but it is not enough power to be my dream car. I am honestly not sure how much torque/hp I would need. I once had a 1970 Buick 455 GS Stage 1 and that car accelerated, handled and stopped effortlessly. This WS6 is the first car I have had that handles curves as effortlessly as the Stage 1.

Anyway, I am certainly not opposed to more power. This car is meant to be a keeper and just a joy rider. It will be off the road from Veterans day to Mothers day so that it will never see salt.

I have an engine hoist and I have used it before. As far as what I can do myself a sbc swap is probably more realistic than a ls (thanks for that advice). I would like to keep the 700r4 tranny and perhsps put a shift kit in.

After considering all the recommendations, I am thinking that the ultimate engine to swap in, while preserving needef clearance for the factory cowl induction system would be a sbc 400. I like the idea of a 400 (sort of a nod to the earlier completely different Pontiac 400s) and more torque out of the box. Sounds like a 2 bolt main block or a DART aftermarket block would be the way to go to try to avoid a short lived motor.

From what I have read in the forums a beefed up 700r4 should be able to handle 400 to 500 hp alright. If you were going to spend a couple of years combing Craigslist and auro salvage yards for parts, what would you get? I could find a 2 bolt main 400 from somewhere eventually. If I swapped the heads for 305 HO heads and found a 83/84 305 carb intake everything should fit and the ram air setup should align. Have no idea what hp a 400 setup like that would make though.

If there is a way to cobble used parts together with a new cam and headers/dual exhaust, have the factory cowl induction still seat properly and make 400+ hp I am all in. That would be a dream car! At least it would for.me. MPG is a consideration, but a secondary one.

 

You could find a 400sbc with some luck but I wouldn't. Finding a virgin good one is super hard. Almost everything that wasn't crushed into a cube has been manhandled and probably .060 over now. The castings weren't very good back then either, poor quality control. If I NEEDED to have 400 cubes in a sbc, I'd get a dart block, but price is a killer for something unnecessary. Everything you're looking to do can be done with a easily available roller cam 350(they made pontiac 350s too if the nod helps)
Even If you found a good 70 vintage 400, DO NOT use the 305 heads. Chambers are way too small and other than vortecs, iron heads are very poor by todays standards. The cost to rebuild doesn't beat the cost to buy good new aluminum that flow better.
I'm not going to talk you out of the cowl induction setup but it's limiting higher power output simply by limiting your intake manifold height. And while the air certainly does flow in from there (I've had one, leaves used to get sucked to the grill all the time) it's probably not gaining anything significant that a better intake wouldn't crush. What I'm saying is, for 300 hp, it's cool and fun. For 400 hp it's a restriction.
Whatever you come up with while you're drafting up your plans, think about this...fast, reliable or cheap. Pick 2 because you can't have all 3.

 

A reman Vortec 350 with an Alex Spring kit, cam in the 220-228 range, headers + 3in exhaust will make well over 300hp and maybe over 350 if you get your fueling right. Like mentioned before, a newer 350 roller engine is a much better choice than an old flat tappet style 400sbc for lots of reasons. I actually sold my standard 400 block and went with a roller 350 myself on the last engine I built.

 

A refreshed stock Vortec 350 with a Performer (Not a Performer-RPM) Air-Gap Intake-Manifold with a Carburetor, and 1 5/8" Headman Headers will produce 300 HP.

 

Thanks for the support! Everything I could have asked for and more. Got some great solutions and am on the right track. Much appreciated!

 

The '88 Formula never had a functional cowl induction. That bulge in the hood was strictly cosmetic. So for the '82-'84 Trans Am cowl induction, you'll have to modify it to make it work. I'm doing the same thing on my '83 Firebird. The plan is to rig up a wide-open throttle switch to trigger a relay for powering the flap solenoid...

 

I think he knows and has the parts he needs. Clearly he'd either pin the flap open or make a setup for the flap to function.