Hey All, I'm very new to carburation and buick 350s. I recently bought a 1968 Buick GS 350. It has a stock intake manifold and stock carb. Car runs good with the carb but I'm really looking to switch it over to EFI. I can't get my hands on a TA perormance 350 intake manifold (which I would do up with direct port injection) so I've decided to use a stock manifold with a GM TBI just to get started. Will this work?? Will the carb for say a small block chevy fit on the small block buick? I just bought a OEM tank with baffles for EFI and an in take pump. Thanks!!! Bryan ---------- Post added at 11:42 PM ---------- Previous post was at 10:12 PM ---------- i think i may have solved my own problem. tbi to quadrajet adapter plate. $40 on ebay with gaskets. thanks, bryan
Like you just found, the only way to do that is to use that adapter. I have talked to quite a few people using them in TBI truck with no issues. Not sure what your goals are with that engine, but stock GM TBI isnt much for power, or ease of tune ability. I think you would be much better off with an aftermarket TBI system. Also you can get the TA manifold brand new for just a little over $300.00. According to most people the stock manifold with some work will be just as good however. Brandon
The stock GM TBI is not very well suited to swapping to a Buick 350... I have looked at these options and the best way to go is either converting a TA intake with bungs for Multi Port Fuel Injection or staying with a professionaly buiilt Buick 350 Q jet carb. Going to a TBI will not give you what you are looking for, it will cost a lot of money and there will be no pay off. The stock GM TBI system is not adjustable and requires custom "chips" to be burned to change the air/fuel metering. It may take 3 or 4 chips to get the tune even close to right and the chips cost $150 each normally. You can get a megasquirt computer to run the TB but again there is cost and lot of trial and error involved with little to no advantage over a carb... Going with a good quality MPFI system is great but when you factor in the intake cost, bungs, paying someone to weld bungs in, etc plus about $2000 for the EFI kit you are into it for a pretty serious amount of money... Bottom line is either do it right with high quality stuff or go with a well built Q jet.
Why not an aftermarket EFI? (Re: Stock Carb to GM TBI - Question) Dear Bryan and V-8 Buick EFI experts, I suppose I'm being naive somehow but did you consider one of the aftermarket EFI systems that are specifically designed to work with older engines like the Buick 350? The EZ-EFI system is fitted on my JW masterpiece engine. http://www.fuelairspark.com/fas/efi-systems/ez-efi-reg-self-tuning-fuel-injection There are a number of other systems out there as well. Yes, they are expensive but people have had good success with them. If you really would prefer a EFI system it might be better to save up and buy something that is proven than to spend a lot of time fiddling with a system that was never intended to work on a Buick engine. Cheers, Edouard :beer
Thanks for the replies!!! The end goal is direct port EFI on a 455 with a manifold that looks something like the attached photo: The car with the 455 is sitting at the moment waiting for restoration. Right now all I have is a 68 GS 350 and a 66 Olds 442 400 to work with. I could prove the concept with the OLDS but would have to do something different with the fuel pump as I don't want to buy a fuel tank I won't need. I'm going to use a megasquirt 3 pro ECU. I already have an OEM gas tank with baffles and an in take pump. I just want something I can use to flesh out all of the electronics without spending a fortune. The advantage of the TBI in my situation is the following: 1) I can prove the concept with a minimal added cost over my final configuration, lets say $250 for the TBI and wiring, $40 for the q-jet to TBI adapter plate 2) I don't have to take the intake off the car or spend an additional $400 for a TA intake and $500 to have bungs welded in 3) I don't have to pay an extra $300 for a different set of injectors, i've calculated the 455 is going to require 60/lb injectors and the 350 between 32-42 When I posted this I didn't know they had q-jet to TBI adapters -Bryan
PS: Another issue I'm going to run into is.... the final 455 will have forced induction. I'm going with a centrifugal vortech supercharger. Most of the aftermarket TBI "kits" dont have provisions for forced induction. they make it easy for a guy to get into EFI, but not run a solenoid to control boost on the wastegate. If Holley's atomic EFI had forced induction capability right now, I'd use that. Bryan
I don't know what your HP goals are but you do realize you are very injector limited with an O.E. TBI. Pretty much the biggest aftermarket GM TBI injectors are 95lb/hr, and I believe most stock GM 350 TBI's are around 65lb/hr. Quick math says 2x 95 = 190lb/hr of fuel potential, which is the equivalent to 23lb/hr multiport injectors, aka you come up way short on the fuel side with an O.E. TBI. Again, I don't know your HP goals, but where did you come up with your injector requirements being 60lb/hr for a 455 and 32-42 hr/lb for the 350? Sounds excessive IMO, as I run 44 lb/hr injectors in my 455 and well away from maxing them out. Though ~$300 for a set of 32lb/hr ones is about right and good for ~400 HP. I run a Holley 640cfm replacement TBI on my T-bird's 428 FE engine. The 640cfm throttle body has bigger throttle bores and required me to grind on the TBI adapter plate, and I have an open Q-jet to square bore adapter under it because the throttle blades did not clear the square bore opening, but did clear the Q-jet secondary bores.
It's either a Holley Avenger/Terminator TBI or an MSD Atomic. Here are some facts about any TBI; The factory GM stuff isn't made to be fiddled with, very small window. Because of design differences the fuel curve on a Buick 350, or 455 for that matter, isn't the same as a 454 or 350 Chevy. As mentioned you'll need multiple chip changes, good luck. All TBI's are just electronic carbs, subject to the same puddling and manifold issues as a carb. And most TBI systems don't control spark the way you really need to, especially on a boosted application. The MSD Atomic is a sealed unit, anything goes wrong and you have to send the whole TB in for repair, that's stupid. If you're hell bent on using a TBI in the interim then get something that'll work on both TBI and multiport, i.e. Accel, Holley or similar. And the original FAST EZ is being phased out for the new 2.0, which is almost twice as much, for a throttle body, can't figure that out either. But as with any Comp branded product, they'll tell you it's the best, even though it isn't. My .02 worth. Best of luck in your project.
