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Re: Who is atually using a GM 454 TBI unit on a SBC?
I put the 454 tbi conversation H.O injectors and H.O bearings with stage 2 hydraulic flat top cam cold air intake and a 1800 stall stage 2 shift kit and silinoids on my 350 vortec and it runs like a beast just don't know how much more hp it has changed the fuel pump out with a 96 and I was told it would make it stronger any information would be great
Re: Who is atually using a GM 454 TBI unit on a SBC?
Originally Posted by Bigacestroker
I put the 454 tbi conversation H.O injectors and H.O bearings with stage 2 hydraulic flat top cam cold air intake and a 1800 stall stage 2 shift kit and silinoids on my 350 vortec and it runs like a beast just don't know how much more hp it has changed the fuel pump out with a 96 and I was told it would make it stronger any information would be great
It's impolite to ask the same question multiple times.
Please use actual sentences, with punctuation and spacing and everything.
Re: Who is atually using a GM 454 TBI unit on a SBC?
Originally Posted by dctrumpet
So, a ton of pics for you to see.
It is actually an easy project to do. You will need to be able to tune your own chips and to be honest with you the only reason why you would want to add a 454 TBI or 305/350 TBI bored to 50mm is if you require more airflow and fuel to support more horsepower.
If your setup is a stock 305/350 there is NO need to add anything bigger to the top end.
If you are adding heads and cam then GO FOR IT!!!!
Don't waste your time/money on a modified 350TBI unit bored to 50mm. You can get a nice NEW 454 for the same price OR buy a used 454 base and have the shafts rebushed for less than a modified 305/350TBI.
Been doing this along time. If you're patient you can get what i said for less than $249 new and less than $200 used with shaft re-bushed.
There are guys who will disagree with me, but that is the great thing about this board. There are a lot of threads that you can read and make the best decision for YOU and YOUR application.
Good luck my friend and please keep us informed of your project and TAKE PICS!!!!!
Thanks
Sean
I know this is an old thread, but I do have one question:
What PROM chip specs did you used with this setup and what service/website you used for it?
I'm doing a very similar setup, but with a Holley 670 CFM throttle body.
Thank you!
Last edited by MazinkaiserPR; Aug 4, 2022 at 09:51 AM.
Re: Who is atually using a GM 454 TBI unit on a SBC?
Kinda depends on WHICH Holley 670 throttle body; and what other engine modifications have been installed.
Holley made a series of "stock replacement" "670" throttle body assemblies that supposedly drop right on a stock engine with no "tuning" required. There were multiple part numbers, specific to various standard engine combinations.
But if you're using a non-stock-replacement throttle body on a modified engine, you'll need computer tuning. I can't help with that.
Re: Who is atually using a GM 454 TBI unit on a SBC?
There are 2 things to running that Holley TBI. First is to ditch the trouble prone Holley injector pod and retrofit a stock GM one in its place. 2nd is move the MAP vacuum line from the rear port to the manifold vacuum port up front. The casting is poorly designed where the MAP fitting sits as it sits directly in the IAC passageway. On cold start when the IAC is open it gives the MAP a low vacuum signal and often sets a code 34 high map code and will run so rich it throws black smoke.
Re: Who is atually using a GM 454 TBI unit on a SBC?
Originally Posted by Schurkey
Kinda depends on WHICH Holley 670 throttle body; and what other engine modifications have been installed.
Holley made a series of "stock replacement" "670" throttle body assemblies that supposedly drop right on a stock engine with no "tuning" required. There were multiple part numbers, specific to various standard engine combinations.
But if you're using a non-stock-replacement throttle body on a modified engine, you'll need computer tuning. I can't help with that.
I'll be using a pair of 059 Vortec heads, a 94 Z28 LT1 cam and already have a 3 inch exhaust system with headers. Will get me a set of Comp Cam 1.6 rockers and a set of LS beehive springs.
Re: Who is atually using a GM 454 TBI unit on a SBC?
Originally Posted by Fast355
There are 2 things to running that Holley TBI. First is to ditch the trouble prone Holley injector pod and retrofit a stock GM one in its place.
Holley has two kinds of injectors in their throttle bodies, depending on when they were made.
I knew the first kind was troublesome. I thought the second-design worked well. The first design has a rubber cover on top of the injector, looks aerodynamic. The second (improved) design is more plain; just the molded-plastic connector as shown in the photos already posted.
First design:
Are you saying that the second-design injectors are still a problem, or is there something in the injector pod itself that's an issue?
I have one of these Holley "stock replacement" throttle bodies; but I've never installed it. On the "list of things to do" "someday".
Originally Posted by Fast355
2nd is move the MAP vacuum line from the rear port to the manifold vacuum port up front. The casting is poorly designed where the MAP fitting sits as it sits directly in the IAC passageway. On cold start when the IAC is open it gives the MAP a low vacuum signal and often sets a code 34 high map code and will run so rich it throws black smoke.
Re: Who is atually using a GM 454 TBI unit on a SBC?
Originally Posted by Schurkey
Holley has two kinds of injectors in their throttle bodies, depending on when they were made.
I knew the first kind was troublesome. I thought the second-design worked well. The first design has a rubber cover on top of the injector, looks aerodynamic. The second (improved) design is more plain; just the molded-plastic connector as shown in the photos already posted.
First design:
Are you saying that the second-design injectors are still a problem, or is there something in the injector pod itself that's an issue?
I have one of these Holley "stock replacement" throttle bodies; but I've never installed it. On the "list of things to do" "someday".
Thanks for that. Potentially very useful.
Neither design works all that well from Holley. The GM injectors are easier to tune since the injector data is already correct for them. The GM injectors are also more obtainable as are the regulator rebuild parts. 1,000 miles from home I want something I can find quickly off the shelf.
NONE of my EFI setups have one off failure parts with the exception of the 48 lb/hr spider on my Express van. I have not had a MFI injector failure on a Vortec though, but have had regulator trouble from it leaking. AUS spider uses a stock fuel meter rebuild kit and a stock GM regulator.
Re: Who is atually using a GM 454 TBI unit on a SBC?
Originally Posted by MazinkaiserPR
I'll be using a pair of 059 Vortec heads, a 94 Z28 LT1 cam and already have a 3 inch exhaust system with headers. Will get me a set of Comp Cam 1.6 rockers and a set of LS beehive springs.
Another 059 headed engine build. Interesting! On a 305 I presume? This fellow is planning something similar...
Re: Who is atually using a GM 454 TBI unit on a SBC?
I've always heard 50mm is a bit too much on a mild 350 much less a 305. I can without a doubt tell you a 46mm unit works great on a mild 350. My bored 46 mm unit sits on a bored out stock intake as well and easily revs 5300-5500rpms. Running 61lb injectors @ 16lbs of spring pressure. Engine is basicly a rebuilt L98. I strongly recommend Sean at SPR Performance he sells on EBay and is a member on this board goes by DC Trumpet. He built mine
Re: Who is atually using a GM 454 TBI unit on a SBC?
Originally Posted by dmccain
I've always heard 50mm is a bit too much on a mild 350 much less a 305. I can without a doubt tell you a 46mm unit works great on a mild 350. My bored 46 mm unit sits on a bored out stock intake as well and easily revs 5300-5500rpms. Running 61lb injectors @ 16lbs of spring pressure. Engine is basicly a rebuilt L98. I strongly recommend Sean at SPR Performance he sells on EBay and is a member on this board goes by DC Trumpet. He built mine
Don't know who said that one! GM used the 2" bore later 454 style with the 1/4" pod spacer even on factory 4.3L V6s along with the 305 and 350. All 3 had the 30 psi regulator and 46 lb/hr high pressure injectors flowing ~74 lb/hr.
Re: Who is atually using a GM 454 TBI unit on a SBC?
Originally Posted by dmccain
I've always heard 50mm is a bit too much on a mild 350 much less a 305. I can without a doubt tell you a 46mm unit works great on a mild 350. My bored 46 mm unit sits on a bored out stock intake as well and easily revs 5300-5500rpms. Running 61lb injectors @ 16lbs of spring pressure. Engine is basicly a rebuilt L98. I strongly recommend Sean at SPR Performance he sells on EBay and is a member on this board goes by DC Trumpet. He built mine
That theory was debunked by the folks of PowerNation:
Re: Who is atually using a GM 454 TBI unit on a SBC?
Since TBI does not rely on a venturi booster signal to pull fuel, there is zero torque loss from a larger throttle body and usually gains to be had even if you stood on the throttle at 1,000 rpm. The 46mm is enough airflow to feed ~400 hp on a decent intake. The stock one is good for ~320-330 hp. TBI experiences very little torque loss even on a single plane intake like a Torquer 2 or a 2bbl victor jr.
Re: Who is atually using a GM 454 TBI unit on a SBC?
Originally Posted by Fast355
There are 2 things to running that Holley TBI. First is to ditch the trouble prone Holley injector pod and retrofit a stock GM one in its place. 2nd is move the MAP vacuum line from the rear port to the manifold vacuum port up front. The casting is poorly designed where the MAP fitting sits as it sits directly in the IAC passageway. On cold start when the IAC is open it gives the MAP a low vacuum signal and often sets a code 34 high map code and will run so rich it throws black smoke.
It is amazing that Holley has done everything they could to give TBI a bad name. First the lousy injectors used on the first design. Then the lousy cheap body castings. Now the wrong MAP pickup location.
I've even seen Holley units on trucks in the JY and just walked on by. Wasn't worth pulling them off seeing the early style injectors.
