305TBI to 350TBI

[TWISTER]

I have done some reading and wondered who has done this in a build thread and what is needed. I was planning on a vortec swap w a cam like suggested by Harris Performance but there sure seems to be a lot of money that needs to be spent on the TBI system to get it to work with a Vortec 5.7. Anybody have a recommendation on this that has done it? Mine is a 87 w a weak 305 in it.

 

[bucket]

A stock tbi 350 swaps right in.

I can't help you with the vortecs and tbi, the little bit of info I got about it scared me away. I decided to go with a 454 instead.

 

[87ChevyR10]

The TBI's chevy provided require a certain amount of vacuum to operate properly. When upgrading engine components that directly effect the vacuum (IE camshaft), the ECM will need to be reflashed as well. On top of that, you will want to upgrade the TBI to have better throttle response and allow more air in. I seriously considered doing the same to my 5.7 TBI; but, found the cost to benefit ratio to be less than desirable. You might consider using a carb instead. That way, vacuum doesn't hinder intake performance. In fact, you will spend less money switching to a carb setup than trying to retain the TBI and the carb will give you better options for performance.

There are cams out there that can be swapped in w/o needing to flash the ECM; however, I doubt the benefits are much better than stock cam.

Good luck with whatever you decide to do.

 

[TWISTER]

Thanks for all the help. So far I was planning on some of the recommendations from Harris Performance on a Summit crate vortec, carb intake and throttle body spacer, 350 injectors and so on. From what I have come up with it looks like I will have more money in the top end of the engine than the engine itself to retain the TBI. There has to be a better solution than spending $2000 on intake TB chip and supporting mods... is the carb the best one? I have a 84 1/2 ton that has been doing well for years with a 355 Quadrajet in it and thought making the TBI work was the best idea.. maybe not?

 

[farmerchris]

If you was going spend that kind of money,the aftermarket efi,Fast,Holley,Eldebrock and etc are about that price and support performance cams and modification, allow all the benefits of efi

 

[TWISTER]

It looks to me the best bang for the buck idea on this would be a crate vortec 5.7 w carb intake and carb. I cant see spending all the time and money to get the TBI to work right and the carb seems to be the best idea for me.

 

[GreaseDog]

My 94 has an L31 crate engine in it., fed by a modified stock throttle body. Performer RPM intake, adjustable fuel pressure regulator. It does require PCM tuning, but it's all worth it. So much more power than a stock L03 or L05.

 

[GreaseDog]

Twister, which crate engine are you looking at.

 

[TWISTER]

http://www.jegs.com/i/GM+Performance/809/12530283/10002/-1

I plan on a cam upgrade before I put this in.

 

[Jims86]

It looks to me the best bang for the buck idea on this would be a crate vortec 5.7 w carb intake and carb. I cant see spending all the time and money to get the TBI to work right and the carb seems to be the best idea for me.

The Aftermarket EFI systems, like Holley, and FAST will self tune for mods, an OEM system wont. I replied to your pM, i dont show up here much anymore. If Carb is what you really want, go for it, but take my air cleaner recommendation into consideration...very important when operating in cold climates, especially with a vortec, where you have no exhaust crossover in the manifold to heat things up. EFI Dry Manifold is Always superior, and in the long run is alot less headaches as far as cold driveability, especially with the Holley Avenger EFI Multiport.

 

[1911fool]

There is a system available from Dynamic EfIs Called the EBL. What he does is take the factory ECMs and modifies them to where they are flashable. No more chips. You can tune them yourself. It also has a learn mode to where it will "fix itself". I have used it on my son's 454SS when we changed cam, heads and intake and kept the TBI. I tried to use chips and it just wouldn't run right. When I used the EBL it was night and day difference.
I have friend who has a TBI '87 with a radical cam, aluminum heads, intake, headers, MSD, flat tops. He tried chips and it wouldn't run right either. We put the EBL on it and I was able to get it running right.

It is really inexpensive when compared to the other aftermarket stuff. My system was $465. with cables.

I used a NB O2, but you can also tune with a WB and it is better. You can turn off the EGR circuit and actually use it as a NOS controller if you want. It has so much more than the factory system.

In these factory ECMs there is a "Lean Cruise" mode. GM turned this off (something to do with emissions). What it does is when the motor is cruising without load it will advance the spark and lean the fuel. It really helps with gas mileage. The EBL turns this back on. On the SS we got 14.8 mpg at 70-75 mph. This was a big block with a TH400 and 3.73 gears turning 3000 rpm.


From now on when I convert on to FI or do changes to an FI motor I'll use the EBL. I'm sold on it.

 

[MadOgre]

Wouldn't a crate tunnel ram 350 from GM be about the same as all this fancy FAST TBI and new block stuff.

Don't know what there charging you guys down there but I looked into the FAST system this last winter and it was about $2800 all said and done. That's just for an intake and fuel delivery. No heads or cam or block!

If your gonna go with a carb then it doesn't really matter what generation block and heads you use except for power combinations.

I thought you could get a tunnel ram 350 for under $5000? I haven't actually checked lately. maybe im wrong.

 

[bucket]

Oh, you mean the RamJet 350? Yeah I think it's somewhere around 5-6K.

 

[MadOgre]

Oops LOL my brain farted again Andy. Yep I meant Ram Jet.

Never heard a bad thing about them, and they have infinite power curve tuning ability.

 

[Driver4r]

I thought you could get a tunnel ram 350 for under $5000? I haven't actually checked lately. maybe im wrong.

You must be registered for see images attach

lil more than 5k