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**NEW** Can OEM TBI Feed a 400??? ** NEW**

Re: Can OEM TBI Feed a 400???

All of the major manufacturers I know of (to include pro-topline) use the fast burn combustion chamber.

Most of these heads should also be available in the "standard" intake bolt pattern, so there's no reason they wouldn't work for you. Vortecs are the ones that went to the goofy bolt pattern, short of the LS motors, etc.
 
Re: Can OEM TBI Feed a 400???

Geez-O-Pete, I think I'm just going to run a Quadrajet, this shite is getting too confusing /forums/images/graemlins/confused.gif
 
Re: Can OEM TBI Feed a 400???

I scrapped the TBI in my '88 after a few problems... I regretted it ever since. Now that I have my '89 I plan to stay w/ F/I (TBI or MPI) if at all possible.
 
Re: Can OEM TBI Feed a 400???

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Geez-O-Pete, I think I'm just going to run a Quadrajet, this shite is getting too confusing /forums/images/graemlins/confused.gif

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That is what I have. A modified edelbrock performer Q-jet on top of my mildly built 406 with the usuall intake, carb, cam ,compression, ignition, exhaust mods. My carbed setup runs very well and doesn't give me much issue but considering that my whole drivetrain has about an average of 10K on it...it shouldn't. I personally don't really like the early TBI setups and from what I have seen they don't run a whole lot better than a good Q-jet and are somewhat expensive to upgrade. I might one day go to fuel injection(if I don't buy an 04' D-max) but I won't bother with TBI and will consider a TPI setup or the edel. Multi port Pro Flo system. /forums/images/graemlins/thinking.gif
 
Re: Can OEM TBI Feed a 400???

Do you know what cam your running? And did you have to modify your tbi chip or is it still the stock one?

P.S. There is some smart dudes on here /forums/images/graemlins/bow.gif
 
Re: Can OEM TBI Feed a 400???

I agree with Dyeager, Pro-topline or Airflow reasearch , even Dart would be a much better deal than the Vortecs, they are really more hassle then good. The World products heads are good but not near the quality as the others out of the box!!! Side by side they are no comparison the casting are by far nicer built and much cleaner, Pro-topline is about equal with AFR but cost a little less. Considered by alot of machinists to be one of the best castings, better than Trick flow and many others by Far! /forums/images/graemlins/waytogo.gif
 
Re: Can OEM TBI Feed a 400???

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Do you know what cam your running? And did you have to modify your tbi chip or is it still the stock one?

P.S. There is some smart dudes on here /forums/images/graemlins/bow.gif

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If your asking me, I have a competition camshafts 268H cam. 454" lift in and out, 218 duration in and out. I am not running TBI, I'm running a modified edel. Q-jet.

As for the heads....I say vortecs on a mild motor running less than 450" lift. They are a good value vs. performance in my opinion and I have seen a lot of guys use them with good success. By far the best head out there is the AFR's... better than world, trick, topline, you name it.(IMHO)
 
Re: Can OEM TBI Feed a 400???

Your cam is probably too big for TBI anyway so it's probably a good idea you didn't try it.

That said, if you have ever been seriously off camber, no carburator compares to EFI. If you swap in TBI in search of more power you're probably not making the best decision compared to a q-jet, but there's no question that TBI will run better at angles.
 
Re: Can OEM TBI Feed a 400???

FYI

$500/pair pro toplines

From the picture though, I see the Vortec intake bolt pattern, which may mean they require the raised runner intake, even if you can request them in the "old" intake bolt pattern.

Still worth asking IMO. "Stock for stock" those heads have better components than Vortecs.
 
Re: Can OEM TBI Feed a 400???

[ QUOTE ]
Your cam is probably too big for TBI anyway so it's probably a good idea you didn't try it.

That said, if you have ever been seriously off camber, no carburator compares to EFI. If you swap in TBI in search of more power you're probably not making the best decision compared to a q-jet, but there's no question that TBI will run better at angles.

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Yeah, angles are a plus with TBI but from what I've seen the only benifets are angles, start up in cold weather, and altitude adjustment. AS far as power they don't seem all that better if any vs. a good Q-jet. I have better throttle response and top end "feed" then my buddies 87' tbi blazer. He has to let his crank over for 2 or 3 seconds before it fires up also...mine fires up in about 1 sec. I'm not saying that carbs are better or anything but performance wise I don't see much benifets with TBI.
 
Re: Can OEM TBI Feed a 400???

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Yeah, angles are a plus with TBI but from what I've seen the only benifets are angles, start up in cold weather, and altitude adjustment. AS far as power they don't seem all that better if any vs. a good Q-jet. I have better throttle response and top end "feed" then my buddies 87' tbi blazer. He has to let his crank over for 2 or 3 seconds before it fires up also...mine fires up in about 1 sec. I'm not saying that carbs are better or anything but performance wise I don't see much benifets with TBI.

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Agian, your truck only has 10k on the ticker... mine has over a 100k and starts up on the first try, except in the winter... then it starts on the 2nd try /forums/images/graemlins/dunno.gif

MPI is better though, but at 2k for a retrofit or 1k for the TBI to MPI updrage but with no additional CFM (on more real power) its a little steep. If i didn't have F/I and was building from scratch (no carb or intake), I would go w/ Edelbrock MPI kit.
 
Re: Can OEM TBI Feed a 400???

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I'm running a .040 over 400 with early 350 heads (non-vortec) and TBI. I'm using an Edelbrock performer intake, with a TBI adaptor plate from Summit, which conveniently has 2" bores, and a 454 TBI unit. I converted the pressure regulator so it is adjustable, and turned the pressure DOWN to about 8 psi. that gives me about 73lb/hr from the 454's 90lb/hr injectors (350 TBI injectors are 55lb/hr). The injectors still have a good spray pattern, and in closed loop the LTMs stay around 128. As said in one of the posts above, the issue is really at WOT (in power enrichment) when the O2 sensor signal isn't used for fueling. The big injectors and the adjustable regulator do the trick. I've got over 60K on this combo. I just wanted to throw in 2 more cents.

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This is interesting, I hadn't thought about reducing the pressure. I will be using a 454 TB and was told that I had to go with smaller injectors for use with a 350 or 406. Any other issues before I try this?
 
Re: Can OEM TBI Feed a 400???

-" no carburator compares to EFI." you are CORRECT!! the aid of having multiple sensors to take the place of an old mechanics "nose and ears" is too great to appreciate. Proper mixture at every point of the spread is something a Quad can never accomplish. The flexability, ability to tune and diagnose, along with the precision and efficiency an EFI system gives is "where its at"! If you dont believe, check this: 4.56s, 35x14.5s, 700R4, 383 long rod stroker, single TBI, AC(cold as h@ll), 9.60's in 1/8th mile, automatic tire smoking ability, and 17 miles per gallon!!! EFI is not to be affraid of, and it is not the wave of the future. It is NOW. I can remember my dad being pissed when they stopped selling leaded gas! He never thought vehicles would perform without it. They did it for a reason. The same reason you cant buy anything new with a carb except a lawnmower. Think about it...
 
Re: Can OEM TBI Feed a 400???

I'm definantly not saying EFI is junk and carbs are best because that is definantly not true. I just personally think TBI sucks.... I would rather spend my money(a little extra) to get a better system because there is a lot of other options out there for FI that work much better and are more "performance" friendly than TBI. I love FI myself and I think the new style sequential injection is the best like whats on the new vortec chevy motors. TBI is the easiest to convert to which is why that is the most common swap but to build a motor that is a high revving, high HP with more radical parts...TBI is the last system I would consider.
 
Re: Can OEM TBI Feed a 400???

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He has to let his crank over for 2 or 3 seconds before it fires up also...mine fires up in about 1 sec.

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Think about what you do before you hit the key when you have a carb. Typically the first thing you do is press the pedal once, which squirts gas down into the intake. Then it's ready to fire when you twist the key. All of my TBI engines will start with just a bump of the key, unless they're cold. Then I have to wait for the gas to reach the cylinders as it cranks over. It doesn't prefill the intake with those big squirters first like a carb does.

But hey, carbs are good things! I mean, they use the same technology as a toilet, so they can't be all bad. /forums/images/graemlins/wink.gif

BTW, don't think that TBI can't make some serious power. The stock TBI won't, but with the right mods it can stay right with a carb. Just as you wouldn't use a 600 CFM 4 barrel on a high revving race 350, you also shouldn't use the stock TBI setup. It just isn't designed for that purpose. There are plenty of aftermarket sources for TBI stuff that will make an engine scream. /forums/images/graemlins/cool.gif
 
Re: Can OEM TBI Feed a 400???

Mine usually fires up with a bump of the starter without touching the pedal at all. I have messed with 2 87' blazers and I wasn't impressed how they ran at all. I relize that you can make the TBI system supply a big motor but my question is why? Why spend all that money on chips and throttle bodies to make an old system put out more fuel when there are much better systems that can be had for just a little more cost? /forums/images/graemlins/dunno.gif
 
Re: Can OEM TBI Feed a 400???

I went with the 350 injectors / 350 TB first and it was too lean. I raised the fuel pressure but my pump maxed out about 16psi (probably could have replaced it but - oh well). Ok in closed loop, but too lean at startup and at WOT.

Then I got a deal on a 454 TB. I played around with the pressure and the base ign timing until I got it set where it ran well. I'm still using the stock PROM, it was easier (cheaper too) to do trial and error this way then trial and error chip burning, although the chip would give you more adjutment flexibility if someone will work with you on it. Cam is a mild RV for low end torque, base timing at 12deg.
 
Re: Can OEM TBI Feed a 400???

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Who are the aftermarket sources of TBI components?

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Two that come to mind are www.turbocity.com and Holley. /forums/images/graemlins/cool.gif
 
Re: Can OEM TBI Feed a 400???

Base timing at 12* /forums/images/graemlins/thinking.gif /forums/images/graemlins/thinking.gif /forums/images/graemlins/thinking.gif /forums/images/graemlins/thinking.gif

Do tell, my 'Burb pinged like a SOB at that setting....It did run good, but I took all of that out....
 
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