In reply to Stefan:
Interesting. I too have been planning on going FiTech eventually - although I'm an MS fan and appreciate the large support community, I really want something closer to a plug-n-play solution. Yes, I realize any non-OE FI system will require custom tuning to optimize it, but out-of-the box the FiTech should still work better on an SBC than a carb.
I've always been under the impression that GM TBI was junk though. Are the TBI/injectors ok for performance use with a better ECU?
In reply to Pete Gossett:
Well, if you're working with a 305 or a mild 350, then I'd suspect the 454 TBI could be adapted and provide enough airflow to match a carb and provide the performance you need. The SBC TBI is 42mm and the 454 is 50mm. General rule of thumb is 1HP per Cubic Inch, so 375-400 for the SBC and 450 for the BBC with the throttle plates and bores expanded to 46/54mm via machining.
This series of articles should help with converting from Carb to TBI, etc.
Here's another site with more GM TBI info and how to improve performance:
I messed with TBI's back in the mid to late 90's. Not a huge fan really. I think I'd rather go with a good carb over those. I know that down the road when I rebuild the motor the TBI isn't going to keep up. I'll be looking for 400 at the wheels, so closer to 500 at the crank and even a bored 454 tbi isn't going to keep up.
I'm trying to do this truck with the fix it right, fix it once mentality. While I'm not on challenge budget here, I'm also not made of money so this thing is getting done in stages.
I am going a different direction with this. You say you re did the wiring and there is black smoke out the rear when it re fires.
Could you have a ignition issue that is being caused by the G's? Something is grounding or shorting or something loose in the ignition system that is being agervated by the high G's. This would explain the smoke on re fire and the fact that it was occurring with a full tank of gas.
Not saying it is not the carb but at least keep your eyes open to other possibilitys.
If it were ignition, I'd expect a pop or bang from the exhaust as the unburned fuel lights off (kinda like what happens with a spark-cut rev limiter).
Yes and no. I had a hard limiter in a couple cars that it just hits a wall and goes dead. No pop or any of that when it comes back.
Like I said just another thing to keep in mind. The quick and easy solution is put a quadrajet on it. I actually liked them better than the holly and a couple other carbs I tried. Easy to tune and I never has any fuel issues on track in my Z28.
Automatic or manual?
If auto, does the tach drop to almost nothing, or nothing?
Manual.
Well, nevermind...
Any chance the fuel pickup is broken in the tank?
Plug wire touching the block or exhaust?
Nope. It would have to be about half the plug wires for that to be the case here.
If the Carburetor is the problem then TBI would help. If it is fuel supply then it won't. I'd start with the tank and the lines. Pickup OK?, pinched line, how is the tank vented ? Check pump volume. One source I have says 4.3 ounces in 10 seconds. This is for an electric pump, engine driven could be less but not by much.
You can extend the carb vent with a piece of hose and a clamp (if the vent's angle is not cut too flush). Should give a little more room for the gas to fill it, if it's dumping from the float bowl.
Have also seen the primary's and secondary's vent be connected by a hose with some holes on the top to allow for air, while allowing had to move from on to the other.
This is from offroading in my k5 years ago, had trouble with a holley but not a Quadrajet. Have seen it some in drag racing.
Got a friend with a 650 holley double pumper I'm going to try. I'll add a fuel pressure gauge at the same time to see where it is.
My C10 with the in cab tank would only see fuel starvation issues below about 1/4 of a tank when using the factory tank with EFI. Fuel starvation at a half tank or more sounds like it's an issue with the carb float bowl instead.
Bobzilla wrote: Nope. It would have to be about half the plug wires for that to be the case here.
We had 1 plug wire touching the engine and it was shorting to ground and caused the engine to shutoff for a few seconds at a time.
Thanks for explaining the float bowl thing!
I know the quadrajets are the budget answer for off-roading and rock crawling for similar reasons.
WOOHOO! Gots me a holley sitting on the counter here at work! Quick Fuel HR650. mechanical secondaries and an electric choke. So excited... I want to stop off at the parts store and pick up some pieces.
Awesome!
Must..... .wait..... until..... weekend...... so hard.
so... installed it on friday. Caught it on fire friday night. A friend came over the following morning and we dialed it in and pulled out a little timing (base timing is now at 12 instead of almost 15). The first thing that came to mind for me was a crazy asian man named Ho Lee Chit. throttle response is LS-like, power is waaaay up, and drivability is so much better. We eneded up getting almost 20" of vacuum and an idle of 680rpm warm. Haven't been to a lot yet to test the lateral load but I don't care at this point!
Also, removed the grenade that was bolted to the waterpump. I know the flex fans have a reputation for coming apart at higher rpms and this thing cruises at almost 3000rpm for an hour at a time getting to events. electric arrives today, but interestingly enough, once the t-stat opened it would just sit at 190-195* at idle parked in the garage.
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