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post #21 of (permalink) Old 01-17-2005, 04:20 PM
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Re: My attempt at the HEI conversion

OK, have another look at "propane trick."
Test -- Make sure you can get liquid propane from the hose by holding the valve below the bottle - next step won't work unless it can.

Do the procedure where you run the long propane hose inside, while driving, hit the accelerator hard - make it burp or backfire. Do it a few times to make sure it still does it.

Then hold the small propane bottle upside down so you get liquid, not gas. Open the valve fast just as you mash the throttle, feeding liquid propane down the throat just before it backfires or stumbles bad.
See if it helps, if it's fuel starvation, the propane will supplement the lack of fuel and it won't fart.
If it still does, it's somewhere else rather than fuel mixture. (By doing that, you are imitating an accelerator pump on a carb -- yes, it works for those too.)

The MAP sensor should "see" the instantaneous drop in manifold vacuum when punching it, and the corresponding voltage change at the MAP should happen. The ECM "sees" the votage change, and instantly lengthens the injector pulse length, giving more fuel -- or that should happen.

Lots of things can cause fuel starvation - even charging system, MAP sensor hose too long or leaking, low fuel pressure etc.

But first it has to be determined if it's fuel or something else.

Lots of other things other than fuel can cause the same symptoms too. But most of them were left behind on the old engine.

Changing over to the diffent engine, then to the HEI only adds more potential trouble spots. I'm a firm believer in "one thing at a time!" I'd rather first determine the cause of the trouble before swapping in - shotgunning - parts.

Questions:
Q - does it backfire out the TB or the exhaust???
Q- When you tested for vacuum leaks, you mean at idle - and when you used just a TINY amount of propane it dropped in speed? Lots of propane, too much, will always cause a drop in R's no matter what the speed -- called drowning!

Add a very little at a time - start by holding the bottle with the valve at the top - getting only gas. pen the valve slowly watching the reaction. If you need even more propane, close the valve, turn the bottle upside down, slowly open again, then you get liquid propane - as it comes out of the hose it expands into gas -- lots of it!

Idle usually upright works best, higher R's upside down.

Q - What happened at say 3000 RPM unloaded with propane?

Q - Can you snap the throttle - unloaded - and make it stumble or backfire?

Q - Does it do it with the vacuum to the distributor disconnected?
Q - What vacuum port are you using -- type of vacuum for the distributor? manfold or ported?

Q - Does it have an EGR valve? Is there a vacuum line running to it?

Q- What is your initial timing at idle set to -- without vacuum connected? What is it at idle with vacuum connected?

Q - The vacuum line to the MAP sensor -- it is direct to manifold vacuum, has no kinks, and is a small vacuum hose designed for vacuum, not fuel or washer fluid? No check valves, and not being shared with any other device. Simple, small, short hose direct to the intake manifold -- not a port on the TB -- right?

I'm no longer an enthusiast of Howell, they are harness builders and chip curvers, not automotive types. They don't seem to understand the basics like what an engine requires for ignition timing advance etc.. And they do things like call out sealing the big bolt holes on the TB adapter to the manifold with silicone -- any automotive person knows that silicone will not seal when gasoline is around. Leak city!

But it's just a simple GM system - millions in use today, nearly foolproof once installed correctly.


He He -- the one thing at a time thing -- This weekend I had to replace our water heater. Of course the outlets are way different, all new plumbing to it had to be put in. While I had the water off, my wife decided to replace an outside faucet that had been leaking slightly, AND she put a new float valve in the toilet. And she did something to the washing machine - don't know what yet, but she said it should fill faster, but now it won't fill at all!
When I turned the water back on, leaks everywhere! I not only had the water heater leaks, but a flood outside (she broke the plastic pipe, and the toilet was flooding all over! (Crossthreaded the hose, requiring a new one.)
ONE THING AT A TIME PLEASE!
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post #22 of (permalink) Old 01-17-2005, 04:46 PM Thread Starter
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Re: My attempt at the HEI conversion

Questions:
Q - does it backfire out the TB or the exhaust???
A - both
Q- When you tested for vacuum leaks, you mean at idle - and when you used just a TINY amount of propane it dropped in speed? Lots of propane, too much, will always cause a drop in R's no matter what the speed -- called drowning!
A - Used a little propane gas through a hole in the air filter housing.


Q - What happened at say 3000 RPM unloaded with propane?
A - Haven't tried it yet

Q - Can you snap the throttle - unloaded - and make it stumble or backfire?
A - I can rev it as high as i want while sitting there. As soon as i'm in gear and try driving, it stumbles at the slightest of throttle.

Q - Does it do it with the vacuum to the distributor disconnected?
A - havent tried it yet

Q - What vacuum port are you using -- type of vacuum for the distributor? manfold or ported?
A - Ported

Q - Does it have an EGR valve? Is there a vacuum line running to it?
A - yes

Q- What is your initial timing at idle set to -- without vacuum connected? What is it at idle with vacuum connected?
A - 10 degrees for both

Q - The vacuum line to the MAP sensor -- it is direct to manifold vacuum, has no kinks, and is a small vacuum hose designed for vacuum, not fuel or washer fluid? No check valves, and not being shared with any other device. Simple, small, short hose direct to the intake manifold -- not a port on the TB -- right?
A - Dedicated vaccuum hose running from the back of the TBI between the inlet and outlet. If you are saying it shouldn't be connected to the TBI, then where? I'm running a edelbrok performer intake that doesn't have many vaccuum ports. Everything is just about hooked to the TBI except maybe the power brakes.

I have been doing things 1 at a time. I tried all previously stated suggestions to no avail with the exception of the driving with propane.
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post #23 of (permalink) Old 01-17-2005, 05:44 PM Thread Starter
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Re: My attempt at the HEI conversion

Well I switched my map sensor from the back of the TBI to the manifold where the brake booster was and the Fuel pressure went from 12 psi to 13.3psi. I can't take it for a test drive tonight, will have to wait till tomorrow. I do appreciate the help.
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post #24 of (permalink) Old 01-17-2005, 07:31 PM
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Re: My attempt at the HEI conversion

Progress! Good!

Disconnect the hose to the EGR valve, leave it plugged till we find the trouble.
Leave the MAP sensor connected to where you just put it - permanently. The Map sharing with the power brakes is fine -- as long as the power brake booster isn't leaking.

Disconect the vacuum to the distributor too. That will put the advance down onto the power curve - again, leave it plugged for now. After it's running great, we'll address that part.

Try driving it - and do the propane test.

What does Howell recommend for fuel pressure? Seems like it's still quite low.

Knowing that it's a E-brock manifold helps eliminate several things I was suspecting -- good!

We'll get it!
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post #25 of (permalink) Old 01-17-2005, 09:33 PM
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Re: My attempt at the HEI conversion

HEY -- just saw your other post on fuel pressure!

Make double, triple, quadruple sure that the pressure line from the pump is going into the TBI INLET!!!
And the return line is to the outlet!!! Disconnect both lines, run the pump, fuel should only come out one of them - the inlet to the TBI!

Reversing them might let it run, but not provide enough fuel to run at higher speeds - under load! Hmmm??? Your symptoms!


I had a customers Volvo with those symptoms -- after my mechanic did the heads. A real puzzler. Drove in fine, didn't want to run right afterwards.
Fortuntely a friend, a former Volvo dealer mechanic now shop owner, stopped by late one night while we were fighting it - just to say Hi. What luck!

He asked "why do you have the regulator in backwards?" Duh!!!
I don't know how long it would have taken us to find it without him, maybe never!

According to your initial post your gauge showed 0, then went up when you pinched it. It should show regulated pressure at the inlet, 0 at the outlet - return line - at all speeds and loads.
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post #26 of (permalink) Old 01-18-2005, 01:38 PM Thread Starter
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Re: My attempt at the HEI conversion

Well the initial test drive was somewhat a possitive one. For the first time since owning a v8 (about 6 years)when mashing the gas, I actually heard what sounds like the secondaries kicking in (if it were a carb) You know that sound. The sound that makes you fall in love with V8's. That deep sound only a v8 can get when getting on it. Unfortunately I have many many exhaust leaks, so there were some back firing and there were still some hickups, but i'm sure once i fix the exhaust (waiting for the temp to come down to work on it) and play with the timing, i'll get it right. Thanks for all those who helped.
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post #27 of (permalink) Old 01-18-2005, 04:06 PM
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Re: My attempt at the HEI conversion

So what made the difference?
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post #28 of (permalink) Old 01-18-2005, 08:15 PM
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Re: My attempt at the HEI conversion

Yeah, what was it?
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post #29 of (permalink) Old 01-18-2005, 08:45 PM Thread Starter
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Re: My attempt at the HEI conversion

The MAP sensor. Plugged it into the manifold rather then the TBI. There are still some fine tuning i'm sure. Have to get an exhaust fixed first. Then i'll let you guys know.
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