Hi there

I have a 1997 Tahoe Vortec engine that I have installed in a 1973 Chevrolet Deville with an Edelbrock Performer Rpm intake manifolds and an Edelbrock Performer Series 750cfm carb, engine all stock except for the above mentioned carb and intake. Problem is that is fouls plugs, cut out at 110km/h,runs very bad, and keeps on killing electrical fuel pumps. Is the Performer RPM too high for a stock Vortec engine and is the 750 carb too big for the engine too? Engine itself is very good as has less than 50 000km on it when I found it. Runs very quite and powerful except those above mentioned problems. Any help or ideas wil be welcome.

Carb seem excessive for the engine. A 600 would be better suited. What kind of fuel pump and pressure are you running?

From what I've read here, Edelbrock carbs are very sensitive to fuel pressure. Too much and they'll flood.

If it runs well at low rpm then I'll say that the intake is okay. The RPM series intakes are for a slightly higher operating range than the regular Performers, 1500-6500 instead of idle to 5500, IIRC. They trade off a little low rpm torque for higher rpm power. Again, if it has good off the line power I wouldn't worry about it.
One question I have to ask about the intake-it is the Vortec style, correct? P/N 7116?

If it is shutting down at speed you have a completely different issue. Same for the fuel pumps. Perhaps you have a leak in the fuel line, allowing the pumps to suck air?

With an electric pump you should have a regulator to set the proper pressure. A return style regulator is best, but a dead head reg can be used.

The 750 carb is a little big, but not obscene; I don't think the size by itself is the problem.
The RPM intake is not optimal for this setup but I again, I don't think its the source of the problem
Getmore is correct, the Edelbrock carbs are very sensitive to fuel pressure, you should be running no more than 6psi at the carb; any more and strange things start happening.

What are you doing for ignition?

Getmore

I run the electric facet fuel pump on it with 3 bar pressure. The intake is the Edelbrock Performer RPM part #7116. All other engine components are standard that come with the engine exept the dizzy that I took from the old engine. What caused it to die out is the fuel pumps as they keep on heating up and dying.

Your intake is fine. The stated 1500-6500 is only optimum conditions. It will run fine below and above.

The 1st thing I will ask is what kind of ignition you are running?

The 2nd thing I will ask is what kind of fuel pressue your electric pump is? Are you using a fuel regulator?

Sounds to me from the description it is more of a timing or vacumn issue.

3 bar... am I reading that right? 1 bar = 14.7psi (right?)
3 bar = 44psi
you need to be running 6 psi. There is your problem, plain and simple

Go buy a low pressure fuel pump and a regulator, total investment of less than $200
I like the Mallory 4110

The timing I have put it at around 10degree without vacuum and at about 30degree maximum. If I advance the timing to about 6degree BTDC it will start revving fast and sounds more like a high performance motor bike than a V8 vehicle. Engine have more power and will spin right from first gear to second gear than it will than launch the vehicle with such brutal force in third gear than will start stalling and eventually dies at around 110km/h. Well I have no fuel regulator on the line as I still await one from summit. Fuel seems running out and I have tried to adjust the carb according to the manuals but no help. This carb was running very fine with my old engine that was also a 350 with a performer intake. As soon as I installed it on the Vortec engine it than starts having this problem.

Is it possible to have the block drilled thru and have the old mechanical pump installed instead of the electric ones that keeps on dying on me and seems to be running out of petrol? What is the possibility of have the partially drilled pump housing drlled thru. Is the a cam or crank behind that hole that will drive the pump should I have it drilled thru?

The fuel pump pushrod hole will have to be drilled and reamed to size by a COMPETENT Machinist b/c it sure the heck isn't a backyard operation!! No way I'd attempt to do it and I'm a "shade-tree" guy!!

Just buy a fuel line regulator and you will be fine. Sounds like you have been trying to use an EFI electric fuel pump b/c they operate at something like you mentioned to overcome injector friction and such..

pdq67

Yeah - stay electric, its a better setup overall. as soon as you go to a proper pump/regulator your durability problems will go away.

When I have to set idle on this motor, should I set that it idles at 1000RPM or should I set it to idle below 1000RPM or 1500RPM? Which RPM range is good for idling? I live in a hot coutry with normal temperature of mostly 32 degree celsius and use 95 octane unleaded petrol.

That engine should idle at 800RPM

Well I have no fuel regulator on the line as I still await one from summit.

As has been posted by others, you NEED to have a fuel pressure regulator or your carb will not run properly. In fact, I don't even know how in heck you can run 44 lbs of fuel pressure (3 bar) with a 6 psi carb. I would suggest as others have also that you use a proper electric fuel pump for a carb application, as a 44 psi EFI fuel pump will probably not last very long being regulated down to 6 psi.

Put on the right electric fuel pump and regulator, and that should end your problems.

Thanks everybody for all your assistance. If any of you happen to come to these parts of the jungle, please dont forget to say hi. Thanks again

What part of the jungle is that, anyway?

with a bypass regulator , bumping it down to 5 or 6 psi is no problem. if you have the stock cam then there isnt a lobe on it for a mech fuel pump anyway. The stock vortec cam would probably idle at 600 rpm, certainly 700 as its very mild.

DJ

What part of the jungle is that, anyway?

Windhoek... Republic of Namibia Southern Africa.

How do I convert PSI to kpa or bars. Since this side we either use bars or kpa. How much is 5psi in kpa or bars?

1 Bar = 1 atmosphere = 14.7psi

Lowend, how come are you not in bet yet? or is 3am not early morning hours in California?

It was about 7am

i am leaning to a high pressure in the fuel! lol

what did you do, put the stock tank and pump in the car too??

Just wondering.

i am leaning to a high pressure in the fuel! lol

what did you do, put the stock tank and pump in the car too??

Just wondering.

79camaro2001, no I did not use neither stock pumps as the Vortec had an intank pump that is electronic and have a huge pressure, meanwhile the Deville had a mechanical pump that wont work on the Vortec block. What i did was buy me an inline electric pump that I normaly use on carburated Volkswagen GOLfs and JETTA. I never had any issues with the mechanical pump that was on the original engine but had to change the whole engine out as I needed more free power that Vortec offers. I guess I was a fool to do the conversion as I had to sell my original engine for less than U$200 complete with everything on it except the dizzy and carb. Worst deal I ever made now hauting me. I really loved the original engine as it was with no head ache except for the lack of power.