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Discussion Starter #1
Hey guys, I'm fighting a problem with my car. I just put a new holley 650 4150 carb on, replaced an edelbrock that is what I thought was causing the car to run bad.

I took the car for the first drive with the new carb on (mind you I only have 28 miles on it after the new restoration) the car ran excellent, no problems at all, I put about 10 miles on it. Came back home, sat in the driveway for about an hour and it was very hard to start, backed it out of the driveway and it stalled. It ran good for a few miles and it kept stalling when at stop lights. I had to brake torque it to get home.

I checked the floats and gas was squirting out of the sight plugs, the gas was boiling as it hit the intake manifold, so I'm assuming it is vapor lock. I finally was able to redo the floats and I adjusted the idle mixture screws, the car was idiling at about 1000 and when I put it in gear it is just dying.

Any ideas on what it could be? Timing is set up good, gas tank and fuel sender are brand new. One note I forgot, when I was almost home the rpms were surging up and down when I had a steady foot on the gas.

302
3500 stall th350
Block mounted fuel pump with a rubber hose going to the carb
 

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Well it could be Vapor Lock so some type of heat shield would help but are you sure it isn't dirt in the line or idle circuit calibration issues. That assumes under throttle she is fine but on the idle circuit it dies. Hard starting could be VL or flooding too.

Surge on the other hand sounds like a vacuum leak at base or hose port or line.


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Sounds like a vacuum leak. Does it have a stock Z28 cam ?

Are you using vacuum advance ?
 

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Discussion Starter #4
The engine stalls out when the idle mixture screws are turned in, also the rpm will vary when setting them. I used a vacuum gauge to set up the mixture screws, and I got a steady 15” of vacuum. The engine will also change rpm/stall when I cover the carb

The can is a comp cam with 236 duration and I believe .490 lift, and I am using vacuum advance.
 

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What brand name of distributor is in the engine. Take the carb back off and start all over. Look at the throttle plates you will see what looks like a line when the throttle plates are closed this is the idle transfer slot. Both primary and secondary need to be adjusted to about .020 up to .040 starting with the secondary. Adjust the idle mixture screws to 1 1/2 turns out. If you have a 4 corner idle system adjust all 4. What is the initial timing set at. Set it at 16 degrees. You will then have to rev the engine to around 3500 rpms and with a timing light with advance adjust it to 36*. The mark on the balancer should be on zero. Read this article carefully: http://www.crankshaftcoalition.com/wiki/Hot_rodding_the_HEI_distributor Start at 13.1 Lubrication. After reading this article you will understand what you are adjusting and why.
 

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(mind you I only have 28 miles on it after the new restoration) the car ran excellent, no problems at all, I put about 10 miles on it. Came back home, sat in the driveway for about an hour and it was very hard to start, backed it out of the driveway and it stalled. It ran good for a few miles and it kept stalling when at stop lights.
Text book Fuel issue on a new build/resto.

It is quite common on new rebuilds to have crap go thu into the carb... stick in the float valves...
yep and clear out and get again...
things like the fuel lines have been dry for a while, vanish flake off the inside .. stuff like that

And will not be vapour lock or boil... todays fuels , unlike the hi octane leaded stuff 40 + years ago, modern fuels are a different mixture of hydrocarbon solvents

If u have an idle advance between 6 and 20 with a total (no VA attached ) between 25 and 40 all in over 2600 rpms (these are not ball park numbers , but extreme min maxs
it will not be dizzy
 

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Discussion Starter #9
The distributor is a msd hei. The slots on the carb are adjusted fine. The secondaries have never moved from stock settings, and I had the mixture screws 1 3/4 turns out because that is what gave me the most vacuum. Initial timing was set at 14 degrees and total is 34 degrees.

I have been starting and running the engine for years now, just couldn't drive the car. Never had a problem until I started driving it. Had been the same problems with my edelbrock, and I put the holley on because I thought the edel was junk.

I purchased a carb and fuel pump spacer and some heat sleeve for the fuel line. Hopefully it fixes the problem, as I did see the fuel boiling.

I'm also running a mix of 110 leaded octane and 93 octane with 10% ethanol.
 

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Discussion Starter #11
Have you checked the gas cap? Make sure it rattles, sometimes it is the stupid stuff.
The gas cap doesn't rattle at all, but its kind of funny you posted this because on my last test drive I forgot to put the gas cap on after i put more gas in and I had the same symptoms. The gas cap does hold pressure in the system.
 

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Check for a air leak before the petrol pump and after the tank...
crap in the filter.

And next time when it cuts out, let it, and right then without turning the engine over check the bowl float levels
 

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I know you see the fuel getting hot, but in my 67 i have the same distributor as you, and had a hot stall issue as well. Mine turned out to be the distributor, and a combination of electrical components overheating. My starter was actually overdrawing amperage and was causing my MSD distributor to cease to function properly when engine temps neared 200. Weirdest gremlin chase ever. Had to ditch the factory starter and switch to a mini, and haven't had the problem since. But maybe i just got a weird MSD distributor, but i tried two different ones, and for whatever reason in my setup it was giving me fits.
 

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Discussion Starter #14
Check for a air leak before the petrol pump and after the tank...
crap in the filter.

And next time when it cuts out, let it, and right then without turning the engine over check the bowl float levels
I can't check the float level because fuel is squirting out of the sight plug and the top float adjustment screw. When I check the floats when the engine is at operating temp it is perfect.

I know you see the fuel getting hot, but in my 67 i have the same distributor as you, and had a hot stall issue as well. Mine turned out to be the distributor, and a combination of electrical components overheating. My starter was actually overdrawing amperage and was causing my MSD distributor to cease to function properly when engine temps neared 200. Weirdest gremlin chase ever. Had to ditch the factory starter and switch to a mini, and haven't had the problem since. But maybe i just got a weird MSD distributor, but i tried two different ones, and for whatever reason in my setup it was giving me fits.
I do have an extra distributor in my garage, if I'm still having the problem after I test it with the carb spacer I'll throw it in. If it makes any difference I do already have a mini starter.
 

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...I'm thinkin its the float settings.
Holley book states it should just barely trickle out of sight plugs when removing sight plug, running.
Maybe trash/dirt spec in the inlet needle? I had to chase that gremlin several times. Frustrating as its symptoms can be misleading if it floods slowly, it'll run, but stall, start, but be picky,,,,,
Vapor lock - IMO isn't it, as to my knowledge is fuel not being present at all, hence vapors-running out of fuel, then slosh- fuel fills up or gets through enough to keep motor running and then can refill carb..
 

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I can't check the float level because fuel is squirting out of the sight plug and the top float adjustment screw. When I check the floats when the engine is at operating temp it is perfect.
geeze m8 that definately wrong.. that bad u have crap in the float valves... remove and clean... set the float level a little low, fire the engine up...and when u remove the site hole plugs no fuel will run out.... now adjust the height up so when u grab a fender and give the car a sideways shake a little splill of fuel slops out, no more

What u have is the classic post build or long time no use, pick up of crap in the fuel system between the tank and carb....could be a bit of rust flake or varnish despoitt off the inside of the fuel lines... what ever.
If happens a 2nd time, drop the factory carb sintered filter back in for a while.
 

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Do what Steps says above.
Mechnical or electric pump?
Do you know what your fuel pressure is?
You can disconnect the fuel line and check it with a length of rubber hose and combination vac/fuel pressure gauge.
It certainly does not sound right that the fuel is pouring out the sight holes.
 

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Discussion Starter #18
...I'm thinkin its the float settings.
Holley book states it should just barely trickle out of sight plugs when removing sight plug, running.
Maybe trash/dirt spec in the inlet needle? I had to chase that gremlin several times. Frustrating as its symptoms can be misleading if it floods slowly, it'll run, but stall, start, but be picky,,,,,
Vapor lock - IMO isn't it, as to my knowledge is fuel not being present at all, hence vapors-running out of fuel, then slosh- fuel fills up or gets through enough to keep motor running and then can refill carb..
If I start the engine and leave the hood open and check the float level when the water temp gets to about 180 the float level does exactly what you say, it will trickle out when I give the car a little bump.

geeze m8 that definately wrong.. that bad u have crap in the float valves... remove and clean... set the float level a little low, fire the engine up...and when u remove the site hole plugs no fuel will run out.... now adjust the height up so when u grab a fender and give the car a sideways shake a little splill of fuel slops out, no more

What u have is the classic post build or long time no use, pick up of crap in the fuel system between the tank and carb....could be a bit of rust flake or varnish despoitt off the inside of the fuel lines... what ever.
If happens a 2nd time, drop the factory carb sintered filter back in for a while.
Carb is brand new and I have had the same problem with this holley and an edelbrock. The edelbrock was actually a lot worse. Once I let the pressure out of the bowls I took the needle and seat out and cleaned them, but they looked perfect. If anything the float on the front fuel bowl is a little low.

Do what Steps says above.
Mechnical or electric pump?
Do you know what your fuel pressure is?
You can disconnect the fuel line and check it with a length of rubber hose and combination vac/fuel pressure gauge.
It certainly does not sound right that the fuel is pouring out the sight holes.
Manual pump, my fuel pressure is around 6 psi.

The fuel doesn't pour out it is actually squirting out like when you crack the bleeder valve on a cooling system. When I had the edelbrock carb on the fuel was actually going passed the fuel bowl and draining into the engine almost completely emptying the bowl which required a lot of cranking to fill them back up.
 
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