Bill in NC

Hey guys I was hoping that someone may have come across this problem before and found a solution. I am currently trying to figure out a driveability problem. The car runs great wherever you go. But if there is not a long enough cool down period (more than 30-40 minutes) before your next trip, it runs like crap. Sometimes it will not start/idle, and other times it will idle at 2,000rpm and die when put into gear. If you can get it running, it takes a minute or so to clear up. It is a 455 being fed by a Holley blue noise maker, "Stage 2" Quadrajet from the carb shop on a Torker intake. I'm thinking maybe the carb body has a crack in it between the body and base plate? I've heard that the Quadrajets have been known to crack and leak fuel and/or air causing problems. I have run many Quadrajets in the past and have never seen one crack or had these same symptoms. Has anyone else had these same issues? I should add that if you do let the car cool down it has no issues starting right up and you're on your way. I thought at first that maybe the heat build-up after shut down was boiling the fuel out of the fuel bowl, but the high idle is throwing me off of that idea as being my only problem.

Thanks for any tips.

TripDeuces

I've never known them to crack but the well plugs are known to leak. That's something I think the Carb Shop would have addressed though. Are you using the regulator that came with the Holley pump? I have no idea on the high idle other than the choke being adjusted wrong or something sticking. Let us know. Beautiful car btw.

Bill in NC

Thanks man, the well plugs are probably what I'm thinking of, and I would suspect that the Carb Shop sealed them. I'm not sure on the regulator brand, I'll have to take a closer look, but by watching the fuel pressure gauge, it did drop a few pounds, but I didn't think a whole lot about it since the car was running very rough at the time and I fugured the voltage fluctuation may have been causing the fluctuation in psi. As soon as the idle smoothed out, the pressure was dead steady.

TripDeuces

I didn't mean is it a Holley regulator I meant are you using one at all? That pump can put out 14psi which is too high as you know. I would keep it between 6-7psi and see if it helps. Too high a float setting will also cause flooding, which kinda sounds like what you have. The fact that it runs fine after a period of time makes me think the fuel is evaporating off within the soaked manifold as the heat gets to it. The voltage should be remaining the same at any engine speed from idle to WOT. Amps will change but voltage shouldn't. What kind of ignition do you run?

Bill in NC

I have an under drive crank pulley which causes the alt to not spin fast enough to pump out 14 volts until I hit roughly 900-950rpm's. It was worse when I had the larger alt pulley that came with the small crank pulley. The alt is an 100amp 3 wire unit to help with the electric cooling fan HEI and the blue fuel pump. Fuel pressure is set at 7psi.

The high idle is really throwing me off. It will rev in park/nuetral, but as soon as you drop it in a gear, the car will fall on its face like it's running out of gas. I've had cars in the past that would boil the fuel out of the carb in the summer after parking, but you could smell the fact that the car was flooding upon start up.

Bill in NC

The car is running a stock style HEI that has been locked at 34deg

TripDeuces

Now it sounds like a vacuum leak

TripDeuces

HEI's require a full 12v+ to operate well. You might want to change that alt. pulley back.

Bill in NC

I agree, I just can't think of where the leak could be coming from that would leak at high temps and seal quickly after running other than maybe in a runner under the intake??

Bill in NC

Or in the carb somewhere

TripDeuces

Could try retorqueing everything, can't hurt

Bill in NC

Gotchya, when I got the car, it had the larger pulley on the alt, causing it not to charge until about 1,100rpm's. It now has the smaller pulley to help with charging at lower rpm's.

TripDeuces

Maybe another stupid question but since this is an older vehicle do you have a dedicated 12v source for the HEI and not the original resistor wire?

joe_padavano

You wouldn't happen to have a one-wire alternator, would you?

Also, the leaking well plugs on Qjets were a problem only on the very early carbs with the cup plugs. From about the 1968 model year on, all Qjets used spun-in solid aluminum plugs that don't leak, yet the leaking well plug diagnosis lives on.

Bill in NC

I will put that on the list of things to check. Good idea, I do know the HEI is very sensitive to anything under 12.5 steady volts.

Bill in NC

Good info on the well plugs Joe. The alt is a 100amp 3 wire.

TripDeuces

I mentioned it because when I purchased my 66 it had a Mallory Unilite set-up in it. It kept stalling out once it got hot. I kept looking at that ballast resistor on the firewall and wondered if it was correct. Sure enough once I got the instructions online it said it needed to be resisted down but not through the original resistor wire AND a ballast resistor. I yanked that thing out and never looked back. Haven't had the problem since. I had a Pertronix do the same thing, which needs a full 12v. Once I fixed that it was like adding 20 hp. I've seen several HEI sputter at high rpm and fall on their face due to this same issue. It's more common than you think.

Bill in NC

Do you happen to know what the voltage would be after the resistor? That sounds like something I really need to look at. I'll check back later tonight and hopefully I have some time to look at this tomorrow. Thanks man!

TripDeuces

Starting it's 12v, running it's 7-8v so you don't burn up points.

442scotty

Sounds like good old fashioned vapour lock to me...very common in the old days..It was always a pain...Its been a long time since I had to deal with that but I think I had to use an inline filter (the see through kind) and make sure it was completely horizontal...I think thats what the fix was but it has been 30 yrs...hope this helps

Bill in NC

I'm pretty sure I found the problem guys lol. I pulled the intake today looking for an intake leak. I found five. And the front two cylinders and rear two cylinders were starting to suck coolant past the gaskets. I know this intake has been cut to compensate for the heads and block being milled, but by lookiong at the marks left on the intake and seing how the gaskets split, warped, and pulled away from the surfaces, I can tell it was cut too far. It is sitting too low, and is not close enough to the cylinder heads to seal and clamp the gaskets properly. I have a Performer intake I can put on it, but I'm not real sure how well it will work with the Comp 292h (part# 42-236-4)? Is any one running the Performer w/ the 292h? Here is just a couple of quick pics.
2011-06-13_200018.jpg
2011-06-13_195945.jpg

Bill in NC

I got the Performer and new gaskets sealed up today. I've made a few changes while under the hood and still have a few things left to button up, like new plug wires, getting the timing set, etc. Here is a quick video of the fire up. Thanks for the help guys
http://www.youtube.com/watch?v=WpWDA...&feature=share

Bill in NC

Got the timing set and took her out and put some miles on her. Everything seems to be great, no more hard starts when hot.