Quadrajet Idle Problem

[67_Eldo]

The third and main issue was the metering rods position in the jets. The thin retainer wire holding the rods somehow moved and was not allowing the rods to fully go down with vacuum at idle. It was no more than one millimetre but made a difference. The rods were also not sitting at the correct depth in the jets. Somewhere in its history it had been altered.

This was the suspected (by the carb guys) culprit in the remanufactured carb I just sent back for replacement.

I didn't open the carb myself because it was still under warranty and I didn't want to throw away my $$$.

My old -- and once-again current -- carb had the other problems listed by Mr. Masters as well.

The current "wisdom of the QJ crowds" indicates that you can use either one or two carb gaskets. My old/current carb used two. When I put my new/remanufactured carb -- with a base that they had machined flat -- on, I used only one gasket in the manual-specified location. The one-gasket carb worked great until the rods got out of whack (via crud in the fuel bowl?).

[impalamansgarage]

Coincidentally, the BG product was mentioned on the most recent episode of the Car Wizard.

https://www.youtube.com/watch?v=8zmXyB38mRg&feature=youtu.be&t=320

Thanks for the link. I had forgotten about this video. I've got my intake manifold off of my 472 right now and I was looking
for a way to clean up my valves. I am going to find some BG 44k and dig in like the Wizard. I've also been rebuilding my QJet, sealing casting plugs, installing brass bushings, etc....

Incidentally my intake came off pretty easy. The bolts were not really that tight and it basically lifted right off
without a fuss. This tells me it probably was not sealing properly.

I've been having idle problems so I decided to dig into the fuel system. I'm glad I did because there are several issues to address. The old QJet was leaking like a sieve.

I'll be documenting some of this stuff on my channel.
https://www.youtube.com/c/impalamansgarage
https://www.youtube.com/watch?v=DipqE3tKUKY&t
https://www.youtube.com/watch?v=pGbNYBE7NXM&t

[Cadman-iac]

I never did understand why the engineers used an all steel intake manifold gasket on the 472/500 engines. I realize that they have a "crush" zone that is supposed to seal between it and the heads, but just how good can it really be?
Doe anyone make a composite gasket for these engines that would be less likely to leak?
That would also probably stop a few other problems too, like the issue of water getting between the manifold and the valley pan portion of the gasket and eventually rusting out and getting into the engine itself.
I had never thought about that before, until I removed the intake from one of my spare engines and seen the rust on the pan under the manifold. Being a dry manifold, the only way water would have gotten in there is by a leaking gasket, maybe when someone had cleaned up the engine with a steam or pressure washer. It's a bit unnerving to think that the simple act of trying to keep your engine looking good can result in ruining it eventually.

It's like the old head gaskets that used to be commonly used before the composite ones were widely available. A leaking head gasket used to be a lot more common issue years ago.

Rick

["Cadillac Kid" Greg Surfas 15364]

The “turkey pan” intake manifold gasket has a secondary purpose beside sealing the intake ports. It acts as a baffle to keep hot engine oil off the bottom of the hot intake and the exhaust crossover passages in particular.
To seal the ends of the intake the pan kit includes two “rubber” gaskets for the end “China rails”. The intake is heavy and these end seals are often moved out of place when the intake is installed thus allowing either one or both of the following.
1. Air and moisture can find its way between the intake and the pan.
2. The lifter valley is not properly sealed and since with PCVs the crankcase is under negative pressure air comes in upsetting the fuel air calibration or when under higher throttle conditions when the PCV is closed, oil can be expelled.
What a dilemma.
Easy fix: Besides making sure the China rail seals are installed properly a good bead of high temp sealer does the trick.
Greg Surfas 

[Cadman-iac]

The “turkey pan” intake manifold gasket has a secondary purpose beside sealing the intake ports. It acts as a baffle to keep hot engine oil off the bottom of the hot intake and the exhaust crossover passages in particular.
To seal the ends of the intake the pan kit includes two “rubber” gaskets for the end “China rails”. The intake is heavy and these end seals are often moved out of place when the intake is installed thus allowing either one or both of the following.
1. Air and moisture can find its way between the intake and the pan.
2. The lifter valley is not properly sealed and since with PCVs the crankcase is under negative pressure air comes in upsetting the fuel air calibration or when under higher throttle conditions when the PCV is closed, oil can be expelled.
What a dilemma.
Easy fix: Besides making sure the China rail seals are installed properly a good bead of high temp sealer does the trick.
Greg Surfas

Greg,
Yes, I know about the seals on the ends of the manifold gasket. What I'm wanting is a way to use a composite material as a gasket between the factory one and the head and between the factory one and the manifold. Basically sandwiching it between to thin composite gaskets that would seal the intake without question. They wouldn't have to be very thick, in fact the thinner the better.
I thought about using a high temp sealer, but you can't be sure how it will squeeze out when the manifold is put on it. Hell, a body could cut those out easy enough and glue 'em in place, let it set up a day or so, and then install it. Seems to me that this would be better than what the factory did. And less likely to have a vacuum leak.
I may try this on my 472 when I get it back together. If I do, I'll let you know how it works out. It certainly can't be any worse than the original gasket.

Rick

PS: What do you mean by "china  rails"? I have never heard that term before.

[64\/54Cadillacking]

I think the both of us are having idle issues at the moment lol.

Actually just this past week I’ve determined that my 64 has a 67 block with 64 heads and distributor. I found this out by removing the distributor to see if was a 67 or 64.
I struggled like crazy trying to get the car running again when reinstalling the distributor. I find out the timing marks on the balancer are off. So everytime I thought I was right at TDC on the balancer, i was off slightly.

Long story short I replaced the original Carter AFB for a Edelbrock Carb with an electric choke which cured the rough start ups and the engine idled and ran much better compared to the Carter.

Also, I’ve tested to see what kind of spark plugs the 429 likes, and after comparing the AC Delco’s, Champions, Bosh, Autolites, and NGK. The engine ran the smoothest with the Autolites. The AC Delcos made the engine run like crap and it idled poorly to my surprise. The NGK and Bosh plugs ran pretty good too, but I found that the Autolites 85 made the 429 run the smoothest.

Remember, AC Delco parts aren’t what they used to be. A lot of there parts are made in China and Mexico now. Maybe the old Delco plugs from way back in the days that were made in the U.S. were great, but not anymore.

So my engine has definitely been Frankensteined. Regarding the idle issues you are having. I dealt with this same exact problem for years and I still do have a rough idle at times, but it was definitely improved by installing the Edelbrock carb, running manifold vacuum to the advance, installing a Petronix III igniter and coil to the car. It’s made my 64 much more reliable to drive too.

Hope this helps!

[35-709]

Autolites are made in China, NGKs are made in West Virginia (probably using Japanese made parts).

["Cadillac Kid" Greg Surfas 15364]

Rick,
I use composite gaskets around the intake ports and high temp sealer on the china rails of my (sorta) race car, but there are literally  millions of cars that ran the stock set up with no issues.
Greg Surfas

[impalamansgarage]

When I'm ready to reinstall my intake I was planning to use some high temp
sealer between the gasket and head and between the gasket and intake.

Question on the front and rear end rails:  Chevy guys usually toss the rubber gaskets and just
use Permatex Ultra Grey. Would the same strategy work for a 472/500 ?

[E Masters]

Not 100% sure but I think metal gaskets were used for heat transfer between the heads and the manifold.