[langss]

On my Chevelle when I rebuilt the carburetor those two holes were completely carbon plugged. No amount of exhaust gas was getting through. I put everything back together as it came apart with the thin "Stainless" shield against the manifold and then the replacement gasket between the shield and carburetor. I was going to run a drill down the two holes and unplug them, but where I had to work on this at the time, that was not going to happen. Later I put Headers on it and as far as I know they are still plugged. Car runs fine, always did.

 

[1966_L78]

Considering we are discussing blocking off the heat passage way under the front of the carb, and having the choke operate properly on a stock cast iron Holley intake,

"You would never have a reason to block the passage at the head. "

I have one, and I drive it winter and summer.


Rocky

Nice solution, BUT the original Poster (Mr. Larsen was asking about blocking off the passage because the paint was burning off on the intake... Set screws under the carb will probably do nothing to eliminate the paint burning on the intake...

True, he'll have to deal with a slower choke (or disconnect the choke)... I live in California, but it still gets cold (typically mid-30's lows in the winter)... I ALWAYS blocked the manifold gasket. A little longer to heat up the engine, but even when it was a daily driver (I ran my 396/Holley intake '66 El Camino everyday when I was in junior college), it wasn't too bad after a few minutes warm up...

 

[rocks66ss]

Jim and I have conversed, and we are on the same page.


Rocky

 

[Dean]

Nice solution, BUT the original Poster (Mr. Larsen was asking about blocking off the passage because the paint was burning off on the intake... Set screws under the carb will probably do nothing to eliminate the paint burning on the intake...

...

That's what was confusing me.

 

[zookpr]

That's what was confusing me.

I agree.

 

[rocks66ss]

Hey Jim, People here seem to be confused about what you were talking about. Please confirm that you were talking about plugging the passage way with plugs, and not blocking the head to manifold.


rocky

 

[1966_L78]

Hey Jim, People here seem to be confused about what you were talking about. Please confirm that you were talking about plugging the passage way with plugs, and not blocking the head to manifold.


rocky

The confusion isn't as to WHERE Jim wanted to block the passage (under the carb or at the head interface, they are both passages for the exhaust cross-over passage)... The confusion lies in the end result (burnt paint) that is unresolved...

Is it a good or bad ideal to block off the heat passage on the intake? This would be on a stock 66 396 with the original holley intake. Car is driven mainly from April to October in MN. Not raced. Just driven for pleasure.

The paint on the intake burns off. Thanks.

Jim's original post implied that he wanted to eliminate the paint burning on the intake. He didn't mention performance, overheating, choke activation (April -October driving season or fuel vaporization in the carb, and he didn't specify where he wanted to block the passage.

I have seen the paint burn near the choke, but NEVER seen it burn up near the carb base...



and after reading about Rocky's mod, Jim asked, specifically...

Does this decrease the likelihood that the paint on the intake will burn/discolor? If the heat isn't necessary to make the car run during the time we drive these cars , it sounds like a great way to prevent the carb from warping due to excessive heat

That went unanswered...

Eric stated

James;

As we discussed, block off the heat cross-over under the carb with the plugs. Leave the passages open at the cylinder head to manifold junction, this way the choke will still function normally. Heated air will run through the cross-over UNDER the carb (which is what activates the choke), but there won't be any hot air present under the front of the carb.

If you block off the heat cross-over at the manifold to head junction, it will take forever for the intake to get hot enough for the choke to dis-engage.

So ONLY blocking the passage under the front of the carb will likely do NOTHING to solve Jim's issue with paint burning off the intake...

Rocky's solution helps keep the carb and fuel cooler, but didn't address Jim's "concern" of the paint burning of the intake (at least as far as his initial post)...

Now, none of us know what other aspects were discussed "off-line" between Jim/Rocky/Eric...

IMO, the main issue (the confusion) is, people still do use the "search" function on this site, and this topic is likely to come up again someday... Just want to be sure people know whether the pipe plug modification will stop the burning of the paint... Does it solve the original problem???

Rocky's mod sounds like a great way to try and keep the carb and fuel a little cooler, block off another potential leak point (or eliminate specific gaskets) while still allowing normal choke operation. But it doesn't address the burning of the intake paint...

That's all...

 

[Jim_66SS]

I have to take the blame for all the confusion. I was not very clear. I was rebuilding the carb; because of leakage problems between the carb and the intake and other gasket issues. I wanted to make sure the carb throttle plate and the main body did not warp, so I wanted to eliminate the heat under the carb. I thought I could also eliminate some paint issues; because I was not that well versed in how the heat passage at the exhaust manifolds and the passage under the carb were designed to operate the choke and heat the carb. I thought I could solve both issues. But the main issue was the warping of the carb and causing a leak. Here are some photos of what I did.

I suppose you might be able to solve both problems by blocking off the passage at the exhaust manifold area. I read a previous post that suggested blocking off one side and also the other side; but leave a 1/4" diameter hole on the drivers side. Longer to heat up the intake and choke. Also another post talked about taking the flap out the the passenger side exhaust , so so much air doesn't go the the carb right away.

I drive the car so the paint is not a major problem. Maybe better paint.

 

[mr 4 speed]

Blocking off the heat passage under the carb will certainly stop any carb baseplate issues,warpage,etc.
That alone will not stop the paint from burning off,as the exhaust crossover is still open thru the intake.I would restrict it and see if it helps.

 

[novadude]

I am running a vortec combo (no crossover on vortec heads) with a low rise GM dual plane and Q-jet. I don't drive the car when the temps get below mid-30s. With a properly tuned carb and well adjusted electric choke, I can jump in on a 40 degree day and drive away after 15-30 seconds with no stalling or other drivability issues.

On carbed daily drivers in PA, that did go out on very cold days, I've always left the crossover open under the manifold plenum.

In my opinion and experience, the crossover isn't needed for a fair weather car. GM had to build vehicles that would run in all weather conditions.

If you have the manifold-mounted thermostatic choke spring, you've got to leave that passage open if you want the choke to work right (regardless of weather). You CAN block the holes that allow heat to pass directly under the carb base.


Sent from AutoGuide.com Free App

 

[Jim_66SS]

Blocking off the heat passage under the carb will certainly stop any carb baseplate issues,warpage,etc.
That alone will not stop the paint from burning off,as the exhaust crossover is still open thru the intake.I would restrict it and see if it helps.

What do you think about blocking off the passenger side and leaving the driverside a little open? Intake should still heat up a little faster; but maybe not get hot enough to burn the paint.

Anyone out there who has blocked the heat passage and this solved burned paint issues?

 

[rocks66ss]

Jim

I'm not sure why your paint burns, But I have never had a problem with it. I put around 1500 miles a year on mine, I would suggest a better paint.


Rocky

 

[mr 4 speed]

James,I would just use the restrictors that come with the intake gaskets.
And I agree w/Rocky's suggestion too...much easier than pulling the intake.
You could always spray the paint into a cup and brush it on.

 

[Jim_66SS]

Jim

I'm not sure why your paint burns, But I have never had a problem with it. I put around 1500 miles a year on mine, I would suggest a better paint.


Rocky

Got a primer and paint to recommend? Car was running hot until I got the cam and timing figured out. Now runs at 190 in 95 degree MN summer heat.

I think I will repair the intake on the car and see what happens.

 

[rocks66ss]

Jim, they make some pretty good heat paints now, but I used Dupicolor, and I have used VHT.

You can use a small steel wheel brush on a drill or dremel tool to remove paint, and as suggested, spray in a cup and brush on, this will take several application, or block around the area and lightly spray. I did not use any primer.

I have a real nice Badger airbrush, so it makes spraying in tight places easy.


Rocky