High Idle leaky intake gasket - Team Camaro Tech
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post #1 of 14 (permalink) Old Oct 7th, 16, 01:42 PM Thread Starter
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Rick
 
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High Idle leaky intake gasket

I'm hoping some of you experienced folks can give me some information so hopefully I can fix the problem. There are two issues. I have a 406 in my car, forged internals, Lunati cam, AFR 195 heads, Edelbrock air gap intake, BG 750 carb and MSD distributor.

1. The car idles higher than normal. Around 1000 to 1100 rpm. I used to be able to bump the accelerator and it drop but that doesn't work any longer. It does this no matter what time of year, cold or hot. When it is first started and just getting warm, it idles just as it should, at 750 rpm. This same thing happened when I had Edelbrock heads on the same motor and a different carb. Also, the accelerator linkage is fine, nothing binding nor any obstructions.

2. Number 7 cylinder has an oil leak into the cylinder. Valve stem seals have been changed/etc. Also did a leakdown and that looks good. Ran a videoscope down the intake and can see where oil is coming in where the intake and heads meet. I have changed gaskets a few times and also tried different manufacturers, running Felpro, Mr. Gasket, Edelbrock, etc. And number 7 still leaks. All of the other ones are normal.

Could the oil leak be causing the higher idle issue? Any suggestions on how to get the leak fixed?

Thanks,

Rick
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post #2 of 14 (permalink) Old Oct 7th, 16, 02:26 PM
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Rick
 
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Re: High Idle leaky intake gasket

Yes it could be causing it. Remove the intake and check it with a straight edge and check for cracks. The cheap Felpro should work not the Ultra.

69 COPO clone, 461" BBC 11.25:1 Compression
840 Rec Heads (2.25/1.88) AED 850 HO carb
Orig Exhaust Manifolds
Straub (Clay Smith) cam, 288/300 .600/.569 109.
TH400, 3500 stall, 4.11 12 bolt posi
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post #3 of 14 (permalink) Old Oct 8th, 16, 06:46 PM Thread Starter
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Rick
 
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Re: High Idle leaky intake gasket

Thanks. I will look at that next weekend, when I take it off, yet again.

Rick
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post #4 of 14 (permalink) Old Oct 9th, 16, 04:22 AM
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Re: High Idle leaky intake gasket

Oil leak would not cause a high idle, but a vacuum leak could. My guess is that you have a vacuum leak on the underside of your intake manifold.


Vince

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post #5 of 14 (permalink) Old Oct 9th, 16, 09:05 AM
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Re: High Idle leaky intake gasket

x2 on this: Oil leak would not cause a high idle, but a vacuum leak could.
Likely two different problems.
Fix the oil leak first. Then address the high idle.
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post #6 of 14 (permalink) Old Oct 9th, 16, 04:11 PM
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Re: High Idle leaky intake gasket

Intake gasket not sealing well under manifold and sucking oil along with air from crank case?

Are you using Felpro 1206 intake gasket?
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Don
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Zdld17:69 Z/RS,306, NOR141111, 9N554XXX, 12A, X3G, 59/59,723, AFR 195,CCC282/290HR, TKO 600, BU1122B1E Owner since Dec 1968

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post #7 of 14 (permalink) Old Oct 10th, 16, 06:26 AM Thread Starter
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Re: High Idle leaky intake gasket

No, currently I have FelPro 1205 on it. This is what AFR recommended for the 195 CC street heads. They recommend the 1206 for the 195 CC competition heads and all other bigger heads. Is the 1206 thicker? Edelbrock recommends their 7201 gasket. I can give it a shot and see if it makes a difference.

Rick
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post #8 of 14 (permalink) Old Oct 10th, 16, 07:20 AM
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Re: High Idle leaky intake gasket

I would coat the intake gasket with Edelbrock gasgacinch on both sides. This makes the gasket stick in place. Aluminum heads are very smooth and the gasket could be moving around a bit when you set the intake on it. I think Mr. gasket makes a gasket similar to the 1205 but its a bit thicker, so you could try that as another option. If you still have sealing issues, maybe you need to have the intake machined. Was your block decked at all?

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post #9 of 14 (permalink) Old Oct 10th, 16, 07:35 AM Thread Starter
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Re: High Idle leaky intake gasket

The block wasn't decked. The interesting thing is that when I had the Edelbrock Performer RPM heads on it, there was not a leak in number 7. But when I swapped to the AFR, it started.

Rick
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post #10 of 14 (permalink) Old Oct 10th, 16, 08:49 AM Thread Starter
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Re: High Idle leaky intake gasket

I called AFR and explained the situation to them. There suggestion was to use the 1266 Fel Pro gasket. It's twice as thick as the 1205. Their claim was the 1206 isn't any thicker and what I needed was more "crush" material. What do you think? Have any of you used the 1266?

Thanks,

Rick
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post #11 of 14 (permalink) Old Oct 10th, 16, 09:41 AM
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Re: High Idle leaky intake gasket

It's the same only twice as thick. It should work fine.

69 COPO clone, 461" BBC 11.25:1 Compression
840 Rec Heads (2.25/1.88) AED 850 HO carb
Orig Exhaust Manifolds
Straub (Clay Smith) cam, 288/300 .600/.569 109.
TH400, 3500 stall, 4.11 12 bolt posi
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post #12 of 14 (permalink) Old Oct 10th, 16, 09:49 AM
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Re: High Idle leaky intake gasket

Quote:
Originally Posted by duskblue69 View Post
I called AFR and explained the situation to them. There suggestion was to use the 1266 Fel Pro gasket. It's twice as thick as the 1205. Their claim was the 1206 isn't any thicker and what I needed was more "crush" material. What do you think? Have any of you used the 1266?

Thanks,

Rick
While the 1206 is thinner, I believe your issue may lie with matching the ports on the bottom. What ever you use, make sure the ports are matched otherwise you will get what's happening. I have the same heads, 1206 is what I use because 1205 didn't seal ports.

Don
TC # 349
Zdld17:69 Z/RS,306, NOR141111, 9N554XXX, 12A, X3G, 59/59,723, AFR 195,CCC282/290HR, TKO 600, BU1122B1E Owner since Dec 1968

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post #13 of 14 (permalink) Old Oct 10th, 16, 01:32 PM Thread Starter
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Re: High Idle leaky intake gasket

Did you just have one port or multiple ports that wouldn't seal? Just curious.

Rick
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post #14 of 14 (permalink) Old Oct 10th, 16, 02:09 PM
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Re: High Idle leaky intake gasket

Quote:
Originally Posted by duskblue69 View Post
Did you just have one port or multiple ports that wouldn't seal? Just curious.

Rick
NONE, I started with the correctly matched gaskets to start with. Its simple , gaskets match the port or not. You have to check this. Did you?

Don
TC # 349
Zdld17:69 Z/RS,306, NOR141111, 9N554XXX, 12A, X3G, 59/59,723, AFR 195,CCC282/290HR, TKO 600, BU1122B1E Owner since Dec 1968

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