Something weird going on

[cudabob496]

Intake off. don't see anything standing out that might cause a vacuum leak, except
on the passenger side head, the metal divider on the intake side, at cyclinders #6 and #8,
between the intake ports of #6 and #8, seems to have a lower spot about 1/2 inch long, that
might have allowed there to be a cross-connection between both intake ports. Plus, there was a paper
gasket above and below the metal pan gasket. So, after 15 yrs, maybe a vacuum leak
should be expected, after all the heating and contraction. Gonna fill the low spot with some
RTV. Doubt it is deeper than a mil or two.

[cudabob496]

might be deeper than 2 mil.
quesiton is, what would symptoms be if #6 and #8 intake ports had a pathway
between them?  Maybe gaskets got old and brittle, and pathway developed?

[turbostang7]

I could be wrong but I don't think leaking between the ports will cause that bad of an issue. They are all open together up by the carb.
I know Diesels are different but they don't even have an intake with separate runners on them just an open plenum that sucks air in.

[cudabob496]

I could be wrong but I don't think leaking between the ports will cause that bad of an issue. They are all open together up by the carb.
I know Diesels are different but they don't even have an intake with separate runners on them just an open plenum that sucks air in.

Makes sense!

[mopar70maniac]

or maybe a leaky float... creating a flooding condition because the float won't rise and seal needle valve?

[timbbuc2]

I was trained back in the day , long time ago to help find a vacuum leak to spray small amount of brake cleaner in the area , and if the engine speeds up wala, Done that on my Ford Sportrac, works like a charm, you dont want to soak it, just a mist around subject areas. You use to use WD-40 when propane was used in it.

[cudabob496]

I was trained back in the day , long time ago to help find a vacuum leak to spray small amount of brake cleaner in the area , and if the engine speeds up wala, Done that on my Ford Sportrac, works like a charm, you dont want to soak it, just a mist around subject areas. You use to use WD-40 when propane was used in it.

Thanks, I agree, but in this case I can not get the car to idle below 1000 rpm.

[734406pk]

Have you tried adjusting your idle mixture screws? Is the float level set to specs and holding? Your problem description appears to be extremely rich idle circuit.

[cudabob496]

Have you tried adjusting your idle mixture screws? Is the float level set to specs and holding? Your problem description appears to be extremely rich idle circuit.

Yes, checked all that.  idle mixture screws are 1.5 turns out
Carb all checked, new metering blocks, float level, etc

Should be installing intake with new gasket in a couple days.

[734406pk]

After you have the engine back together, try turning in the idle mixture screws and see if the engine will clear up and idle. You may find that you can screw them all the way in and there is no difference. That would indicate that you have an unmetered fuel issue.

[cudabob496]

After you have the engine back together, try turning in the idle mixture screws and see if the engine will clear up and idle. You may find that you can screw them all the way in and there is no difference. That would indicate that you have an unmetered fuel issue.

Yes, thanks, tried varying them, no help.
If new intake gasket does not solve problem, Holley
thought it might be an unmetering fuel problem as well.
But everything is new in carb.
Maybe also MSD Digital Box is screwy.
Float viton needle seat assemblies are 2 years old. Inspected and see no problem.
But have new ones to install as well.  But float levels are good!
Its crazy!

[734406pk]

Well I guess the first step is to get the engine up and running again and see from there. To test for unmetered fuel in the idle circuit, you would turn in the adjustment screws. If they screw in and seat with no or little change, there is an unmetered fuel problem, a blown power valve for example. Get her up and running and we will see what you've got. 

[cudabob496]

I agree. Have put in new power valves, and no change.
Took off one valve cover and inspected, but haven't taken the other off yet.

[734406pk]

I agree. Have put in new power valves, and no change.
Took off one valve cover and inspected, but haven't taken the other off yet.

Don't bother taking off the other valve cover just yet. Do you have a compression gauge if and when the time comes to test?

[cudabob496]

Don't bother taking off the other valve cover just yet. Do you have a compression gauge if and when the time comes to test?

ya, leak down test will be a good idea if necessary.