Head gasket?

[COCHEV]

ok, basic stats:

86 350 engine- new to me but not new by any other standards
125-135 comp in all but cyl 4 and 6
cyl 4 dead hole
cyl 6 about 60 psi

runs with noticable miss...duh

engine running with rad cap off and coolent is churnin like the the colorado river...

so, head gasket blown between the two cyl???

 

[badmix]

Pull valve cover, see if pushrods and rockers are still entact. My buddy just went thru this with his lincoln. # 6 & #7 cyinders were just like yours, 60-90 on one and dead on the other. Also it could be the headgasket between those cylinders has gone away.

Also when you pulled the plugs what did they look like? foul'd, this could be indicator of something amiss as well.

also hook up a vacuum gauge in your engine bay and see how it acts.

http://www.earlycuda.org/tech/vacuum2.htm


When you did compression check did you do the "wet" test as well.

If wet test results in higher compression, its the rings, if it doesnt change, its the valve train.

I would do some more testing like I showed b4 tearing into headgasket

 

[COCHEV]

only did a dry test. the plugs in the bad holes were black. all the rest were light brown. i will pull the valve cover off today. took all morning just to get all the emisions crap out of the way to get to said valve cover

 

[dyeager535]

Coolant should be moving vigorously if the thermostat is open. You are looking for bubbles with a bad head gasket, although never had the problem, and I wonder with adequate coolant movement, if you'd even notice them?

 

[COCHEV]

well, the coolent was also somewhat foamy/bubbly i pulled the valve cover and didn't really notice anything out of the ordinary. thats not to say that i still might not have a couple of bad valves... guess a tear down is next.