Scout car engine trouble.

[HQ-88]

I have been asking around about this issue I am having with my scout car, and I am hoping I can find the answer here. My scout starts up and runs smooth, but the 2 most rear cylinders (the 2 closest to the firewall) are dead. I have a good strong blue spark on all new plugs, timed correctly, clean/rebuilt carb. Compression test indicates that cylinder 6 is a bit worn, but nothing to sever that it would kill both cylinders. I installed a new head gasket just to be sure, and still no luck. Sprayed for intake leaks, everything checked out but putting a new gasket on just to be sure. While I had the head off I cleaned all of the carbon build up out of the block, and observed all of the valves functioning as they should. I also did a vacuum test using a gauge, and while the engine was running engine vacuum was all over the scale!

I am at a complete loss here,

Any idea's or help would be greatly appreciated.

 

[CMPPhil]

Hi

When nothing seams to be the cause, go back ask what is the most stupid thing you would not expect. So in that vain, are the plug leads reversed?

Which engine are you working with, I'll be seeing some gus this weekend at the Weare Rally that have worked on scout cars, will ask for thier thoughts.

Cheer Phil

 

[HQ-88]

The firing order should be correct, I checked it twice. Going to check the vacuum lines, one in particular going to the brake booster that I am starting to suspect (the only obvious thing I have overlooked). The engine is a Hercules JXD. Looking forward to hearing back

 

[NDT]

Do this basic check: Remove the two rear spark plugs, set them on the head with the plug wire attached. Remove the wires from 1-4. Put your finger over the #5 plug hole and have someone crank the engine. Your finger should be blown off the hole at the exact time the corresponding spark plug fires. Repeat for #6.

 

[CMPPhil]

Hi

Thought some of the other members of the forum might enjoy looking through the TM on the JXDhttps://www.google.com/url?sa=t&sou...CCMwAA&usg=AFQjCNE5PZLHU0KSTf524AV24ABuOiQnlA

Hope the link works.

Cheers Phil

 

[HQ-88]

Made a lot of progress today. I temporally capped the brake booster line, and that did the trick! Turns out, booster had a leak, and that was causing the last 2 cylinders to get leaned out and not run. I completely over looked this a few times... I am having a problem getting the manifold gasket to seal. I cleaned the surfaces real well, but it just leaks exhaust. I suppose I will probably have to get the manifold machined smooth. Not sure if there are any other tricks to getting it to seal. I really don't want to go through another gasket.