vacuum leak comes and goes with heat

[thistle3585]

The original vacuum reading I posted was with the screws at 1.5 turns. I haven't pocked up a compression tester yet. Not sure what a leak down test is and I'm sure there are a lot of miles on this engine. I swapped it in awhile back when the other went out.

 

[thistle3585]

I completed the compression test. Cylinders 1,6 and 8 were 125. 3,5 and 7 were 128. 2 was 130 and 4 was 120.

Other observations... Cylinders 4 and 6 had a fair amount of oil on and around the plugs. I am running Champion RN14YC plugs.
I turned the idle mixture screws to 1.75 turns. I reset the timing and the mark was jumping a bit between 3 and 7 degrees. I couldn't get a steady reading.

 

[Lumpy Grits]

That 'jumping' marker is a sure sign of sloppy timing chain.
LG

 

[Torxhead]

That 'jumping' marker is a sure sign of sloppy timing chain.
LG

Yup, time for a new chain, gears, and probably a front seal.

 

[thistle3585]

Thanks. So I'm guessing my best bet is new chain and sprockets? This is my first time doing such work. Anything I should look out for? I guess I'm just going to go through it as its done on the manual.

 

[Torxhead]

The radiator should come out, and get a gear puller to remove the vibration dampner. You might also find some videos on You Tube.

 

[Lumpy Grits]

Did you ever change out the dizzy cap/rotor yet?
What are your plug's gap set at?
Your compression readings while pretty even, are on the low side.
What weight engine oil are you using?
What octane fuel do you run?
LG

 

[thistle3585]

Dizzy and rotor are about 200 miles old.

Gaps are whatever they were out of box.

I believe oil is 10W30.

Fuel is 87 octane.

 

[Lumpy Grits]

Pull the plugs and gap to .035-.038. NEVER trust the plugs to be gap'd 'rite' from the box.
Try prem fuel.
Step up to 15W-40 oil and a can of Restore.
LG

 

[thistle3585]

Pull the plugs and gap to .035-.038. NEVER trust the plugs to be gap'd 'rite' from the box.
Try prem fuel.
Step up to 15W-40 oil and a can of Restore.
LG

Are you suggesting this as a possible solution to my problem in lieu of changing the timing chain and sprockets?

Also, my oil pump is leaking pretty bad and I have a new gasket on its way. Since that is attached to the timing cover could that be causing any of this issue?

I am looking at the Edelbrock Performer-Link True-Roller Timing Chain Set at Morris 4x4. Any feedback on what to get? Also, I figure I'm pretty much going to be pulling the front end off the engine so what all should I replace while I'm in there?

 

[Lumpy Grits]

You'll have new chain etc and the rest of the motor is still worn.
Hope you know how to prime that oil pump after you reassemble it. You'll need a screwdriver shaft, drill motor and must remove the entire dizzy assembly to do this 'prime'.
IMO-Rebuild the entire engine.
But till then-Try my idea.
BTW: I use Restore in my 120K mile, 30+yr old engine and she runs great. Passes smog in Ca. with ease--
I also use Castrol 20W-50 oil.
LG

 

[thistle3585]

Thanks for all your help. I'm thinking I'll replace the timing chain and gears, plus rebuild oil pump since I have it apart, and see where I stand at that point. It should run about $100 in parts so if anything it will be a learning experience. Not ready for an engine rebuild yet.

 

[Lumpy Grits]

Research your parts suppliers before you buy.
Avoid ALL China made stuff!!
Best of luck,
LG