Ok, just finished the compression test...Cylinders 1-7 average 145-150 consistantly...Cylinder 8 on the other hand averaged 120-130 max... As for the pics, the system wouldn't let me upload them but as stated above, each look very similar with the base being blackened (soot), electrode is light brown and the strap is uniform grey...

 

Hrm....odd that the one cylinder is low. Maybe the rings haven't seated yet? You should still be able to smoke the tires though. Once you get things working right, you might actually want to do a good burnout to try to seat the rings in that cylinder.

If anything, the plugs suggest it's running a hair lean. Ideally you should have a mostly clean plug withlight tan deposits on the insulator. Grey or white deposits indicate a lean condition. The baseis usually going to be darker as it doesn't heat up as much and won't get hot enough to burn all of the carbon off.

Go and check the timing (bothstatic and dynamic, with the VA disconnected)and report back. That's the first place I'd start with a sluggish engine.

 

timing is is good idea.

The compression sounds good...even with the plug wire off of cly 8 you should still be getting much better times.

Let us know what you find with the timing.

-Gun

 

Thanks guys...Appreciate the troubleshooting path...Just a quick question though, I can check my timing but the static vs. dynamic comment kinda threw me...How would I go about checking them...

 

Hey guys one more thing I forget to add..Not sure it provides any more insight, but I do have periodic backfires through the carb and for the life of me, I can't figure out why...Anyone know?

 

not a real timing expert but based on starfury's explanation it sounds like dynamic is done by watching the mark at idle and then revving up the engine and watching it advance. With static you remove the Vac advance line from the dizzy so it cannot advance its self and watch what it does...Thats a half way guess and im not sure how it would help hopefully someone can clear that up.

As for the backfire that could be from timing...and about 10 other things like failing valves or a cam.
Start with timing it should be about 7 ish at idle and around 30 something when revved up I would think. If its at all above 10 at idle I would back it off a bit.

-Gun

 

Backfire through the carb is usually the carb going lean or arcing with the spark plug wires. The 2.5 exhaust is probably hurting too. That cam isnt much more than stock. Whats the compression ratio?

 

No idea what my compression ratio is, though I'd like to know...Initial timing without VA is about 6-7 degrees and just gave her another full turn on the A/F screws (3.5 full turns)...Now with respect to timing, I was having trouble starting it and ending up finallytaking to a shop several weeks ago to have them set it correctly (which I'm thinking they didn't) and the guy told me that it was set to 40 degrees total..Not sure how he got that,but if initial is only 6-7, I'm questioning it...

What do ya think?

 

It would have to be very lean to get a backfire through the carb like that, and it would be noticably misfiring while driving, if it moved at all. I'm not even sure it would do it at all with that cam; it doesn't have much valve overlap at all.

The backfire actually sounds like it could even be cam timing or poor valve sealing, but we'll start with the ignition timing.

Static (or initial)timing is set at idlewith the vacuum advance hose disconnected from the distributor and plugged. With that cam, 8-10* is probably fine. To check dynamic timing, leave the VA disconnected and rev the engine up. This will show you how much and how fast the mechanical advance advances the timing as rpm's increase. Somewhere around 3k rpm it should top out, ideally stopping at ~32* @ 2800rpm. This is your total timing. If it differs drastically, you'll probably need to change out the advance springs/bushings in the distributor.

 

Those screws will only affect the mixture on the idle circuit. Backing them out leans the mixture, which I don't think you need to do at this point.