Determining Cam Timing Error

[Xnke]

Ok, so I have had my engine together for a while, run it for about an hour total, and have put two miles of running on the clock. I have followed the break in I've always used, namely, accelerate to about 50mph, then let off the gas and let engine braking slow the car 4 or 5 times, thus, using the engine vacuum to pull the rings against the cylinder walls. It's always worked well for me, in the past.

 

However, I believe I may have installed my cam wrong, I think that the cam timing is retarded too much. The engine runs fine, however cranking advance is 20*BTDC, less than 18* and it will pop out the carbs every time. The cranking compression is only 90PSI. Every cylinder is exactly the same, but this engine was built with a 9.5:1 compression ratio. I should see something along the lines of 180PSI.

 

My cam is a Delta Camshaft regrind, and when I installed the cam I installed it with a new timing set, and set the dowel and chain up for the #1 sprocket position. Everything seems to point to a retarded cam timing: the large amount of advance needed, the low cranking pressure, and the fact that the engine doesn't really wake up till about 4500RPM.

 

Am I on the right track here, or barkin up the wrong tree?

[ozconnection]

Yeah, that's worrying. The small compression readings suggest cam timing alright.

 

Hot comp. test?

 

Sound build up, comp rings put in correctly, cam timing verified by degree wheel, ignition verified by timing light?

 

I wish I could jump through the computer to help you out. Other than what I've written here you're just have to triple check everything you can. Obviously something like the rings is something you can't easily check visually. A leak down test might help here. Don't assume anything to be correct until you have checked/tested it.

 

Good luck mate.

Edited April 13, 2010 by ozconnection

[Xnke]

Found out the cam was ground with the wrong index, so installed as it is it is 2* retarded to start, then i was off a tooth for another 9*...11* retarded total.

 

Got another compression tester and checked compression again, it was 130lbs, before moving the cam. Old compression tester has been marked and thrown out...inaccurate readings.

 

Advanced the cam the 9* from the slipped tooth, checked compression again, 155lbs. Nice increase! Advanced the cam to the #2 position, compression jumped up again to 177lbs per cylinder. Now we're cookin!

 

And it now doesn't take 22* of timing advance to get it to crank over and run!