Hi
I you have been having a compression discussion with Bill Hoaglan.

I would like more input, I know my compression, I know Bill's point of view.

My compression on an engine with about 700-800 hours is:
Dry #1-50 #2-45 #3-45 #4-55 lbs.
Wet #1-52 #2-46 #3-47 #4-56 lbs.
My valves are set to 8 thou clearance on a warm engine. And my engine runs quite well right now, in my ignorance, I have no complaints.

Bill figures my compresson is way too low.

Could some of you quote your compressions and comment on my numbers. I have searched the WEB and am not finding any data.

Tx

Guy

Where Are You From? Peace River Alberta

Do You own a car built by Durant? 1926 - W5 Model M

The engines of this era had low compression by today's standards as the fuel was poor.So if you have engines designed to run on 'dirty water' these numbers seem fine. At one time manufactuers made 'home market' engines and export engines with lower compressions due to the poor fuel. Too late to actually 'cc' the combustion chambers to find the true compression ratio.Look at it this way- you can run on the cheapest gas available. But Bill Hoaglan has probably forgotten more about engines than I know! Ross

I just went out and did a compression test on my '29 W-4 engine, this engine is in the car that I am currently restoring and was rebuilt by a previous owner, the car hasn't been on the road since the rebuild although I had the engine running last fall, I am sure the rings are not fully seated as of yet.
Dry test #1-60 #2-55 #3-55 #4-60
Wet test #1-75 #2-70 #3-70 #4-75

on the first wet test recording I was getting near 80 but in consecitive tests it dropped back to the above figures.

While the plugs were out I also took off the front valve cover and did the quick camshaft timing check outlined by Carl in his post by turning the engine over until the #1 (or any) exhaust valves just closes, the piston on that cylinder will be at top dead center (exhaust stroke) the piston can be observed through the spark plug hole...It seamed to work and took just a couple minutes.

Where Are You From? Leavenworth, WA / Yuma, AZ

Do You own a car built by Durant? '23 Durant Touring / '29 model 40 coupe