Early 218 compression reading

[mach0415]

The engine in my 1947 P15 is actually a 1939 D13 218. I understand that these earlier engines had a lower compression ratio. What is the acceptable compression reading range on these engines?

I adjusted all the valves' clearance to .014" while cold and found the reading to be 85psi before and after the valve adjustment on all 6. Is .014" correct for the earlier engines, as well? I got some tappet noise after adjustment, so I will need to recheck I will try another gauge, but it does have some blowby through the ventilation tube, so I can assume rings is the culprit. It seems this engine has suffered from a lack of maintenance over the years, since there was a good bit of sludge in the pan and behind the valve covers.

Note - I also noticed slight bubbling of oil residue where the head meets the block at the head gasket on the passenger side of the engine (between #2 and #3) while it was running. I am assuming I need to either re-torque the head or replace the head gasket.

Edited October 29, 2011 by mach0415

[Rusty O'Toole]

A 39 engine had 6.5:1 compression ratio, so a compression reading of 85 PSI is quite good. The main thing is that it is uniform on all cylinders, or close to it. That means your engine is in good shape. Usually if the compression is good and the oil pressure is good, your bearings, pistons, rings, and valves are all good.

Sometimes if an engine has been out of commission for a long time it will burn a little oil until it gets a few hundred miles on it.

Try retorqueing the bolts, if that does not work a new gasket will be needed.

My data only goes back to 1942 but .008 (intake) .010 (exhaust) was standard on Chrysler built flatheads. It was supposed to be checked hot.

[mach0415]

Thanks for the info! I will go and readjust the valves to get rid of the noise. This puts me more at ease, at least. I do believe I have them adjusted too loose.

[Rusty O'Toole]

Complete instructions can be found in the Technical Tips section.

http://www40.addr.com/~merc583/mopar/framesets/techtipframeset.html

[greg g]

loose is better than tight. are you sure the top of your tappets have not been concaved from wear, If they cup, you can not get a true reading or get them quiet.