compression on flathead
 

i have a 8ba that ran perfect. Then noticed started to smoke out the exhaust when you let off throttle. Then started to run a little rough. Did a compression check and all the cylinders were between 180-190. Any ideas thanks.

Re: compression on flathead
 

I'd like to know more about that engine, 190# cranking compression? what is in the 8BA engine? bore, stroke, cam, type of heads, pistons clearance from top of piston to head, how any miles on the engine? Interesting. Walt

Re: compression on flathead
 

I'd be tickled pink to have those numbers!

Re: compression on flathead
 

I think you may have a compression gauge error. Stock to slightly modified pressures are about 90-110psi. Regardless, your pressures are consistent and that's good.

How you've driven this car and running condition may be the cause of what you're experiencing. Driving slow and careful or for short trips with carb adjustment problems can cause the rings to load up with carbon and cause the oil control rings to become stuck. This will cause oil smoke either upon acceleration or deceleration.

You may want to take it out on a back road and wind it up through the gears. If it then runs better, a close look at the carb may be in order.

Lonnie

Re: compression on flathead
 

Might try running a can of Seafoam through gas and crankcase. I had some smoking a couple years back and put seafoam in both gas and crank. So far, no more smoke.

Re: compression on flathead
 

If this is a stock engine with those compression numbers you can probably shovel the carbon out of those chambers.

Re: compression on flathead
 

Never saw a compression test that hi, yet.