HaxbySpeed

Nothing. Take it for a good hard run and recheck your compression with it warm. Make sure all your plugs are out and crank it till it stops climbing on the gauge. Do every hole the exact same way and if you have one that's more then 15lbs different you can do a leak down test on that cylinder, recheck your valve lash, or do a wet test.

vetteguy

I don't know how long it takes to break in a freshly rebuilt motor but I would imagine it is barely broke in. I haven't had much running time on it since it has always had some sort of problem since I got the motor back. The motor is now running the best it has ever ran since I got it back. Well it ran well when I got it back less the oil leaks, vacuum leak and cooling water getting into the oil. Now that I've got that fixed and the valves adjusted it's running the best it has ran in a long time. Less the compression varience. I couldn't imagine it would be anything too crazy.

I can do a test with the motor warm but I really don't see how that will will change my cylinder pressures any more than with a cold test. As far as the pressures between cylinders is concerned I would think that the differences would be pretty close to the same. I'll check it out though and hopefully maybe it will improve...

I don't see how leaving it as is will cause any damage but I don't want to take any chances either... I don't want to afford another engine rebuild because a piston hit the valve.

fireboatpilot

Your tenacity and courage to jump in there and try to do some of this work is commendable. However it seems a little obvious that you lack some of the understanding of a few principles. Checking your compression with a warm engine right after the engine has been run gives you a more accurate reading of whats going on while running. Heat has expanded parts that will seal better. Oil has circulated and coated cylinder walls, pistions etc what improve compression as well. Valve seals, seats and guides are at operating temps so on and so forth. If your readings are still far apart on any cylinders then something else is worng and the engine should be diagnosed and fixed before something BAD happens. PS Auto engines are very different when assembling than marine engines and some parts are also different like gaskets, clearances, cam specs etc. It seems that your engine builder, although he may be a great auto engine builder was not familiar with a marine engine. I had a similar experience with a local race car engine builder and one of my older engines. I'm sure his rebuild of my engine would have worked out well in my race car but lasted about a week in the boat. My fault for not doing my research and failure to ask him the right questions. I know more now.

fireboatpilot

As for break in time, there are many schools of thought on this as well. Some guys break them in on a dyno, not that expensive and tells you alot about your investment. Easier to find any problems and correct them than working on it in the boat. Varying the rpms, speed and load on the engine every minute or so for the first hour has been used as well. Do a search on here for engine break in. Chances are though that whatever damage has been done IF ANY isn't going to correct itself at this point and will need to be repaired. Keep us posted.

dereknkathy

if the valves are sticking, that could happen. that's why i feel you should pull the heads. how did these valves get adjusted so tight you had no compression on 4 cyls anyway?

vetteguy

I followed the opposite cylinder method listed on Century Performance's website as I had mentioned above. To quote it, it says:

"Intake Valve Adjustment: ENGINE OFF!
■ with #1 cylinder Intake Valve at full valve lift .... Adjust #6 Intake Valve
■ with #8 cylinder Intake Valve at full valve lift .... Adjust #5 Intake Valve
■ with #4 cylinder Intake Valve at full valve lift .... Adjust #7 Intake Valve
■ with #3 cylinder Intake Valve at full valve lift .... Adjust #2 Intake Valve
■ with #6 cylinder Intake Valve at full valve lift .... Adjust #1 Intake Valve
■ with #5 cylinder Intake Valve at full valve lift .... Adjust #8 Intake Valve
■ with #7 cylinder Intake Valve at full valve lift .... Adjust #4 Intake Valve
■ with #2 cylinder Intake Valve at full valve lift .... Adjust #3 Intake Valve

Exhaust Valve Adjustment: ENGINE OFF!
You will notice that this is the same procedure and sequence as the intake valves listed above. Only now you are adjusting ONLY the exhaust valves the same way.
■ with #1 cylinder Exhaust Valve at full valve lift .... Adjust #6 Exhaust Valve
■ with #8 cylinder Exhaust Valve at full valve lift .... Adjust #5 Exhaust Valve
■ with #4 cylinder Exhaust Valve at full valve lift .... Adjust #7 Exhaust Valve
■ with #3 cylinder Exhaust Valve at full valve lift .... Adjust #2 Exhaust Valve
■ with #6 cylinder Exhaust Valve at full valve lift .... Adjust #1 Exhaust Valve
■ with #5 cylinder Exhaust Valve at full valve lift .... Adjust #8 Exhaust Valve
■ with #7 cylinder Exhaust Valve at full valve lift .... Adjust #4 Exhaust Valve
■ with #2 cylinder Exhaust Valve at full valve lift .... Adjust #3 Exhaust Valve"

I used the "jiggje" to move the push rod up and down rather than the spin method. When I found zero lash I gave an additional 1/2 turn of preload on the valves.

dereknkathy

ok, take the 1/2 turn off. set them like solid lifters. now you are sure they aren't holding the valves open. now do compression test and see whatcha got. something was holding valves open. either they were sticking from sitting, the lifters pumped up, or they were set too tight.

vetteguy

I'll try that tomorrow and see how that works for me and I'll post the results.

Thanks again!

vetteguy

I had reset the valves and only used 1/8th of a turn. I ran the boat up to temp and went to run the compression test. I tried to crank the motor and the valves were so tight it was tough to crank the engine hard enough for me to tell if I had a reliable compresion reading. Well I got one on one of the cylinders but I can' say it was a true reading because of how hard it was to crank the motor. I only ran the test on one of the cylinders and the test read less.