Picked up a set of sbc heads that I was told came off a higher mileage car. I did a weep check and within 2 days almost all the gas I used to fill all the chambers up with has leaked out from all of them. What exactly does this indicate and what can I do to remedy this. I have heard that "lapping in" the valves may work. Any thoughts?
Dumb question about checking heads
- Thread starter Sandmann
- Start date
I haven't heard of doing a test like that. How exactly is it done? I would think the gas would evaporate somewhat quickly.
I think lapping the valves would never hurt. I would definitely do it if I was reusing a used set of heads. Checking the heads for cracks and warping would also be important.
I think lapping the valves would never hurt. I would definitely do it if I was reusing a used set of heads. Checking the heads for cracks and warping would also be important.
If your gonna check the heads that way use penetrating oil. it won't evaporate like gas will, and if it last 2 days i wouldn't have a problem using those heads.
bowtie81 said:
Thanks for the advice. I have used the oil instead and they have been sitting for almost a week now and no loss of oil at all. Not bad for $20 "running" heads \
/
Good deal. It's worth replacing the valve seals in the heads now, while they are on your workbench.
It just determines that the valves are sealing all the way in the seats. If its sat for 2 days with oil and no leakage you should be good. Most machine shops I have seen will put vacuum to the ports and see if it holds that way. Either way you are proving the same thing.
I know this thread is kinda old but, it IS informative.
I have a engine that hasn't ran in 6~8mo.
Now the situation...I was checking, "valve install height" and when I hooked the air up to the spark plug port, air was pushing through the valve seats on "some" of the valves. Would this happen from the engine sitting and the valve not being opened/closed in quite awhile while...or do I gots a sealing problem?
I have a engine that hasn't ran in 6~8mo.
Now the situation...I was checking, "valve install height" and when I hooked the air up to the spark plug port, air was pushing through the valve seats on "some" of the valves. Would this happen from the engine sitting and the valve not being opened/closed in quite awhile while...or do I gots a sealing problem?
Oh yeah. Forgot to mention that. All the rockers were off so, no valve events going on...all valves shut...but, obviously not sealed tight. I "personally" think that they are ok since the engine hasnt ran in a good couple months.
I "personally" think that they are ok since the engine hasnt ran in a good couple months.I could hear air from all of mine on my current motor :? Granted I pretty much just took them apart, cleaned them, put new valve seals in, & reassembled. I had to remove the springs for one thing or another after the engine was together, that's when I heard it. Engine's run fine for me the past two summers, but when everything comes apart for new springs, studs, etc. I'm doing some lapping.
