high/low compression question

[ross1]

in the hanes manual for an 89 it says compression should be 156 psi while doing the tests i got the following for my cylinders
1 170-180
2 170-180
3 135 dry 160 wet
4 170-180
5 170-180
6 190-200

not a very detailed gauge so these numbers are approximate but also looking through the haynes for a 90-92 the compression should be 171.
and plugs 1,2,6 were drenched in oil on the threads not so much up top so i don't think my valve covers are leaking since i redid them about a month ago

what i'm trying to figure out it how do i check or can i check without pulling the head as to whether it's
a. worn exhaust lobe on cam (don't think so since it idles fine)
b. carbonized (can it be cleaned without removal) if so what chemical is recommended
what is a leakdown test.

i don't know that it matters for this problem but mods/maint.
new hoses/gaskets throughout most of the engine HKS 1.2mm bead type
jic bullet exhaust
defcon dp
hks bov in conjuntion with factory one (hks was sticking in the winter and i still haven't removed the stock one since it's warm again)
new wiring harness

any help appreciated
ross

 

[Bishop92t]

You could check the valve clearances without removing the head or do a leakdown test...but that's about it. I'd take the head off and bring it somewhere to get pressure tested, could just be a bent/leaky valve, valve stem seal, etc.

 

[souprat]

a leakdown test is when you set the cylender you are testing to tdc and through the spark plug hole you pressurize the cylender. then watch your pressure gauge and see if it drops. if it does listen for air in the dipstick(ring problem), at the tb and exhaust(valve problem). i think theres a writeup in the referance section on how to make a tester and do a test.

EDIT: when i did my test i got 180 on 1-6. your numbers sound normal except for #3 and #6.

 

[ross1]

thanx guys, i read the link at the bottom of bishops sig thats why my question was done, and so far it seems to work as i got help from peoples names i respect here...

thanx again guys,
ross