2.7 compression
 

G'Day All

just did a cold compression test of my 2.7

i dont have much history on the car other than it has been rebuilt some time in the past

i runs well revs well no smoke seems generally good all round

im about to remove the engine and transmission and everything else for a full body restore thats where my money is going at this stage

anyway back to cold compression i got approx 100psi + - 5 across all 6

not sure if this means a top end pull down any thoughts

Regards Michael
http://forums.pelicanparts.com/uploa...1327913202.jpg

First off, it apears you have the wrong coil in place. With a CD box, you require a Bosch 001.
When you warm up and seal you should have 145# or slightly better. The 100# cold with the +/-5 is good all around for cold as there is enough compression for ignition.
Bruce

coil
 

yes i have been told about the coil i will be replacing the ignition system during overhaul.

are you suggesting that simply by bringing up to operating temp an increase of up to 45psi

i was also told that doing a cold compression test with kj intact reduces the air flow therefore reducing overall outcome.

does that sound right

regards michael

Could be the cranking speed is lower than normal or the engine is tired (worn rings).
Squirt a teaspoon of oil into each cylinder and retest. If the compression increases close to normal, I'd suspect the rings.

Sherwood

my 2.7 with 8.5 CR pumps 150 cold (6 bumps) - and hits 75 on the first bump at 60*F

my 2.8 with 10.5 CR pumped 175 with 75 on first bump at 70*F

.

i suspect a set of ring are in order hopefully not much else as all my money is going on body at this stage

Make sure you have the throttle fully open when doing the compression test.

A closed or partially closed throttle will depress the readings.