|WYG|SS

im going to do a compression test on my 4.9l. what should the readings be around?

87Ford

all should be within close psi of each other like if one is 150psi +-15psi is about ok tolerable but your looking for like 150 154 146 thats good but if you see like 120 then 150 you have a problem

dr_bowtie

make sure when you do a compression test that all plugs are out and the throttle is wide open...unhook the coil and the injectors or pull the fuses..

91351

your compression is 8.8 to 1

dr_bowtie

not near enough...with that long of a rod you could easily get away with 10:1 with the timing they have mapped in the ECM...

91351

you confused me and i was tryin to be a smart ***

dr_bowtie

Joke backfired then eh'?

what part confused you....?

91351

are you saying that a stock 6cyl has 10.1 to 1 compression

dr_bowtie

No...you said it has 8.8:1 correct...?

I said not near enough and that it could handle 10:1 easily on the factory timing maps....with the rod length the engine currently has...and a bigger flowing head...

Just meaning 8.8:1 isnt enough...not near enough...

91351

ahhhhhhhhh gotchya