yea 90-100 psi if it still runs your flirting with disaster to take it out, at 120 you might as well get it threw your head in the next year your going to need a rebuild or repower depending on your pocket.
what i dont get is that the motor there is a tag saying rebuilt motor with some numbers on it and the pistons say i think .090 or something like that. i have a 5.0 motor you think that will have power for my boat?? View attachment 92364View attachment 92365
maybe i did the compression test wrong lol. the way i did was i just removed one plug at a time and crank over like 5 or 6 times, is that right? i was reading online and people are doing the test like this, remove all plugs then wot then crank 4 or 5 times so is thats the way i have to do it?
maybe i did the compression test wrong lol. the way i did was i just removed one plug at a time and crank over like 5 or 6 times, is that right? i was reading online and people are doing the test like this, remove all plugs then wot then crank 4 or 5 times so is thats the way i have to do it?
Ayuh,... Pull All the sparkplugs, set the throttle to Wot, choke open, 'n roll it over a few times...
When the needle stops rising, that's yer #s,...
Usually 4 to 6 pumps is enough, but you'll figure it out..
It might take a season, or 10 seasons to get down to Rebuildin' compression #s...
ok so i got some new numbers. 2 4 6 8 dry is 180 and wet is 200 and 1 dry is 155 w180 3 155 w180 5 160 w180 7 130 w160.. are them numbers ok? i think i must of adjust 1 3 5 7 to much cuz i put in a new head kasket on that side....
ok so i got some new numbers. 2 4 6 8 dry is 180 and wet is 200 and 1 dry is 155 w180 3 155 w180 5 160 w180 7 130 w160.. are them numbers ok? i think i must of adjust 1 3 5 7 to much cuz i put in a new head kasket on that side....
So, if I were to summarize, would it be right to say that the 2468 cylinder bank is all 180, and the 1357 bank is about 155 except for #7 which is 130. And you changed the head gasket on the 1357 bank.
You can expect the cranking pressure in psi to be about 17 to 20 times the value of the compression ratio. An engine with a CR of 10:1 should generate between 170 and 200 psi. Most boats have CRs in the 8 - 9 range, you will have to look yours up. And a good rule of thumb is that PSI readings within 5% of the highest and lowest cylinder are very good, 10% - 20% is runnable, and anything over 20% indicates the need for the problem to be found.
