Logo
FULL SITE MENU

Chrysler 318 Optimum RPM for running

B

bhimself

New member
I have just purchased a 1964 Tollycraft with a 318 Chrysler engine. The motor starts easily and runs smoothly.
The compression is good but there is "blow by" at higher RPM.
The previous owner cruised at about 1600 RPM max (often short distances) and claims that this is both ideal and adequate for such an old motor. The mechanic says the blow by is probably due to the rings being gummed up by being run at such low speeds and often
for very short distances. He says the engine can run at 4400 RPM and suggests that cruising and running longer at 2400 - 2600 RPM
with a gas and oil anti gunk treatment added might free the rings and reduce the blow back.
The previous owner is convinced that that would damage the motor.
Anyone have any idea or thoughts about what RPM this motor should be run at ?
Thanks.
Brian:D
 
bhimself said:
I have just purchased a 1964 Tollycraft with a 318 Chrysler engine. The motor starts easily and runs smoothly.
The compression is good but there is "blow by" at higher RPM.
The previous owner cruised at about 1600 RPM max (often short distances) and claims that this is both ideal and adequate for such an old motor. The mechanic says the blow by is probably due to the rings being gummed up by being run at such low speeds and often
for very short distances. He says the engine can run at 4400 RPM and suggests that cruising and running longer at 2400 - 2600 RPM
with a gas and oil anti gunk treatment added might free the rings and reduce the blow back.
The previous owner is convinced that that would damage the motor.
Anyone have any idea or thoughts about what RPM this motor should be run at ?
Thanks.
Brian:D
Click to expand...

Last spring I purchased a lyman with a 360, great compression and oil pressure but would not run above about 2200 rpm (previous owners preferred speed) I took it out and laid the gas to it about 2400 rpm, backed off and did it again, 2600 rpm, again 2800 rpm, again bang, really loud backfire and jumped to 3600 rpm. Has worked fine since.
 
Propped correctly--and not on an underpowered boat--that motor will cruise all day at 2,500 rpms burning about 8 GPH (and last a loooong time).

Jeff
 
Like Jeff says, correct prop with clean bottom should put you in the 4000 rpm range. My twin 29' sedan does 3500 loaded down, semi clean bottom. First and foremost, check your distributors. Original distributors surely will need to be updated with new ones. You will not get full timing advance. That will damage your engine. LOTS of threads on here about that subject. Search and read this forum. LOTS to learn.
 
Back
Top