502 reach only 4200 rpm ?????
 

My friend reworked is motor 2 week a go ( the oil pressure drop and the buzzer sound he stop the engine and after some investigation he find the inlet of the oil pump decoupling and he decided to change piston and ring and the bearing of cranck , big job ....) and reput the motor in the boat good compression and when he go to try it he never be able to reach is maximum rpm , it is what we check

1- put brand new plug
2- check the pressure at the fuel rail 28 psi (with the return close)
3- 8 dergree timming

Anybody have any idea ?

I know my english is not very good but ask and i will try to respond the best i can , because i hang around about long time and i alway's found what i need , my friend desperly need your help (here in North the season is very short ....)

Best Regard's

Re: 502 reach only 4200 rpm ?????
 

sounds like its not getting spark advance.

Re: 502 reach only 4200 rpm ?????
 

If it is a 502 Mag the fuel pressure should be 38 psi or 42 psi depending on the year.

Re: 502 reach only 4200 rpm ?????
 

mine is 43 psi

Re: 502 reach only 4200 rpm ?????
 

what type of boat & what are yuor drive ratios & what propellor is fitted . a good wot op range is 4600-4800 rpm. any lower and detonation may result

Re: 502 reach only 4200 rpm ?????
 

Ok this is the update , like HOTTZU98 say , the advance timming is not right , my friend made the adjustement , with the help of another mecanos , and every body is happy , thank's a lot for all the info you bring here you rock
Ok it's the time to schedule our vacation in the north of the lake michigan CIAO