Here's the situation, 1990 Redline marine jet boat engine,basically stock has a performer intake a straight up timing set and a marine distributor no vacume advance. an engine builder in Spokane tore it apart to check the engine before installing in another jet boat said all it needed was rings,rods and mains ok! get it back put it in and it wont run off idle without popping through the intake , checked ignition wiring goood checked distributor not getting any advance out of it changed distributor.started it backup same thing! tore the timing cover off 2.5 teeth off on the cam retarded.(some engine builder ) changed that, put it all back together,same thing, god bless America what the hell! sitting scratching head taking more of my very thin hair to the grave! Ok now questioning the guy who put it in,He say the only thing he did different was put a ballast resistor in line for the coil ,checked that all out and found he had the distributor wired through the resistor! now were getting some where fixed that and no more back fire YIPPIE ! So I set the advance to a conservative 26 degrees and (no more than 30 on a marine engine) and we went through the pace's now we cant get more than 2900 rpm's!!!! upped the timing to 30 degree's the same should be able to get at least 3500 out of it. I have done everything I know external to fix this thing ! now what????? compression is 140 pounds all cylinders!

 

what timing doing with timing light? maybe some more timing. Is your carburator opening up all the way. sounds like only half a carb working?? had vacume sec not open and do same situation?? good luck and check back with us.

 

Timing is dead nuts runs up to 26 degree's with the advance , and the secondaries are working fine!

 

It sounds to me like you are still having some type of ignition problem. Is the motor using the stock duraspark II ignition system?

 

sounds to me like you got about 8 to 8.5 compression ratio..should have 9 to 9.5 ratio are you sur that is a marine engine???it also sounds like you have to big a pump on the engine.. if the guy that changed the engine from one jet to another,did he change the pump with it???

 

hi it's me again;;;check the intake manifold by the distributer and see if there is any rtv sealant that looks new..if there isn't then he did not change the rings,cause you have to pull the heads and intake to get the pistons out to put rings on them.. it sounds like the guy put a car engine in and put your valve covers and carb on that engine witch puts out about 245 ponies at about 4500 rpm..boat mech are not as honest as they should be...easy check for blow-bypull the pvc valve out of the valve cover pan and see if there is a puff of gassesor a steady stream of "air" coming out of the hole..no air no blow-by=good rings