Indmar 351W 3000RPM max? UPDATE.

[1000dollabill]

Well for anybody that read my first thread

http://forums.iboats.com/showthread.php?t=213310

Still no solution. Except now the boat does not backfire. Just sails along at 3100 rpms. even manually fully opening the secondaries will not make it climb over 3100 rpms. just makes it suck a lot of air. Still no backfire.

new ignition system.
new fuel system.
135 psi in all cylinders.
correct prop in like new condition.

I don't get it.

Please help with any ideas.

Thanks,
Bill

 

[Reel Poor]

Re: Indmar 351W 3000RPM max? UPDATE.

Did you do Dons fuel system test? If so what were the results.

A worn cam lobe(s) would also cause the poping.

 

[1000dollabill]

Re: Indmar 351W 3000RPM max? UPDATE.

yep, did dons test. Fuel system is 100%. No popping anymore.

Runs like a champ.... to 3100 rpms.

thanks,
Bill

 

[mkast]

Re: Indmar 351W 3000RPM max? UPDATE.

Warm the engine up.
Put a vacuum gauge on the engine, I'm wondering what the reading is at idle?

 

[qaztwo]

Re: Indmar 351W 3000RPM max? UPDATE.

around 3000 to 3300 depending on throttle postion is when my secondaries want to open up, 351w also. You should not have to manually open them, how old is carb, does it have vac or mech linkage to secondaries. Also if your sitting in your driveway they will not open up if vac.

 

[qaztwo]

Re: Indmar 351W 3000RPM max? UPDATE.

I just read your original post, sounds like your secondary side is starved for fuel. I know how I would check it, but its not the safest way. So I will say start at the fuel level in the sec bowl, not the float level.

 

[1000dollabill]

Re: Indmar 351W 3000RPM max? UPDATE.

Well, last two times I checked the plugs the rear 4 were all pretty carbon covered (shut engine off after holding at 3000 RPMS.) Compression tested again and all but #1 were 135. #1 was 150. This was on a cold engine. Oil level was pretty far above "safe" on the dipstick. Changed oil, oil is now at the proper level.

Prop seems to be in good shape with some pitting on the rear facing surfaces.

I'm still lost here. doesn't seem like it's running on all 8. But when I pull the wires off the distributor while running at 1000rpms a noticable stumble occurs.

Could weak spark keep me from breaching the 3200RPM mark? Still need to plumb in a vacuum gauge.

ANY SUGGESTIONS WOULD BE APPRECIATED.

Thanks,
Bill