1987 Looper v4 140 RPM only 4000

[nymack66]

I remove a SS 14x3/8 x 19 only going 3000 to 35000 rpm, I install a 14.8 x 17 aluminum it is a 15 spline prop 3 blade
Remember I am restoring this boat I have no base line to work with , Please see www.nymack66.com for some photo etc , I am stump in regards as to why the engine is not giving me the RPMs everyone is talking about !!

[THEFERMANATOR]

I would try a 15 pitch stainless wheel myself, but somethin don't sound right here. Are you sure your hitting on all cylinders under load? Is the timing set to 18 BTDC @ 5000 RPM's(very important that it is set at 5K as the power pack has about 4 degrees of advance in it with RPM due to trigger and stator outputs). Loopers are CRITICAL of timing. I would get you a bo0ok and go through the carbs top to bottom, make sure the plastic bodies are not warped. Then set the timing and go from there. To bad you aint closer, I'd help you figure it out as I'm fairly proficient with the V4 90 degree loopers.

[nymack66]

Timing and link and sync was done by local dealer Boat Tune. I can only assumed it was done correctly
Carbs re-built inside out
Carburetor 397907 & 397908
Idle Air Bleed #28
High Speed #61D (I am not sure what he replace this jet with )
Intermediate #16

[THEFERMANATOR]

Those sound like the early 87 same as 86 carbs. These are the ones I am running. I'm jetted with 63D's main, 14's intermediate, and 34's(or 36's not 100% certain on which) for idle. This works excellent in mine running 50%1 pre-mix with PENNZOIL synthetic blend oil. But I have some very mild porting done in the exhaust ports behind the sleeves, and my air box has been slightly ported as well and I have a .020 over bore. I still trhink there is a problem with your link and sync or in the timing department. These engines are CRITICAL of timing. 2 degrees to much and meltdown happens, 2 degrees not enough and your 140 is a 115. THEY HAVE TO BE DEAD ON! I learned this one the hard way.

[nymack66]

Here is what installed
Idle=28
High=64D
Intermediate=Starboard side=16
Intermediate=Port Side=20
Note per the Parts Manual this odd sizes for the Intermediate is normal for this engine
I will test it on the lake hopefully on Sunday

[nymack66]

I forget to mentioned I change the High Speed jets back to 61D per repair manual , I will test and post the results