A motor, mid range, acting lean, until 5500 RPM

[Skoontz]

Had a weird test day today....Motor ran like heck, great speed, and power, until KT backed off a tad then got back into it. The mid RPM had no power, and motor died. Motor would start when choke was out, and when pushed in would speed up. The minute she let off, it would die.

History, carb was boiled and rebuilt before this test. Float set level with carb body.

Fuel pump squirting 2 feet off engine block.

Stumped here.... Seems like some sort of pressure leak in crank case, but, was sealed with Permatex, and, did not see any bubbles with sopa spray....

got any ideas before I yank it apart?

[ricochet112]

How long did you boil the carb?

[Skoontz]

Mike:

Had the carb in overnight, washed with water then used compressed air to blow all the holes, jets, etc.

Some history.

Prior to the carb cleaning, the idle jet was set at around 2.5-3 turns, which, to me seemed very far out, which is why I thought it was dirty.

[ricochet112]

OMC never recommended more than 20-30 minutes in cleaner, it would burn off the sealer coating and leave the aluminum porous.

[bandit64061]

Wow!!!

Had a weird test day today....Motor ran like heck, great speed, and power, until KT backed off a tad then got back into it. The mid RPM had no power, and motor died. Motor would start when choke was out, and when pushed in would speed up. The minute she let off, it would die.

History, carb was boiled and rebuilt before this test. Float set level with carb body.

Fuel pump squirting 2 feet off engine block.

Stumped here.... Seems like some sort of pressure leak in crank case, but, was sealed with Permatex, and, did not see any bubbles with sopa spray....

got any ideas before I yank it apart?

I'm glad i don't have those probs., only prob. had today was chainsaw carb. had to be cleaned as we cut wood, life is sort of like carmele mountain???

[Jack Stotts]

Sounds like the engine is set too rich. What kind of engine is it?

[Kev43V]

any chance its the lower crank seal?

[Skoontz]

Mike:

Do you know what sealer OMC used to seal the Aluminum?

Jack:

The motor is an A stock OMC, .030 over, using Boyeson Reeds. The motor has 5 hours on it since the rebuild, and the 50° hone lines are still in the cylinders.

We are running a 56 jet.

Kev:

When we did the rebuild, seals, bearings, etc were used. I'm supposing a lower seal could always go bad however.

This brings a question though. We used Permatex between the crank cases, the brown goopy stuff. I have tried the soap spray on the seams, and did not see any bubbling, but then consider we had to run very high throttle to full throttle to let the motor run long enough to try and see what was what.

The reason for the carb rebuild was that before, we had OK midrange, but, that low speed jet had to be run between like 2.5-3 turns out from the body, and that seemed way too far in itself.

I'm thinking of making a carb plate with and air nozzle, and using a hand tire pump, or regulated air, like 5-10 lbs to see with the soap if we have bubbles (leaks) going on. Does this sound like a good idea to check?

[Jack Stotts]

Sorry, but I know absolutely about those engines as well as many other things. Jack

[Skoontz]

Jack:

Pleased to meet the acquaintance of another J.O.A.T.M.A.N.

(jack of all trades, master of none)

[ricochet112]

I don't know what they use. In service schools they always said to not boil too long so as not to remove the coating/sealer. I have used a spray varnish/shellac to help out some porous carbs in th past for a temporary fix.

[SeaBat]

Call your local Locktite supplier. I seem to recall (memory is foggy) that they made an anerobic product for sealing porus aluminum castings.
Bill Thomas 36-R

[Tomtall]

Hmmmmmmm

Motor ran like heck, great speed, and power, until KT backed off a tad then got back into it. The mid RPM had no power, and motor died. Motor would start when choke was out, and when pushed in would speed up. The minute she let off, it would die.

Skoontz - Check the crank seals upper and lower and reeds. When KT backed off the gas it created high crankcase va***e which could have caused problems in those areas.The carb soaking overnight should not have affected the carb. If the coating was taken off you can re-seal with spray urethan. The outside coating was to seal the carb. to prevent fuel weaping out onto the outside of the carb. which was a potential fire hazard. This is why they mentioned it at service school. Good luck!

[Skoontz]

Thanks all!

I was leaning toward seals/reeds.

Tom:

Matter of fact, I'm thinking of going back to OEM reeds in the first place.

[Jeff Akers]

Bill, The OEM CC sealer is called "Gell seal II" I use it on all the engines I build, even my MOD stuff and have never had a leak.

It comes in two sizes... 1.69-fl.oz P/N 327361.....or the small size .20-fl.oz P/N 324073

You could most likely seal your A motor with the smaller size, just get two to be sure.