MCCULLOCH The official McCulloch thread

[the 28inch mac man]

Hello, may I ask how I would go about pressure testing. Do I seal at manifold in air box and exhaust. If this holds then check off and if not do I remove tank and repeat with bare intake . Next if fails I remove clutch and flywheel ( soap and water).
I will also get a supply of seats as Mark stated the swelling makes the Flat back unpredictable from day to day.
I do want to run with the flat back but am hedging my options, picked up two tillotson’s. The 63F is in great shape and the 87DT is rough but will get cleaned up. Also aware that a 090 carb can be used as well.
The sdc seems to be a little out of reach.

I've been thinking about that 797. Is this the same carb you ran saw with when you had the tank off? If it is it should be pulling gas. I there any chance the impulse hole between the tank and reed plate is blocked?

 

[Sloa]

I've been thinking about that 797. Is this the same carb you ran saw with when you had the tank off? If it is it should be pulling gas. I there any chance the impulse hole between the tank and reed plate is blocked?

Yes same carb, before snow fall ( three days) attempted to pull over . There is a disclaimer/disclosers to be said. Tank is new old stock which I believe is a 440 maybe?. No decompression machining Or enforcement in a few key placement for it to have factory decompression. Also intake manifold must have been for a d-port. My 797 tank is in relatively good shape but I did not want to seal with red kote . So looking off old tank to knew, filled in intake with jb weld and have a working decompression lever, carb kit from cinic( old diaphragms in working condition but rather pregnant)Runs on prime so I know the reeds open/ close. Filled tank with gas (does not leak) five days total with no sign. Gas poured from line so no obstruction from filter. Put red plastic zip tie down pulse hole and made sure I didn’t seal up. I am thinking the carb to manifold gasket I was using was not thick enough as well the impulse hole I will make a little larger. Check valves and make sure all clear. Spare needle o-ring seats if they swell from day to day as Mark has observed.

 

[Sloa]

So if I take back down to block and pressure test then build back up and do a test once again no more guess work. But hope a carb problem as have a replacement and will be comparing idol and response. Liked the response from flat back, rough at first but it was like the machine had a memory. Had to hook my finger forward and pull back trigger, half way threw break in it had full response with it finding idol quickly after acceleration with no assistance.
We have almost two feet of snow with another foot in the next couple days coming. Take the work saws outside when time to tinker with gas but not wanting to loose pieces. Also will change old fuel line to tygon. I have a super 6-10 and really enjoyed using it up until bar tensioner buckeled up on me. It has a small carburetor and running .354. So large carb new sprocket and wrap handle from Mark if he still has and a 20” 3/8 bar chain.
Happy thought, spring means time for the McCulloch’s so want to be ready. Last summer went south and picked up the 6-10. Hopefully do the same this year. There is a pm 700 , only 600 km away and only local pickup.