23hp Vanny help

gn386

So here is the run down on the equipment that's been added, double valve springs and billet retainers, modded head gaskets (1 layer), dominator 2bbl carb, light polishing and port matching on the heads, E3 plugs, and 30 deg key on crank. Went to start it up today and would not run, backfires through the carb and has a good thump on the exhaust never really fired. Tested spark and that looks good, compression is right at 65lbs(think is good since it has not warmed up), pulled the cover and timing marks are lined up and gas is blowing out of the carb so it seems like fuel is a non issue. Can't figure it for the life of me, can the lash be wrong at the factory setting? Any help advise/ help is appreciated.

BGW

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csason

I would pull the 30 degree key from the crank and start there..

just off the bat.

I would also make sure I had the carb trimmed back so it didn't keep the chambers too wet till I got it running.

just a guess.

Dave in VA

That seems a bit low.

gn386

Well rings are not seated yet and the manual I have says that brother never reply specified compression . Matter of fact the only example they give is a percentage of varied compression between the cylinders. But I am not sure I was thinking that it might be low since on a car double that can be seen. I am pulling the flywheel tonite to check the keyway, I have heard those shear as well and its not too uncommon on a new motor.

blake80

what did you set the valve lash too and how did you set it?

gn386

Confirmed- the 30 degree keyway from cpp has broken. I need to call tomorrow. As far as the lash it was set to.005 or something like that using a feeler guage. Guess I need the new keyway to start..... Unless I can just advance the gears. Anyone?

blake80

That happened to me also when i first put it in my motor but i figured out why. When i put the fly wheel back on i didn't tighten it to spec.

gn386

Definately could see that... I torqued it to the 150lbs but **** if the compression bumps hard. I can almost remember when it probably broke since the first crank bumped really good then the backfiring started and the tone changed. Everything I read says it is definately worth putting in, but there has to be a better way such as degreeing the cam or something since the motor is split open.

blake80

If you put the high performance cam in, you may need to open the valve lash to. 007. If your going to call tom, ask him about it. But the key is just to set the timing, but the torque of the bolt is what will actually hold the fly wheel in place and not the key.

CART-ZILLA

I used to run my go cart motors without a key and just tighten it down tight..