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Slots in Series A head vertical fins

vincenttwin

Well Known and Active Forum Website User
VOC Member
I have the usually crack between the spark plug hole and both valve seats on my cast iron A head , I do not have the slots talked about in Oct's MPH Tech Report by Bill Parr,
that is meant to stop the crack from happening.
Does anyone have an head that has the slots and could send me an picture of them, and do they really work.

My poor old valve seats are so recessed into the head that you can not take the head off in the frame as the top of the valve hits the cross tube of the frame.
New seats to go in, the new seats will be further out into the dome of the cyl head it looks to be about 1/4",
, So I guess I will have higher compress and better return of the valves by the springs after the job is done..

thanks
Peter Allen
 

vincenttwin

Well Known and Active Forum Website User
VOC Member
Brian
It must only happen on the higher power singles. mine is up to 8:1 ,trying to get a few more HP
up here at 8000 feet
I will be over for the London to B run , cheering Colin on , I hope to have my Bon the road while there.

cheers
Peter
 

mercurycrest

Well Known and Active Forum Website User
VOC Member
Peter,
My original head has the crack, and like yours, it had sunken seats (as it does again). When whoever rebuilt it put inserts in, that fixed the problem with the crack.
NAPA has an entire catalogue of valve seat rings to choose from...... pick some good austenic cast iron ones.
Cheers, John
 

vincenttwin

Well Known and Active Forum Website User
VOC Member
Brian , yes a few folks do live above sea level , its fun trying to remember which jets you have in when you take it to lower elevations.

180 main up here and I go up to an 210 at 1000 feet and below.

peter
 

vincenttwin

Well Known and Active Forum Website User
VOC Member
Bruce
Yes they do in the form of a FCU , fuel control unit. .

When I first got my A running up here in Colorado , It ran very rich , not enough air and too much fuel, so take a little bit off the slide (belt sander) and put smaller main jet in it ,runs great now , but the first time to Texas ,got it very hot and seized
it , 2nd time I figured it out , put a bigger main jet in it,
cheers
Peter
 

vincenttwin

Well Known and Active Forum Website User
VOC Member
Roy yes you can get a new head from Conways, but that would take the fun out of fixing the old one and if replaced all the old stuff I would soon have an 2011 Vincent.

So far no one has seen an head with slots cut in the vertical fins.

cheers and Happy New Year.

Peter
 
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