this may be a dumb questions, but are the valve clearance specs and adjustment still the same with the big bore?

 

yes, it is.

 

^^Are you sure Scott?

I thought that Bill said there was less clearance between the piston at the top of it's stoke and the valves with the 351.

 

My response is based on multiple other posts saying the valve clearance spec does not change with the big bores, per their discussion with Mr. Blue. I don't see any reason why adjustment would be any different.

Anyone know differently? Please let us know.

 

Zomby Woof probably knows for certain...hopefully he'll see this thread.

From my pea-brain point of view, I cannot see how the big bore would change the valve adjustment settings. I mean, you aren't changing lift and duration settings of the valves themselves...it's just a piston change...and it's not a crown-shaped top.

 

jhoff, there may indeed be a closer space between the piston crown and the valves, but I'm sure Bill designed the piston to operate just fine in the existing environment. Changing the valve adjustment spec...I'm guessing you mean reducing the valve clearance...would diminish the performance of the stock cams and not capitalize on the displacement gain. And if I understand correctly, Bill has tried at least one set of hotter cams on one of his engines which bring higher lift into the mix.

 

FWIW the relief cuts in my 331 piston were quite a bit deeper than the ones on the stock piston... this is probably why the valve clearances don't change ?

 

Just chiming in with my specs. The valve clearances are the same for the 351. I now have a 124 DJ main a 35 pilot at 1.5 turns out, with the starter circuit drilled out the needle is on # 3 and the bikes starts instantly, runs very clean and pulls hard all the way to 8k. The tail pipe looks much nicer than before I leaned it out. I have the snorkel off but the air box top is still in place. I am at sea level.

 

great thanks for that gives some confidence in leaning up a bit potentially. What is your elevation?