valve lash
- Thread starter mini drag bike
- Start date
- Tags lash valve
Wow..you have proven the whole science and automotive community incorrect:doah:.....till then...check Affordablekarts.com.....its also in ther DIY section. Set cold....intake .002 and exhaust .003 . Roll motor over and recheck. Then install valve cover and run. Very basic and doesn't make it any simpler. :thumbsup:
I am Not saying that the manufactuers lash settings are incorrect, always go by the manufacturers specs!
What I said was that I agreed with prowler about the expansion, The lash DOES grow when hot because the block and or heads expand with heat increasing the lash clearance.
Not looking to argue or debate here, just trying to get the correct information to the original poster, that is why I ended my statement with the suggestion of calling a free tech line at a cam grinders such as Lunati Cams to verify this..............
What I said was that I agreed with prowler about the expansion, The lash DOES grow when hot because the block and or heads expand with heat increasing the lash clearance.
Not looking to argue or debate here, just trying to get the correct information to the original poster, that is why I ended my statement with the suggestion of calling a free tech line at a cam grinders such as Lunati Cams to verify this..............
Just a basic manufacturers spec and procedure. When it comes to extreme builds or specialty cams and roller rockers..things very. Just providing basic info for a novice builder because most on here are really new to all small engine design and repairs. With stamped rockers and basically stock motor...manufacturer specs work out the best.
Ha! I was wrong! According to one well known cam MFG, when HOT values are listed, use this chart to compensate for COLD settings:
THIS IS NOT INTENDED AS A SMALL ENGINE GUIDE!!
Iron Block Iron Heads Add .002"
Iron Block Aluminum Heads Subtract .006"
Aluminum Block Aluminum Heads Subtract .012"
The obvious inference here is that aluminum expands so much that the valve train expansion is redundant.
THIS IS NOT INTENDED AS A SMALL ENGINE GUIDE!!
Iron Block Iron Heads Add .002"
Iron Block Aluminum Heads Subtract .006"
Aluminum Block Aluminum Heads Subtract .012"
The obvious inference here is that aluminum expands so much that the valve train expansion is redundant.
Well, you know how it is. Guys like me who have been wrenching on engines a long time in the back yard are stuck in the past. :thumbsup:
That valve lash "rule" used to be one of the axioms. Set her loose to not bend push rods, get her hot and set lash. Like on hot rod boats when you don't want to let it sit over the winter with spring pressure on it.
As you probably know, most of the aluminum motorcycle engines out there have gone to OHC with shims inside of cam buckets. That was a cold setting.
OK, done with excuses. Sorry Cheezy, I had to come clean with my lack of knowledge on clone OHV's-
That valve lash "rule" used to be one of the axioms. Set her loose to not bend push rods, get her hot and set lash. Like on hot rod boats when you don't want to let it sit over the winter with spring pressure on it.
As you probably know, most of the aluminum motorcycle engines out there have gone to OHC with shims inside of cam buckets. That was a cold setting.
OK, done with excuses. Sorry Cheezy, I had to come clean with my lack of knowledge on clone OHV's-
Well, you know how it is. Guys like me who have been wrenching on engines a long time in the back yard are stuck in the past. :thumbsup:
That valve lash "rule" used to be one of the axioms. Set her loose to not bend push rods, get her hot and set lash. Like on hot rod boats when you don't want to let it sit over the winter with spring pressure on it.
As you probably know, most of the aluminum motorcycle engines out there have gone to OHC with shims inside of cam buckets. That was a cold setting.
OK, done with excuses. Sorry Cheezy, I had to come clean with my lack of knowledge on clone OHV's-
That valve lash "rule" used to be one of the axioms. Set her loose to not bend push rods, get her hot and set lash. Like on hot rod boats when you don't want to let it sit over the winter with spring pressure on it.
As you probably know, most of the aluminum motorcycle engines out there have gone to OHC with shims inside of cam buckets. That was a cold setting.
OK, done with excuses. Sorry Cheezy, I had to come clean with my lack of knowledge on clone OHV's-
Spend some time on Bob's 4cycle and you'll find that just about all the clone racers will set there lash to as near zero as they can (cold). The lash does grow as "these" motors get hot. And that growth in lash is lost power to people that work every part to a min/max spec. I know it seems backward from what we've seen in other engines but that is how it is.
The .002/.003 is the factory spec but set it at that cold, then run it and check it and it will have opened up.
The .002/.003 is the factory spec but set it at that cold, then run it and check it and it will have opened up.
I am on there...if you really wanna get technical. Then what kind of valves..stainless? factory? What kind of seats? Standard? Race? What kind of cyl head? Aluminum stock? Race? Modified stock? What is the valve spring height? Standard spring? 18lb.? Duel spring? More? What kind of rockers? Stamped steel? Rollers? What kind of push rod? Steel? Aluminum? Chrome moly? How far is the piston in the hole? which head gasket are you running? which piston? Flat? Dished? Raised? What can is it? Was it degreed in in? Is it advanced or retarded? The list of factors is endless. In other words....KEEP IT BASIC. Most people have no clue on most of what I just said and will never check it. And depending on metals...expansion is different. Standard metal valves and standard metal push rods in the clones tends to expand and close the gap..which is why the manufacturer recommends that spec. Have a good day:thumbsup: