Just getting back into builds after a long duck hunting season and some real cold shop temps up here - I am rebuilding a 78 that was "pro-built" by a small shop during the chopper hay days of the early 2000's - motor has all S&S lower end in orig HD cases - the knuckle-heads used stroker pistons with a 4.25 S&S stroke wheel set - the shop told the guy it was low compression pistons - those are the most expensive low comp pistons (TRW 2800's) I've ever seen - anyway - pulled the heads apart - the valves were about 040 over stock in overall length and about .010 oversize in stem diameter - guides were ampco - but the odd thing is the exhaust guides were .581 and .583 - hmmm - .581 - WTF - I assume the shop turned down these kibblewhite ampcos on a lathe or crank grinder to this odd OD to fit an overbored guide bore due to loose guides? - anybody know if they ever made oversize guides like .020 over? Kibblewhite makes .025 over but not 20 over - anybody ever come across these longer valves - I have longer thin stem valves but these are .040 longer overall and thicker stem (by about .010) - I checked Evo valves and no dice

 

yea Taiwan tedd ( v twin ) had sold mistakes in valves for years as well as 100s of other things

throw it all away - check this first to confirm that its all junk - at 1/2 cam lift you need degree wheel and dial indicators look at the location of the rocker arm center spot to the valve tip as it relates to the center of the valve

what really wants to happen is the center of the valve to 1/2 the camshaft lift, the rocker arm center of the pad wants to be in the center of the valve - this make the rocker ratio correct and does not push the valve side ways when in operation

you might see staring on the valve top pad - that's incorrect valve spring pressure

you can mike the valve stems and see if they are out of round - rocker arm not centered to cam lift

in extreme eff ups you will see] scores on the push rods as they are rubbing the tubes

you are saying knuckle heads and you posted in the shovel section

knuckleheads do not live in hi compression no matter who tells you otherwise its been tried 1000s of times with a very disappointing ending

I was not able to get 2800 pistons last year when I re did a stroker knuckle so I used the 2900 - 4 3/4 stroke 9 1/2 pistons in a 4 5/8 stroke - the relocation of the pin gave me 8 1/4 to 1 and I used a K Andrews cam 270 duration as the lift was .410 I believe

we make a special lower retainer in the shop that has 2 bottom o rings to seal the springs tin pocket as the paper gasket just does not do it well after a while even when glued

watch your spring pressures and the top retainer to the top cover height ( the cut out for the retainer ) - I have seen the top cover open the valve slightly when tightened

we machine the guides for the blue rubber seals on the intakes only - watch the travel some we remove the bottom of the top retainer, to increase the distance between the bottom of the top retainer, and the top of the seal so it does not hydraulic the oil into the seal

 

AV&V offers guide blanks that we have used many times.
Over length valves seems odd.
Again, AV&V, Manley, PM, all will have correct lengths.
Scott

 

I went to the race shop this morning but none of the guys in the head shop made it in today - I was gonna grab all the guides and valves and post pics - couldn't find the stuff cause they were screwin around wit the stuff Friday - these are shovel heads - I meant the knuckle-heads that built a 4.25 stroker with 2800 pistons - producing essentially no compression - the previous owner paid that shop 4 grand to build the motor - guess I know why that shop went out of business - there was a problem with the rocker geom and stem height - I'm just gonna dump the guides and valves - I could use guide blanks but I think I will turn down Kibblewhite Ampcos to give a .002 tight press fit - I'll try the EV8 stainless forged valves - found a supplier that has some old Kibblewhite sets - more snow here - shop is still cold so buildin will slow again

 

heat the head to 250 at least

AV&V is goodson products I have used them a lot great stuff but pricy

 

good info
Im trying to learn more about shovel head motors, so this is all good info

I am going to post a pic of the heads I have after I removed the vavle springs the guide just fell out.

I took it to a friends shop and they fixed it for me with an oversized guide, he then cleaned the heads and lapped the valves and put all new guide seals

 

 

when they are loose like that the bore is typically tapered and needs to be dressed - you can just blast an oversized guide in - which is what most shops do but I always overbore to ensure the bore is perfectly round and square to the seat pocket - I dont lap valves anymore - modern cutting equipment does not require valve lapping - we pull vacuum on the head and verify this - if you lapped you should check the stem height and shim the springs - add shims to balance whatever the butt height is about 1.50 from the top of the valve guide - those are umbrella seals - dump them - buy Vitons - make sure you buy the correct ones for your guide OD - either .565 or .620

 

ok thanks man

I know he did use shims under the springs and used the viton seals
he said the bore was perfectly round but he did not mention anything about it being tapered, so honestly I don't know if he checked it. It was his thought that the last person that installed the guide used one that was not the correct fit or was not tight enough.

Ive got the motor all back together but i have not fired it up yet because I still have some other things to work on the bike first

 

what I see is performance springs after market and the old style guides that were tooo tall for even a small performance cam

everyone has the soup they like in taste - I like the blue rubber seals on cast iron valve guides - but that is my shop and what we do

that plastic valve seal in my opinion made contact with the bottom of the top valve retainer cracking it

I use that type seal in drag motors we build for the shops NHRA super gas car, as we want some seepage,