'80-'81 valve springs

[gil57usa]

What is different about the '80-'81 valves, springs, etc from the other years?  I have a '81 FXS and want to install a different cam.  I keep seeing references that spring spacing may be required for '80-'81.  Can someone please explain what it's all about?

[HotRodShovel]

I am pretty sure it has to do with the height of the valve guides.  My understanding is that 80/81 had taller guides and therefore needs either new shorter ones or existing ones machined down.  This is a great question.  No doubt the resident experts will educate both of us if I am wrong.   

[gil57usa]

I had a valve job done a number of years ago and the guides were replaced.  I wonder if they're the newer style.  Does anyone know how high the originals are or what the height of the newer ones are? 

[HotRodShovel]

I'm surprised no answers on this yet. Have faith. There are some very knowledgeable people here who can get your question answered. Can you call the shop who did your valve job.  More than likely he got rid of those guide heights.  I think ultimately you might have to remove your heads to confirm this.  Either way, if I were faced with this question and was committed to installing a cam out of stock range, where the manufactures states they are NOT bolt in.....I would pull the heads and have them checked by a qualified shop. 
If things are not properly clearanced the damage can be catastrophic. 
My advice..pull the heads and send them to a good shop. Better safe than sorry.

I'm installing a L51 cam and sent my heads to a friend, highly qualified professional shop to check my heads for clearance because of the radical cam lobes. Also using matching Leineweber springs and they are tricky and need to be seated correctly.  So I practice what I preach.  I'm not just throwing words around.   good luck..

[Hogman]

I'm surprised no answers on this yet. Have faith. There are some very knowledgeable people here who can get your question answered. Can you call the shop who did your valve job.  More than likely he got rid of those guide heights.  I think ultimately you might have to remove your heads to confirm this.  Either way, if I were faced with this question and was committed to installing a cam out of stock range, where the manufactures states they are NOT bolt in.....I would pull the heads and have them checked by a qualified shop. 
If things are not properly clearanced the damage can be catastrophic. 
My advice..pull the heads and send them to a good shop. Better safe than sorry.

I'm installing a L51 cam and sent my heads to a friend, highly qualified professional shop to check my heads for clearance because of the radical cam lobes. Also using matching Leineweber springs and they are tricky and need to be seated correctly.  So I practice what I preach.  I'm not just throwing words around.   good luck..

TOTALLY Agree With John Here! TOTALLY, Especially the RED Highlighted Part!   




ME

[Hybredhog]

    Stock "springs" are pretty much the same from pre '80 to post '81, the difference was in the use of new 5/8" guides, and the lower spring collar to accommodate guide seals (what a concept) . The spring pressure difference is very minimal & due to new measuring points. Pre '80 9/16" guides "held up" the lower spring collar, and stem protrusion was measured from the cast rim around the guide. 1980 specifically didn't use guide seals yet, but the floor around the guide wasn't machined to be the new lower collar base yet. In approx. '81 they finally came with a lower collar with a larger center hole to fit a seal on the guide. So for 1980's just get a set of later lower collars & level off the floor, so that the seal will be lower (if the top of the guide is trimmed down), giving more travel room between the top of the seal to the bottom of the top collar. Most bolt in cams need .500 w/safety margin travel room, larger cams need their lift spec plus +-.050" safe room. But most any "large" cam also needed high lift spring with more travel to coil bind, and the top collar usually rides higher to help. 1980 guides & lower collars had no room for a seal, so either the collar's center lip had to be grounded off or the floor had to be machined & use later collars.
    At this point in time most heads have been modified, and already have had a valve job. but if you run into a truly stock '80 head, now you know.

[Hillside Motorcycle]

I'd suggest AV&V springs.

[david lee]

im confused years ago i had a andrews b grind cam installed in my 1980 lowrider and nothing else was changed

[Hybredhog]

im confused years ago i had a andrews b grind cam installed in my 1980 lowrider and nothing else was changed

    Being that 1980's didn't have guide seals, there was a bit more travel room. BUT at .485 lift the stock springs were maxed out to coil bind, and basically you got lucky & didn't crash anything. Without knowing the whole story, and the history of the bike, I would make a guess that at one time it had a "valve job" , and the stem protrusion was increased & the spring pack was opened up, giving more travel if the springs weren't shimmed. Also during that "valve job" the valves get sunk into the seats, creating more valve to valve clearance. So just bolting a B grind into a totally stock head would be catastrophic.

[david lee]

im confused years ago i had a andrews b grind cam installed in my 1980 lowrider and nothing else was changed

    Being that 1980's didn't have guide seals, there was a bit more travel room. BUT at .485 lift the stock springs were maxed out to coil bind, and basically you got lucky & didn't crash anything. Without knowing the whole story, and the history of the bike, I would make a guess that at one time it had a "valve job" , and the stem protrusion was increased & the spring pack was opened up, giving more travel if the springs weren't shimmed. Also during that "valve job" the valves get sunk into the seats, creating more valve to valve clearance. So just bolting a B grind into a totally stock head would be catastrophic.

thanks for that information what i do know is when i bought this bike back in 1984 i had the rockers reshimed due to a rattle but wether that involved the valves i dont know.this is a stock motor.the person who installed the cam is a well known harley mechanic whome ive bealt with since ive had this bike

[Hillside Motorcycle]

And OEM Shovel springs, have the strength of used bubble gum.
Kibblewhite also offers a spring-only, that uses OE upper/lower collars.