Zero valve lash

carl

carl

True Classic
I built up a 1500 motor last winter with a euro cam and the fire ring machined off a US 1500 head. Been sitting in my basement and now since I have entered another one of my "idle hands are the devil's workshop" phases I decided it's time to install it in the Fatrat. Not sure what I'll see as the stock 1500 motor with IDFs and header currently in the car runs soooo sweet.

Anyway, I pulled out the "built" motor and along with my usual tag "NO OIL" was a "valves not adjusted" tag. So I went to do that as it's a whole lot easier to do out of the car. Turns out all the valves had no lash, couldn't get any feeler gauge in there. Tight enough that some of the shims can't be lifted out. Original plan was to loosen the cam box bolts to give enough clearance....but....it actually makes more sense to remove the cam box, remove the fat shims and install skinny shims on all eight buckets, reinstall and THEN start a normal adjustment with too much clearance but plenty of clearance for the shims to come out. All comfortably done in the basement with no timeline and getting plenty of exercise since all my tools are upstairs in the garage.

This timing is stupid as I have a non-running for years 124 spider showing up within the next week and I'll spend all winter getting that back on line. But retired guys have plenty of free time but not enough garage space.
 
Just curious, is it a actual Fiat Euro cam or one of the aftermarket clones? I ask because many (all?) of the clones have a different base circle dimension (smaller) than the factory cam, which naturally would affect the lash/shim sizes. Eventually I'll be doing this with one of the clones and I may find a similar situation.

It just occurred to me you said the head is milled. That also has a big effect on the lash so your situation may not be the same as mine even if we had the same cam (my head isn't milled for the turbo application).
 
The cam was sold to me by one of our members as an actual euro cam. As others have discovered, Fiat does not put any identifiers on their cams so other than a rigid measurement there is no way to know. Seems to clearly be a Fiat cam, usually the after market folks put some kind of identifier on the end plate. Milling the head should have no effect on valve clearance since the metal is taken off the block mating surface with no impact on the valves or cam box. In any event, I removed the cam box, installed shims 20 thou smaller and then worked back from there to get the clearances correct. Wasn't that time consuming to pop the cam box off, replace shims and bolt it back down.

I just have to remember that this is probably an interference motor now.
 
Dr.Jeff said:
Just curious, is it a actual Fiat Euro cam or one of the aftermarket clones? I ask because many (all?) of the clones have a different base circle dimension (smaller) than the factory cam, which naturally would affect the lash/shim sizes. Eventually I'll be doing this with one of the clones and I may find a similar situation.

It just occurred to me you said the head is milled. That also has a big effect on the lash so your situation may not be the same as mine even if we had the same cam (my head isn't milled for the turbo application).
Click to expand...
Because the maximum lobe height is limited by being able to slide the cam in the cam box on the Fiat SOHC, high lift cams also require a smaller base circle as the gross lift is determined by the lobe height minus the base circle height (radius). The cam I am using has 10.6 mm of gross lift and has a smaller base circle than the stock cam even though it was made on a new CMC billet.
 
carl said:
The cam was sold to me by one of our members as an actual euro cam. As others have discovered, Fiat does not put any identifiers on their cams so other than a rigid measurement there is no way to know. Seems to clearly be a Fiat cam, usually the after market folks put some kind of identifier on the end plate. Milling the head should have no effect on valve clearance since the metal is taken off the block mating surface with no impact on the valves or cam box. In any event, I removed the cam box, installed shims 20 thou smaller and then worked back from there to get the clearances correct. Wasn't that time consuming to pop the cam box off, replace shims and bolt it back down.

I just have to remember that this is probably an interference motor now.
Click to expand...
Thanks. My "clone" Euro cam is definitely a reground aftermarket item with a smaller base circle, so it will be a different situation. And you are right; I was thinking of cam timing, not lash, when I commented on the milled head. Sorry for the confusion. ;)
 
dllubin said:
Because the maximum lobe height is limited by being able to slide the cam in the cam box on the Fiat SOHC, high lift cams also require a smaller base circle as the gross lift is determined by the lobe height minus the base circle height (radius). The cam I am using has 10.6 mm of gross lift and has a smaller base circle than the stock cam even though it was made on a new CMC billet.
Click to expand...
Good point. I know the stock Euro spec factory cam has more lift than the others, but as far as I know they still have the same base circle.
 
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