View Full Version : Valve clearances
06-04-2008, 01:57 AM
New poster. Tried searching but didn't see the answer. I have to change the cam cover gasket and while I'm in there I want to check the valve clearances. It's a circa-'93 DF51V with the F6A SOHC 12-valve turbo. Anybody know the valve clearance values for that engine? Thanks!
06-04-2008, 06:38 AM
In my book it has a 2 valve and 4 valve engine specs. I'm going to assume yours is the 4 valve 4 per cyl x 3 = 12 valve.
COLD: IN: 0.08 mm EX: 0.10
HOT: 0.12 mm 0.12
Hope this helps you out.
06-04-2008, 12:25 PM
Thanks a bunch! Leave it to the fastidious Japanese to print both cold and hot specs. Though it's a little strange that the hot temp clearance is greater than cold temp. You'd think it'd be opposite, so that when the engine cools off the tolerance doesn't go from wide to really wide.
06-04-2008, 01:52 PM
I'd like to know what HOT is. I've use to do it on my old Ramble American hot and it was no fun. I think I'll stick with doing it cold:D
06-04-2008, 05:22 PM
Yep. I know the feeling. I have a '49 Buick model 46S sedanet with the original straight-8. The service procedure for checking valve lash is three pages long, much of it to do with warming up the engine properly (they recommend you drain the coolant and replace it with straight water if you're going to just let it idle up to temp in the shop--doesn't everybody replace the coolant for that?).
After you warm it up, you have exactly 10 minutes, according to the manual, to take the rocker cover off, take the plug plate off, take the plugs out so it's easier to crank by hand, take the oil bath aircleaner off so you have clear access to the tappets, and check and adjust the lash on all 16 valves before the engine cools enough to alter the gaps. Apparently, they didn't think to put in a cold temp figure.
06-04-2008, 05:39 PM
on volkswagens with stock aluminum push rods you have to adjust the valve lash to .006" cold only.
when you start to beef the valve train up for a better cam you have to run steel push rods. the expansion of the magnesium engine case, iron cylinders and aluminum heads vs. the steel push rods is such that you set them at "zero" valve lash. that is to say you set the push rod tight, then back it off just enough that it will spin between the rocker and the cam follower. cold. but when it heats up i have seen .012" - .020" valve clearance.
my race motors ran better when i set the valve lash warm, but when the engine cooled off it wold hang a valve open sometimes... that's why they have two different settings for hot and cold, so you don't hang a valve open and burn it... back to my old theory about valves.. i'd rather hear them than smell them :)
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