cold valve lash vs hot

Chris Smith

I installed my cam,valves, timing chain and #1 piston today. I checked the cam numbers on the engine vs the cam card and it came out perfect. The cam card says valve lash .010 intake .012 exhaust hot running. Does it sound reasonable to add .002 to each figure for a cold setting and break in the cam at those settings?

tigermoth

why wouldn't you set the correct clearances once the engine was warmed up after the initial start? regards, tom

PAULARGETYPE

TOM
: I ALWAYS SET MY VALVES COLD AND I ADD .003 LASH( I'VE ALWAYS MIKDE TIGHT) I HAVE BIG HANDS AND A LARGE BODY THAT DOESN'T FIT TO WELL UNDER THE EXHAUST MANAFOLD I HAVE NEVER HAD A PROBLEM AND I'VE BEEN DOING IT THAT WAY OVER 45 YEARS

tigermoth

thanks paul. regards, tom

[Deleted User]

I agree with Paul. Pulling all that stuff out of the way, and trying to set the lash correctly after the engine is in the car is a pain in the back, knuckles, and other parts. I feel you can get the lash closer to specs. on the bench. Add a couple thou and forget it.

[Deleted User]

The user and all related content has been deleted.

J Spencer

In 1990 I put new valves and guides in my 51 Pacemaker, set the lash .002 more than factory hot settings. Last year and 25K miles I rechecked the valve lash and they were still right on.

Jim Spencer
WNY Chapter

[Deleted User]

Valve lash is about how you will drive your car. I set my valves cold, intake .014 and exhaust .017, that is for normal driving. Now when I do a cross country trip, I set my valves.020, intake and exhaust. My engine now has 142,000 since rebuild, and has never been touched. still have 120 lbs compression. With today,s gas which is made to burn hot, you need more clearance, this is not the fifties. Walt

tigermoth

walt, what numbers would you use for a '35 212 cu.in. 6cyl. ? thank you. regards, tom

[Deleted User]

I would set them for normal driving at intake .oo8 and exhaust at .010 with a cold engine. If you plan on a 200 or 300 mile trip, set cold at .009 and .011. With today's gas which is made to run hot, set 6 and 8 with a hot engine you will have valve trouble. Like I said above, this is not 1935 the year for your car. Walt.

Geoff

It's no big deal to set these when hot. Access is relatively easy, and the exhaust pipe is not in the way so much that you can't get around it, and the valve chest is easily accessible. Why not do it the way the factory advocated, and do it hot? Then you know you have the correct clearance. You can only hazard a guess at what expansion takes place, and it depends on whether you have silicone steel or stainless valves.

terraplane8

Another way is to measure the valves when hot, then again when they are cold and the difference between the two will be apparent. Thereafter one can adjust the valves cold without getting burnt. Or in my case taking so long that the engine goes cold before I am finished.

Chris Smith

My concern is more with the initial 20 minute break in period on a fresh cam. To me, it would make no sence to set the lash at hot specs on a cold engine for the break in when everything I've every heard or read about flat tappet cam shaft life basically says the first 20 minutes are the most important. After the break in and first oil change, I will chew on what lash to go with after that. I agree with Walt that fuel is different from the days Hudsons ruled the roads and appreciate his and everyones chim in on this. I would also point out the engine oil and filters are also different and far superior to what was avaliable 60 years ago and should go a long way towards a fresh 60 year old engines life ( if you include the flat tappet additives that everyone now offers) . Going forward my thought on running more lash than the cam grinder suggests is It would effectivly make the cam smaller, less total lift, retarded valve action and less power. Yeah I know it's not a race car and I won't drive it like I stold it, but I didn't spend the extra money and time adding and doing all the 7x mods not to have ALL the potential power it will offer. BTW I will will be running long tube headers so I'm not sure if that will afford me more or less room to perform lash adjustments in the car but I would guess less. )