Valve Clearance

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Model T Ford Forum: Forum 2015: Valve Clearance
Top of pagePrevious messageNext messageBottom of page Link to this message  By Donald Curtis on Thursday, June 18, 2015 - 09:13 am:

What is the proper or recommended valve clearance for a 1918 T


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jack Daron - Brownsburg IN on Thursday, June 18, 2015 - 09:28 am:

I set mine on 0.0015 on the flats of the cam lobe. that is using an original cam and accepting some wear. Others will probably have their own ideas,depending on new cam,etc.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Thursday, June 18, 2015 - 09:32 am:

It's a lot of job to set the valve clearance with original solid lifters. Usually a little extra play doesn't do much harm - it just makes a little more sounds. With adjustable lifters it's easy. I went for 0.010 for intakes and 0.015" for exhaust with a reground cam. Original cams often have a little more play.

If you have the head off, you can try the piston position method, but I doubt you'll notice any real change in power or smoothness?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dale Peterson College Place, WA on Thursday, June 18, 2015 - 09:40 am:

Valve clearance works well with the new computer ground cams, but if you are using an original old cam, use piston travel to set the valves. It makes for a much better running motor. We just tried to do a 21 by gap and found a difference of several degrees when checking after for position. The exhaust valves were opening as much as 1/2 inch early in one cylinder. And that was using 20 thousandths clearance.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Leck - Ohio on Thursday, June 18, 2015 - 10:42 am:

Donald, I recently was doing some valve work on my '22 and looking back to the forum archives I found this discussion in 2009 with some sound advise from Glen Chaffin. http://www.mtfca.com/discus/messages/80257/94685.html?1249483184

The reason I was doing valve work was because while out for a drive, the #2 intake valve retaining pin wore through the retainer and boy does that cause some engine problems. I thought I broke my crankshaft before I figured out the problem. Luckily I wasn't too far away from help and temporarily fixed the retainer and the engine running normally again pretty quick. Anyway, while I was in there tinkering with that, I thought I'd check my valve clearances. I found the adjustable lifters set to .029-.031. I remembered reading that with new stainless valves one could go down on the clearance quite a bit and that's when I found Glen's post explaining why and how. Well, after I adjusted the intakes to .010 and exhaust to .015, wow, what a difference in the way the engine sounds (less clattery) and there is a noticeable difference in performance, climbing hills and top end, it even runs cooler. I'm pretty sure I still have the old "wore-out" cam so there are a few tricks to be learned when running a stock engine. And thanks to the helpful people here, I'm learning!

John


Top of pagePrevious messageNext messageBottom of page Link to this message  By Adam Doleshal on Thursday, June 18, 2015 - 11:32 am:

And to answer the question that was originally asked:

Fact:

The FORD SERVICE MANUAL recommends a clearance of 1/32" or the thickness of a "worn dime". 1/32" is equal to .031" if you use feeler gauges.

Most hobbyists do set their valve clearances at something closer to .010". On the engines I've re-built, I generally shoot for .010" to .011".

Opinion:

Adjustable tappets are a waste of time for me because they take far longer to adjust than grinding the stem off the valve and if everything inside the engine is clean and in good order, there should be no reason to adjust the clearance until the valve guides are worn to the point that the valves should be replaced with an oversize stem anyway which means you are back in there with the head off anyway.

The only learning curve for the beginner is that there is a small amount of skill involved in grinding the stems so they are nice and flat and also don't get ground off too much. You have to own a bench grinder with an adjustable tool rest so you can position the end of the valve very near 90 degrees to the wheel.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Thursday, June 18, 2015 - 12:27 pm:

if it's a new rebuild with new cam...follow the mfg's spec.

if it's a worn engine, to get proper valve action relative to piston position, the gaps will likely be all over the place. That's why folks have suggested using piston position to set valve opening/closing

The Ford Service Manual fully describes setting valve events relative to piston position. I've done it and found that old engines can be made to be pretty peppy that way, though often times the valve/pushrod (lifter) clearance will be large with this method resulting in a noisy engine.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Eckensviller - Thunder Bay, ON on Thursday, June 18, 2015 - 01:22 pm:

I don't have the procedure handy but when you do the piston position check what are you doing with the valves? I would have thought that if uneven wear was the problem, grinding more off couldn't help, could it? Do you install new valves and just shorten the stems to suit or do the old ones just sort of get evened up?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Friday, June 19, 2015 - 05:58 am:

usually by the time you're tempted or perhaps driven to this exercise, there is wear on valve seats. "Short" valves can be "lengthened" slightly by mild recutting of valve seats or regrinding valve heads. Alteration to the seats should be undertaken with care so as to not overdo it. Once cleaned up, if valve is still too short, simply replace it (and always have the valve face ground, even if new). You're right, in that grinding off length is not specifically the fix. You'll potentially end up with a variety of gaps depending on what the last guy did and the wear on the cam shaft.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tony Bowker, Ramona, CA on Friday, June 19, 2015 - 11:42 am:

Jack, I think you put in one too many 0 in your suggestion, surely you meant 0.015".
That is a little tight for a standard Model T camshaft, Ford recommended 1/32" which is closer to 0.030". With a modern camshaft you can go down to 0.015 or even 0.012".


Top of pagePrevious messageNext messageBottom of page Link to this message  By Glen Chaffin on Friday, June 19, 2015 - 01:23 pm:

Setting valves by piston travel today is old school. It never was a good idea and you wound up with a very noisy engine because every valve had a different setting.We no longer use cast iron head valves and reducing valve clearance from 0.031 in to 0.015 in will increase your high end performance at least 20 percent. That is more than all of the cam design improvements combined.
So just set your valve clearance to 0.015 and you will have a good running, quiet engine. Sure every valve will have a different lift, duration and valve timing but it will be minor and the engine will run well. If that doesn't please you just buy our new 280 cam. It has been optomized for performance and doesn't need to be advanced. It is already advanced.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Warren on Saturday, June 20, 2015 - 08:37 am:

I second that Glen, I have built two engines using Glen's suggestions and they run great! I also advanced the stock cams the 7.5 deg and have been clocked at 55mph. Many in our club have also commented on how good, and quite they run. They are both in 26 touring cars.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Glen Chaffin on Saturday, June 20, 2015 - 11:11 am:

Smart man John. I am not as dumb as I look.


Top of pagePrevious messageNext messageBottom of page Link to this message  By bob middleton on Sunday, June 21, 2015 - 08:51 pm:

I have always just set at .015 and been happy enouf


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