Looking for comments on a pushrod or pedestal shim issue:

Background: Ford 360 "FE", 1972. Crane 343904 cam kit (343901 RV style). Crane 96801 light springs. No coil bind. Engine is rebuilt with minimal machining, perhaps .005" milled off the head only. Head gasket used is .020 shim steel. Original pushrods are measured by machinist at 9.590" plus or minus .002. COMP CAMS #7704 pushrod-checker says optimum length pushrod would be 9.475 (plus preload).

I gather that .040 is midpoint in Crane Cams hydraulic lifter preload range. Sounds like the Crane recommendation is between (.020 - .060). This engine will see very low and very high temperatures, so the midpoint might be the best target (?).

Question: Can I shim the rocker stand .050 to get the right preload, or do I have to order custom pushrods? I figure the perfect mid-preload value would be obtained with 9.515". That is not a stock choice, nor available easily. This is on the ball-ball type pushrod.

Details:
Check was done on a cold engine, at or just after TDC. Four pushrod positions checked at #! and #4 cylinders. These were the highest and lowest compression cylinders Engine now runs OK at startup, and worse with temperature rise. Cold compression is 129 - 150 at 2,200 feet altitude. Vacuum guage is steady with up to 17.5 " water if tuned for highest value. Don't know if jetting is right yet. ( Ignition checked with scope and it is near perfect with ALL new components.
Proposed fix: My math indicates the original pushrods are .095" too long. So I'm thinking a pedestal shim of half that would do the trick. Recommendations?

Kevin

 

Shimming would be the easiest way. Big thing to do is check how the rocker touches the valve tip before/after adding the shim. .05 isn't a ton of difference, and with a very mild cam it shouldn't change location that much.

You could get some valve spring shims and slide them in without much effort.

 

Thank you Freightrain.

Given the need for pedestal stability, I wonder if anyone makes a pedestal shim for the FE specifically. I've been surfing for part numbers, and haven't found anything in a couple of hours. The ones I see are for other non-FE applications.

The oil passage up through the one pedestal would have to remain clear, and I suppose the shim O.D. would have to be reasonable.

The idea of using a spring shim sounds pretty good, and a little dimple for the oil passage shim might locate it well enough. A vendor, PPPCenter.com has the right thickness, if I end up using a spring shim.

Kevin

 

I would post this on the 332-428 Ford FE Engine Forum website. The guys over are the bomb on these engines. Interesting topic.

 

Or post in the FE forum in the engine sections on this site.

 

If you get the large diameter shims it will work fine. I have the same set up on my race car. I run Dove HD rocker set up and needed to shim it up slightly. The shims are like 1 1/2" outside diameter, and maybe 5/8" inside. I just lay them on there and bolt the rocker stands down. With the large inside hole, oil gets through without issue and that set up has been that way since 1996.

Don't sweat it.

 

I agree, this should be moved to the FE engine forum. Perhaps a moderator will oblige.

I ordered the 0.050 shims, and the cost with shipping was under $23.

Crane cams says they don't make pedestal shims for the FE, and recommended using another splash shield. (3 total!) Just cut off the vertical portion and use the flat part. My first guess is the valve spring shim solution would be cheaper - I'll check.

Custom pushrods were $160 and up plus shipping. Notsogood.

Surely, my block and/or head were surfaced more than the machinist recalled, or the SS valvestems were not trimmed the appropriate amount.

Nowhere did I see any mention that a pushrod adjustment of unit "A" could alternatively be made with a A/2 thickness shim at the pedestal. This would make sense, but there may be some non-symmetrical geometry issue. Don't take my word for it at this point.

Thanks for the input Gents!

Kevin

 

Pedestal Shims were installed today. Here's some thoughts:

1) They come in packs of 16, so share extras with a buddy.
2) Use some wheel bearing grease on the shim to hold it in the center while you gently bring the rocker shaft down.
3) Note the warning in the manual about turning the crankshaft to 45 degrees past TDC. That is the position of least load on the two shafts.
4) This would be simple and easy with the engine removed, or an OK job with the hood off. Then there is the dumb way I did it...
5) Order shims with the smaller hole in the middle. A half-inch is plenty, even for the oil gallery stud.
6) A second pair of hands would be good for this project.
7) use a torque-wrench, and a clicker type would be handy.
Now hopefully I didn't toast the valves with excessive lift in the mean time...

Kevin

 

Chapter Two:

This big hassle should be seen as a vote for getting the adjustable rocker arms, before messing with anything having to do with pushrods! Once you get those, you can measure for the right length pushrods. Then again, all that costs money, and the shim option is cheaper. $23 for the tool, which you need anyway, and $12-26 for the shims.

I removed the rocker shaft on the other side of the engine, and put the .050 shims in. Again, I carefully aligned the ones that had oil flowing through the holes. These would be the second pedestal back, from the front on the passenger side, and the third one on the driver's side. (Cylinder #2 and #7) Don't use silicone seal to locate it, just put the stands and bolts in place finger tight, and center the round shim with your fingers.

The results were the same as the first side. The engine ran much better, but the pushrods sounded a bit loose, and got louder with a warm engine. Must be bad math. So I pulled all the pushrods out on the second side, and had a machinist check then very carefully. HO! One was bent, and shorter.

OK, I half expected that to be the case, since stupid me put the engine together without checking. Back to the math... Yes, I goofed a little. Here is the story, and it will show you how to do it right.

There are at least seven stock pushrod lengths, and mine are 9.590 inch. (Most places don't carry this length. NAPA does.)

All the good rods where within .002", either way. Two were now down to 9.584 and 9.580" due to bending. I didn't notice any bend while looking at them. You can roll them on a flat plate to check, if you have one. Keep them in order.

My rebuild used a head gasket of .017" thin-shim-stock, lightly surfaced heads with new valve seats, a different cam, and different lifters. The manufacturer suggests not using the stock clearance measuring technique with these new lifters. So I bought an adjustable pushrod checking tool. The basic length a pushrod "should be" kept coming out to 9.475".

Next, there is the preload issue. The pushrod has to be longer by at least .020 inch. This keeps the engine quiet when cold, and protects the hydraulic lifters from extending fully, and beating out the snap ring. So the ideal would be 9.495".

The original pushrods were too long. 9.590 - 9.495 = .095 too long.
No wonder I bent one or two pushrods a bit. That is longer than the plunger travel. Sheesh, was I lucky !

Pedestal shims drop both ends of the rocker arm, and so you need a shim thickness value half of the above value. About .0475 inch for me. So I chose the closest shims I could find, .050 inch (50 thousandths). Hint: Go a little thinner, rather than thicker, and you'll be good.

With perfect sizing of everything, this would be right. But with the shorter two pushrods and a little too thick of a shim, it caused some clatter on my engine.

As a final thought, if I was a racer, I'd buy a new set of pushrods, all the exact same length, Use adjustable rocker arms, and set for minimum preload. Us real-world people might save some money, and go with another .010 inch of preload. In any case, measure with an adjustable pushrod made for the purpose, and work with your machinist to figure out what the resurfacing is likely to do to your clearances.

Luck!

 

The 0.050 shim was too thick, even with a set of new pushrods. I'm thinking, that when you use the measuring tool, you need to really unscrew it firmly. That can be a trick with oily fingers!

It worked just fine when I reduced the shim (stack) by .005. So, in my case, I went from a measured need for .0475 to .045 shim stack, and that was what worked best.

The other benefit was that the idle became smoother, and vacuum went up.

...and yes, I know I'm talking to myself here....