To confirm I did this right:

I created an adjustable-length pushrod out of a pushrod that is now too long for my build.

I am measuring the pushrod length off a lifter in the lowest or closed position (on the cam lobe heel). I adjusted the rod to the longest possible length where the rod can still spin when it's in position, and there are threads of the adjuster screw showing above and below the rocker screw collar. The rocker lightly 'clicks' against the closed valve end, but there is nearly no rocker motion.

Is this the correct length, as I want it, or should adjust the rocker to a different setting for accurate rod length?

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Why do you need custom length rods? Aren't you doing a stock type rebuild?

Thanks for the link, but that information doesn't make sense as it relates to what I'm trying to do: setting up a pushrod of a certain length, and sending it off. I'm not measuring it; I just want to set the length correctly and send the rod to Smith Bros. and ask them to make me a set that length.

Before I send this rod off though, I want to know I set the length up correctly for the valvetrain. I need to know what I'm looking for. Is the rocker supposed to be able to rock back and forth at all and lightly 'click'? Or should there be no rocker movement, but the rod should still twirl?

Thanks.

The rebuild is mostly stock, but the head was milled and the block was decked enough to need new rods. And yes, I did check the length of the rods carefully to be sure I actually did need new rods.

Actually the method of just getting the adjustment out of your pushrod has absolutely nothing to do with correctly determining what length pushrod you need. The link provided shows exactly the correct procedure to follow to do this. There is a whole science behind this process and is much more indepth than what you are trying to do, and can lead to severe valvetrain failure if you dont make every effort to follow the instructions provided. There is some margin for error, but too long or too short of a pushrod will not make for a good day. Read the link carefully and consult with a performance machine shop if you feel its something you cant do yourself.

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There's no such thing as too much cam....only not enough engine!

If you do, here is what you want (caveat, I have only done this on mopar V8s but it's the same basic procedure):

- Set the valve up with cold clearance of like .002 or so.
- Make sure that the adjuster has a few (at least 1) threads above the ball
- Turn the crank to mid lift on the cam (1/2 of the total lift of your cam, use a dial indicator)
- Look at the angle of the adjuster screw to the pushrod from the end of the head. Is it perfectly straight? If not, adjust the pushrod length (and the adjuster screw) until everything lines up straight.

That's about the best you can do with shaft rockers. Just ensure that you have enough threads to adjust the valve clearance either way, and that the angle between the pushrod and adjuster screw is as straight as possible.

Another thing to keep in mind is that because of the geometry of the rocker arms, you will get a few thousandths more lift with a longer pushrod. So check your lift at the valve, and factor that into your measurements too.

That link is misleading. Not only is it using V8 terminology (intake side vs. exhaust side), it is describing what happens when you change pushrod length on a stud-mounted-rocker valvetrain.

On a shaft-mount rocker you can not change the wipe pattern of the rocker on the valve tip without changing either the height of the rocker (with shims, not recommended) or the valve length (grinding or lash caps). No matter how long or short the pushrod is, and where the adjuster is, you will get the same wipe pattern on the valve tip.

The Ford six guys at Classic Inlines are having those issues and their heads are also rocker shaft style, they must be doing something more extreme or radical than the Slant guys are to be having to do this.

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There's no such thing as too much cam....only not enough engine!

I had to order new pushrods after building the Valaints Erson 280/270 9.25 CR motor. I milled mebbe 160 thou ,,,,,and increased lift

The adjusters hit the rocker cover and geometry was such that I needed lock nuts on the adjusters.

I adjusted the valves. Measured how far the adjuster stuck up past the rocker and compared the distance to a stocker. The difference was how much shorter a pushrod I ordered from Smith Bros.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Similar to Sandy:

I actually had issues on my original 9:1 super six build with a .09 scrape on the deck, and a .01 scrape on the head with a felpro head gasket and a comp252. The cup on the stockers were in contact with the underside of the rocker at full lift, these also left me with '0' threads under the rocker as well (late forged crank and BL head combination, first time engine had been rebuilt).

So I had to do the adjustable rod, roll the engine over on the stand by hand after mocking it all up and finding the right height that gave a good 'wipe' across the end of the valve stem without going over either end. Then sent that pushrod to Smith Brothers, they set it and 12 good pushrods back.

Depending on the combination of parts and wide variations of tolerances in manufacturing with heads, you might end up with a head that has a lower profile after milling and having a deeper chamber that might put the pushrods on the riding edge of the adjusters even if the SCR calc shows only 8.5:1....( chamber volume may not be compromised as much on a seat regrind and stock valves vs. the O/S valve and new seats).

So far anything else I have put together needed custom pushrods even on reground cams in mild upgraded blocks due to rocker geometry and the pushrod cup.

-D.Idiot

Thanks for the replies. To get into more detail, the cups on at least 3 of my 12 pushrods were jammed under the rocker adjuster collars at lift (not even sure if it was full lift) and the adjuster screws were fully backed all the way out. I could plainly see the rods were set correctly in their lifters. This was with the rocker shaft torqued down appropriately, which to me indicates yes, I must get new rods, as the shafts would not twirl, they were locked tight and any rotating of the engine/cam/lifters would have bent them.

So to summarize, I should do the following:

Rotate cam until the lobe is at mid-lift, and use a dial indicator.
Check geometry of rod to ball adjuster: if straight = golden. If not straight, correct length until it is. Keep one or two threads above the ball, and one to two below the adjusting nut on top.

There is nothing else I need to check? I.e., the rocker shouldn't 'click' and the rod should be able to twirl, but the wipe pattern is stationary and non-adjustable, and that's it?

Thanks all.

And as others have mentioned make sure that the adjuster does not hit the valve cover, and that nothing hits the rocker or anything else.

The wipe pattern is adjustable, just not with pushrod length. If it's really bad you might be able to fix it but it is another discussion.

Could be, however I have noticed that a lot of the info on their site is cut & paste from other sources, I don't think there is much thought being put into it.

just out of interest has anyone machined a deeper recess into the lifter pushrod socket area to avoid the need of custom pushrods?

I don't think anyone has gone that route. Probably because the cost to the average user to have it done outweighs the price of a set of custom pushrods
at most competent US machine shops that have the tools and know-how. Also if the build is mildly hi-po the stock pushrods flex too much against heavier spring pressures and tend to bend or fail, I noticed on the last 2 sets of 3/8" pushrods I got from Smith Brothers, the cups on the end have a good recess for the adjuster ball, but the edge of the cup is lower allowing the angle of the rocker arm to be steeper and not have any contact with the cup or rocker (to the point that I mocked up a bore and they would work up to .650 of lift, if the head actually could flow enough to use it...LOL)...

-D.Idiot