? For the Forum on Adjustable Pushrods

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Lordsoflolo

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Newbie here. I posted my story in the welcome section. I was wondering if someone has some advice or can steer me to a article on adjustible pushrods. I bought a rebuilt 1968 340 for some dude and he told me to replace the push rods with adjustible rods. I bought a set from Crower. Now, I've always been more of a parts changer than a mechanic. I want to be as hands on as possible so I can say I built most of the car. I was pretty good around cars in my teens and 20's but at 47, I've been away from it for a while. Help a brother out so I do this right?
 
Buy one adjustable pushrod to figure length and then buy a set of cut to fit or custom length pushrods.No way you want to run adjustable pushrods. Or do you mean adjustable rockers?
 
The push rods are adjustible. The engine builder told me to replace them and now I can't get a hold of him.
 
Can you ask more of a point question? I cannot understand what you actually are after.
 
You don't want to run adjustable push rods in an engine. You use them to figure out how long you need, then get cut to length and run those.

The threaded rod and lock nuts for the adjustable push rods will make it much heavier and more prone to valve bounce which can DESTROY YOUR ENGINE. You want to lower the valve train mass whenever possible not increase it.
 
If it actually needs an adjustable valvetrain (solid lifters?) the best way to get there is with readily available adjustable rocker arms. There is nothing special about a 340's valvetrain where it would require adjustable pushrods. I'm not so sure they will "DESTROY YOUR ENGINE", but there are much better alternatives.
 
69_340_GTS said:
I'm not so sure they will "DESTROY YOUR ENGINE", but there are much better alternatives.
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Have you ever over revved an engine and had valve float?

I did and put a rod through the side of the block when the piston hit the valve, and bent the rod like a pretzel... I call that DESTROYED....
 
krazykuda said:
You don't want to run adjustable push rods in an engine. You use them to figure out how long you need, then get cut to length and run those.

The threaded rod and lock nuts for the adjustable push rods will make it much heavier and more prone to valve bounce which can DESTROY YOUR ENGINE. You want to lower the valve train mass whenever possible not increase it.
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Wrong. Adjustable pushrods are FINE in an engine. Not one thing wrong with them. Several companies sell them as sets to RUN. I have a set by Hot Heads in my early Hemi, for example.
 
Adjustable push-rods were just a option for those engine combinations that require valve adjustment. I have a solid lifter 273 but it has the original rockers and shafts. Nothing more is needed unless you're building a race engine with mega lift and you need the adjustable aluminum rockers. Most hydraulic cams with the correct length pushrods work fine... tmm
 
Not a thing wrong with adjustable pushrods, as was said.... I ran some years ago on a oval track 360, because we were required by rules to run stock non adjustable stamped rockers. So we had hughes engines adjustable pushrods to set preload on the lifter. That engine probally had thousands of laps on it turning 4500 to 7000 all night long. Won a **** ton of races also.
 
Dubob said:
Here's a quick article on valve train geometry which in essence is what it sounds like you're working towards. I personally am not familiar with using adjustable push rods across the board in a running engine.

http://www.hotrod.com/how-to/engine/116-0401-setting-pushrod-length/
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Very good article. I learned some things. When I built my 273 I had milled the heads, a thicker head gasket, different cam, and although still solids, different lifters. What a mess. Tolerance stacking is what it's called. A few + thou. there, a few - thou. there. Things just didn't line up. I got different pushrods and shimmed the rocker shafts. That looks better. I didn't check it with a marker though. Learn something every day. tmm
 
RustyRatRod said:
Wrong. Adjustable pushrods are FINE in an engine. Not one thing wrong with them. Several companies sell them as sets to RUN. I have a set by Hot Heads in my early Hemi, for example.
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Not like the picture of the one I saw earlier today that I think he's referring to. I tried to find it, but couldn't. It had too much mass...
 
Those are called checking pushrods. Not adjustable pushrods.....and like you said are used only for finding the correct pushrod length for a given application. but you knew that already, Master Splinter.
 
RustyRatRod said:
Those are called checking pushrods. Not adjustable pushrods.....and like you said are used only for finding the correct pushrod length for a given application. but you knew that already, Master Splinter.
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Rusty, these are the pushrods they are talking about. A full set of 16. Not my choice but some engineer somewhere thought they were a good idea.
 

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replicaracer43 said:
Not a thing wrong with adjustable pushrods, as was said.... I ran some years ago on a oval track 360, because we were required by rules to run stock non adjustable stamped rockers. So we had hughes engines adjustable pushrods to set preload on the lifter. That engine probally had thousands of laps on it turning 4500 to 7000 all night long. Won a **** ton of races also.
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X2 when class rules require stock non adjustable stamped rockers
 
The old Mopar power books called for adjustable pushrods. They were fine at the time. IMO - times change and I wouldn't run them. Too much of a problem with weight and potential failure points especially given any real RPM (aka not Harleys...lol). But some builders might still think they're good and in the case of some early hemis they are mandatory. Again - they were never meant for high rpms and big spring loads though.

To the OP - you can use them. if you have a hydraulic cam you would be best served to tell us what you have for a cam and lifters. If you don't know, then start with a preload figure of .020" measured between the plunger of the lifter and the plunger retaining clip )intake must be off for this). If it's a solid lifter camshaft, I would start with lash of .025" as measured between the rocker tip and valve stem tip.
 
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