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pushrod length with roller cam

Posted By: bigblk66_coronet

pushrod length with roller cam - 02/12/23 12:34 AM

I'm building a 512 stroker out of my 440. Swapped it over to roller cam and this whole process is new to me and a learning experience. We figured out how to measure the pushrod length, Cam was on base circle and tdc. We did the whole process and measured from ball end to bottom of the cup.. Its a howards 565 hydraulic roller with Harland Sharp 1.5 rockers. we cam up with 8.059 on exhaust and 8.072 on intake. i know there are a lot of things to consider when it comes to the length. does it sound like I'm in the ball park? just looking for some input. i don't need any smart ass comments . just tryin to make sure this is right. Thanks for any help!
Posted By: Cab_Burge

Re: pushrod length with roller cam - 02/12/23 02:48 AM

How much adjuster preload length are you using?
Real unusual to need to different length pushrods on a street motor with standard port 440 type heads, common on the heads that need offset rocker arms on the intake valves like the Indy 440-1 and Eddy Victors: scope:
Posted By: Stanton

Re: pushrod length with roller cam - 02/12/23 05:04 AM

With any hydraulic cam you need to check the length with the appropriate preload on the lifter. This can be a little confusing ... Have the lifter on the base circle as you've done. NOW lets say (for example) that the preload requires 1/2 turn of the adjuster and then it wants 2 threads showing. Set the adjuster so only 1-1/2 threads are showing. Now adjust the pushrod so it has zero play.. That's the length you need. If you were to turn the adjuster another 1/2 turn you'd have the correct preload and the two threads showing on the adjuster.

For a solid cam you'd set the adjuster with two threads showing, the appropriate feeler gauge between the valve and rocker tip and then set the pushrod for zero play.
Posted By: Stanton

Re: pushrod length with roller cam - 02/12/23 05:07 AM

Quote
8.059 on exhaust and 8.072 on intake.


exhaust valve has been sunk further in the head OR valve tip was ground more on the intake valve.

Double check both of those lobes are on the base circle - rock the cam back and forth with a dial indicator on the lifter.

.012" difference is only 1/4 turn on the adjuster and not visible to the eye

Hydraulic cams are forgiving but I'd rather have a pushrod .010 too short than too long and possibly hitting the rocker at full lift








Posted By: Cab_Burge

Re: pushrod length with roller cam - 02/12/23 05:48 AM

When you close with remarks like you made you are asking for a fight in my world work shruggy
That being said some of us on here want to help others that need it. up
On your deal not knowing which head and head gaskets your using as well as is it a stock uncut deck block or is it a aftermarket block deck to blueprint specs for a Hi Po build limits what can be said on the specific length needed to get them perfect shruggy
Posted By: Stanton

Re: pushrod length with roller cam - 02/12/23 03:07 PM

Quote
When you close with remarks like you made you are asking for a fight in my world

Whoa, chill man! All he said was he didn't want any smart-ass remarks. I feel for him. I say pretty much the same when I ask for help on here. There are far too many people who don't have anything positive to contribute but want to get their post count up.
Posted By: Stanton

Re: pushrod length with roller cam - 02/12/23 03:19 PM

Quote
On your deal not knowing which head and head gaskets your using as well as is it a stock uncut deck block or is it a aftermarket block deck to blueprint specs for a Hi Po build limits what can be said on the specific length needed to get them perfect


As for all this, while it would be nice to know, it really doesn't matter from where we sit. The engine is in front of the OP. All we can do is advise him on the process.

And FWIW, I think adjustable rockers are totally wasted on any hydraulic cam - regardless of the application.
Posted By: fourgearsavoy

Re: pushrod length with roller cam - 02/12/23 08:23 PM

Make sure the cam is on the base circle as that is the only true way to measure for pushrods. TDC is not always on the base circle of the lobe. This may be the reason for the difference in your readings. I measure #1 and #6 so you can get an average for both banks just in case the decks or heads have been unevenly machined. Check it for both banks and get an average length. You will be good with something in the middle with adjustable rockers and a hydraulic cam twocents

Gus beer
Posted By: Cab_Burge

Re: pushrod length with roller cam - 02/12/23 08:49 PM

Pushrods can have two different lengths depending on it they are ball and cup or ball and ball. Ball and ball have one length, the overall length, from the tip of one ball to the tip of the ball on the other end scope
Ball and cup have two different lengths, overall and effective length, the overall total length is measured the same as a ball and ball, from the bottom of the ball to the top of the cup wrench The effective length is from the bottom of the cup to the tip of the ball[b]. I use a 5/16 ball set in the cup and measure the overall length from the top of the bearing to the tip of the ball and the other end and then subtract half of the diameter of the ball bearing which is .156 scope
There are many choices on pushrods other than the type and lengths, the diameter of the tube, the thickness of the wall, the design of the wall, straight, single taper or dual taper and if they are heat treated or not.
IHTH.
Posted By: RapidRobert

Re: pushrod length with roller cam - 02/13/23 12:51 AM

I would also checkout "engine tech: valvetrain geometry" by straub on utube. you might checkout info on the valve tip wipe pattern. iirc uncle tonys garage had a vid on they were loosing alot of power cuz the preload (not sure if it was too little or too much) was not correct.
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