Edelbrock Pushrod length vs Stock?

Hello Everyone,

I am looking for feedback on the length of pushrod used when running the Edelbrock cylinder heads? I know this can vary based on deck height and other variables. Also... what rocker arm did you use?

This is the first time I have built an BBB with Eheads and to get the geometry correct I would need a 10.425 long pushrod. That seems a bit crazy!

Thanks in Advance!

 

Get a pushrod length checker to know for sure, then order.

 

Hello Mark... I did that but the number I am getting 10.425 seems long. The method I used is having the cam at half lift with the centerline of the fulcrum to the roller tip being perpendicular to the valve.

 

The spec in the Edelbrock catalog clearly states that SB Chevy 1.6 rocker are to be used, so you should have a world of choices in that regard!

Did these Heads ship from ED assembled?

How does the base circle of your Cam being used differ in size from a stock Cam?

 

That does seem long John.. I have not done an E head motor with a flat tappet yet, they have all been roller cams, which of course take considerably shorter pushrods. Typical pushrod length in that motor is about the stock 455/flat tappet size.. 9.350-9375"

With Buick style heads/valvetrain, that same roller motor is about 9" on the pushrods. So figure around .350ish ball park longer for the E heads.. or around 9.700 for a flat tappet cam. Your almost an inch longer than that..

If you have a high lift flat tappet, (small base circle) and are using Chevy lifters,(.060 deeper seat height vs Buick lifters) then you could have some seriously long pushrods, near 10", but your half an inch beyond that, which would make me look twice.. as you did..

 

9.650"x 3/8. TA1420, They are hardened for the guide plates. In stock

 

Thanks Mike...I told my friend Tom to just order the parts from you. I am missing something when doing the measuring.

 

Yeah, you want the lifter on the base circle NOT half way up the lift!

Surprised no one else caught that;

You use your adjustable pushrod with the lifter resting on the base circle of the cam(@ zero lift) and adjust it until the rocker tip is just before the centerline of the valve tip so when it pushes down on the valve tip at the bottom of the "lift" the rocker tip is just after the centerline of the valve tip.

The rocker tip only travels around .060" at the most, so with around only .030" before the centerline would be in the ballpark without having to go through the travel if you have setup enough valve trains, you could put your thumb up and get 'r right in the sweet spot. GL

 

For the best average lenght push rod and the best average centered rocker to valve contact point you WANT to check at the 50% of total valve lift point, not on the base circle!
If Cam your checking uses lash you need to compensate for that.

 

???????????????

If you do that without the valve opening you'll think you need a MUCH longer pushrod than you really need, unless you subtract that 50% lift. But even then the lifter is going up a ramp, not being pushed straight up which can give a false "center of the lift" reading with a flat tappet cam.

Never heard of doing it the mentioned way, I have always started on the base circle(which should ALL be the same on every lobe)and get my checker pushrod to the length where the rocker tip is just before the center of the valve tip. To confirm it is correct I check the pattern of rocker tip travel by rotating the crank twice with the rocker installed. Doing it this way, I have NEVER gotten a measurement over an inch longer than I needed!

The lifter rides on the base circle of the cam 50% of the rotation(180*) so that IS a good start point for the beginning of the rocker's tip's travel with 100% of the lift being the end of the travel. Doing this puts the centerline of the rocker tip on the centerline of the valve tip @ 50% of the lift, but you don't start there to achieve that.(at least I don't) You would have to have the valve held opened @ the 50% lift point and the lifter on the 50% lift to set it up that way, I don't really see that as practical.

 

Maybe you can question comp cams on this as with light checking spring installed this is how there site explanes how to check for the needed push rod lenght!

 

With that little tid bit of info(in bold) I don't need to look up their website to know what they wrote.

Let me guess;

You start your initial pushrod adjustment on the base circle where the rocker is installed just before center of the valve tip and rotate cam to the 50% lift point and adjust the pushrod length so the rocker tip is on the centerline of the valve tip if its not already there. Never read the comps instructions on their website, been doing this LONG before I ever went online so......... Learned the old tried and true technique to get a before and after centered rocker tip pattern of travel that has worked great for years. I'll have to try this way out, might save me a couple minutes?

Still not sure how he got just under an inch of what he needed? If he took the measurement without the valve opened it would of been shorter not longer? Unless a hyd. lifter was used and was collapsing because he didn't use a checker spring? But still that shouldn't be an extra inch.

 

HOW you measure is somewhat dependent on WHAT tools you have, and how much time you can devote to the effort.

Most (but not all) folks want the pushrod length that provides the shortest sweep at the valve tip, even if it's NOT centered. Better to be slightly off-center and have a short sweep, than to be on-center with a longer sweep--assuming you aren't running off the valve tip.

I have no idea what tooling you'd need to measure "the centerline of the fulcrum to the roller tip being perpendicular to the valve" and do it with any accuracy.

Then, inevitably some guy tells you to put a solid lifter in the engine for checking...without mentioning that you'd need to compensate for the change in pushrod socket height from a solid lifter to a preloaded hydraulic lifter.

I don't have protractors, dial-indicators that register on the valve retainer, etc.

I blacken the valve tip with a Sharpie marker each time I try a different pushrod length, and roll the engine over starting with an adjustable pushrod set to stock length. At full lift, I look at the lifter to see how far it's collapsed, and then I know to subtract enough length from the final pushrod measurement to compensate. Then I do it again with a change to the pushrod length. When the shiny mark on the valve tip gets wider, I go the other direction with pushrod length. When I have the sweep as short as it gets, I'm done except to confirm the pushrod length on another valve or three. I tend to test both intake and exhaust on cylinders 1 and 6, four attempts at measurement. That gets me both banks, front and near-the-rear, and both cam lobes (intake and exhaust).

Sometimes all the intakes are the same, and all the exhausts are the same...but intakes are not the same as the exhausts. And if the measurements are "all over", you'd better inspect valve tip height.





THEN you have to measure the adjustable pushrod you've just used the SAME WAY YOUR PUSHROD SUPPLIER DOES. (There's at least three different ways to measure a pushrod, and they give different length results.)

After you've gotten your "perfect" length(s), you can round to the nearest 0.050 increment that still gives you some lifter preload.