Need some pushrod help

[MB43]

First off, the pushrods I have now are too long. What bad things would happen by using pushrods that are too long?

Next, I picked up a Comp Cams adjustable "checking" pushrod to see what size I really need. How do I use it? There's no "cup" on the end, it's just rounded off like the other end of a normal pushrod.

 

[AdamR]

Mikel a pushrod that is too long can hang the valves open. CompCams should have sent you a checking pushrod that was ball/cup..

If your currant pushrods are too long why not use some shims inder the rocker shafts ?

 

[BARRACUDA340S]

Do you have adjustable rocker's?

schiming the rocker shaft will change the geometry so be careful.

 

[MB43]

Mikel a pushrod that is too long can hang the valves open.

And what would that do to the motor?

CompCams should have sent you a checking pushrod that was ball/cup..

They sent me what I ordered, which was this one:

http://www.powerandperformancenews....=H_CHK_PR&Category_Code=PSHRDTL&Store_Code=CC

It doesn't look like they make with with a cup.

If your currant pushrods are too long why not use some shims inder the rocker shafts ?

I'd rather just use the correct length pushrods.

Do you have adjustable rocker's?

Yes, I have the Crane gold rockers. A few of the adjusters started going south on me, that's what started this whole mess. Crane sent me a new batch of adjusting screws & nuts, then I found that some of the rockers were banged up. Crane sent me some replacements, when I put it all together I found that the adjusting screws don't poke out under the rocker enough. There's supposed to be 2-4 threads showing, I've got none - and about 1/8" until any will poke out, so these pushrods are WAY too long.

I changed the heads a few months ago... I knew these heads were milled, but I didn't know how much. Now I'm guessing that it was quite a bit, since the pushrods were find with the old heads.

 

[AdamR]

If the valves are being hing open your gonna loose compression. It probably wouldnt run right though so you would know something was wrong.

I would call compcams and see if they have a ball/cup type.

did you have trouble getting the intake bolted up when you changed the heads ? with alot of milling even if the milled the intake surface you'll usually have trouble lining up the bolt holes. On my 440 I had to open the bolt holes on the intake up to get the thing bolted down.

 

[MB43]

If the valves are being hing open your gonna loose compression. It probably wouldnt run right though so you would know something was wrong.

Yep, had some issues. The whole car was shaking... Not always, but some times. Like it was running really rough. But it sounded fine.

I would call compcams and see if they have a ball/cup type.

So... The one I have it no good?

did you have trouble getting the intake bolted up when you changed the heads ? with alot of milling even if the milled the intake surface you'll usually have trouble lining up the bolt holes. On my 440 I had to open the bolt holes on the intake up to get the thing bolted down.

Actually, I did! I had to ditch the cork gaskets and just use RTV to get the intake to sit correctly on the block.

 

[AdamR]

I dont see how the ball/boall checking pushrods could work.

Next time the intake is off just open the bolt holes up 1 size. It will make lining all the bolts up easy.

 

[MB43]

I found that Smith Brothers makes a checking pushrod with a cup on one end. I guess I'm gonna have to buy that one...

 

[BigEdsGarage]

Comp doesnt make a cup type checking pushrod.

Just throwing some things out for you. If everything was fine with the old heads but problems arouse when you installed the new ones I would question if the installed height of the springs is different. If the valves are longer than stock the same thing would happen. There is a better chance of the problem being caused by that than milling of the heads. Did anyone go through the heads or did you buy them assembled? If you said it was running rough this would also indicate some valvetrain problems. Shimming rocker shafts is not a prefered method of correcting height issues due to the fact that raising the rocket shafts will push the rocker tip towards the exhaust side of the head, offsetting it on the valve surface. It works, but there are better ways. If they were new pushrods installed it almost sounds like they were the wrong length for solid/hyd cam, but you said they were fine before. If the heads have had a valve job done it is possible that someone sank the valves deeper into the seats, which would also cause you to have to back off the adjusters. Just a few thoughts.

 

[MB43]

Thanks for that info. I found out (the hard way, I guess) that Comp doesn't make what I needed. Like I said earlier in this thread, I got the correct one from Smith Brothers. Today I picked up a caliper so I can measure it properly, hopefully a new set of pushrods will be on order come tomorrow.

The heads that were on this motor (with these pushrods) when I bought it were basic 360 heads - 974 castings - machined for larger valves with a minimal amount of material removed during surfacing.

The heads I have on there now are 340 heads - 894 castings - with better springs, big valves, porting, polishing, and quite a bit of milling. I didn't know how much milling, though. I bought these heads assembled and slapped them on the motor without doing much more than painting them the same color as the block.

Have a look at the difference from the pushrods that I was using to the checking pushrod. The checking pushrod is the black one:

Think they were too long?

 

[Coyote Jack]

With that much of a difference your lucky you didn't bend or break somthing Mikel. That is a big change in alignment for the valve train.

Jack

 

[MB43]

With that much of a difference your lucky you didn't bend or break somthing Mikel. That is a big change in alignment for the valve train.

Jack

Tell me about it.

I did break some stuff, though... I had a few adjusting screws go south on me, and I beat up a couple of rockers.

The ones that were in there were 7.491" overall, the adjusting pushrod is 7.015" overall. That's almost half an inch!

 

[AdamR]

Good thing the adjusters were the weakest link !