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View Full Version : Pushrod length Question. Help Needed.



pearl95sc
05-18-2004, 10:44 PM
Alright, months back when I installed my cam, (car still aint done yet) I wasn't educated to the whole re-grinding process of cams. I only thought they came as new solid cores. In my ignorance, I installed back my original pushrods. I did the whole scribe mark check to determine the new length. Now before makaing any marks, i could only spin 4 of the pushrods, and there was no up and down play in any of them. After making the first mark, and turning over the engine a coupe of times, I used a tape measure and came up with a 1/16 difference between the second mark. With my measuremeants, I came up with the following....

Stock pushrod length is 7.125 inches
Needed pushrod length is 7.1875 inches

Does this sound right? I remember reading older posts of people who often get regrinds using 7.2 length pushrods. I need to order these things soon, so Any and all help is appreciated. Lemme know asap. Thanks, Alyn.

Also, if anyone needs to see the camcard, lemme know, as I can post it if needed.

fastsc92
05-19-2004, 09:29 AM
if you get them from a SBC, with OE rollers then they should be 7.195 long....which is what i have and they are doing just fine. What cam are you running in that thing? If you are building a high HP motor you might want to look at getting some 1 peice design rods. I believe i used a 2 peice design from comp, and a set of 16 was like 35 bucks. I'd look into trick flow pushrods from summit, they are top of the line and are only 85 bucks for a set of 16 that are 7.195-7.200" long. They are 5/16" pushrods by the way.

scotte
05-19-2004, 11:13 PM
i just did the casm swap too

you can get melling replacement pushrods at 7.200
at autozone i pay'd about $20 for 12 of them

ask for pushrods for a 94 camaro z28 w/350ci 5.7l v8

your going to love the cam

i'm still breaking new bearings in (i've clock 300 out of 500 mi. needed before i start stomping on the load pedal)

but i can tell you the level of acceleration that used to take 5 psi of boost
now takes none :D :D

on the highway it feels like a diff. car

ahh the glory of unlimited passing power

scbird1
05-19-2004, 11:28 PM
With the new cam did you use new lifters, pushrods and what rockers are you running? On my big block Pontiac`s we just threw a new cam in but we always replaced the entire valve train. With hydrolic lifters we never had to change pushrod length. If you reuse any parts they must be put back in the same spot. Let us know how it runs.

pearl95sc
05-20-2004, 12:13 AM
Well, everything was back together, but I did have some valvetrain noise. Perticularly, what drove me nuts was that friggin bad lifter. So, I figure since i need to get the correct length pushrods, I should change lifters also. Being they had about 30k miles on them, and hearing horror stories of fords reman. engines having lifter problems, It seemed like a wise choice. The car ran amazingly, and had some sick pull, along with a nice grunt from the exhaust, so I got no complaints there. I just want everything to run smooth and quietly at idle like it should. If you wanna see the cam card, here is the link (http://sccoa.com/forums/showthread.php?t=39520) to the old thread that I posted it in. When I talked to a tech at crower, he was on the money when he said that I would have a hella amount of low end torque. I can easily spin the tires up through third, counting there is 9/32 of tread on these babies. (10-12/32 is new).

Mark, with regrinds, you gotta make up for the area removed by adding length to the pushrods. The whole reason for not changing the lifters originally was because I ruled the tick out as an exhaust leak from the manifold. I didn't put everything back in the same order either, so the sound moved from one side to the other. Weird huh? Also, found out that my 94 doesn't have a rod knock, but whatever that rattle is, I'm sure it isn't good. Either way, its still movin, and lovin that shift kit.

Thanks to all the replies, I'll order a set of trick flows, or call crower back and order a set of pushrods from them.

scbird1
05-20-2004, 12:40 AM
But a regrind means they added some material to IE increace the duration and lift. I think they cut it down and add steel back just to cut it down again for a larger lobe. Our lifters rarely go bad and sometimes I think Im crazy to replace them but I dont like to take things apart again so I just replace what I can. Mark

David Neibert
05-20-2004, 11:09 AM
I think they cut it down and add steel back just to cut it down again for a larger lobe.

Nope, no material is added, they reduce the diameter of the base circle. That is why longer pushrods are required.

David

scbird1
05-20-2004, 01:05 PM
How dose this create higher lift to open the valve more?
If you shorten the duration the valve will not stay open as long. I have been rodding for 30 years. Can some one tell me how this works? :confused:

David Neibert
05-20-2004, 04:18 PM
How dose this create higher lift to open the valve more?
If you shorten the duration the valve will not stay open as long. I have been rodding for 30 years. Can some one tell me how this works? :confused:


If you grind the base circle of the cam (portion of the lobe that lifter rolls on when valve is closed) and not the lobe itself to a smaller diameter, the lobe lift will now be higher relative to the base circle of the cam.

Basically, since you can't add material, you take it away from another area of the cam to accomplish the same thing. Re-grinds do have limitations and typically if you want long duration and high lift with a small base circle, the ramps are going to be very steep and hard on the rest of the valvetrain.

David

scotte
05-20-2004, 07:23 PM
i put new ford racing lifters in
new pushrods

i reused the stock rockers

scotte
05-20-2004, 07:35 PM
ddp.......

scbird1
05-21-2004, 09:11 PM
Thanks dave , its clear to me now. You add a longer push rod and that takes up the differance. That must be hard on the lifters. I hear someone is making new cores now.

pearl95sc
05-21-2004, 09:19 PM
I would love to have had a solid core based cam. Kinda kickin myself for not taking that machinist position a few years ago. I could have just put in the specs, and have grounded up a new cam, plain and simple. Things would have been a lot easier. Oh well, I do like the improvement, albeit, the thing is a p.i.t.a. to get figured out right. I'll be happy when all said is done, and the friggin car is back together again.

scbird1
05-22-2004, 11:15 AM
Didn`t they give you any spec`s on what your push rod lenght would need to be with the new reground cam? You would think for the money they charge they would supply the right push rod. Hope to see her on the road soon.

pearl95sc
05-22-2004, 10:23 PM
I'd have thought there was a required length, or recommended length, but AI called crower, and they said there is not. This was because everycar is different. Depending on gasket height, the decks of the heads, etc. Strange, but good to know. As far as cost, I bought the cam off of ebay a while back for like $100, so I couldn't complain. Came in the original box, with all manuals, assembly lube, etc, you get the idea.