[Nuckollsinc]

OK hopefully everyone seen my dyno graph. Well I found a borken inner spring on my triple rate springs and under the broken spring were 2 20 thousands shims that were ate down to 2 little 1/8" rings. Then upon putting it back together I noticed that the pushrod was bent a little on that spring. Then I looked the rest over and noticed that on the #3 cyl. the exh valve was bent really bad. So I looked up the number 4086 and 4087 looks to be stock length pushrods I dont see stock length pushrods working with a .714 lift cam solid roller.

[bigdog7373]

Sooooo...... What are you asking? Valves hitting the pistons?

[Nuckollsinc]

No the valves arent hitting the pistons. Im asking if stock length push rods would be the cause of how the graph looks. Also why would the shims get ate up under the springs. My engine guy couldnt figure out why they would use to thin 2 20 thousands shims instead of one 40 or 60. There isnt a mark on any of the pistons.

[Nuckollsinc]

Also if anyone is familiar with the numbers 4086 and 4087 on pushrods there isnt any other markings on them.

[johnsongrass1]

Check the valve guide. If it were to tight and froze the valve the pushrod could bend. Valve heads don't bend unless they hit the piston.

Get your self a plastic pushrod checker, $15 most places. it will get you a ball park measurement on what you need.

[DoubleVision]

info I get with pushrod numbers 215 - 4086 and 215 - 4087 are big block chevy pushrods by Clevite. 4086 being Intake and 4087 being exhaust. These are stock replacement pushrods that sell for around $15 on ebay.

[Nuckollsinc]

I guess I dont understand why in the world they would use these kind of cheesy stock style pushrods with this kind of motor.

[ericnova72]

Running with the broken spring will tear up the shims. With a broken spring the spring rate is lower allowing the spring to surge and jump around on the seat, and the broken pieces have jagged ends.

It is possible that the stock length pushrod is correct, but it is also possible that stock length is incorrect, the only way to know is to check out the rocker geometry. Valve stem length, valve lift, cam core base circle diameter, pushrod cup position in the lifter, pushrod cup position in the rocker all play into this, you don't ever know what length is correct until you check it. That's why pushrods should be the last part purchased, the length can't be determined on paper, you have to check it at assembly or trial assemble it up beforehand to determine the correct length.

I would hope with a solid roller you are using either 3/8" diameter .095"+ wall thickness or 7/16" diameter .080"+ wall pushrods, 5/16" is way too small.

[ericnova72]

Originally Posted by Nuckollsinc

I guess I dont understand why in the world they would use these kind of cheesy stock style pushrods with this kind of motor.

I would guess that whoever put the engine together doesn't know as much as they think they do....

[Nuckollsinc]

Yeah I was happy to find out that everything was correct that was told to me. Bored 30 over 12:1's forged pistons, gm performance crank and rods, Comp cams .714/.714 solid roller, comp cams roller lifters, erson 1.7 roller rockers, cam was advanced 2 deg. Compression all checked 180-185. Everything in the engine looks all new. Crosshatching in the cylinder all looked fresh. So I was confused why they used a stock push rod. I will borrow a pushrod checker and get busy.

[SSedan64]

That's Nuts, stock Pushrods with Triple springs on a Solid Roller Cam!

[American Muscle]

what size motor? with the combo you have I would expect higher hp/tq numbers. Was this on a chasis dyno?

[BigRoy1978]

Originally Posted by SSedan64

That's Nuts, stock Pushrods with Triple springs on a Solid Roller Cam!

THAT is why they bent...

[Nuckollsinc]

Yes thats a chassis dyno 460 bbc 4500 stall th400 4.56's.
They are 3/8" pushrods

One question when checking pushrod length do you need to be at zero lash or set the rocker arm with a feeler guage? I have a solid cam and solid lifters. I did the sharpie test and both intake and exhaust are on the very back of the stem. BUT that was with setting .028 and .030 lash turning the motor 2 times by hand.

[cobalt327]

I have always set the geometry/p-rod length at zero lash, using an adjustable p-rod.