360 stock push rods length reusable

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Slantsix64

Slantsix64

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hey guys I'm building a 360 for my a body it's a 1979 block I'm having the heads milled .045 going to be running this camshaft here are the specs, my question is can I reuse stock push rods or would I need shorter ones, what would be the most lift I could run with stock push rods on a small block. Thanks I'm advance!

Cam Style:Hydraulic flat tappet

Basic Operating RPM Range:1,300-5,600

Intake Duration at 050 inch Lift:218

Exhaust Duration at 050 inch Lift:224

Duration at 050 inch Lift:218 int./224 exh.

Advertised Intake Duration:262

Advertised Exhaust Duration:270

Advertised Duration:262 int./270 exh.

Intake Valve Lift with Factory Rocker Arm Ratio:0.462 in.

Exhaust Valve Lift with Factory Rocker Arm Ratio:0.470 in.

Valve Lift with Factory Rocker Arm Ratio:0.462 int./0.470 exh.

Lobe Separation (degrees):110

Grind Number:CRS XE262H-10

Computer-Controlled Compatible:No

Lifters Included:Yes

Lifter Style:
 
When you torque the rocker shafts down, take note of how far the pushrods compress the plungers in the lifters. Typically you would want around .060 preload on the lifter. So what you're looking for, is the distance between the plunger and the snap ring that holds it in.
 
Maybe.....maybe not. What head gasket do you plan OP? That plays into the equation. If a .028" head gasket is used (which is close to stock thickness), then you'll lose pretty much all of that .045" from the available lifter piston travel, and with tolerances stackups, the odds are good of some bottoming out. If you use a kit Felpro head gasket, the the extra .020-.025" thickness reduces some of the lifter piston travel that you lose from the milling.

The above is just the head milling compensation. If a valve job is done, and the valves are sunk into the seats at all, then this becomes worse and compresses the pistons down in the lifters even more.

As noted, measure the preload in the lifter pistons... with that much milling and the tolerance stackups, you probably need to look at them all. BTW, the preload is from the OUTER ring under the retaining clip, not the inner circular thingy... (at least for the most common oil-through lifters...) And you look at each one when on the base circle (valve fully closed).

If this is a low buck build, then it is conceivable to use shims under the rocker shafts to compensate the height changes. The shim thickness is 2/3 times the pushrod length you want to compensate. E.g., for a .045" correction, use a .030" thick shim.
 
nm9stheham said:
Maybe.....maybe not. What head gasket do you plan OP? That plays into the equation. If a .028" head gasket is used (which is close to stock thickness), then you'll lose pretty much all of that .045" from the available lifter piston travel, and with tolerances stackups, the odds are good of some bottoming out. If you use a kit Felpro head gasket, the the extra .020-.025" thickness reduces some of the lifter piston travel that you lose from the milling.

The above is just the head milling compensation. If a valve job is done, and the valves are sunk into the seats at all, then this becomes worse and compresses the pistons down in the lifters even more.

As noted, measure the preload in the lifter pistons... with that much milling and the tolerance stackups, you probably need to look at them all. BTW, the preload is from the OUTER ring under the retaining clip, not the inner circular thingy... (at least for the most common oil-through lifters...) And you look at each one when on the base circle (valve fully closed).

If this is a low buck build, then it is conceivable to use shims under the rocker shafts to compensate the height changes. The shim thickness is 2/3 times the pushrod length you want to compensate. E.g., for a .045" correction, use a .030" thick shim.
Click to expand...
The head gasket is the thicker one which is .054 compressed, how would I check the clearances that would be after I torque the rocker arm shaft to 17inch pounds? I usually never check any clearances and it turn out fine as long as I don't go crazy on the lift, but I wanna get this done the right way and check everything. Guess I got a lot of reading do I need a dial indicator?
 
A dial indicator would be good on many fronts but that would do the trick on how far the pushrod goes down into the lifter.
 
The only real way to tell is to get an adjustable checking pushrod, set it up and measure it. If it was mine, I would go ahead and get a custom length set. They're cheap.
 
According to his numbers, he is positive @ .009.
(Longer length, an amount not to worry about, or even talk about.)
 
Yeah I would get a adjustable pushrod and check. If finding out I could run the stock pushrods after checking then I'm just out the money for the adjustable pushrod. However I already have a adjustable pushrod..lol
 
rumblefish360 said:
According to his numbers, he is positive @ .009.
(Longer length, an amount not to worry about, or even talk about.)
Click to expand...
Actually, he is about .015-.020" long just based on the gasket change and milling. But that assumes the valves have not been sunk due to a valve job. So not 100% known.....

BTW, OP the torque on the shaft bolts is 15 ft-lbs. But for this, just snug them down.
 
nm9stheham said:
Actually, he is about .015-.020" long just based on the gasket change and milling.
Click to expand...
He PM’d me missing info.
Let’s see, milled head .045. Install a head gasket at .054. So, .054 - .045 = ?
No biggie.
 
Slantsix64 said:
hey guys I'm building a 360 for my a body it's a 1979 block I'm having the heads milled .045 going to be running this camshaft here are the specs, my question is can I reuse stock push rods or would I need shorter ones, what would be the most lift I could run with stock push rods on a small block. Thanks I'm advance!

Cam Style:Hydraulic flat tappet

Basic Operating RPM Range:1,300-5,600

Intake Duration at 050 inch Lift:218

Exhaust Duration at 050 inch Lift:224

Duration at 050 inch Lift:218 int./224 exh.

Advertised Intake Duration:262

Advertised Exhaust Duration:270

Advertised Duration:262 int./270 exh.

Intake Valve Lift with Factory Rocker Arm Ratio:0.462 in.

Exhaust Valve Lift with Factory Rocker Arm Ratio:0.470 in.

Valve Lift with Factory Rocker Arm Ratio:0.462 int./0.470 exh.

Lobe Separation (degrees):110

Grind Number:CRS XE262H-10

Computer-Controlled Compatible:No

Lifters Included:Yes

Lifter Style:
Click to expand...

Measure and Select Pushrods for Mopar Shaft Rocker Systems
 
not maybe in this case but if a reground cam or one with lots more lift- base circle may be reduced

verify your base circle before installing that new cam
 
Wyrmrider said:
not maybe in this case but if a reground cam or one with lots more lift- base circle may be reduced

verify your base circle before installing that new cam
Click to expand...
It is a comp cams XE262
 
rumblefish360 said:
He PM’d me missing info.
Let’s see, milled head .045. Install a head gasket at .054. So, .054 - .045 = ?
No biggie.
Click to expand...
Mmmmmm..... I see the error that leads to .009"....the original head gasket thickness is missing.

You subtract the difference in the gasket thickness from the .045" to get the changes. With the original shim at .025" (per my '65 FSM), and knowing that those Felpros are not consistent at .054" compressed thickness, but average around .050", that is a .025" gasket thickness change and a total change of .020". With those particular head gasket variations, then it can be .016-.024" change.....

Not to mention factory deck height variations, valve work, past work, tolerances on the pushrod lengths, rockers, cam and cam position..... there are a LOT of moving parts that can cause this to vary. The original lifter piston float tolerance was +/-.060" for a reason.
 
nm9stheham said:
Mmmmmm..... I see the error that leads to .009"....the original head gasket thickness is missing.

You subtract the difference in the gasket thickness from the .045" to get the changes. With the original shim at .025" (per my '65 FSM), and knowing that those Felpros are not consistent at .054" compressed thickness, but average around .050", that is a .025" gasket thickness change and a total change of .020". With those particular head gasket variations, then it can be .016-.024" change.....

Not to mention factory deck height variations, valve work, past work, tolerances on the pushrod lengths, rockers, cam and cam position..... there are a LOT of moving parts that can cause this to vary. The original lifter piston float tolerance was +/-.060" for a reason.
Click to expand...
Your still missing information and correcting me is out of line.
 
If that has been shared via PM, that is fine. The rest of us can only go on what is presented.
 
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