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Old 12-02-2021, 07:09 PM
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TCSGTO TCSGTO is offline
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Default Restricted Pushrods?

What’s your guys opinions on running restricted pushrods on a street app? I have a set of Crower SR lifters I want to run on a HR cam and have never run the restricted rods but a lot of people do. What are the pluses and minuses of using them on the street.
The Edelbrock heads have poorer oil drain back than stock heads so in my thinking having less go up top isn’t necessarily a bad thing, or is it?

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68 GTO,3860#
Stock Original 400/M-20 Muncie,3.55’s
13.86 @ 100
Old combo:
462 10.75 CR,,SD 330CFM Round Port E's,Old Faithful cam,Jim Hand Continental,3.42's.
1968 Pontiac GTO : 11.114 @ 120.130 MPH

New combo:
517 MR-1,10.8 CR,SD 350CFM E's,QFT 950/Northwind,246/252 HR,9.5” 4000 stall,3.42's
636HP/654TQ
1.452 10.603 @ 125.09
http://www.dragtimes.com/Pontiac-GTO...lip-31594.html
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Old 12-02-2021, 07:16 PM
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I use 0.040" restricted pushrods on my race motor with a SR cam and in my brother's motor with a HR cam and both motors get plenty of oil to the top end and don't have any issues.

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1967 Firechicken, 499", Edl heads, 262/266@0.050" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3550#. 10.01@134.3 mph with a 1.45 60'. Still WAY under the rollbar rule.
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Old 12-02-2021, 07:31 PM
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Sirrotica Sirrotica is offline
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Basically 2 schools of thought,

One, that flooding the valve train, and springs removes heat and less likely to burn a pivot point on rocker arms, and keeping the springs covered removes heat that lessens spring life.

Two, that too much oil in the upper end with marginal drain back from the restricted aftermarket heads can cause oil pump starvation leading to bottom end failure due to oil starvation, and aeration of the oil.

My own preference, is to keep oil in the pan as much of the time as possible. If I were to use aftermarket heads, I would look into exterior oil drains plumbed from the heads to the pan. It also might lessen windage/aeration, keeping some of the oil out of the valley that would return outside of the valley. Keeping oil off the spinning crank is always a good thing.

You have to deduce which line of reasoning you think will have a better outcome.....

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1973 T/A (SOLD)
2005 GTO
1984 Grand Prix

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Old 12-02-2021, 07:43 PM
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krisr krisr is offline
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Quote:
Originally Posted by TCSGTO View Post
What’s your guys opinions on running restricted pushrods on a street app? I have a set of Crower SR lifters I want to run on a HR cam and have never run the restricted rods but a lot of people do. What are the pluses and minuses of using them on the street.
The Edelbrock heads have poorer oil drain back than stock heads so in my thinking having less go up top isn’t necessarily a bad thing, or is it?
With your drain back, I know when I got my heads from Butler they cleaned up the drain holes and ground little "pathways" to help with oil flow. I run a solid roller on the street, just normal 3/8" pushrods that aren't restricted. I think the smallest orifice is the hole in the rocker arm (Crower SS) so figured that it's an unneeded deal for me. No issues with sucking the pan dry, oil pressure or drain back here. I went with the theory that oil up in the top is better to cool the springs in a street deal and run a Canton trap door sump, around 6-7qt from memory with a home prepped 60psi pump.

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'71 Holden HQ Monaro - 3850lbs race weight, 400c/i - 11.4 @ 120
'66 Pontiac GTO - 389, 4 speed street cruiser
  #5  
Old 12-02-2021, 10:47 PM
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Torquewar Torquewar is offline
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This is sore spot for me since i purchased e-heads in 09. The drains holes are basically horizontal, big engineering mistake in my opinion. So I’ve been trying to keep oil out of the top end . Ive run restricted rods for yrs without issue . This engine is beat on regularly , no part failures.
I have ground channels to expedite flow and have 2 drain lines per head to help with oil drain.

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Old 12-03-2021, 10:45 AM
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leeklm leeklm is offline
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Another consideration is how much clearance you have with your lifter bores. Bill M reminded me of this recently... if they are sloppy and using restricted push rods, you will be pushing more oil up around the lifters vs increasing available pressure/volume for bearings.

Although you would still accomplish the goal of less oil going up to the heads, but maybe not adding much additional volume to the bearings. The better fix is oil restictors in the lifter bores, but of course not quite as convenient as push rods!

Sent from my SM-G965U using Tapatalk

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68 Firebird-- Street/Strip - 400/461 Eagle Forged Bottom End & Ross Flat top pistons. KRE 325 CFM D port, Ultradyne 263/271 @.050, .4267 lift. Crower Solid roller lifters and 1.65 stainless rockers. Quickfuel 1000 on Torker2 intake and 2" open spacer. Hedman 1.75" headers. TH400 w/brake. Ford 9" w/3.80 gears & 28x9 Hoosier pro bracket drag radial. Best ET: 1.35 60ft, 6.29 @ 107.20 mph, 9.99 @132.33 mph. 3,300 race weight

Last edited by leeklm; 12-03-2021 at 11:37 AM.
  #7  
Old 12-03-2021, 11:52 AM
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I've ran restricted pushrods for quite a few years. When the heads were reworked a few years ago Dave Bisschop, he said there was zero issues with my valvetrain.

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466 Mike Voycey shortblock, 310cfm SD KRE heads, SD "OF 2.0 cam", torker 2
373 gears 3200 Continental Convertor
best et 10.679/127.5/1.533 60ft
308 gears best et 10.76/125.64/1.5471
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