logo
12 Port News - Features
12 Port History
Casting Numbers
Online Store
Tech Tips
Become a Member
Previous Thread
Next Thread
Print Thread
Rate Thread
#75373 06/02/13 12:13 AM
Joined: Sep 2011
Posts: 51
C
Active BB Member
OP Offline
Active BB Member
C
Joined: Sep 2011
Posts: 51
Leo's book recommends a chrome moly .075" wall thick pushrod for street use. Where can these be sourced thru because I'm not seeing them in places like Jegs and Summit.

I'm running a Clay Smith cam with a 560 lift in my 292 and I just broke a stock one. I'm hesitant to go back together with a stock pushrod and I'm wondering what caused it to break in the first place.

Last edited by Countn'Carbs; 06/02/13 12:17 AM.
Joined: Jan 2005
Posts: 2,123
Likes: 3
P
1000 Post Club
**
Offline
1000 Post Club
**
P
Joined: Jan 2005
Posts: 2,123
Likes: 3
Every cam manufacturer sells them, as well as Smith, Trend and Manton.
The important thing is the biggest diameter that fits, wall thickness is an afterthought. If they don't make .075" (not familiar to me) get the next thicker size, the weight penalty is too small to bother with.

panic #75395 06/02/13 11:22 PM
Joined: Apr 2004
Posts: 3,566
Likes: 37
1000 Post Club
****
Online Content
1000 Post Club
****
Joined: Apr 2004
Posts: 3,566
Likes: 37
I like using Smith Brothers Pushrods. You may consider upgrading to 3/8 pushrods that are .080 wall. With the 292 PR length of 11.6" give or take, they are like spagetti when only 5/16 diameter. You will have to open up the holes in the head and get guide plates.


Inliner Member 1716
65 Chevelle Wagon and 41 Hudson Pickup
Information and parts www.12bolt.com

Joined: Jan 2005
Posts: 2,123
Likes: 3
P
1000 Post Club
**
Offline
1000 Post Club
**
P
Joined: Jan 2005
Posts: 2,123
Likes: 3
X2 - do it, one less thing to worry about.

panic #75407 06/03/13 10:25 AM
Joined: Sep 2011
Posts: 51
C
Active BB Member
OP Offline
Active BB Member
C
Joined: Sep 2011
Posts: 51
Yeah I hear ya as much head work as we did on this head...we didn't open it up for 3/8" pushrods.

Guess I'll see what I can accomplish in the 5/16" family. This cam is just a little 280 degree hydraulic with recommeded springs and I figured stock pushrods would be fine....guess not.

Joined: Sep 2008
Posts: 3,673
Likes: 42
1000 Post Club
****
Offline
1000 Post Club
****
Joined: Sep 2008
Posts: 3,673
Likes: 42
Its really uncommon to break a pushrod with such a small cam, I would look for other issues, like coil binding of the valve springs, or retainer to guide clearance. Never assume the machine shop was spot on.



Class III CNC Machinist/Programmer
Joined: Sep 2011
Posts: 51
C
Active BB Member
OP Offline
Active BB Member
C
Joined: Sep 2011
Posts: 51
I'm going to pull the other pushrods tonight and see how they look.
When I put this together I checked to insure the rockers (stamped long slots) weren't maxing out on their slot and that the springs weren't binding. With only a .560 lift the retainers don't come close to the guides but I will double check all of this.

I've got some Trends on the way that are .105" wall. The stocker that broke is .060" wall.

Joined: Nov 2012
Posts: 551
L
Major Contributor
Offline
Major Contributor
L
Joined: Nov 2012
Posts: 551
Tom

Will stock pushrods work for your medium lift cam and bigger valves with after market rockers ratio 1.75


Josh
72 gmc lwb air ride 5 speed (soon) turbo 292 II# 6102
lowboygmc #76668 08/28/13 11:43 AM
Joined: Nov 2012
Posts: 551
L
Major Contributor
Offline
Major Contributor
L
Joined: Nov 2012
Posts: 551
Anybody?


Josh
72 gmc lwb air ride 5 speed (soon) turbo 292 II# 6102
lowboygmc #76669 08/28/13 01:34 PM
Joined: Sep 2008
Posts: 3,673
Likes: 42
1000 Post Club
****
Offline
1000 Post Club
****
Joined: Sep 2008
Posts: 3,673
Likes: 42
What kind of head work will be done?



Class III CNC Machinist/Programmer
Joined: Nov 2012
Posts: 551
L
Major Contributor
Offline
Major Contributor
L
Joined: Nov 2012
Posts: 551
I have toms medium lift cam larger valves 1.94 1.6 lump purts hydraulic lifters after market 1.75 ratio rockers screw in studs


Josh
72 gmc lwb air ride 5 speed (soon) turbo 292 II# 6102
lowboygmc #76675 08/28/13 06:43 PM
Joined: Sep 2008
Posts: 3,673
Likes: 42
1000 Post Club
****
Offline
1000 Post Club
****
Joined: Sep 2008
Posts: 3,673
Likes: 42
Are you using guide plates? Just as a personal preference, regardless of engine type, I never use the stock pushrods in any engines I build for myself or other people. I always use hardened.



Class III CNC Machinist/Programmer
Joined: Nov 2012
Posts: 551
L
Major Contributor
Offline
Major Contributor
L
Joined: Nov 2012
Posts: 551
No guide plates and those can be obtained from any place stated above?


Josh
72 gmc lwb air ride 5 speed (soon) turbo 292 II# 6102
lowboygmc #76683 08/28/13 11:40 PM
Joined: Apr 2004
Posts: 3,566
Likes: 37
1000 Post Club
****
Online Content
1000 Post Club
****
Joined: Apr 2004
Posts: 3,566
Likes: 37
Josh,
I have used stock pushrods with that cam. Had one bend. I suggest getting new pushrods from Smithbros. Same diameter but with a heavier wall thickness. Also suggest waiting to get them till the engine is bolted together. Then you can measure the correct length needed. Use the old ones as a reference length.


Inliner Member 1716
65 Chevelle Wagon and 41 Hudson Pickup
Information and parts www.12bolt.com

Joined: Nov 2012
Posts: 551
L
Major Contributor
Offline
Major Contributor
L
Joined: Nov 2012
Posts: 551
Well i got oem ones from napa and they were all proper length i guess you would say do you have a part number from smithbros? And hows the valve cover coming did you get my order for my harmonic balancer?


Josh
72 gmc lwb air ride 5 speed (soon) turbo 292 II# 6102
lowboygmc #76685 08/29/13 12:13 AM
Joined: Apr 2004
Posts: 3,566
Likes: 37
1000 Post Club
****
Online Content
1000 Post Club
****
Joined: Apr 2004
Posts: 3,566
Likes: 37
PM sent about your order.

You will have to contact Smith bros about part numbers.


Inliner Member 1716
65 Chevelle Wagon and 41 Hudson Pickup
Information and parts www.12bolt.com


Moderated by  stock49, Twisted6, will6er 

Link Copied to Clipboard
Who's Online Now
0 members (), 125 guests, and 27 robots.
Key: Admin, Global Mod, Mod
Newest Members
Hairyclive, THarper, crash, ocean1907, Jabez House
6,816 Registered Users
Sponsored Advertisement
Sponsored Advertisement
This Space is Available
Powered by UBB.threads™ PHP Forum Software 7.7.5