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Discussion Starter #1 (Edited)
I was reading the new issue of CHP today and there was a small writeup in their Q&A column about needing a hardened fuel pump pushrod for use with the ZZ4 cam.

Since this cam is what I have in my motor, I am wondering if I have the correct pushrod installed in the block now. I am using ARP-134-9701 (Summit part #) which is listed as a lightweight chromemoly pushrod, but it says nothing about being hardened.

Need I be concerned? :confused:

*Edit - I did some searching online and it is more confusing now since a lot of people online are saying to use a bronze-tipped pushrod. I hate conflicting stories. It is confusing and frustrating.
 

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I don't know what a HARDENED fuel pump pushrod is. ALL fp pushrods are hardened. They might mean lightened. As in the hollow pump rod with the hardened tips. It's lighter and won't float the fuel pump. Dave
 

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Discussion Starter #3
65 Post said:
I don't know what a HARDENED fuel pump pushrod is. ALL fp pushrods are hardened. They might mean lightened. As in the hollow pump rod with the hardened tips. It's lighter and won't float the fuel pump. Dave
According to what I was reading, the billet steel roller cams can cause problems with the fuel pump pushrod; at least regarding GM's ZZ4 cam.

It wasn't really explained very well regarding whether the fuel pump cam lobe was likely to get chewed up or if the fuel pump pushrod was likely to get chewed up if there was a problem with an improper pushrod.

At this point I'm inclined not to worry about it due to the inconsistency of the info available. I think my motor may have bigger problems on the horizon that are going to require a tear-down. :rolleyes:
 

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Billet Cams, must use a Bronze tipped fuel pump push rod.
Comp sells a bronze tip fuel pump push rod part # 249-4607
Billet cams require a bronze tip on the fuel pump rod, or you will wear off that fuel pump lobe off the cam in a big hurry.
Other companies make bronze tip pushes as well, not just comp.
 

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Discussion Starter #5
Here's one of the sites that posts conflicting info. Sallee is usually my first source of info for ZZ4 related info. The two guys discussing the topic here appear to have two different perspectives.

The "Scott" person sounds like he works for Sallee, but it isn't clear.

http://www.sallee-chevrolet.com/Discus/messages/3418/4285.html?1091136581

Also, the guy in the June '06 issue of Chevy High Performance says to use GM part number 3704817 which uses some "special heat-treat process" on the pushrod for use with a billet cam.


Thanks for your input 68. :)
 

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Discussion Starter #6
NovatoriusRex said:
Here's one of the sites that posts conflicting info. Sallee is usually my first source of info for ZZ4 related info. The two guys discussing the topic here appear to have two different perspectives.

The "Scott" person sounds like he works for Sallee, but it isn't clear.

http://www.sallee-chevrolet.com/Discus/messages/3418/4285.html?1091136581

Also, the guy in the June '06 issue of Chevy High Performance says to use GM part number 3704817 which uses some "special heat-treat process" on the pushrod for use with a billet cam.


Thanks for your input 68. :)
FYI - I dug a little deeper into that GM part number. It appears that Sallee includes that pushrod in their turn-key crate kit (Fastburn 383 w/ ZZ4 cam), so if they're going to warranty those motors with that pushrod, it seems like that'd be the correct one to use.

I think I'm going to take out the ARP one I had been using and put in the GM part before I do some real damage; assuming I haven't already.
 

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Discussion Starter #8
Update

I pulled my ARP pushrod out tonight to look for any signs of damage and the end of the pushrod that rides against the cam's pump lobe was perfectly clean and smooth still. It doesn't appear that this entire topic was an issue.

Just to be on the safe side though, I did replace it with the GM part I referenced earlier.

FYI - Replacing the fuel pump pushrod with the motor installed in the car is a PITA!!! AND, this one sorta PO'ed me, the bolt hole on the front of the block that's supposed to be tapped all the way through the block to hold the pushrod up ISN'T tapped all the way through on 1985+ production (not aftermarket GM) blocks, or at least it's not on mine. :mad: After fighting with the pushrod for a while, I had to get in my real car and go buy some grease to use to hold the pushrod in. :rolleyes:

It's all back together and purring again. Next up, fuel mixture adjustments; this thing is running RICH! Stinky. :eek:
 
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