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Author Topic:   Pushrod Guide Plate
RC Racing
Dirt Maniac

Total posts: 144
posted January 06, 2003 03:40 PM
Hoping the "Forum" can help this engine neophyte

Regarding pushrod guideplates. Have a general idea what they're used for, but not sure of all the details. Could somebody comment and/or explain more about their use and necessity. What engine configurations and/or situations are they not required, wouldn't hurt, definitely required, etc.

Also, do you think they're necessary in a mild engine (ie, min 76cc heads, no roller tip or roller rocker arms, 10.5-to-1 (4) valve relief pistons, .450 max lift cam, 4 BBL carb,pump gas, probably run 6000 - 6500 rpm range)

Appreciate the helps folks

RC Racing
Dirt Maniac

Total posts: 144
posted January 07, 2003 09:08 AM
Noticed there were a number of "views" of this post, but no replies.

So here's another request for informative knowledgeable, replies.

Thanks in advance

------------------

KPLugnut
Dirt Freak

Total posts: 408
posted January 07, 2003 09:50 AM
With that kind of target for rpms, and an otherwise stock valvetrain, yes, definitely guideplates will be required. Or at least a darn good idea. The stock sized holes that the pushrods go thru in the heads serve as a cheap method of keeping the pushrods and rockers aligned on the valve stems, but that is only for street use at much more mild rpms.
Your typical racing engine (even the entry level kind) is very hard on a stock valvetrain, and anything you can do to control the wild harmonics, and errant movement and flex will be a benefit to both the lifespan of the parts and to improved valve timing, which leads to increases in power to some extent as well.

Hope that helps, but in a nutshell, definitely install guideplates and studs, and drill out the pushrod holes in the heads with at least a 1/2" drill or use the drilling fixture that is available to do elongate the hole properly.

KPLugnut

avenger
Dirt Full Roller

Total posts: 33
posted January 07, 2003 04:13 PM
I was having trouble knocking lobes off off cam(4 cams),and drilled out the hole to 1/2 inch and put guideplates on motor and honed out lifter bore and never took another lobe off.I am not sure which fixed it but will drill out everytime now,and run guideplates,they are cheap.I did go to a better pushrod than stock so the guideplate didn't scrape off the metal into engine.

runllm2
Dirt Roller

Total posts: 17
posted January 08, 2003 12:35 AM
When using a cam under 490 lift you shouldn't need long slot rockers with stock instaled hights on the springs and valve. When running guide plate your "should" use chrome moly push rods. So that they don't shave on the guide plates. They are very expensive about $70 for a cheaper set I think. I've used just the hardend ones and had them work they didn't shave at all ($40). I've used stock and found out the hard way that they shave themselves against the guide plate untill they break. My advice is get the hardend ones. If your on a tight budget You could just pin the stock press in studs. Just take a drill, drill through the cast and stud. Take a punch and pound the roll pin in. Your local machine shop will have the drill bit size and roll pin for you. Your not running a lot of lift so you can get away with a lot of cheap stuff. But the more you spend the better the reliability is going to be (i.e. ***** in studs chrome moly push rods, ploy locks, retainers, rockers). The only thing going to kill your stock valve train parts are RPM's.

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