mellings pushrod for magnum heads?

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63dartman

63dartman

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I know there was a thread with the mellings pushrod part number for the magnum head conversion, I just can't find it. Anyone?
 
Melling MPR-89 pushrods i found this on mopar chat but i dont know what website to get the pushrods from with a price
 
well, I'm not sure if they are the right ones, I have a little confusion about the lifters. On mopar website they say you need the amc lifters for the conversion. I thought you could just use any hydraulic flat tappet lifter as long as it has the hole on top for oiling through the pushrods.
 
yup just cross reference the numbers go to bigblockdarts.com and they have it all and i believe that those push rods are the right length
 
If the Melling pushrods are the same 7.625" length as the Mopar Performance ones they are likely a little short especially if you have had any decking to the block or heads. You would be better off mocking the engine up and ordering custom length pushrods.

Regarding lifters most after market ones have provisions to oil through the pushrod and the same one is listed for AMC and mopar applications. It's just that if you order for the AMC application you are sure that you won't wind up with true mopar lifters that don't have the push rod oiling provisions.
 
Duster, just ordered them from Mancini, I sure hope they fit. If not I will get some cut to fit, just hate to waste my cash though.
 
Actually the melling MPR-89 pushrods measure 7.601, they are a ball/ball end with a drilled body all the way through. They are 5/16" diameter and about $3.00/ea.
 
I ended up with Comp Cams rods that are 7.70 The stock Mopar conversion rods at best gave me .015 of lifter preload and was noisey. I used the .024-.028 Mopar head gaskets. If anyone wants a set of 31 Mopar conversion pushrods...$30 shipped and you can't ask what happened to #32!!!!
 
I am using the MP 7.625" long ones and with the block decking I had done there is only 0.027" of preload. The engine is noisy at start up but quites down when warm.
 
edbux said:
I ended up with Comp Cams rods that are 7.70 The stock Mopar conversion rods at best gave me .015 of lifter preload and was noisey. I used the .024-.028 Mopar head gaskets. If anyone wants a set of 31 Mopar conversion pushrods...$30 shipped and you can't ask what happened to #32!!!!
Click to expand...

The PN is 7823-16. They're for a Ford. $48. thru Summit. Lifter preload should be .060" I referenced these tech articles:

Lifter preload http://www.keitheickert.com/tech_support/Adjusting_The_Valve_Train.pdf

Pushrod length http://www.keitheickert.com/tech_support/Pushrod_Length.pdf
 
0.060" is generally accepted as the maximum preload for a hydraulic lifter. If you had 0.015 with a 7.625" pushrod and went to a 7.700" that is 0.090" of preload, 0.030 more than the max.

You are likely to have pump up issues at higher rpms resulting in valves being held off the seat.

The 7.650" pushrods from Summit seem like the way to go.
 
did you measure your length or just used them???
and how do you know how much preload you have??? i need to know these things
 
The threads in the magnum head that holds the rocker pedestal on is a 5/16-18 thread. 18 threads per inch equats to 0.55" per revolution. Pick a cylinder and get the lifts on the base circle of the cam (both valves shut on compression). Slowly tighten the bolts while feeling the play in the push rod between the lifter. Once there is no more play and you can still rotate the push rod in your fingers tighten the bolt until the pedastel bolts on the head.

If the bolt rotates 1/2 revoltion then you have 1/2 of 0.055 or 0.027" of preload. More revolution is ore preload less is less.
 
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