pushrod nightmare

[dave571]

O.K. I've dissassembled a running 1978 400 engine. Taken .085 of the block deck to get compression up to 9.7, with composite gasket and 516 casting, small chamber heads.

The 516 Heads are from a 1966 361, out of a 66 charger. While doing clearance checks(piston to valve) I noticed that the push rods are too long. Not a surprise after decking the engine. I tracked down some rods that are about .100" shorter than the ones that were in the 400. The ones that were in the 400 apear to be stock length(I checked the measurement, don't remember the spec right now)

Doing the final assembly after fitting rings and brgs clearances ect, Got the heads bolted on. I'm using a cam/lifters that were originally bought to be used in a 1970 440.

Bolt the shafts on yesterday, with the shorter pushrods, and notice that the lifters are bottomed. Way too much preload.

After chasing my head up my butt for several hours, I notice the lifters have a very narrowand deep, recess for the push rod end to fit in. The lifters that were in the 400 just had normal looking, round recesses. The push rods that were in the 400 just sit on the outer rim(of the recess on the 440 lifter), and don't go into the recess(neither do the new pushrods)

Went to the guys house, who I got the heads from, and found his pushrods. They are narrow on the lifter end and look like they will fit into the lifters I'm using. They are slightly longer than the ones I took out of the 400(less than 1/16")

What the hell is going on? Why are the lifters different? has anyone seen this before? It seems really weird that the pushrods out of the 66 engine seem to be a match(I think they'll still be too long, but I didn't get a chance to check today)

I also had a speed shop price a cut to fit pushrod set at $200. Sounds outrageous to me. I would think the money would be better spent on adjustable rockers.

The obvious solution is adjustable rockers(I've been avoiding that to save on money). Does anyone know if the mp kit 4120974 requires different push rods(from stock) , I'm assuming it does.

Sorry about this being a book.

[Hammer 74]

To answer your last question, most adjustable rockers need a pushrod with a cup on one end and a ball on the other. The other question is out of my league.

[451Mopar]

You need to measure the pushrods you have, for a baseline.
According to my Comp Cams catalog, here are some possable choices for 5/16" pushrods with ball ends for hydraulic lifters and non-adjustable rocker gear:

High Energy Pushrods:
#7883, Appears to be a stock replacement type pushrod for the 383-400 Mopar. Length = 8.575"

#7834, Replacement type for Ford 429-460 (same diameter and ends as the mopar rod.) Length = 8.550 (0.025" shorter.)

#7843, Ford 429-460 as above, but 0.060" shorter, Length = 8.490" (0.085" shorter than the Mopar #7883 rods)

Magnum Pushrods:
#7402, Mopar 383-400, same size as above, but slightly different rounded end type. Length = 8.555" (0.020" shorter than #7883.)

#7532, Ford Boss 351 C, same ends as above but 3/8" diameter. Length = 8.492" (0.083" shorter than the #7883.)

My Crane cams catalog dosen't show pushrods for a383-400 Mopar with non-adjustable rocker gear. The closest I can find is part #52680-16, again for a Ford Boss 351. this is a 5/16" diameter, Length 8.500"

Lunati sells them in two series, Pro Series and Performance replacement, both are 8.555", the big block Fords are also the same length.
Pro-Series Part #82740 (expensive, list $250, racer net $139), Perf. Replacement part #83740 (List $125, Racer net $78 form 1997 price list?)

Mopar Performance pushrods are 8.57" in length, Part# P4529557 for set of 16.

I can't find my Crower Cams catalog, but they should be simular in length.

All the cam companies will sell you custon pushrods too, but they may cost more.
There are adjustable pushrods and "cut-to-length" pushrod kits avaliable also.

I just wanted to point out that Ford pushrods may work if you need shorter pushrods. The only difference is the Ford pushrods have hollow ends (for rocker arm oiling.)

If you find an off the shelf pushrod that is close (on the long side) you can make small lifter pre-load adjustments by shimming the rocker shafts, but I would try to keep the shim thickness less than 0.025".

[jelsr]

Since I'm home I can't give any measurements, but I have hit this before and have some pushrods with the small dia ends on one end. Think I even have a set of mech pushrods with the same small end for the lifter. If you need some dimensions, I think I can come up with them for hyd and mech.

[dave571]

using the adjustable mopar rods, for measuring, At zero lash, zero lifter preload, I get 8.390" Problem is, these rods have the fat lifter end, and don't fit in all the way.

Ignoring that, It would seem I need rods about 8.450-8.490?

I can't really ignore that, though.

With the skinny end factored in, I'm not sure. The recess for the end, in the lifter, looks like it is at least .100" deep.

I'm going to take the pushrods from the 361(skinny end) in to the shop tomorrow. See if they shead any light on the situation.

Is there a spec for lifter preload? I haven't been able to find one, but I'm thinking 50-100 thou. Does this sound reasonable?

[451Mopar]

Normal Lifter Pre-Load is 0.020" to 0.060" according to my Crower Cams book.

[Billydelrio]

Dave571
It sounds to me that you have a lifter for a 5/16 ball end , but have 3/8 ball ends on the pushrods. I ran into this a few months ago with a set of Mopar pushrods. The 3/8 tube had 3/8 ends, but I wanted a 3/8 tube with 5/16 ends.
Billy

[Dennis Jokela]

Dave:

I don't remember when they changed the lifters and pushrods, I think around 1968. The early lifters use the small ball pushrod like the 66 361 pushrods that you got from your friend. The lifters for the 440 cam are also the early type. They are not for a 70 engine.

Dennis Jokela

[dave571]

Thanks for the input guys.

I tried a large hole lifter today, and find that even with the pushrods that are shorter than the ones I took out, I still have ove .200" lifter preload.

Way too much.

Were the push rods, base circle, lifter height, different on any of the earlier engines?


ps. Ive checked the valve height, ect and found they are all good.

[MOPARVANN]

If I remember correctly I ran into this problem in 1969 and here is what we did. The small end push rod / lifter setup was used through 67. An AMC lifter was used when we changed over to the pushrods with 3/8 on both ends.(AMC and 68 up MOPAR lifters are the same)The pushrods that you have that are only slightly too long may just work if you shim the rocker shafts. We shimmed the shafts with .010 brass shim stock cut and stacked before anyone had heard of this procedure, now Mancini sells the shims in kits of different thickness. Just one word of caution when using shims---don't block the oil passage around the 2nd bolt, this is where all oil for the heads passes. I have run as much as .080" shim with no problem, just pay close attention to the rocker/valve relationship. If this still fails it looks like adjustable rockers are in your future. I have seen several sets at fair prices for sale on ebay. Good Luck either way.