340 pushrods same as 318?

7.51 std length hydraulic. late 273 with hydraulic lifters, 318, 340, 360
6.78 pre magnum roller
6.925 roller magnum (92 up)
7.23 hyd. lifter with adjustable rockers
7.34 solid lifter (273)

These guys are all correct, however don't take it for granted that your 318 pushrods are the correct length! I went through this with my 340, I installed the rocker arms/etc. and had all kinds of slop, the rocker arms were rattling terribly. Had all kinds of thoughts on what was wrong, it turned out that my 318 pushrods had worn (shorter) almost 1/16", enough to make a huge difference. They looked fine! I bought a new set, and they were snug, like they were suppose to be, and it runs nice and quiet.

340-360 pushrods are longer than for a 318. I bought a new set that were shorter, they rattled around knocking clips out of the new lifters. Turned out that the parts store gave me some for a 318. They then ordered some for a 340 that were perfect.

I've never actually compared them but I would think that the 318/340/360 hyd cam ones would be the same. What dimention on the block/head/rocker arm setup is different between those 3 that would require different length pushrods? the only thing I could think of is if different cam lifts used different lengths to keep the geometry correct

IMO if it had the 3/8 pr and worn rockers then swap to 318 5/16 pr I could see them being a little shorter

with it apart and then bolt back down before start up some are gonna be loose and move around

they will pump up and force the rockers into each other

they mag pushrods are shorter and have diff rocker set up style (fulcrum) so they would be diff from pre mag roller lifter pushrods

some pre mag rollers have a 3/8 hollow pr and oil through roller lifter as well oils the old LA
rockers (oils both ways) early pre mag pushrods were 5 1/6 and solid

make sure you got the left and right offset in the right spot per cyl also

that could cause a problem

if using the fat pr in 318 heads check for clearance in the push rod hole of the head

later pre mag heads have a larger pr hole in them than early LA heads

I have never had a prob just swaping pr around,I roll them on glass to see if the are bent and run them

Mopar part number for 318 340 are different in my 73 book 2899561 (318) and 2899567(340 and 360). Funny thing, until I checked I would have argued that they were the same. Of coarse then again a different part number doesn`t necessarily mean the length is different though.

I found no reference online that they supersede. Here is a NOS vendor listing for the two numbers.

PART NO DESCRIPTION YEAR QUANTITY PRICE
2899561 PUSHROD 1968 /273,318
2899567 PUSH ROD /8 CYL 1968-93

I wonder if it could have something to do with early 273's having solid lifters?

An aftermarket cam can cause the push rounds to be too short if it is a small base circle.

THE REAL ANSWER is this: On any high(er) performance engine one is better off building the engine, measuring the pushrod length and getting pushrods to match the correct length. There are way too many variables. Deck height, rocker type, cam grinder, lifter type and manufacturer, milled heads, head gasket thickness will all alter the distance between lifter and rocker arm.

R.

the lifter will take up a small amount with the plunger and oil pressure

its non adjustable hyd and maintanes the lash with the oil pressure,installed the pr should have some preload to the plunger of the lifter

low oil and the lifters rattle and tap

but...to short is to short and should be measured like said

but I have rolled a many stock jy engines around in the yard swapping heads 1-2 pistons from block to block,used valves and no lapping of the seats and the like and have never had probs not measureing things...maybe just good luck..but hickabilly come to mind

some ran better than other and they all died in the mud truck eventuly..but mud and water was the killer

good luck with it