Adj. rockers off 273 for strong 340-will they last?

[SIXPAK340]

i picked up a set and a half of adj. rockers off a 273. 3 shafts,pushrods for 2 sets, rockers for 1 1/2 sets for about $25 i know they'll fit and that the ratio has to be more accurate, but will they hold up in a strong 340 mag. it has a hughes cam with 515-535 lift with matching springs. also is there anything to look for before putting them on. d#*n thing won't let me in under my name, any way i still need info

gilbo

[This message has been edited by SIXPAK340 (edited December 13, 1999).]

[cudadude]

sixpack,
i dont see any problems running the rockers. they are the same ones used on the 273/275hp commando in 66. i have run those on a 273 with a 528 lift purple shaft and twisted the living s@$t out of it with no trouble. Get ready though to adjust your valves on every monday after a good sunday run. even with the jams they are bad about coming out of adjustment.need to check the shafts you bought carefully to check for straightness and thet they are the correct ones for the mechanical rockers. a lot of people dont know there is a difference between the shafts

[GILBO]

thanks cudadude, what do i look for to make sure i have adj. rocker shaft. this is gilbo in case i come up under sixpak340 again!

[cudadude]

gilbo,
first look at the very end of your shaft where the plug is. the hyd. shaft will be smooth , where the mechanical shaft will have a notch cut into it. the second is slide a couple of the rockers off the shaft and look at the oiling holes. the hyd. shaft will have only one hole drilled where the mechanical shaft will have 4 holes 2 of which will be drilled into eyebrows for improved oiling under higher rpm's.

[PRO]

gilbo,one problem I see with your proposal is used shafts and rockers,these parts develop a wear pattern over time and if you remove them from their original position and reinstall them in a different configuration you may be accelerating wear and tear and kicking up some metallic debris into your oiling system.As long as you keep them in the original position and their not worn out they'll work fine.One thing not to overlook is if you have milled or surfaced the heads or block and or installed new valves,inspect the rocker tip to valve stem relationship,do this by turning the crank with valve train installed.the rocker tip should be near the middle of the valve stem,it could be off to one side a little,as you rotate it should go nearer the center of the stem,if it goes more toward the edge of the of the stem you'll need to shim the rocker shafts or get longer/shorter pushrods.I have a good adj.set w/pushrods if anyone needs them($75).Also a new set of crane 1.5 ductile iron shafts and rockers are less than $200 from Jegs or Summit.....PRO..

[rat roaster]

I have bought these good deal 273 adj rockers and shafts . The only problems I had was push rod length and oiling . Crane makes hydraulic length push rods. After you get them on and adjusted make sure they are oiling properly.I have found that if they are high milers they can be worn to a point were they oil poorly to the valve springs.A friend of mine who was a ss/aa racer (the old trapper)built alot of small blocks at his business told me that they wear ovaly and the pressure from opening the valves wore them on the front side were the shaft oil oil is . This makes them oil hardly at all,you can either bush the rockers or banna grove the shafts.I had a couple of swap meet sets that ended up this way ,really hard on valve springs and valve tips.The first time I experenced this I thought I had a turned cam bearing (the oiling holes to the top end covered)but after putting on some new cranes the thing oiled great ,45 ps1 idle & 75 psi @ 3500 rpm .Whatch for this when you use the old 273 stuff. If you cut banna groves cut them from the oil hole on the shaft towards the valve spring . All stock dodge rocker shafts have a notch on the end by the plug. The notch goes forward on the drivers side ( 1 cylinder ) and to the back on the passinger side ( 8 cylinder )plus the notches point down. Make sure the oil holes face down and toward the exhaust . The Crane stuff is the best way to go. The Comp cams pro magnums are really ,really nice .

[This message has been edited by rat roaster (edited December 13, 1999).]

[This message has been edited by rat roaster (edited December 13, 1999).]

[DartGT66]

One feature not good woth the 273 rockers is the adjustment. The 'snug' screw just isn't too reliable in a well used set up. I would at least change the adjusters to screws and nuts, available from MP, P4120636. However, the new adjustables aren't that much more expensive, I would propably just use new ones.

[340king]

I would definitely look into replacing the pushrods. They are mild steel and swell when stressed heavily. This may account for the frequent adjustments previously mentioned as it caused mine. They tend to shorten as they swell. The swelling is most noticeable on the ends.

I recommend purchasing new banana groove shafts from MP. Pre-lube them liberally prior to start up. This will undoubtedly tighen up the shaft clearance giving better oiling to the valve tip and springs.

[caveman]

Pushrod length is wrong,the 273 used a solid lifter cam,which used a shorter lifter,when you use these in a motor with hydralic lifters the pushrods are too long .You will have to run the adjusters all the way up to the point where they could hit the inside of the valve cover(mine did)

[GILBO]

thanks for all the info. i think i'll go with some crane roller tips, no time to get cheap now! have them on my 440 in the 1.6 ratio, an love them! thanks again