Mopar 496 low deck

[cgarb]

Have a fellow racer that I help out from time to time having some trouble with his Mopar. It's a low deck block, has Indy heads on it with Harland Sharp rockers, comp roller lifters and he's been using Smith brothers pushrods. After less than a full season of running his new pushrods, some of them the ends are turning blue from heat and I assume lack of lubrication. He needs a new set of lifters because 2 pairs have a rough wheel so I was wondering if he could buy the Crower lifters that have the oiling provision for pushrod oiling, swap out the adjusters on the rocker arms from the ball type to the socket type and run a normal 3/8th pushrod with the 210* undercut on the one end? Is there anything else that needs to be done to oil through the pushrod? Can you run the oil in the rocker shafts still also or do you need to block that off and only oil through the pushrods?

[Geoff2]

The oil feed holes in the rocker shafts have a bias. If the shafts are fitted the wrong way, you get much reduced, if any, oil flow to the rockers. So shafts should be checked first for correct orientation before throwing a pile of money at it.

[PRH]

The HS rockers have upper and lower holes in the shafts, which are on center with the bolt holes.

Since you’re not mentioning external oil lines for the shafts, these are EZ heads?

How much lift?
What rocker ratio?
What kind of spring loads?
Are the adjuster screws set so that the lip of the cup in the pushrod is definitely lower than the feed hole in the rocker?

EZ heads often need some clearancing for the intake pushrods.

If you add pushrod oiling with those rockers, you’ll still need some oil coming through the shafts to oil the bearings and valves.
Pushrod oiling with those rockers will only oil the adjuster screw.

Make sure the oil feed hole in the lifter is correctly oriented.

Changing to cup style adjusters will likely increase the rocker ratio...... make sure you have enough room built into the motor to accommodate it.

[Racing68]

What i learned about racing a BB chrysler with stock style shaft rockers, that is pretty much normal. Best thing we ever did was put a Jesel shaft system on with pushrod oiling. You will thank me and yourself after doing it.

[andyf]

I use the AMC solid roller lifters from Comp Cams on my engines. The AMC lifters have pushrod oiling but don't cost any more. The standard Comp solid roller lifter doesn't have pushrod oiling or roller oiling so it isn't worth buying but their AMC lifter works just fine in a Mopar block. You will need to get the Mopar tie bars.

If it was me I'd just stay with the cup and ball style pushrod setup but order them with oiling. Smith Bros can do that for you. Run the normal rocker shaft oiling for the shafts and then the pushrod oiling for the pushrod cups and you'll be golden. You might drop a few pounds of oil pressure but if you're running a good pump it will be fine.

Here is an article I wrote for Car Craft that shows the same problem and the solution: https://www.hotrod.com/articles/trying- ... m-testing/

[cgarb]

Thanks Andy....that's what I was after.

[andyf]

The Crane solid roller lifter is high quality and pushrod oiling. It will also fit and work in a stock block like the Comp AMC lifter. I had a bad experience with Crower selling me solid roller lifters that didn't work in a stock block. The sales guy told me they would work just fine but the oil hole was located in the wrong place. Crower wouldn't take the lifters back so I lost money on that job. That was the last time I bought anything from Crower. Moral of the story is that sometimes to get the correct part you have to smarter than the guy who works there.

[Tuner]

I use the AMC solid roller lifters from Comp Cams on my engines. The AMC lifters have pushrod oiling but don't cost any more. The standard Comp solid roller lifter doesn't have pushrod oiling or roller oiling so it isn't worth buying but their AMC lifter works just fine in a Mopar block. You will need to get the Mopar tie bars.

If it was me I'd just stay with the cup and ball style pushrod setup but order them with oiling. Smith Bros can do that for you. Run the normal rocker shaft oiling for the shafts and then the pushrod oiling for the pushrod cups and you'll be golden. You might drop a few pounds of oil pressure but if you're running a good pump it will be fine.

Here is an article I wrote for Car Craft that shows the same problem and the solution: https://www.hotrod.com/articles/trying- ... m-testing/

Andy knows what he is saying here. I will add if there is no pushrod oiling, the pushrod length must be correct so the ball and cup are located so they get oil from the rocker piss hole. If the pushrod is too long the oil hole will be below the ball and socket and they will scuff. The Mopar engine book describes this pushrod length issue.

[PRH]

The Crane solid roller lifter is high quality and pushrod oiling.

Not all Crane solid roller lifters have provisions for pushrod oiling.

While pushrod oiling will likely solve any issues you’re having, if you figure out why you’re having the issue in the first place it might be quite a bit less expensive than buying a set of lifters.

I’ve built numerous roller cammed bracket race Mopar engines over the years, some with .800+ lift roller cams and the accompanying spring loads....... many of which have hundreds and hundreds of passes on them, having been in service for several years...... and none have pushrod oiling...... or are burning up pushrods or rocker screws.

[Walter R. Malik]

Have a fellow racer that I help out from time to time having some trouble with his Mopar. It's a low deck block, has Indy heads on it with Harland Sharp rockers, comp roller lifters and he's been using Smith brothers pushrods. After less than a full season of running his new pushrods, some of them the ends are turning blue from heat and I assume lack of lubrication. He needs a new set of lifters because 2 pairs have a rough wheel so I was wondering if he could buy the Crower lifters that have the oiling provision for pushrod oiling, swap out the adjusters on the rocker arms from the ball type to the socket type and run a normal 3/8th pushrod with the 210* undercut on the one end? Is there anything else that needs to be done to oil through the pushrod? Can you run the oil in the rocker shafts still also or do you need to block that off and only oil through the pushrods?

I do that very thing all the time with oil going to both places however, with some pushrod oiling roller lifters you NEED to have lifter bushings in the block as the roller cut-away in most will expose the bottom of the main oil gallery some when near maximum lifter rise.

The last Mopar engine I built with this issue which was not an "all out" race engine ... I merely had custom bushings made a couple thou bigger than the stock lifter bore size, (no machining of the block was necessary), and bushed those bores down to Chevrolet .842" size then used small block Chevrolet lifters with pushrod oiling and a smaller roller diameter.

[andyf]

That is a good point but I've used the Comp AMC solid roller lifter with 0.470 lobe lift so it will handle quite a big lobe. I think the limit is somewhere around 0.500 lobe lift but it varies from block to block. It is something that should be carefully checked once the lobe lift gets over 0.450. I never figured out any easy way to measure the oil gallery height so I pressurize the oil system and slowly rotate the camshaft to see if there is any leakage.

[cgarb]

I'm going to order 1 and check for issues before I get too far into the project. Thanks for the help everyone.

[Walter R. Malik]

That is a good point but I've used the Comp AMC solid roller lifter with 0.470 lobe lift so it will handle quite a big lobe. I think the limit is somewhere around 0.500 lobe lift but it varies from block to block. It is something that should be carefully checked once the lobe lift gets over 0.450. I never figured out any easy way to measure the oil gallery height so I pressurize the oil system and slowly rotate the camshaft to see if there is any leakage.

The amount of lobe LIFT has nothing to do with it. It is all within the lifter body design.
No matter whatever the lobe lift is, the nose of the camshaft lobe is in the same vertical location near max lift.
The base circle is merely smaller with the higher lobe lift; Unless it is a re-grind or a small base circle camshaft.

[cgarb]

Dragging this back up...engine is assembled with new roller lifters, custom smith brothers pushrods and new adjusters. We were priming the engine with the valve covers off and there is an excess of oil coming from the rockers. They are Harland Sharp shaft rockers for Indy heads. Should there be a restrictor for these rockers because they are bearing design and not a bushing type rocker?

[Geoff2]

Are the rockers oiled through the shafts as mother Mopar designed it, or through the prods?

I know some engine builders used to instal a Carter AFB jet in the rocker shaft metering hole in the block [ under the head gasket, drill & tap ] to limit upper end oil on high rpm engines.