LA heads on a magnum block

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jacksdodges

jacksdodges

jacksdodges
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So what do you have to do to get a set of la heads(78) on a magnum block (99) ? A kid across the street put a set of la heads on a magnum block. No oil to the top end. Used a 78 head gasket. There are no oil holes in the magnum block.
 
yup...that is the problem....no oil thru block to heads...
 
The "answer" is easy, LOL. Oil for LA engines comes up through the BLOCK and up through the HEAD into one of the rocker stands, and into the rocker shaft.
 
No easy solution. Either have a machine shop drill the block like a LA is or figure out some other way to plumb oil to the rocker shafts.
 
Yeah. you can do it, but it's probably expensive.
 
and is the magnum cam drilled to supply oil up those holes.....
 
...or Mag heads.
 
think about this for awhile.
drill and tap the rocker stands that supply oil to the shafts on the la heads. use #3an fittings and hose pumped from the oil sending unit hole in the back of the block.
 
Ooooh, an "engineered" solution.
 
I think his best thing to do is find another LA block. Hes just a kid and doesn't know hardly anything about cars. And he is working in a all chevy shop so they cant help. Their the ones that told him the blocks were the same. He put his old la cam in the mag. My son went over there and helped him get it timed and started it up for him. It sounds good except no oil upstairs. We squirted oil on the rockers and it ran good and sounded pretty good. Thanks for all the help.
 
might work with non adjustable rockers....but with adjustable rockers ...you need some how to get the oil inside the shaft....
 
You're swapping from a system that hits the shafts with pressurized oil for about 10° of 360° degrees of cam rotation to a metered flow of oil for 360° of rotation. Personally - I'd do everything I could not to have to run LA heads on a Magnum short - but if a customer told that's what they want I'd go the pushrod route before I did anything else. That's a lot more oil spraying up there than any shaft delivery system. The factory shaft system is virtually a splash system anyway given the allowed volume.
 
bOb shingler said:
think about this for awhile.
drill and tap the rocker stands that supply oil to the shafts on the la heads. use #3an fittings and hose pumped from the oil sending unit hole in the back of the block.
Click to expand...
thats exactly what i was thinking...:thumblef:
 
Same way Chevys have oiled for decades and magnums continue to do: Splash. Oil comes up the pushrod, out the hole in the top of the rocker, runs down to the shaft - fills the rocker and runs down to the valve tip.
 
The Magnum cam is the main issue as mentioned, no oil holes in the #2 and #4 journal. I made a fixture I use on magnum blocks to drill them for shaft oil. Works great and is 100% dead nuts perfect.

In the later years of the LA engines, they ran oil thru the shaft as normal, but also ran hollow pushrods that oiled thru with the lifters that oiled thru right to the rocker. These rocker arms had a little deflector on them right above the pushrod seat on the rocker arms, just like a Magnum rocker does. It was around 1989-1992, somewhere in there. All roller cam engines.

If you you run oil thru pushrods, you have to have these type rockers or try and drill a hole in the pushrod seat to get the oil to flow down into the bottom of the rocker. You dont need a ton with a stock cam, only 200# spring pressure.
 
And here is what he did. He got some hallow 454 chevy pushrods and they were to long so he put a washer under the rocker shaft on all the stands tighten them down and bent the washers to fit the contour of the rocker shaft, fired it up and he got oil up thru the pushrod. How long do yall think this will last?? It running now
 
Wow-I guess where there's a will, there's a way, but I'm guessing any fouled up geometry is going to wreak havoc on guides or tips...
 
jacksdodges said:
And here is what he did. He got some hallow 454 chevy pushrods and they were to long so he put a washer under the rocker shaft on all the stands tighten them down and bent the washers to fit the contour of the rocker shaft, fired it up and he got oil up thru the pushrod. How long do yall think this will last?? It running now
Click to expand...

My guess is he screwed up the rocker arm to valve stem tip geometry. If it's a real mild cam it may last a while, maybe. I sure wouldn't have done it. Let me guess, he's too cheap to spend $50-60 for the right pushrods? Or the Chevy guys told him it's ok to do it that way, just like they told him the blocks are the same
 
If the cam's not that big like Fishy said - it might last for a little while. Otherwise - don't plan for a long and healthy life.
 
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