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The mopar .904 lifter is bigger than a GM lifter.
https://www.slantsix.org/forum/viewtopic.php?t=67104		 Page 2 of 2
Author:  CNC-Dude [ Sat Feb 25, 2023 4:32 pm ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
Yes, it's still going strong! I worked there from '84 til '99. Their main focus is still roundy round, but their fame originally came from their Chevy 6 cylinder that dominated from about '77 to '88 in numerous NHRA classes. Im sure you know their history...
Author:  Charrlie_S [ Sat Feb 25, 2023 5:36 pm ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
Quote:
Quote:
Why have mushroom lifters not stayed in favor?
That is still a viable option for seeking to stay with a flat tappet cam without the expense of going to a roller cam. Provided, mushroom tappets are available for the Slant. Also, as slantzilla pointed out, a little more difficulty to install and the bottoms of the lifter bores have to be spot faced to allow the mushroom to have clearance at full lobe lift to not hit the block inside the cam tunnel.
I don't know of any readily available mushroom lifters for a slant. The old MP big block lifters could be used, but they are hard to find, as far as I know. However, a few years ago, I thought about trying this, and bought a lifter for a VW, and a Ford "Y" block. These are both mushroom lifters and are available. However the lifter bore in the slant block would have to be bushed to a smaller diameter to use them.
Author:  drgonzo [ Sat Feb 25, 2023 5:38 pm ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
Glad to hear it. You guys were and I'm sure they are still a top tier shop.
Author:  slantzilla [ Sat Feb 25, 2023 9:03 pm ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
IIRC, the Mopar mushrooms required spot facing the block around the bottom.of the lifter bore too.

I had a Y block 292. The lifter body was not real big, around .400" or so.
Author:  Charrlie_S [ Sun Feb 26, 2023 4:11 am ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
Quote:
IIRC, the Mopar mushrooms required spot facing the block around the bottom.of the lifter bore too.

I had a Y block 292. The lifter body was not real big, around .400" or so.
As far as I know, any mushroom lifter needs the lifter bore spot faced. And yes, both the "Y" block Ford, and the VW lifters have a very small body diameter.
Author:  Greg Ondayko [ Sun Feb 26, 2023 7:52 am ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
is the spot facing required be cause the bottom of the lifter bore on the casting is not square with the bore that the lifters reside in?


Greg
Author:  CNC-Dude [ Sun Feb 26, 2023 9:14 am ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
Not really, it's more to allow the mushroom portion of the lifter to have a cavity to fit into so it doesn't hit the block inside the cam tunnel at full lobe lift....so it's really a clearance issue due to the design of the lifter.

Also, something that makes mushroom tappets difficult is they can only be installed in the engine from inside the cam tunnel side of the block...with the block upside down. So to do cam testing you'll have to pull the engine out of the car and turn it upside down to remove the cam because the lifters can't be removed from the topside....
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