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The mopar .904 lifter is bigger than a GM lifter.
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Author:  DadTruck [ Fri Feb 24, 2023 7:15 pm ]
Post subject:  The mopar .904 lifter is bigger than a GM lifter.
I know a lot of folks here use Oregon Cam Grinding, and I have also.

For the cam that is in the slant that is in the 68 Barracuda, I spent some time on the phone with Ken at Oregon while he was searching through his catalog for a cam with a minimum lifter size above the standard GM lifter.

We got there eventually. I spoke with Ken again recently to see if he has made progress in listing the mopar grinds that require a minimum .904 lifter separately to make those easier to sort to. He said that he has not because the mopar regrind business is not that much of the business at Oregon, and he does not believe that a faster lobe ramp makes much of a difference.

I think that a faster valve opening can be a performance improver.

below is a link to the FAQ page at Hughes Engines. There is a good explanation there of why a faster valve opening can up engine performance.

https://www.hughesengines.com/TechArtic ... stions.php
Author:  Greg Ondayko [ Sat Feb 25, 2023 2:43 am ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
Its one of those things that would need an " Engine Masters" type episode of tests with the same cam ground with the GM Lobes and the more aggressive ramps of the .904" lobes whilist keeping all other conditions the same, to verify Hughes' proclamation.

While it sure makes sense to me that there is more power to be gained by taking advantage of the aggressive ramp, one would not know how much if any gain actually is to be had without some independent testing.

I would be interested to know for sure.

Greg
Author:  Charrlie_S [ Sat Feb 25, 2023 3:52 am ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
Quote:
I think that a faster valve opening can be a performance improver.
Back in the old days of "stock eliminator" racing we had to run "stock" cam specs. Stock lift and duration. The stock cheater cams had faster ramps and lift rates. They did make a difference. I don't know if I still have my Lunati cam 65 Valiant 170. I ran the lash on that cam at .002 intake, and .004 exhaust (hot). The major limiting factor on the lift rate was the requirement for stock spring pressure.
Author:  volaredon [ Sat Feb 25, 2023 5:53 am ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
How much of that extra power is eaten up by the lifters having more friction, having to climb the steeper ramp?
Author:  CNC-Dude [ Sat Feb 25, 2023 6:22 am ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
Not enough that it wont keep you out of the winners circle. This is actually old technology and thinking, but it is highly successful! When I went to work at one of the most successful race shops in the southeast beginning in 1984, our bread and butter was dirt track small block Chevy race engines. Even back then we were putting the Ford lifters that are .875" into the Chevy blocks that were .842" and seeing tremendous results. All the Nascar teams had already been doing for it for many years, and before that, they used the mushroom tappets exclusively to basically do the same thing.

We also had several dozen drag racing National Champions we did engines for in NHRA classes from Stock Eliminator, Super Stock, Modified Production, Comp Eliminator and Pro Stock. And I can tell you that the biggest secret to their successes was the cam technology they used, which was faster ramps providing more power under the curve. Now can that same thinking and concepts apply to the Slant? Absolutely! How much...?

Well, if you had a group of 10 Slant racers and used cams from Lunati, Comp, Isky, Crower and any other respected name that utilized faster ramps, and you had one Slant guy that used an Oregon Cams grind where he doesn't believe in faster ramps as being any benefit, you would never see that Oregon cam racer in the winner circle. Ask Mike Jeffries, you definitely will never win in Stock Eliminator without a cheater cam that uses the faster ramp design....
Author:  69a100 [ Sat Feb 25, 2023 7:09 am ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
Like I always say, "Nobody sweats the details like GM, and they don't"! Sounds like Oregon Cams does the same? JMHO
Author:  drgonzo [ Sat Feb 25, 2023 7:46 am ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
I agree with CNC-Dude. When I was racing dirt hobby stock cars at Rome and Dixie speedway back in the '80s, we had a .425" lift hydraulic cam rule. I was running a SBC. I called up Schneider Racing Cams and told them the cam rule and the rest of the engine specs. From them I got a .420"/.420" lift, 250/250 @.050, 107 LSA grind. Those lobes were short and FAT. I won races with that cam in several different engines.
I think if we want every ounce of power available, then faster ramps have to be part of the equation.
Author:  Rick Covalt [ Sat Feb 25, 2023 8:04 am ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
Why have mushroom lifters not stayed in favor?
Author:  slantzilla [ Sat Feb 25, 2023 10:54 am ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
Quote:
Why have mushroom lifters not stayed in favor?
Probably for no other reason than time marches on. Roller lifters made them obsolete.

Plus, mushrooms are a pain in the butt to install/remove.
Author:  slantzilla [ Sat Feb 25, 2023 11:28 am ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
I'm going to say his statement about the market not being there is true. Look at the majority of builds here, very few use a camshaft with any hair. Slant guys appear terrified of big cams, stall speed, and gear.
Author:  CNC-Dude [ Sat Feb 25, 2023 3:20 pm ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
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.
Author:  CNC-Dude [ Sat Feb 25, 2023 3:22 pm ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
Quote:
I agree with CNC-Dude. When I was racing dirt hobby stock cars at Rome and Dixie speedway back in the '80s, we had a .425" lift hydraulic cam rule. I was running a SBC. I called up Schneider Racing Cams and told them the cam rule and the rest of the engine specs. From them I got a .420"/.420" lift, 250/250 @.050, 107 LSA grind. Those lobes were short and FAT. I won races with that cam in several different engines.
I think if we want every ounce of power available, then faster ramps have to be part of the equation.
You may have had engine work done by us and I'm sure you raced with many of our customers at Dixie and Rome in that time period....
Author:  hyper_pak [ Sat Feb 25, 2023 3:52 pm ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
How do you know that one cam or another has a .903/.904 ramp?
Author:  CNC-Dude [ Sat Feb 25, 2023 4:05 pm ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
The cam manufacturer will have to tell you what their lobe profiles are designed and made for. As far as you or I knowing that without them telling us, there is no way to know that without asking them since they designed the cam master that makes their cams.
Author:  drgonzo [ Sat Feb 25, 2023 4:19 pm ]
Post subject:  Re: The mopar .904 lifter is bigger than a GM lifter.
I never had any engine work done by you guys but some friends did. I had my machine work done locally and assembled my own engines. Those were good times. Is that shop still around?
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