LA vs. Magmun: pluses, minuses

[SpeedThrills]

In the future, I'll be building or buying a 360 stroker (408?) for my 74 Dart Sport. It'll be a street-strip car, only being used for cruising and some runs at the track for fun. Hoping for high 10's. What are the hp and rpm limits for cast vs forged cranks and stock vs R3 blocks? Definetly using aluminum heads. What do the Magnum and LA offer? What would be best for this use?

 

[SpeedThrills]

There's certainly lots of info on these two motors. With more research, I've found that either one's good to about 450 hp w/ cast crank. Opinions? I don't want to get into that replacement 340 or R3 range. ($!) I'm thinking about a forged crank and piston version in either LA or Magnum. Want to keep the compression on the high side w/ a mech. cam if I use the LA. Is there a good selection of cam profiles available for the roller Magnum? What is their (roller) rpm limit? I know the Ford roller's are rpm limited by their weight. Generally, what rpm is max for a 4" stroker in a stock block w/ forged parts?

 

[Casey Davis]

Maybe this will will help you learn more about what a magnum can do vs. an L.A.

http://www.hotrod.com/techarticles/engine/hrdp_0804_small_block_mopar_engine/index.html

 

[66dartgt]

I seem to remember there being a limitation to the lift on magnum heads - something just over .500" lift. I dont believe the older LA heads had this issue.

 

[mopar_1974]

Women like magnums better

 

[valentek]

I'm sure you can go over .500 on the Magnum roller and stock rockers. I'm running a Hughes Engines cam with .544 lift with stock 1.6 rockers. You may want to take a look at their site and read the info/tech papers, they answer a lot of questions. Also I would recommend SA Books SA104 (How to Build Big-Inch Mopar Small Blocks). It is full of good info and has a few builds with parts used and dyno numbers.

Valentin
69 B5 408 FB

 

[sharpie]

it starts to grind after .52 lift on stock magnum heads. You can, however, redrill/tap for stud-mounted rocker arms, but that's not really suggested.

 

[SpeedThrills]

Thanks for the responses. Casey Davis- Pretty good power increase, and it's a 360. Thanks! Valentek- I should have mentioned that I have that book. It is helping a lot. I'll check out Hughes' site. Thanks.