Yes!
Magnum vs LA block...differences...preferences
- Thread starter Caco2120
- Start date
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mderoy340
Well-Known Member
This is a good read for year to year block changes:
Sorting Out: Chrysler’s 238, 318, 360 Engines, Doug Anderson, Automotive Rebuilder, April 2000
Sorting Out: Chrysler’s 238, 318, 360 Engines, Doug Anderson, Automotive Rebuilder, April 2000
Super-Cuda
MOPAR .. Move Over, Plymouth Approaching Rapidly!
Thanks WRB426!
The color is called Emberglo pearl here in Canada. It is a Jeep color Code PYC.
You can see the whole resto in Members Restorations, page 3 I think. title Is "Supercuda's back"
I used comp 8043-16
basically any of the lifters that can be used in .300 aftermarket blocks, like bam 2018-16/2019-16
howards also makes a set.
1008-16’s OK?
i can't find any specs on them.. are they an old number ?
They look tall, but without measurements, I tried to find some measurements on Google. But no dice.
Total body height, bottom of the wheel to the top of the lifted body; 2.21
Top of litter body to top of the oil band; 1.0090
Oil band; .27105
Top of lower lifter body to the bottom of the roller;
Approximately .900
The jaws of the caliper aren’t deep enough to accurately measure.
Top of litter body to top of the oil band; 1.0090
Oil band; .27105
Top of lower lifter body to the bottom of the roller;
Approximately .900
The jaws of the caliper aren’t deep enough to accurately measure.
it's the link bar that doesn't sit high enough with "normal"(like hughes 4723 or howards 91717) solid roller lifters.. from roller to top of link bar I think is damn near 3"... unfortunately the engine is already together or I would pull it out and measure my comp rollers.
EDIT-- aha, found a document about prosport 1000 and pro plus 2000 series lifters both are designed for .300" taller aftermarket blocks as well. I think those would work, they do look tall enough in the pictures.
http://www.hughesengines.com/Upload/BAM_lifters/BAM.pdf
pishta
I know I'm right....
I got the same dress! MP chromies and matching hat..hiding a Pro-flow EFI TB.
Super-Cuda
MOPAR .. Move Over, Plymouth Approaching Rapidly!
Cool!! How's the pro-flow working? How about a pic?
Bumping this up. Would like to see @pishta 's feedback on the Pro Flo but.......
I just bought a MP crate Magnum block from @GTXJohn that is a NOS block. I don't have immediate plans to build it right now because I currently have engines built for all my cars but I'm just going through the brainstorming phase on it.
Some questions I have are which (LA vs. Magnum) has the better rocker gear? What is better for higher rpm and longevity, pushrod or head oiling? What head (LA or Mag)? Is one head/intake bolt configuration better (I hear valvecovers seal better on Mags)?
My plans for a future build include hyd. roller lifters, Trick Flow or Performer or Promaxx heads filled and drilled offset rockers/ pr's ..... I do also want to run an LA timing cover and w/p.
I've got the block and now just deciding on what direction to go when I see deals on parts come along. Mag heads/intake or LA heads/intake?
I just bought a MP crate Magnum block from @GTXJohn that is a NOS block. I don't have immediate plans to build it right now because I currently have engines built for all my cars but I'm just going through the brainstorming phase on it.
Some questions I have are which (LA vs. Magnum) has the better rocker gear? What is better for higher rpm and longevity, pushrod or head oiling? What head (LA or Mag)? Is one head/intake bolt configuration better (I hear valvecovers seal better on Mags)?
My plans for a future build include hyd. roller lifters, Trick Flow or Performer or Promaxx heads filled and drilled offset rockers/ pr's ..... I do also want to run an LA timing cover and w/p.
I've got the block and now just deciding on what direction to go when I see deals on parts come along. Mag heads/intake or LA heads/intake?
I think the LA rocker gear is better with the bar system.
Oiling the rockers ether way is fine. The shaft has a longer path which is not a longevity issue or problem.
The LA system for higher RPM. The Magnum gear will need a little help with high lift cams. A “Girdle “ like the. Chevy uses is needed.
LA or Magn head? I would go the LA route for the above bar shaft for rockers and larger selection of intake manifolds. Thanks n head bolt configuration, the Magnum installs easier. That’s it.
Valve cover sealing. The Magnum has a waste in better sealing simply due to more hood down points around the valve cover. Why this would matter to yourself only implies you don’t know how to seal a gasket.
LMAO! We know that’s not true.
We know proper pedal and even a half as quality gasket will seal. I like the Mr. Gasket (IIRC) that MP used. Rubber surrounding metal. I’ve used cheap cheap auto tire gaskets, expensive gaskets, niche company’s gaskets, Edelbrock gaskets. They all seal the same if properly done.
I usually use a Superformance gasket and never have a problem with leaks at the valve covers. The question on the different bolt mounting styles was pretty much for intake and heads. I have never messed with a Magnum and have always wondered why they changed the mounting style.
If I use LA heads on a Mag block what head stud kit would I buy?
I've used Superfpormance gaskets before. They work excellent.
"If I use LA heads on a Mag block what head stud kit would I buy?"
I dont know how you dont know this. The question is almost like answering your own question. Using LA heads? Use LA studs/Bolts.
"If I use LA heads on a Mag block what head stud kit would I buy?"
I dont know how you dont know this. The question is almost like answering your own question. Using LA heads? Use LA studs/Bolts.
Like I said, I have never messed with a Magnum but I know the studs are different. Didn’t know if the reasoning is because of the heads or the depth of the bolt holes in the block.
I’ve always just thought of the Magnums as a whole other animal then I got this NOS Mopar Performance block and doing some discovery, LOL
He he he, oh the fun of this stuff. The Magnum block only lacks LA head oiling passages, has the spider hold down over the cam and is generally a better casting . I think it has more nickel in it. The outside metal flakes off when there is a lot of rust on it. I never seen that with an LA block.
They changed the mounting styles because most LA ended up looking like this.
This a a 80K LA greasy mess, that somebody never paid attention to the valve cover leaking.
What is that engine in? PS unit on the passenger side?
Its a 318 LA in a W200 sno-commander, the PS set up is factory because the truck came with a snow plow.
I built a 408 based on a 360 magnum. Used LA heads. All I did was use push rod oiling. I used Rhodes magnum lifters, with the factory dog bones and spyder retainer. Worked great....
Dan the man
Well-Known Member
The magnum blocks still use the out dated 2 piece rear main seal. The cylinder heads use flimsy rocker arm design, limited intake manifold selection, cylinder heads that are known for cracking. I don't know if this is true or not but I've heard that a 0.040" over bore is pretty much the limit on the magnum blocks. If it was up to me, I would have designed the block to be able to take a 0.060" over bore with out any issues. Block deck height would be more equal from end to end and side to side. All cylinder head bolt holes would be blind holes as would the mains, block webbing would be thicker and designed so the bolts would not enter the water jacket so 4 bolt caps could be used and all 5 main bearing caps would be designed for the use of 4 bolt main caps. Thicker deck surface. And the cylinder head cracking issue would have been resolved. All of those quality improvements would have made for a better small block. The magnums have a 9.0:1 cr, the la's have a 8.4:1 cr. Only difference that I've heard mentioned was the difference in the cr, hydraulic roller cam, pistons and cylinder heads that crack. I see that the magnum heads get a lot of attention for being a budget cylinder head. Do they all eventually crack? Would the use of the Chevy style rocker arms require the use of rocker arm stud girdles? Wouldn't a magnum block be a better performer with like edelbrock or tf cylinder heads?
Wow! Lots of questions and.. whew! He we go. I’ll answer the high points with a thought at the end.
The 2 part main seal may be “Out Of Date” but still works well as one would only need to be careful in doing the job.
I like the LA bar for the rockers better myself. What I do like is the ability to use a cheaper Chevy rocker. The rocker girdle would be good for a race engine and not really needed for a street or street strip engine. Adding one would be a good plus. This I can’t argue, but is it really needed?
On over bores, IDK if the .040 is true. But it doesn’t really matter for two reasons IMO. One, the amount of overbore that is available is of very little HP gain as it only adds 5 cubic inches from the OEM 4.00 bore size. The benefits of a bigger bore are not really coming into play here. How much it can be bored out should be a fact finding four with a sonic checker. It has been said that 340’s are the best and thickest cylinder walls to bore out to a whopping 4.1 or better. I’ve had a few sonic checker that would and have failed at a .020. The machinists I worked with called the stock cylinder bore unacceptable even for a mild cam change. Then I have one that the machinist say we can go to 4.125, no problem!!!!
WTF? IDK!
Truly the bottom line is, a thicker cylinder wall is power!
Less flexing, no wobbling, great sealing…. That’s power buddy! Yea!
Making a block with blind holes requires more metal which adds weight. The Chrysler small block is heavy enough. The race block is even heavier. Adding blind holes with more metal… more weight. Less is better for racing but not at the expense of longevity. But I’m seeing blocks from the 70’s still in service in some not so light duty vehicles making good power. Must be that high nickel content exceeding other brands race blocks.
That also brings me to the advertised compression ratios. While the Magnum has a higher advertising ratio, how many people are actually trying to make some serious street steam with a 8.4-1 comp ratio with an engine that stopped being produced in the early 2000’s? The LA advertised ratio is actually lower, sometimes in the mid 7’s. BTDT & checked it out myself.
I don’t know if “ALL MAGNUM HEADS” eventually crack. Even if they do, the crack in the head doesn’t affect performance. Sometimes it affects about seal. Yes that affects performance I know. However, if you don’t know they’re cracked and the engine runs strong and you don’t remove the heads to check, how will you know that correct? You don’t you don’t! And you’ll never know until you physically check to see if they have cracks. LA heads crack as well. Do not before then to thinking they don’t.
All engines perform better with higher flowing heads, period! So if you took a stock magnum engine swapped out the top end for an Edelbrock RPM package and don’t touch the cam, the performance gain is marginal. Why? It’s the head flow amount at the low lives the cam provides coupled with the very very short duration and exceedingly wide centerline of the stock him it’s pathetic for performance. While the stock magnum engine is pretty good for what it is, taking the short block and giving it a better top and build and camshaft will wake it up, as it would with any engine. The half point of compression is a plus but still at 9 to 1, only mild cams will be entertained at that level.
I can’t think of a single person taking a 50 year old LA and expect a huge performance gain with just a top end swap. The bottom end on original stock (inside parts) LA engines for any use beyond a simple grocery getter is not going to be a good idea to use and this be rebuilt with the proper piston for the goal the owner is seeking.
My thought here is on your comparison making is not an accurate one and not debatable based on the age of an LA engine which is 99.9% probability of being simply worn out. While magnum engines can still be found in great shape.
Now a Magnum that has very low cylinder west and hood rings can still be found would be a good Candidate for a good street performance cam engine, a LA would not. At a 9.0-1 ratio for the Magnum, great street rail driver like power can be made. Also a wise person would add an overdrive trans.
The 2 part main seal may be “Out Of Date” but still works well as one would only need to be careful in doing the job.
I like the LA bar for the rockers better myself. What I do like is the ability to use a cheaper Chevy rocker. The rocker girdle would be good for a race engine and not really needed for a street or street strip engine. Adding one would be a good plus. This I can’t argue, but is it really needed?
On over bores, IDK if the .040 is true. But it doesn’t really matter for two reasons IMO. One, the amount of overbore that is available is of very little HP gain as it only adds 5 cubic inches from the OEM 4.00 bore size. The benefits of a bigger bore are not really coming into play here. How much it can be bored out should be a fact finding four with a sonic checker. It has been said that 340’s are the best and thickest cylinder walls to bore out to a whopping 4.1 or better. I’ve had a few sonic checker that would and have failed at a .020. The machinists I worked with called the stock cylinder bore unacceptable even for a mild cam change. Then I have one that the machinist say we can go to 4.125, no problem!!!!
WTF? IDK!
Truly the bottom line is, a thicker cylinder wall is power!
Less flexing, no wobbling, great sealing…. That’s power buddy! Yea!
Making a block with blind holes requires more metal which adds weight. The Chrysler small block is heavy enough. The race block is even heavier. Adding blind holes with more metal… more weight. Less is better for racing but not at the expense of longevity. But I’m seeing blocks from the 70’s still in service in some not so light duty vehicles making good power. Must be that high nickel content exceeding other brands race blocks.
That also brings me to the advertised compression ratios. While the Magnum has a higher advertising ratio, how many people are actually trying to make some serious street steam with a 8.4-1 comp ratio with an engine that stopped being produced in the early 2000’s? The LA advertised ratio is actually lower, sometimes in the mid 7’s. BTDT & checked it out myself.
I don’t know if “ALL MAGNUM HEADS” eventually crack. Even if they do, the crack in the head doesn’t affect performance. Sometimes it affects about seal. Yes that affects performance I know. However, if you don’t know they’re cracked and the engine runs strong and you don’t remove the heads to check, how will you know that correct? You don’t you don’t! And you’ll never know until you physically check to see if they have cracks. LA heads crack as well. Do not before then to thinking they don’t.
All engines perform better with higher flowing heads, period! So if you took a stock magnum engine swapped out the top end for an Edelbrock RPM package and don’t touch the cam, the performance gain is marginal. Why? It’s the head flow amount at the low lives the cam provides coupled with the very very short duration and exceedingly wide centerline of the stock him it’s pathetic for performance. While the stock magnum engine is pretty good for what it is, taking the short block and giving it a better top and build and camshaft will wake it up, as it would with any engine. The half point of compression is a plus but still at 9 to 1, only mild cams will be entertained at that level.
I can’t think of a single person taking a 50 year old LA and expect a huge performance gain with just a top end swap. The bottom end on original stock (inside parts) LA engines for any use beyond a simple grocery getter is not going to be a good idea to use and this be rebuilt with the proper piston for the goal the owner is seeking.
My thought here is on your comparison making is not an accurate one and not debatable based on the age of an LA engine which is 99.9% probability of being simply worn out. While magnum engines can still be found in great shape.
Now a Magnum that has very low cylinder west and hood rings can still be found would be a good Candidate for a good street performance cam engine, a LA would not. At a 9.0-1 ratio for the Magnum, great street rail driver like power can be made. Also a wise person would add an overdrive trans.
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