Which block is a better stroker candidate?

[comoxian]

OK, I've decided to put a stroker into my '65 Dart. I'm going to pull the 273 and store it for possible re-installation should I change my outlook.

I have managed to locate a '92 360. It's carbureted, which leads me to believe that it is an LA block. Please correct me if I'm mistaken. I haven't had a chance to look for any info on the actual motor and don't know the lineage of the Magnums.

If by chance it is a Magnum, would I be better off finding an LA or adapting the Magnum to suit. I'd like to keep it appearing to be period correct, in my warped way of thinking .

There is also an '81 2bbl 360 that I may be able to get.

Is either of these two a more suitable block to stroke? Or should I look for something else? It's not like I'm going to use much of either, more or less just the block. Most parts would end up being aftermarket, wouldn't they?

Is there anything else that I should look for when buying a donor motor?

Thanks one and all, you guys are great. I'm learning a lot by being here.

[dust]

Both will work just fine for you, as long are you stay within .030 overbore. (anything over that is risky). The ideal would be a pre-1974 block, thicker cylinder walls.

My preference would be the Magnum engine if the heads were to be reused. If you are going after market with heads and valvetrain then I'd go with the LA engine and the superior (and more affordable) rocker design. LA blocks are drilled for LA heads and Magnum heads can be used on an LA block if you want to. But you can't use LA heads on a Magnum block without block modification.

Check the numbers on the 1992 engine, does it have a mechanical or electric fuel pump? I doubt it is a Magnum if it is carburated but who knows, could be converted...

[dodger1]

Magnum has 10-bolt valve covers, all LA's are 5-bolt like your 273. A 92 would be injected I'm sure, but may be a throttle-body LA which can sorta look like a carb. Not positive of the changeover to 5.9 Magnums - thought it was 92 but maybe 93?

[rumblefish360]

Dust makes a good reply, I just wish to add to it. Not nit picking here. Just 2 cents extra.

Originally Posted by dust

Both will work just fine for you, as long are you stay within .030 overbore. (anything over that is risky). The ideal would be a pre-1974 block, thicker cylinder walls.

A sonic check will let you know if more of an overbore is possible but I would tell you a thicker cylinder wall is a stronger and longer lasting wall with better abilty to seal with the pistons and rings. If you have to overbore the cylinders, fine. Otherwise, don't bother in doing so. It'll add about 5 cubic inchs total. A power gain to hard to see even with a dyno.

A Pre '74 block is said to be thicker, this has proven to be bunk mostly. However, you could allways get on in hopes that it is a old 340 casting and has such thick walls.

Originally Posted by dust

My preference would be the Magnum engine if the heads were to be reused. If you are going after market with heads and valvetrain then I'd go with the LA engine and the superior (and more affordable) rocker design. LA blocks are drilled for LA heads and Magnum heads can be used on an LA block if you want to. But you can't use LA heads on a Magnum block without block modification.

Superior valve train? You betcha!
Cheaper valve train? .... I don't think so unless your JUST replaceing the rockers @ approx. $80. The hardened shafts will add to that quick. Upgrading to a 1.6 ratio like the stock Magnum will run ya a bunch. But don't be in a hurry to do so. You can allways have a cam ground with some serious lift ground right into it.

Originally Posted by dust

Check the numbers on the 1992 engine, does it have a mechanical or electric fuel pump? I doubt it is a Magnum if it is carburated but who knows, could be converted...

Magnum engines started in '93. It is most noted by the vertical attaching bolts for the heads and 10 bolt valve covers. Other things are mech. fuel pumps are LA engines. (For the most part, at least stock they are.)
The brackets up front. Hard to miss Magnum brackets and there belt system.
The front cover where the fuel pump is bolted into on LA engines, is thinner on Magnum engines. Theres no provision for a fuel pump on a Mangum engine.

The engine mod to bolt on LA heads to a Magnum block is drilling the oil passages from the deck on down. This could be done when the engine is totalllly rebuilt.

Bolting Magnum heads onto a LA block requires AMC lifters and hollow pushrods of the proper length. MoPar has it all in there catolog.

318's became Magnums in '92.

[tenchu80]

hughesengines.com for a complete stroker kit, just specify if overbored. Both heads have there good points and very little if any bad. LA- common shaft design keeps the rockers all in a row and eliminates the need for a valve train girdle(think chevy) and the valve stems were a little thinner which allowed a little more airflow. Magnum-where designed specifically with quench in mind which is power efficient for amount of fuel spent and helps control detonation.
On a second note, magnum rockers and set up in pairs per cylinder; not quite as rigid as an LA but for maintenance is easier. If you have one bad pushrod then you just remove that pair of rockers, not the whole set off the cyl head like you'd have too with an LA.

[dust]

Good information Rumble, but a few questions...

Originally Posted by rumblefish360

A Pre '74 block is said to be thicker, this has proven to be bunk mostly.

How was it proven bunk?

Originally Posted by rumblefish360

Superior valve train? You betcha!
Cheaper valve train? .... I don't think so unless your JUST replaceing the rockers @ approx. $80. The hardened shafts will add to that quick. Upgrading to a 1.6 ratio like the stock Magnum will run ya a bunch. But don't be in a hurry to do so. You can allways have a cam ground with some serious lift ground right into it.

Cheaper? yes if you are going aftermarket. Rocker assy's for LA $100-250 (mostly IIRC) with many choices and Magnums are around $500 with very few choices. Non roller cam/lifters are cheaper too. And according to Dave at Racer Brown, 1.6 rocker arm ratio for at least the intake is the way to go if you want to increase cam specs. I don't remember why... Improved geometry?

Originally Posted by rumblefish360

The engine mod to bolt on LA heads to a Magnum block is drilling the oil passages from the deck on down. This could be done when the engine is totalllly rebuilt.

I think you also have to drill the heads in some cases. Check this out:
http://www.allpar.com/mopar/LA-V8-en...ead-swaps.html
I spoke to the guy who wrote this, he knows his stuff and is more an willing to help.
But that seems a little off topic now.

[comoxian]

Originally Posted by dodger1

Magnum has 10-bolt valve covers, all LA's are 5-bolt like your 273. A 92 would be injected I'm sure, but may be a throttle-body LA which can sorta look like a carb. Not positive of the changeover to 5.9 Magnums - thought it was 92 but maybe 93?

It definitely has a Holley carb on it, or so it seems. I haven't seen a throttle body badged Holley, but what do I know.

I forgot about the valve cover difference. I will check that out on Monday. It's sitting on the floor, under a shelf, behind a couple other engines in our shop.

Would I be able to get 408ci out of it without stressing out the block?

[valiant64]

Holley did make throttle bodies for the 360. I had one on my 89 Dodge 1/2 Ton truck. Stroker kits are available for the 360/408 thru several vendors & should be no problem provided the block you use is in good condition.

[dust]

Originally Posted by comoxian

Would I be able to get 408ci out of it without stressing out the block?

It'll be fine. The block is likely a LA roller like my 1989 360 block which I stroked to 408.

[kick_the_reverb]

There's a big chance that the 92 is an LA-roller cam block. It would probably be better to use since you can use a factroy hydraulic roller lifters (with the factory retaining spider), along with a re-ground cam or "hydraulic roller retrofit" (which will be cheaper since you'll be using the cam only).
Since it's an LA block, you can use LA heads or Magnum heads with no problems. However, it's usually a good idea to use closed chamber heads with zero deck pistons and .039" thick head gasket, so if you decide to get LA heads, spend the bucks on Edelbrock (they have closed chamber). If you use Magnum style heads, a good idea would be to use EQ Cylinder heads (which you can get cheap) - they can be had with Magnum intake bolt pattern (p/n 318A) or LA intake bolt pattern (p/n 318B). Which ever head you use, don't just bolt it out of the box - the Edelbrocks sometimes come with valve guides that are too tight. Check each new head for straightness, proper surface, etc.
I would start by sonic checking the 92 block (and magging it for cracks, of course). If it's good, use it. If not - move on to the next one.
Good luck,
Ran

[Rug_Trucker]

.040 is OK on a 360. I have 150K on mine. It was bored and run .040 over before I got it. How many miles? I have no clue! I gave it a light hone and put in new rings and flat tops and have been wailing on it since 2001. I have at least 150K on it.

A friend of mine had 2 340 blocks and a '67 318. He sonic checked them all and the 318 was thicker!

He built it into a 402 stroker. And it is for sale! He got a 340 at the nats he's is going to build into a 426

[rumblefish360]

Originally Posted by dust

Good information Rumble, but a few questions...

How was it proven bunk?

Hennsley mototrs overbore's 318 to 4 inchs for there 4 inch ram crank mototrs. They have sid this on blocks before.
On the early 360 blocks, sonic checking made by mags, members here and other places have noted this. about 360 blocks.
Sonic check before you ever go beyond a spec that makes you uncomphy or like Dust said,, .030 can't hurt and to check, if anything, will give you peace of mind. That can not be beat.

Cheaper? yes if you are going aftermarket. Rocker assy's for LA $100-250 (mostly IIRC) with many choices and Magnums are around $500 with very few choices. Non roller cam/lifters are cheaper too. And according to Dave at Racer Brown, 1.6 rocker arm ratio for at least the intake is the way to go if you want to increase cam specs. I don't remember why... Improved geometry?

Rockers for LA heads are cheap in the HD replacement rockers from MoPar. Thats the only cheap ones I have seen. Mech. rockers I have noted were approx. $179. 1.5 or 1.6 ratio from I think Crane.
Rollers start around $300, give or take.

OR

Drill and tap Magnum heads for Chevy Rockers vs the $500 that you seen. I actually never seen them that much.

I'll do some homework on this and letcha know what I come up with. No time right now. This is close to a drive by porting as it gets for me.

I think you also have to drill the heads in some cases. Check this out:
http://www.allpar.com/mopar/LA-V8-en...ead-swaps.html
I spoke to the guy who wrote this, he knows his stuff and is more an willing to help.
But that seems a little off topic now.

I think not, Thats on topic, well, kind off if you look into areas of possiblitys.
The tapping of cylinder heads for cross breeding a LA & Magnnum or for use of other parts can be a great idea.

TTYL Dust and all.

[rumblefish360]

OH, someone said 1.6 on the intakes. This is something that may or may not help because of the size cam you have, Hyd. lifters can fail to perform at the increased ratio sometimes. (I don't mean fial as in destroyed.)

It can be very combo specific. It can't hurt to try going 1.6 on only the exhaust as well, then 1.6 on both side.
What the heck. Whats the worst that can happen (So long as you have clearance.) You go faster/slower and you go back to the 1st combo?

[rumblefish360]

Hey Dust, I did a little looking @ summit racing. I found these pages.
A LA shaft mount rocker arm page;

http://store.summitracing.com/egnsea...=KeywordSearch

And a Magnum rocker page;

http://store.summitracing.com/egnsea...=KeywordSearch

Magnum/MP's 288 for 16 arms.
LA/MP's @ 9.95 each, 16 for, $159.20 What ones are these?

UGH! Eyes don't wanna work tonight fellas. Well, theres some pages.
If I'm wrong, I'm wrong. Appologies.