mild 360 dodge buildup

[prairiehotrodder]

I'm not a dodge guy, but i have a customer with a 68 dart with a 273 and he wants more power and the 273 is worn out. I suggested a mild 360 and he liked the idea. He doesn't have a core but i have a couple. I have a 99 360 magnum and a 78 360 truck engine. He is looking for enough power to squeal the tires and just be a fun cruiser. Are there any dodge experts that would suggest which core i use ? It will stay carbeurated. I'm not sure of the condition of my cores but either one will have to be torn down, maybe re-use some parts, maybe a true rebuild. not looking to spend big money or go racing.
thanks
Brian

[PRH]

Either will work fine....... they both have their pluses and minuses.

The magnum will have a HR cam, and the heads are likely to be cracked.

If the heads are usable, the Magnum will be the easier path for the level of performance you’re talking about.
Re-ring it, go thru the heads, regrind the cam, intake for a carb........ done.

[PackardV8]

Either will work fine....... they both have their pluses and minuses.

The magnum will have a HR cam, and the heads are likely to be cracked.

If the heads are usable, the Magnum will be the easier path for the level of performance you’re talking about.
Re-ring it, go thru the heads, regrind the cam, intake for a carb........ done.

X2 on the Magnum. Unless it came from a low mileage wreck, the heads will be cracked. The good news is he wants aluminum heads and intake anyway.

[PRH]

I didn’t see any mention of aluminum heads.

[lefty o]

id opt for the 78 for a core.

[PackardV8]

I didn’t see any mention of aluminum heads.

he wants more power . . . He is looking for enough power to squeal the tires

Full explanation. By the time he buys new Magnum iron castings, new valves and gets it all set up, the loaded aluminum heads aren't that much more of a stretch.

Reason I know this is my machinist has this discussion with would-be Mopar customers regularly. One guy was stubborn. He just wasn't going to spend the money for new iron or aluminum heads. Every weekend, he'd go to the U-Pic yards around town and pull a pair of heads. He'd get charged $50 up front to clean, mag and pressure test them and they were always cracked. Finally, he was told pick up his pile of junk and take it somewhere else. When reaches that point, no one was going to be happy when his engine was done.

[F-BIRD'88]

Rebuild the 273 and supercharge it.
Word is there is a Weiand 142 blower kicking around this forum that needs a new foreverhome.

[prairiehotrodder]

Thanks for the help friends,

lets assume the magnum heads are cracked, Is the magnum short block still an advantage ? I read that the bores and pistons are usually much less worn and that the factory roller cam setup (with an upgraded cam of course) would be worth using ? Also designed with better gaskets to prevent leaks ? am i on the right track ?

[PRH]

Assuming the stock heads are cracked.........
If you can do some minor porting yourself, there are Chinese magnum castings available.
They flow a bit less ootb than the stock heads, so you’re going to want someone to spend a few hours cleaning up the ports.
Edelbrock makes aluminum replacements, but they’re not that cheap, and they’ll require different rockers and pushrods.

The early heads oil the shafts through a passage in the heads.
Magnum heads are pushrod oiled.
Trying to pushrod oil the stock LA rockers isn’t likely going to work out very well, and a 99 magnum block isn’t likely to have the oil passage drilled from the cam bearings to the deck for LA head oiling.
However, there are some aftermarket rockers for LA heads that can be pushrod oiled......... but that’s an added expense.

“If it were me”, if the magnum heads were cracked, but the rest of the core was decent......... I’d prep a set of the Chinese magnum heads and keep it all magnum.

It will likely be the cheaper option to end up with something decent.

This is somewhat based on the assumption that the magnum core will be in better condition to start with than the LA 360.

Might require pulling them both at least partially apart to make the final assessment.

The 78 360 will likely have a true CR of under 8:1 as is.

There is a video or two from Richard Holdener on some junk yard Magnums.

[PRH]

One more thing with regards to the cracked magnum heads.........

I have heard that when pressure tested, they don’t usually leak, and have seen where people have just installed seats in the non-leaking cracked heads and carried on.

Depending on what machine shop costs are like in the area you live, fixing the stock heads may or may not be cheaper than the Chinese replacements.
At this time, the Speedmaster magnum bare heads are $339/ea(on sale).

There’s also the option of buying some reman heads off a place like Odessa.

[Krooser]

One more thing with regards to the cracked magnum heads.........

I have heard that when pressure tested, they don’t usually leak, and have seen where people have just installed seats in the non-leaking cracked heads and carried on.

Depending on what machine shop costs are like in the area you live, fixing the stock heads may or may not be cheaper than the Chinese replacements.
At this time, the Speedmaster magnum bare heads are $339/ea(on sale).

There’s also the option of buying some reman heads off a place like Odessa.

Pretty normal to see cracked Magnum heads that perform perfectly fine in all but all out competition. Saw the same in Ford Flatheads.

[PRH]

If the vehicle that Magnum core came out of was worked pretty hard, not only will the heads likely be cracked, but I’ve seen them with some pretty significant exhaust seat recession as well.

As with most of this stuff....... which direction to go often comes down to how big the budget is.

[PackardV8]

One more thing with regards to the cracked magnum heads.........

I have heard that when pressure tested, they don’t usually leak, and have seen where people have just installed seats in the non-leaking cracked heads and carried on.


Pretty normal to see cracked Magnum heads that perform perfectly fine in all but all out competition. Saw the same in Ford Flatheads.

For true. It comes down to whether one is giving a warranty on the work. My machinist won't rebuild a cracked head. Might run and last, might not and he just won't take the chance.

[PRH]

Looks like Promaxx has assembled Magnums for $409/ea.

In stock at Summit.

[rebelrouser]

been a mopar guy my entire life, not sure that makes me an expert or not. I also vote for the magnum engine, mainly because it has roller lifters. I have built several 360 based 408 strokers. They all turned out very well, set up for the street with a mild idle, and all made over 400HP. And since they were not to be raced, used cheap stroker kits with cast cranks, lots of them on Ebay for around $1,500.00 Used stock heads with some pocket porting. If you use the stock rotating assembly, make sure you get some pistons to get the compression up a little, most of the ones I checked have less compression than the specs given, they are just a turd with a mild cam and less than 9 to 1

My personal street car is a 69 cuda with a procharged 408, I makes 600HP and is really fun to drive, electronic fuel injection on pump gas. I use RHS X heads for that build.