why could early 360s run with 250 plus HP stock?

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DusterBoy15

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why could old 360s run 250 plus horsepower with stock pistons deepin the hole and stock carb and cam and so on.....


if these were made like this can you just use almost any piston at zero deck to get a good amount of compression?

i just want to know how they were able to make that much horsepower with stock parts
 
Not sure how early you are talking about.My 73 had dished pistons.A friend had a set from a 71 engine that were flat tops.Everything else(?) was the same...maybe camshaft was different.Installed a Crane 260 cam(427/454 lift)and the truck would hit 80mph at the 2-3 shift whereas the stock cam would top out at 79mph in the 1/4 mile.What are you putting together?Bob
 
I HAVE TWO 71 360s THEY BOTH HAVE FLAT TOP PISTONS, AS OPPOSED TO LATER MODEL DISH PISTONS. THE FLAT TOP PISTON WOULD HAVE MORE COMPRESSION THAN THE DISH. THAT AND A BIT SMALLER DECK HEIGHT I BELEIVE ARE THE ONLY DIFFERENCES.
 
74 and 75 hi po 360's had the same cam as 340's did. I beleive they were rated at 240 hp.
 
Not sure what the question is. But, if you took that same 8.5:1 engine and built it with a zero deck you would gain a significant amount of horsepower. The compression ratio with zero deck this could easily be calculated. I built two zero deck 360 magnum engines and they ended up in the 11.5:1 range, but the heads have a smaller combustion chamber than the old 360's

The 250HP are you refering to the 360 4bbl engine used around 1974? Why would that be a surprise that it made 250hp? It had a 4bbl carb, 340 cam, reasonably good exhaust manifolds, 340 valve springs, reasonable flowing heads etc.
 
I would question whether any factory 360 ever made advertised horsepower. The parts were decent, but the execution was sloppy. That's assembly line work for you.
 
well im asking becasue what if someone wanted to build a stock based motor wit stock parts besides cam,springs and so on just like stock pistons and rods but Zero deck would it even last long? flat top pistons at zero deck
 
You couldnt mill a block far enough and keep enough meat in the deck to get factory flat tops to zero deck. The last '87 360 I tore down had a factory center dish, but basically a flat top type ring, and they were .180" down in the bore. The areas around bolt holes on the deck are thick, but there are spots in the deck that get as thin as .300, and you'd be cutting more than half off. Other factory flats are way down there too. Plus, it's extra meat for milling, and that means more $$. I had extra passes on a block cost me $200 before becuase it was "extra work". Better pistons are $280, and makes the intake fit right, and pushrods fit right, and bolt holes deep enough to clamp well, etc. It get's back to "is it worth it?" The answer is no. But, if you built it right, it's easy to get 275-300hp from a factory type piston and no compression or quench. But you have to get the right package and realize the limitations.
 
ook i get it becasue some pistons are made certain ways like maybe longer or bigger thats why they are able to make certain compressions at maybe the same piston hight
 
A stock HP 360 (1974-75) will make 240 honest horse power. This is what I like about the 360, it responds well to bolt ons. Even though its a low comp engine, it makes good torque & will run off pump gas. I ran one in a Chrysler 5TH Avenue, built to the E58 specs, headers, Thermoquad carb, true 2 1/4 daul exhaust, stock convertor & 904 trans., 2:94 suregrip 8 1/4 rear end. This car wieghed in at 4100 LBS. It ran 14.80's! That comes to 249.96 Horse Power at the rear wheels! Now the 360 does respond real well to a set of zero deck pistons. It just depends on what you are gonna use it for.
 
Not to mention where the readings are takin from with what accer. bolted on.
 
or you could mill your heads down to 49cc with the mopar thin gaskets and have 10:1 with stock pistons. Of course you have to get the intake fitted and then there is the valve to piston clearance that might be a problem if you run a big cam. Custom fit pushrods......and on and on.That's what happened to me when I took my heads in to be milled and didn't specify a minimum cc to the builder. He just did what I said and milled the heads .050.
Seems to run fairly good in my 63 dart with 3.23 and 904. Haven't been to a track or anything yet but, I hope to soon. When I build my next 360 it will definately be zero decked and correct pistons to improve the quench area and flow.
 
I think he's just sying a all stock 360 with zero deck pistons, then the other part, of course are changed, cam, intake, etc...

Sounds like a regular hot rod/performance build to me.

Why he would think this wouldn't last is beyond me. It's only done all the time. A normal performance build is just that.
A swap of compnets starting with pistons to desire compresion ratio with a upgrade in cam cam related compnets, intake and carb with headers etc....
normal stuff.
 
If I'm understanding his question correctly he is wondering why the LA 360's were rated at 250 horse compared to rated to 230 of the Magnum maybe? If that's the question, the answer is pretty simple.. Carb vs Injection. A decently tuned carbed motor will make more horse than a conservative tuned EFI motor. The EFI motor will make more torque though.

Until just a few weeks ago you were stuck with "canned flashes" for the EFI Magnum. Now that SCT has a full blown tuner available it will be interesting to see how much you can squeeze out of a EFI Magnum motor.
 
look up dyno'd 360 combo's in the search engine of this web site, see what kind of power can really be made. You gotta be patient, bro, take the time to save for the right basic components, like good pistons, and the rest is exactly what has been implied...Bolt On. The amount of rated power in the 360 also changed because the method of measuring that power changed during the advent of the smog era. You might get a book like "Building High Performance Chrysler Engines" that give some of the history of the LA block and how it progressed through the years. It will answer all these questions, too.
 
o ya i know im getting me some good pistons and have everything else jsut need the money for the head work and should be all good but im prolley gonna save up till i have enough for everyhitng which will be next year or year after that way everyhting gets done at once
 
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