High torque 360 LA build camshaft recommendations

Brooks James

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A friend wants me to build a 360 La for his Ram truck. It is a work truck always loaded and pulling a loaded trailer. He is interested in as much torque as possible.
Years ago I put together a 350 SBC with the early small valve " power pack' (triangle on the front of the head) heads. With a small Sig Erson cam. It pulled very strongly but was all done at 5000 rpm.
I have a set of 67 273 heads and was thinking of putting them on the 360.
Cams have changed over years, what would you recommend for a cam ?
Mid 70's 360 la probably around 8:1 compression
Stock tranny and converter
3.54 axle
About 28 tires
Stock single exhaust with catalytic conv
Thermoquad on factory iron intake
 

jazak5

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mopars are not chevys and not everything works together /with those 273 heads you're going to lucky to see 3000 rpms! you're still going to need air to build torque just less overlap to build cylinder pressure
 

justinp61

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I can't think of a single 360 application that I'd use 273 heads for.
 

Garrett Ellison

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I've had some experience with a 360 industrial / truck engine once that had an oddball casting number of 857. They where like 234 industrial heads except they had exhaust instead of water going through the manifold crossover. They where small port like 234 industrial, so I imagine they had small valves and closed chambers. It was done at 4000 rpm, but it would blow the tires off at will up anything before then in a W150. I would stick with some bowl work and a good valve job on the stock heads and would give this camshaft a whirl.
Howards Cams, Hydraulic Flat Tappet Camshaft, Chrysler SB 273-360/318, 208/214 @ .050, .479/.494, 110 LS - Competition Products
 

Brooks James

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I've had some experience with a 360 industrial / truck engine once that had an oddball casting number of 857. They where like 234 industrial heads except they had exhaust instead of water going through the manifold crossover. They where small port like 234 industrial, so I imagine they had small valves and closed chambers. It was done at 4000 rpm, but it would blow the tires off at will up anything before then in a W150. I would stick with some bowl work and a good valve job on the stock heads and would give this camshaft a whirl.
Howards Cams, Hydraulic Flat Tappet Camshaft, Chrysler SB 273-360/318, 208/214 @ .050, .479/.494, 110 LS - Competition Products
That's what I'm talking about pulls like a freight train
 

OldmanRick

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Hey Brooks, that 350 build was a blast from my past...
Many moons ago my buddy started pulling his 67 Camaro race car around with a 66 Impala Wagon 283 2bbl/PG/2.73. He bought a flat top 350 short block, cleaned up the 283 heads and bolted them on with a mild hyd and the original intake and carb. Guessing the open trailer/race car weighed 5,000 ish. It worked like a champ and didn't roll over til about 4800 r's.

I'd love to see how a 360 would perform like that with the small heads? If you could find a SP/2P intake for under that TQ, i actually have one i'm not selling :), i think it could be a great engine for what he's looking for.
 

Ironracer

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Hey Brooks, that 350 build was a blast from my past...
Many moons ago my buddy started pulling his 67 Camaro race car around with a 66 Impala Wagon 283 2bbl/PG/2.73. He bought a flat top 350 short block, cleaned up the 283 heads and bolted them on with a mild hyd and the original intake and carb. Guessing the open trailer/race car weighed 5,000 ish. It worked like a champ and didn't roll over til about 4800 r's.

I'd love to see how a 360 would perform like that with the small heads? If you could find a SP/2P intake for under that TQ, i actually have one i'm not selling :), i think it could be a great engine for what he's looking for.
I've got one of these hanging around too! Lol.
 

AJ/FormS

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IMO
The big ports and the 1.88 valves are not the problem.
The problem is the lack of cylinder pressure, which translates directly to lazy cylinder-filling at lower rpms.
A cam with a later closing intake valve will just be lazier, and make less pressure. I'm with Rusty, the stock 252* 112LSA cam is just right.
I highly recommend that you do a compression test and see where the engine is at.

With 3.54s and 28s. 65 mph will be 2760 @ zero-slip, maybe 2900 at 5%. Therefore you can run a 2800 stall no problem which is what I would do.
Forget the cam, install the 2800.
The TQ is the right carb for the job.
If you want more bottom end, Your #1 go-to is to increase the cylinder pressure.
There are several ways to do this;
you can increase the Compression ratio. Or you can close the intake valve sooner with an earlier-closing intake valve event.
IIRC the stock 360 2bbl cam specs are 252/260/112. In 4* advanced this will give you a nice small Ica of 54* and at say 7.8 True Scr, that should get you about 128psi at 500ft elevation.
With iron heads you can bump that to around 160psi, still on pump gas.
Follow along with me in this exercise;
Lets say we target 155psi for the sake of towing.
With no other changes, this would require an Scr increase to 9.2.
A stock 360 has a swept volume of 737.21 cc. To get to 9.2Scr, the total chamber volume would need to be not less than 89.9cc.. With 72 in the head and 8.6 in the gasket, yur already at 80.6, so the flat-tops gotta be no lower than 9.3cc which is .045 in the hole. I'm pretty sure the stockers are around .150in the hole. So yur kindof screwed with the stock pistons. However;
the engine doesn't much care how you get these 89.9ccs. You can push the pistons up closer to the deck, or use a thinner headgasket or install heads with smaller chambers, or even shave the heads that are currently on it.
Lets say your pistons really are .150 in the hole(30.9cc), and lets use the .028 gasket (6.8cc). Now yur up to 37.7cc, so then the heads gotta come down to 52.2cc. Can you shave the stockers that far?
IDK but if you could yur just making a lotta problems for yourself in fitting the top end back together. A better idea, IMO is to just buy heads with smaller chambers. Of course the best idea is to just install KB107pistons which will come in at about .012 below deck, which is 2.5cc. Now with the .039 gasket(8.6cc) you are up to 10.8cc, leaving 79.1 for the heads. Which allows lots of room to play with camshafting.
This is just an exercise.
The stock 252* cam will have the potential to powerpeak at around 4500. That means the Torque peak will be at around 3000. That means a 2800 stall is bang-on. Or even a 3000.
The 212* cam that Rumble mentioned is a 260/260/110LSa cam and installed at 104, will have about the exact same Ica, so is another excellent choice. Because it is on a 110, it will have a lil more overlap (40*versus your 32*) which has the potential to increase your power just a hair over the factory 252*cam. The additional 8* of overlap with log exhaust valves is of no great importance. Nor is the extra exhaust duration because it is all in the overlap. It's a great cam, but not much of an advantage over the stocker, which you already have....... if it's any good, lol.
So there you have some things to think about.

If you ask me what I would do, the answer is hands down to raise the piston crowns up closer to the decks. It's just too easy. and you will never be sorry. Whereas if you shave the chit off the heads yur just opening up a can of worms that lead to a domino effect. After the heads go back on you will find out that the intake flanges will have to be shaved, then the china wall is too tall, then the ports no longer line up. So the money you saved on pistons (and probably boring etc) all gets used up in machining, and not every machine shop gets it right the first time.
Yes you could install the 273 heads and get the cylinder pressure you want. And yes it will run just fine. But beginning at around 3500, those tiny ports and valves are gonna put the brakes on airflow and by 4000, like you said, she will be wheezing pretty hard. Forget passing-power which at 55mph will be about 3700 in Second gear. No horses left in that barn.......... especially not at say 128psi CCP,(Cranking Cylinder Pressure).

Ok so now, I gotta tell ya something, that is gonna mess everybody up.
In about 1975, I installed a 340 in a 65 Valiant Wagon. But not yur typical 340. I was 22 and poor as can be, but I recently inherited this junkyard 340 short (no cam), and a complete 1969 318 top end, plus it's cam. So I slapped it all together, installed the only exhaust that would fit, namely Hooker fenderwell headers, and turned the key. Up until my Barracuda,(see Avatar) that Valiant was my favorite all-time combo . It was a GREAT street car. Tons of torque, pulled like a freight train, got stupendous hiway fuel economy, and revved to no end even thru the 2bbl, lol.
But like you said, there wasn't much after 4000.
So what was different about that 340-2bbl?
Well, for starters, it had a boatload of cylinder pressure. Make that a tanker-load. The 318 cam, IIRC is a 240/248/112 and in at 108 has an Intake closing angle of 44*.. Man that is really slamming the door. I never measured the compression on that combo, but it wouldn't surprise me to find out that it was pushing 200psi. Hey, I just remembered something, I still have that engine!, altho it is all in parts, lol. I'll have to go find that block someday and check the date on it.................

Anyway I can almost hear Rumble snoozing in the background, so I'm outtahere, lol.

Happy HotRodding
 
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Rat Bastid

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This is a case where you SHOULD use a stroker. It’s idiotic to strangle an engine with shitty heads and then think you made more torque. You didn’t.
 

Brooks James

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I've got one of these hanging around too! Lol.

This is a case where you SHOULD use a stroker. It’s idiotic to strangle an engine with shitty heads and then think you made more torque. You didn’t.
This is for a specific application. Not everyone is looking for MAXIMUM hp and tq. Have you read Rusty Rat Rods "guide to hot rodding
bliss " ??
Obviously you are not speaking from personal experience, bigger is NOT always better
 
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Rat Bastid

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This is for a specific application. Have you read Rusty Rat Rods "guide to hot rodding bliss " ??
Obviously you are not speaking from personal experience, bigger is NOT always better


And you’d be WRONG. This is an example when adding stroke is a benefit. Choking an engine with shitty induction is mindless.

And THAT is from personal experience.

BTW, have you had one of your induction crippled engines on a dyno to measure torque output? I’m thinking you haven’t. Maybe you ought to invest in some dyno time and then get back to me.
 

Brooks James

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And you’d be WRONG. This is an example when adding stroke is a benefit. Choking an engine with shitty induction is mindless.



And THAT is from personal experience.

BTW, have you had one of your induction crippled engines on a dyno to measure torque output? I’m thinking you haven’t. Maybe you ought to invest in some dyno time and then get back to me.
 

Brooks James

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Hmmm... let's see, Decent stroker kit $2200, Machine work $1000 plus. If you're going that route it would be sacrilege to not have good heads, at least $1000. Decent intake and carb $700, etc
Because it's going to be a rering, valve job, hot tank job, minimal machining, and he already has the motor, it will cost about a $1000. It sounds like you have fat cash to spend, believe me , not everyone does
 

Bewy

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Isky Super cam as per earlier post.
The tight LSA & short duration will give it tq.
I think it would be idiotic to use that big of a cam that it needs a stall c'ter with a truck that pulls a loaded trailer. All you would do is convert tq to useless heat.
 

Brooks James

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Isky Super cam as per earlier post.
The tight LSA & short duration will give it tq.
I think it would be idiotic to use that big of a cam that it needs a stall c'ter with a truck that pulls a loaded trailer. All you would do is convert tq to useless heat.
Agreed, this is a work truck
 

Rat Bastid

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Hmmm... let's see, Decent stroker kit $2200, Machine work $1000 plus. If you're going that route it would be sacrilege to not have good heads, at least $1000. Decent intake and carb $700, etc
Because it's going to be a rering, valve job, hot tank job, minimal machining, and he already has the motor, it will cost about a $1000. It sounds like you have fat cash to spend, believe me , not everyone does


No, I don’t do back yard shade tree stuff.

My point still stands. Using some undersized, under valved heads makes no sense. It looks good on paper, sounds brilliant on the web.

Of course, that’s only if you’ve never done any testing using a dedicated tool other than your ***.
 

mgoblue9798

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A friend wants me to build a 360 La for his Ram truck. It is a work truck always loaded and pulling a loaded trailer. He is interested in as much torque as possible.
Years ago I put together a 350 SBC with the early small valve " power pack' (triangle on the front of the head) heads. With a small Sig Erson cam. It pulled very strongly but was all done at 5000 rpm.
I have a set of 67 273 heads and was thinking of putting them on the 360.
Cams have changed over years, what would you recommend for a cam ?
Mid 70's 360 la probably around 8:1 compression
Stock tranny and converter
3.54 axle
About 28 tires
Stock single exhaust with catalytic conv
Thermoquad on factory iron intake


Just my two cents but the engine you want for your described application is a 5.9 magnum with an upgraded cam. Best bucks down approach.
 
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mgoblue9798

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This is a case where you SHOULD use a stroker. It’s idiotic to strangle an engine with shitty heads and then think you made more torque. You didn’t.

Chrysler did plenty of dyno testing on their engines. There was a reason they installed heads on 413 industrial engines with 1.88/1.50 valves. It all depends on the purpose for the engine.
 
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