cam selection advice

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lil red

lil red

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thinking about pulling the 360 out of the express truck and looking for advice or suggestions on a camshaft.
The engine now is :
original 79 360 block
cast flattop pistons, about .090 below deck (maybe 8.5 - 8.7 cr, i think the factory dished yielded about 8-1)
rhs indy heads with ss 1.92 intakes and 1.6 -1 adjustable rocker arms
ld 340 intake
750 street demon carb
mopar .450.455 268 272 duration camshaft
shorty headers from a mid 90s dodge ram magnum with 2.5 inch headpipes and 2.25 inch tailpipes out the stacks

Transmission is the original 727 loadflite with a factory equipped 2200 stall
3.55 gears with a 28 inch tire

The truck is primarily street driven and 6000 rpm would be about the most I turn it. The truck used to have an old set of j heads on it a few years ago, and it was a pretty fun combination that pulled strong to about 5300, but with the new heads the truck seems to want to pull above that rpm but seems limited by the camshaft. I maybe wrong ( hence the needed advice), but the mopar cams seem to work well with the older factory gear, but im wondering if the new heads should take advantage of the higher lifts and agressive profiles of modern grinds - hughes, lunati, comp, etc.
I had a post a while ago about a stroker, but in reality a nice 375 - 400 horse 360 would be good with the amount i use the thing. I came into posession of a set of speed pro h116cp pistons which should give about 10 - 1 compression with the 62cc head.

with the bump in compression should i move up a step in duration to a 274, A lot of guys on here run the comp xe274 which seems to a preferred line, but then again most have an abody instead of a 4500 lb truck.

just wondering what you all think,
 
also, i recall reading that the lunati voodoo grinds were designed harold brookshire from ultradyne, and the mopar cam profiles are ground to take advantage of the larger lifter dia, not a chevy grind..
 
The 340 268 is a lot smaller then an xe275hl its about on par with a xe250h cam.

If you go 10:1 you'll be stuck going with a large cam like xe285hl. Above xe262h you start moving the powerband away from idle-1500 rpm making gears and stall more mandatory.

Depends whats more important to you under 3000 rpm or above. Id care about under 3000rpm and go with xe268h at most or something similar.
 
273 said:
The 340 268 is a lot smaller then an xe275hl its about on par with a xe250h cam.

If you go 10:1 you'll be stuck going with a large cam like xe285hl. Above xe262h you start moving the powerband away from idle-1500 rpm making gears and stall more mandatory.

Depends whats more important to you under 3000 rpm or above. Id care about under 3000rpm and go with xe268h at most or something similar.
Click to expand...

Was considering the voodoo 268 276 ,with the 1.6 ratio , lift is .527 .547, rpm range from 1800 to 6200. Heads flow 238 at 550 lift
 
Just make sure your not over compressing your engine for that cam. It probably wants more like 9:1 with pump gas.
 
With those iron heads and a 68* ICA of 68* the compression wants to be 10.5 with an easily obtained tight-Q
At 8.0 it must be pretty soggy out of the gate
I would do a compression test to see where you are at.
 
Last edited:
AJ/FormS said:
With those iron heads and a 68* ICA of 68* the compression wants to be 10.5 with an easily obtained tight-Q
At 8.0 it must be pretty soggy out of the gate
I would do a compression test to see where you are at.
Click to expand...

actually it performs well for the combination but im just looking for a little more....would you suggest larger AJ..
 
We used a XE275HL with those exact pistons set at zero deck clearance in a 360 with Edelbrock ALUMINUM heads. No problems on the street with 91 octane pump unleaded. With your iron heads and quench, it's a gamble. Maybe look into having one ground on a 112LSA, unless you want more gear/converter and then you could go with the XE285HL. Make sure you have valve springs compatible with the rpm range and lift of these cams!
 
thanks fellas ..... still would like to add compression and camshaft to reach a 400 hp goal....possibly 284* with more stall, but would like to keep the 3.55s although i have considered an overdrive unit with 4.10s
 
lil red said:
thanks fellas ..... still would like to add compression and camshaft to reach a 400 hp goal....possibly 284* with more stall, but would like to keep the 3.55s although i have considered an overdrive unit with 4.10s
Click to expand...

I think with those 116 pistons installed at zero deck and a XE285HL, possibly ground on a 112LSA (Comp will do it pretty reasonable, via Summit Racing even, or direct), would not detonate with a reasonable timing curve and good cooling. I made 400hp back in the '90s easy-peasy with a MoPar .528" solid (MILD, pulled 15" vacuum) and KB107 pistons (practically the same as your SpeedPro's) with unported "J" heads. You have a flow advantage over my setup, if the intake/carb/headers are matched well. I had no quench (open chamber heads) and had no spark-knock issues with 91/92 octane unleaded pump fuel.
 
lil red said:
thinking about pulling the 360 out of the express truck and looking for advice or suggestions on a camshaft.
The engine now is :
original 79 360 block
cast flattop pistons, about .090 below deck (maybe 8.5 - 8.7 cr, i think the factory dished yielded about 8-1)
rhs indy heads with ss 1.92 intakes and 1.6 -1 adjustable rocker arms
ld 340 intake
750 street demon carb
mopar .450.455 268 272 duration camshaft
shorty headers from a mid 90s dodge ram magnum with 2.5 inch headpipes and 2.25 inch tailpipes out the stacks

Transmission is the original 727 loadflite with a factory equipped 2200 stall
3.55 gears with a 28 inch tire

The truck is primarily street driven and 6000 rpm would be about the most I turn it. The truck used to have an old set of j heads on it a few years ago, and it was a pretty fun combination that pulled strong to about 5300, but with the new heads the truck seems to want to pull above that rpm but seems limited by the camshaft. I maybe wrong ( hence the needed advice), but the mopar cams seem to work well with the older factory gear, but im wondering if the new heads should take advantage of the higher lifts and agressive profiles of modern grinds - hughes, lunati, comp, etc.
I had a post a while ago about a stroker, but in reality a nice 375 - 400 horse 360 would be good with the amount i use the thing. I came into posession of a set of speed pro h116cp pistons which should give about 10 - 1 compression with the 62cc head.

with the bump in compression should i move up a step in duration to a 274, A lot of guys on here run the comp xe274 which seems to a preferred line, but then again most have an abody instead of a 4500 lb truck.

just wondering what you all think,
Click to expand...

Have you actually weighed the truck, my 78 w-150, 4-speed, short box weighs 4400 on a certified scale with a full tank of gas, I would think a 2wd truck would be a couple of hundred lbs lighter.
 
sireland67 said:
Have you actually weighed the truck, my 78 w-150, 4-speed, short box weighs 4400 on a certified scale with a full tank of gas, I would think a 2wd truck would be a couple of hundred lbs lighter.
Click to expand...

eh...took a stab at it...you get the idea, it weighs more than a dart...
 
sireland67 said:
Have you actually weighed the truck, my 78 w-150, 4-speed, short box weighs 4400 on a certified scale with a full tank of gas, I would think a 2wd truck would be a couple of hundred lbs lighter.
Click to expand...

My '85 D-150 shortbed 318/A-833 O/D weighs a touch over 4000. Surprisingly, a standard cab '90 Dakota 4x4, 3.9L V-6 weighs more!
 

forphorty said:
IMO, iron heads+mild cam+10.5+pickup= detonation
Click to expand...

Yeah maybe
A 360 with an ICA of 68*, with a
A) Static compression ratio of 10.5
Effective stroke is 2.69 inches.
Your dynamic compression ratio is 8.14:1 .
Your dynamic cranking pressure is 163.52 PSI.
V/P (Volume to Pressure Index) is 133
But I'd set it up with the .028 gasket, and about .030 Q,
and if it rattles on pumpgas, the easy fix is just a gasket swap (.039), to drop the Scr to 10.2/ Q of .041, and
B) Static compression ratio of 10.2:1.
Effective stroke is 2.69 inches.
Your dynamic compression ratio is 7.91:1 .
Your dynamic cranking pressure is 157.55 PSI.
V/P (Volume to Pressure Index) is 128
And just a133/128=3.9% loss of VP or lower rpm performance...or
C) you could retard that cam 2* and get
Static compression ratio of 10.5:1.
Effective stroke is 2.64 inches.
Your dynamic compression ratio is 8.01:1 .
Your dynamic cranking pressure is 160.14 PSI.
V/P (Volume to Pressure Index) is 128
With just a loss of 133/128 =3.9%
Whichever is easier,lol.
But I said:
"With those iron heads and a 68* ICA of 68* the compression wants to be 10.5 with an easily obtained tight-Q"
I didn't say he should build it with 10.5, even tho I would.

To the OP
I like to live on the edge, and find out what works or doesn't. So if I have to take the pistons out, and machine a couple of CCs into 'em, then that's what I would do.
I find great satisfaction when the engine comes alive with decent compression. And I am done with low Dynamic compression engines.
I put aluminum heads on my engine Specifically so I could run 11.3 Scr.. Power due to better flow was secondary. I ran a tic over 200psi on my gauge, with that combo, and had incredible low-rpm performance. Mr Wallace says 192psi@169VP. Unfortunately the .028 gasket wasn't up to it, so I regrouped at 10.9 with the FelPro .039. And yes, I milled the block to pop the pistons up to maintain the Q.
I know what you're thinking; "what a crapload of work for maybe 6%".
Well;
That 6% represents about 1 cam size bigger on the top, and one cam size smaller on the bottom. So I run a 230* cam and get 235* performance up top, and 225* torque on the bottom.
For a couple of hours work, and the milling.
And now you know me.

But AJ you say, how can this be?
Well give Mr Wallace a workout
Using 11.3 for aluminum heads, and 9.5 for CI, and run a 270 cam thru the mill with a 59* ICA, and see what you come up with; just for low-rpm performance...... which is about 99% of where a streeter lives.
I mean think about it; you'll drive around at under 4000 rpm for 20 minutes, and maybe get one or two opportunities to run the tack up for a total of 10 seconds. That's a ratio of 1200/10= or less than 1% of the time.
BTW,
I run 87E10 in my engine, at a cost savings of over 20 cents per liter, or about $0.91Can per gallon Imp
I drove about 8000 miles that first year, and about the same for 5 years running.
Annually,I probably averaged guessing 18 mpg Imp or consumed 445 gallons Imp. So I saved about $405 annually. In 5 years I saved over $2000
In about 3 years I broke even on the outright purchase of the heads. Over a valve job on my 202 heads, I would have broke even in maybe 2.2 years. Over ported Xs to make similar power, I imagine I broke even in the first year.
On the street; absolute power is more bragging rights, cuz about 99% of the time you won't be using 100% of it, and probably 80% of the time you will be using less than 25% of it. These are the times that a high Dynamic C/R is paying off BigTime, in low-rpm Torque production.
Because Why? Because you are running around, letting the pressure do the work, and saving gas all the time, and probably a lot of wear and tear on the engine as well.
Think about it;
If you run just 5% less pressure than what might be optimum, Then you are gonna have to be running deeper into the carb 100% of the time, to make up for that ~8psi loss in cranking cylinder pressure. And that is costing you fuel,all the time.That 8psi cranking pressure could be up to, maybe 40psi in running cylinder pressure, and typically maybe half that.
Why do you think some older non-EFI cars got such atrocious fuel mileage while others were so much better. Look at their cylinder pressures.
They say it was the pollution controls. What it really was, was greed on the part of the oil-barons. They figured out how to sell us 20 or 30% more of their watered down fuel, and told it us it was to save the environment. So they cranked the pressures way down, and the world was a better place.
LOL
Now the pressures are back up..... but the engines are waaaay smaller.
They always give us less and charge us more....... :(
 
Last edited:
AJ/FormS said:
Yeah maybe
A 360 with an ICA of 68*, with a
A) Static compression ratio of 10.5
Effective stroke is 2.69 inches.
Your dynamic compression ratio is 8.14:1 .
Your dynamic cranking pressure is 163.52 PSI.
V/P (Volume to Pressure Index) is 133
But I'd set it up with the .028 gasket, and about .030 Q,
and if it rattles on pumpgas, the easy fix is just a gasket swap (.039), to drop the Scr to 10.2/ Q of .041, and
B) Static compression ratio of 10.2:1.
Effective stroke is 2.69 inches.
Your dynamic compression ratio is 7.91:1 .
Your dynamic cranking pressure is 157.55 PSI.
V/P (Volume to Pressure Index) is 128
And just a133/128=3.9% loss of VP or lower rpm performance...or
C) you could retard that cam 2* and get
Static compression ratio of 10.5:1.
Effective stroke is 2.64 inches.
Your dynamic compression ratio is 8.01:1 .
Your dynamic cranking pressure is 160.14 PSI.
V/P (Volume to Pressure Index) is 128
With just a loss of 133/128 =3.9%
Whichever is easier,lol.
But I said:
"With those iron heads and a 68* ICA of 68* the compression wants to be 10.5 with an easily obtained tight-Q"
I didn't say he should build it with 10.5, even tho I would.

To the OP
I like to live on the edge, and find out what works or doesn't. So if I have to take the pistons out, and machine a couple of CCs into 'em, then that's what I would do.
I find great satisfaction when the engine comes alive with decent compression. And I am done with low Dynamic compression engines.
I put aluminum heads on my engine Specifically so I could run 11.3 Scr.. Power due to better flow was secondary. I ran a tic over 200psi on my gauge, with that combo, and had incredible low-rpm performance. Mr Wallace says 192psi@169VP. Unfortunately the .028 gasket wasn't up to it, so I regrouped at 10.9 with the FelPro .039. And yes, I milled the block to pop the pistons up to maintain the Q.
I know what you're thinking; "what a crapload of work for maybe 6%".
Well;
That 6% represents about 1 cam size bigger on the top, and one cam size smaller on the bottom. So I run a 230* cam and get 235* performance up top, and 225* torque on the bottom.
For a couple of hours work, and the milling.
And now you know me.

But AJ you say, how can this be?
Well give Mr Wallace a workout
Using 11.3 for aluminum heads, and 9.5 for CI, and run a 270 cam thru the mill with a 59* ICA, and see what you come up with; just for low-rpm performance...... which is about 99% of where a streeter lives.
I mean think about it; you'll drive around at under 4000 rpm for 20 minutes, and maybe get one or two opportunities to run the tack up for a total of 10 seconds. That's a ratio of 1200/10= or less than 1% of the time.
BTW,
I run 87E10 in my engine, at a cost savings of over 20 cents per liter, or about $0.91Can per gallon Imp
I drove about 8000 miles that first year, and about the same for 5 years running.
Annually,I probably averaged guessing 18 mpg Imp or consumed 445 gallons Imp. So I saved about $405 annually. In 5 years I saved over $2000
In about 3 years I broke even on the outright purchase of the heads. Over a valve job on my 202 heads, I would have broke even in maybe 2.2 years. Over ported Xs to make similar power, I imagine I broke even in the first year.
On the street; absolute power is more bragging rights, cuz about 99% of the time you won't be using 100% of it, and probably 80% of the time you will be using less than 25% of it. These are the times that a high Dynamic C/R is paying off BigTime, in low-rpm Torque production.
Because Why? Because you are running around, letting the pressure do the work, and saving gas all the time, and probably a lot of wear and tear on the engine as well.
Think about it;
If you run just 5% less pressure than what might be optimum, Then you are gonna have to be running deeper into the carb 100% of the time, to make up for that ~8psi loss in cranking cylinder pressure. And that is costing you fuel,all the time.That 8psi cranking pressure could be up to, maybe 40psi in running cylinder pressure, and typically maybe half that.
Why do you think some older non-EFI cars got such atrocious fuel mileage while others were so much better. Look at their cylinder pressures.
They say it was the pollution controls. What it really was, was greed on the part of the oil-barons. They figured out how to sell us 20 or 30% more of their watered down fuel, and told it us it was to save the environment. So they cranked the pressures way down, and the world was a better place.
LOL
Now the pressures are back up..... but the engines are waaaay smaller.
They always give us less and charge us more....... :(
Click to expand...

I totally agree with but 99% of the people aren't gonna play with different CR, cams, gearing, tunes etc.. to come up with a perfect combo. Thats why I feel most shouldn't push the limits on Cr, my engine runs strong on 9:1 sure I could go 10:1 but everything got be spot on all the time. And for most can turn their car into a hassle they don't want to drive.
 
thanks aj, love your explanations.. (I usually mix a double rum and coke to sip, cuz it takes me an hour to comprehend it)
but seriously, thanks everyone, alot of decisions to make..as usual.
 
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