ProComp/Speedmaster aluminum heads

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j par said:
You currently run them? Do you run them on a stroker? Do you just Street Drive? Automatic or 4-speed?
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I ran them till about a month or two ago when the heli coils for the rocker shafts pulled out the head and snapped the shaft and destroyed my valve covers, never using bolts on shafts again lol.
The cnc heads were on a 408 w 11.5:1 and a solid roller(257/[email protected] .640/.645 not taking lash into account.), 904 w 4500 converter. Best run @6800ft DA was 11.8@113 (6500rpm shifts) all steel car, just missing the back seat.
Replaced them with trickflows. Direct swap @ 7900ft DA shifting at 5800-6000(low) and soft launch was [email protected]

And I street drove them alot.

The other stroker has ootb speedmasters that aren't cncd. With a basic 9.9:1 and a lunati hyd roller .560/.565 lift voodoo. They have been on it for a couple years now. No problems with them, best run when the engine was in the dart was 12.44@107 on a 6000ft DA.
 
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You made a reference in picking the CNC SM heads over the 596 s and I guess what I was asking is what was your thoughts over the unported SM heads over the 596's?
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Obviously......only one way to know for sure.
And, it would depend on what they were tested on.
However, with reference to a 500+hp stroker........ intuitively I feel it would just be a typical “good/better/best” scenario........ with the major variable being exactly how good the ported 596’s are.

If it was a set of real “ported” 596’s, they could easily be better than the ootb unported SM heads....... in which case the “good” vs “better” test might not play out as hoped.
Though, that’s not a likely scenario for a targeted 500+hp build with typical “home ported” 596’s.

If I were building it, neither version of the SM heads would get used “ootb”, which would tip the scales more in their favor.
 
The cnc heads were on a 408 w 11.5:1 and a solid roller, 904 w 4500 converter. Best run @6800ft DA was 11.8@113 (6500rpm shifts) all steel car, just missing the back seat.
Replaced them with trickflows. Direct swap @ 7900ft DA shifting at 5800-6000(low) and soft launch was [email protected]
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Not accounting for the difference in DA, @34-3500lbs...... the 1.5mph improvement shows a 15hp gain.

I’ll be looking forward to seeing what it goes in better air, which an optimized shift point.
 
PRH said:
Not accounting for the difference in DA, @34-3500lbs...... the 1.5mph improvement shows a 15hp gain.

I’ll be looking forward to seeing what it goes in better air, which an optimized shift point.
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I'm not even sure what it wants to shift at.. it spins to the rev limiter (7200) so quick it's hard for me to feel a layover point. I obviously dont want to spin the sucker into Oblivion either.
 
Toluene56 said:
I'm not even sure what it wants to shift at.. it spins to the rev limiter (7200) so quick it's hard for me to feel a layover point. I obviously dont want to spin the sucker into Oblivion either.
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I doubt 7200 is the sweet spot............ I also don’t think it’s 6000.
My guess is, best ET will be somewhere in the 63-6500 range.

You just have to experiment and see what works best.
 
PRH said:
I doubt 7200 is the sweet spot............ I also don’t think it’s 6000.
My guess is, best ET will be somewhere in the 63-6500 range.

You just have to experiment and see what works best.
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I agree, thats why the limiter is at 7200, I just don't want it to rev to the moon.
 
MOPAROFFICIAL said:
Get into the .575 range.
Engle KV3 solid
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The cam was ground from its original 464 purple performance cam to a Oregon cam grinding solid lifter number 175 cam. Which is a 107 lobe separation 259 267 @50 with a 546 566 lift with 1.5:1 rockers. The next year after the motor was built I took the heads off and took out the 1.88's and put in 2.02's and Hughes 1.6:1 roller rockers and that yielded a 586 - 603 lift...
Likely too much lift for my head which probably would work a lot better with the SM's but..
I definitely don't want to go back to that cam it did not idle.. it ran as wicked as it sounded, but it idled like crap.. which also sounded real cool but....
 
If I try the SM's I would definitely like to leave my cam as it is and see if I get any change. It would give me good knowledge on how the 596's were holding up to the task...
 
j par said:
If I try the SM's I would definitely like to leave my cam as it is and see if I get any change. It would give me good knowledge on how the 596's were holding up to the task...
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Not necessarily.
It might just show you that with a small cam, better heads don’t do all that much for you.

From the “everyone’s an expert file”, IMO that 10deg split of your current cam isn’t helping you any.
 
PRH said:
Not necessarily.
It might just show you that with a small cam, better heads don’t do all that much for you.

From the “everyone’s an expert file”, IMO that 10deg split of your current cam isn’t helping you any.
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I'd love to know why you think that, but maybe on my massive reconfiguration thread would be a better place then mucking this thread up with a cam suggestion possible rabbit hole LOL...
 
j par said:
I'd love to know why you think that, but maybe on my massive reconfiguration thread would be a better place then mucking this thread up with a cam suggestion possible rabbit hole LOL...
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I think you should give Mr Porter a call, he has been known to map grinds for a given combo and they do work.
 
j par said:
I'll try to chat him up when and if a cam change comes....
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While I don’t feel your current cam is as good as can be had for your goals, it wouldn’t be way up on the list of things that needed changing either(a pair of matching carbs would be higher on my list).

As for the 10deg split.......
Ask yourself what part of the engines power band would you like to improve the most....... and how does that 10 extra degrees of exhaust duration fit in with that goal?

Where you want to make more power, and where I might want to make more power....... may not be on the same page.
In either case, that extra ex duration isn’t having much affect on the output one way or the other.
It’s a minor tweak.
 
PRH said:
While I don’t feel your current cam is as good as can be had for your goals, it wouldn’t be way up on the list of things that needed changing either(a pair of matching carbs would be higher on my list).

As for the 10deg split.......
Ask yourself what part of the engines power band would you like to improve the most....... and how does that 10 extra degrees of exhaust duration fit in with that goal?

Where you want to make more power, and where I might want to make more power....... may not be on the same page.
In either case, that extra ex duration isn’t having much affect on the output one way or the other.
It’s a minor tweak.
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For discussion and learning purposes in your opinion where would you or would you not under what applications would you like or not like the extra 10 degrees of exhaust?
 
I do remember by leaving the center line the same or however we were talking about manipulating the cam to help bleed a little compression to be able to run straight pump gas switch never happened or did happen but I was having issues with it turning off...
 
For discussion and learning purposes in your opinion where would you or would you not under what applications would you like or not like the extra 10 degrees of exhaust?
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It’s truly an “it depends” situation........ with a virtually endless set of variables.
Way too many to get into here.

I can’t really think of an application as mild as yours where I’d lean towards a big split though.
Unless it was an off the shelf cam that someone happened to like, and that’s just how it came.

I’m sure the place that ground it for you had a reason they did it that way.
Get their take on it.

This had some interesting stuff in it:
Mopar Performance Purple Shaft Camshaft - Mopar Muscle Magazine
 
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75 Duster with the bare CNC Speedmaster heads. Moved it into the bay to put roll bar in it....and hopefully put it on a diet.
 
Well it looks like a waiting game...
Come on black Friday!!
That sale a few years ago, CNC'ed heads, rockers, airgap intake, and some massive Holley style carb for like $1400..
 
j par said:
Well it looks like a waiting game...
Come on black Friday!!
That sale a few years ago, CNC'ed heads, rockers, airgap intake, and some massive Holley style carb for like $1400..
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Guy tells how he sold all the extra stuff and I think his old heads and ends up $250 in to new CNC'ed heads.
 
I was just future trippin on trying to swap heads while the motor is still in the car??
I'm not sure even if I loosen the headers at the exhaust as well? Maybe have to lift the motor a little?
I might be waiting to pull the headers out for some paint touch-up anyways...
 
j par said:
I was just future trippin on trying to swap heads while the motor is still in the car??
I'm not sure even if I loosen the headers at the exhaust as well? Maybe have to lift the motor a little?
I might be waiting to pull the headers out for some paint touch-up anyways...
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I've swapped heads many times with the engine in the car and the cheap headers. Really it's not too bad.... but if you want to touch up, that's a different story
 
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