[Johnny406]

Sorry, another SM head post.

I picked up a set of the Speedmasters during the Black Friday sale. I know they are going to need a little work like removing the tangs, upgrading the valve locks and perhaps a better valve job.

With that said and in my case, would these heads be an upgrade for me over my KRE 290cfm 74cc D-ports with no other changes (minus headers)?

Can I use my ARP D-port head studs with them?

[steve25]

Speed master only makes a round port version of a Pontiac head so you can't do a apples to apples comparison.

In short here's what will happen in my opinion.

The speedmasters start off as per there web site at a port volume of 230 CCs, your worked over KRE heads even at flowing 290 cfm are not at 230 CCs.

If both heads flowed close to the same amount of air at the same lift then the Speedmaster heads with there greater port volume will hold on to the peak HP number that they make longer before nosing over turn like the KRE heads will.

The question then becomes will this effect take place in too high and narrow of a rpm range to be of benefit to you motor combo as it is now.

I guess you will find out.

I don't know the Cam spec's your running, but here's another guess on my part.

I don't think you where running enough valve lift to even make the best usage of those KRE cnc D port heads in terms of what they flow.

[Stan Weiss]

Originally Posted by steve25

Speed master only makes a round port version of a Pontiac head so you can't do a apples to apples comparison.

In short here's what will happen in my opinion.

The speedmasters start off as per there web site at a port volume of 230 CCs, your worked over KRE heads even at flowing 290 cfm are not at 230 CCs.

If both heads flowed close to the same amount of air at the same lift then the Speedmaster heads with there greater port volume will hold on to the peak HP number that they make longer before nosing over turn like the KRE heads will.

The question then becomes will this effect take place in too high and narrow of a rpm range to be of benefit to you motor combo as it is now.

I guess you will find out.

I don't know the Cam spec's your running, but here's another guess on my part.

I don't think you where running enough valve lift to even make the best usage of those KRE cnc D port heads in terms of what they flow.

Steve,
The SD Performance web site lists the 290-295 heads @ 197 cc.

https://www.sdperformance.com/listPr...?categoryID=49

Stan

[mysticmissle]

2nd gen (2 lengths) Round port eheads head bolts and studs work w speed master. Do not know if k dports use same length studs as e round ports

[Johnny406]

Thanks gentlemen, here's the cam card of my current camshaft. I'm currently running .580/.584 lift with the VooDoo HFT and Rhoads V-Max lifters.

[Tim Corcoran]

So Johnny, what is your current HP, TQ, 1/4 mile ET/MPH? If you put the SM's on how will you judge the change?

[Johnny406]

Originally Posted by Tim Corcoran

So Johnny, what is your current HP, TQ, 1/4 mile ET/MPH? If you put the SM's on how will you judge the change?

Hi Tim, 11.63@116.68 my current best "on motor" run. My car is about 3200 race weight and I race in Pueblo Colorado at 4800 feet elevation.

This is my only timed 1/8th mile 125 shot nitrous run I have (right lane).

I would love to pick up .3 in the quarter on motor if I swap the heads.

[ponjohn]

No data, but I don't think you'll pick up. The SD KRE heads are very efficient. Many of those heads used in combos on this site that make nearly 600hp.

[Tim Corcoran]

I think it's a toss up if you would gain anything by putting the SM heads on. I think you would gain more with a cam change. I think this Ultradyne solid lifter flat tappet cam would wake up that motor some, Adv. 288/296 lift .612/.630, Dur. 255/263 @.050 and 108 LSA. Tim at Bullet Cams could grind one up for you. This is one of Harolds favorites I ran it in a 455 with mild 6X ported heads and it was a screamer. If you were going to run N20 with this cam you would want to have it ground on a 110 LSA. If you wanted to go with a hyd roller you might consider this Voodoo Hydraulic Roller, works with moderate nitrous and small superchargers. Very healthy idle quality. ;Advertised Duration (Int/Exh): 294/302 ;Duration @ .050 (Int/Exh): 243/251 ;Gross Valve Lift (Int/Exh): .560/.565 ;LSA/ICL: 110/106. You may want to run this cam with 1.65's. with the correct springs to go with it. Going with a hyd roller is costly though and you would want to run the Johnson lifters and they are over $800 bucks or run the Comp new Evolution lifters but I would not use any of the others.

[KGTO]

Originally Posted by Tim Corcoran

I think it's a toss up if you would gain anything by putting the SM heads on. I think you would gain more with a cam change. I think this Ultradyne solid lifter flat tappet cam would wake up that motor some, Adv. 288/296 lift .612/.630, Dur. 255/263 @.050 and 108 LSA. Tim at Bullet Cams could grind one up for you. This is one of Harolds favorites I ran it in a 455 with mild 6X ported heads and it was a screamer. If you were going to run N20 with this cam you would want to have it ground on a 110 LSA. If you wanted to go with a hyd roller you might consider this Voodoo Hydraulic Roller, works with moderate nitrous and small superchargers. Very healthy idle quality. ;Advertised Duration (Int/Exh): 294/302 ;Duration @ .050 (Int/Exh): 243/251 ;Gross Valve Lift (Int/Exh): .560/.565 ;LSA/ICL: 110/106. You may want to run this cam with 1.65's. with the correct springs to go with it. Going with a hyd roller is costly though and you would want to run the Johnson lifters and they are over $800 bucks or run the Comp new Evolution lifters but I would not use any of the others.

Not to disrupt the thread, but FWIW I still run that UD cam from back when Harold had the company. When we dynoed the combo and hit it with a 150 shot it worked surprisingly well. Really picked up and we were all surprised since the 108 LSA should not have worked so well. My point to the OP, if you were to choose that cam, as Tim says, it's a great one.

If you do swap heads let me know, I'm going to purchase a set of KRE D ports

[Johnny406]

Thanks everybody for your input, I really appreciate it.

Since the SM heads have the bigger runners, I will install those on the 463 with a solid roller Paul Kippens sold me sometime back. I have new Howards Cams 98541 springs and new Comp Cams retainers and locks to go with it.

The KRE D-ports along with the Dougs headers I'm running will go to the future 428 for my 81 T/A.

[Tim Corcoran]

Solid roller in a street car, hmmmmm

[ta man]

Run more valve lift...

[Steve C.]

I run the UltraDyne 288 solid roller lobe on the intake side, but with 292 on the exhaust side.
0.4176" lobe lift / 1.65 intake and 1.6 exhaust.
Set at .022" lash.
With a 110 LSA.

505 CID
Peak torque 4400 /4500 RPM average
627-630 ft.lbs. TQ
Average peak power at 5750 RPM (depending on the pull 5600-5800 RPM)
625-630 HP



.

[Biscayne]

Are the D ports forsale?

[Johnny406]

Originally Posted by Biscayne

Are the D ports forsale?

No, they will be going to the street car or a spare motor. THanks for asking.