When does custom porting become beneficial?

[Tartilla]

Carnut1 has a great write up on his 093 head porting. He really got it to the next level, and got them flowing as good as a Vortec if I remember correctly. 2.02/1.6 valves.

Speaking to 3rd gen mods...I once saw an IROC at the 1/4 mile track in the pits...with all the TPI flow aftermarket stuff...

I asked him if he removed the acoustic baffles in his air cleaner system that are restrictive....pulled the box open...and there they were...

[rfoll]

You mentioned Dart 165 heads and i thought I would share some experience. With just a little pocket porting they seem to flow quite well. On a 412 inch sbc we have power over 5500 rpm. I am including a link to the original post so you can read about the suggestions. They aren't cheap, but for the money you get a modern port and chamber. viewtopic.php?t=66666&hilit=dart

[RobZ28]

You mentioned Dart 165 heads and i thought I would share some experience. With just a little pocket porting they seem to flow quite well. On a 412 inch sbc we have power over 5500 rpm. I am including a link to the original post so you can read about the suggestions. They aren't cheap, but for the money you get a modern port and chamber. viewtopic.php?t=66666&hilit=dart

I have read that thread and I agree, they are excellent heads for many different engine needs. There is one thing about those heads I do not like, and its the water jackets in the heads arent very big. This can be a good thing to a porter who wants more area to create volume or a specific shape, but it most certainly is a bad thing to someone with a street car in hot climates that wants the best cooling you can get to prevent detonation with an iron head. Regardless, I am pretty sure I will just have to mitigate that with some porting in the water jackets for more flow and a cooling system that works better. In this video he explains how you can help the problem.

Check out this video and you can see how limited the water jackets in that head actually are compared to a vortec.

[steve cowan]

I ran those heads in different configurations for a number of years from 10.6.1 - 11.65.1 compression in my 3620 pound streeter.
A few years ago on my dart 383 block those heads made 522 ftlbs @ 5300rpm and 570hp @ 6600rpm.
Average CSA was 2.15" still with 1.94" - 1.5" valves.
Ported strip dominator intake, 240 deg comp roller.
At the track I ran MS109,with a bigger cam it would of run pumpgas no problem I believe.
Drove that car alot including towing a box trailer to and from the track,never showed any signs of heat distress and it gets pretty warm where I live in summer.
That engine combination ran a best of 10 56 @ 126 mph
@ 3620 pounds.

[RCJ]

Brezezinski is known for cheater iron oval track heads. Oval track cars see Temps that street won't be expected to see. For the guides to fall out I would expect the car to be raced at over 250 . We never had our dart heads run any hotter than any other head.

[BLSTIC]

I have read that thread and I agree, they are excellent heads for many different engine needs. There is one thing about those heads I do not like, and its the water jackets in the heads arent very big. This can be a good thing to a porter who wants more area to create volume or a specific shape, but it most certainly is a bad thing to someone with a street car in hot climates that wants the best cooling you can get to prevent detonation with an iron head. Regardless, I am pretty sure I will just have to mitigate that with some porting in the water jackets for more flow and a cooling system that works better. In this video he explains how you can help the problem.

What's the cooling system like on your car? There's a lot to be said for the late model style high mounted header tanks that are plumbed to effectively eliminate bubbles and air locks. The one in my Aussie Falcon was particularly effective.

I see some people complaining about overheating with big engines in cars from the 60s/70s and blaming the engine when they don't even have a recovery cap, let alone a fan shroud or good airflow through the core.

[RobZ28]

I ran those heads in different configurations for a number of years from 10.6.1 - 11.65.1 compression in my 3620 pound streeter.
A few years ago on my dart 383 block those heads made 522 ftlbs @ 5300rpm and 570hp @ 6600rpm.
Average CSA was 2.15" still with 1.94" - 1.5" valves.
Ported strip dominator intake, 240 deg comp roller.
At the track I ran MS109,with a bigger cam it would of run pumpgas no problem I believe.
Drove that car alot including towing a box trailer to and from the track,never showed any signs of heat distress and it gets pretty warm where I live in summer.
That engine combination ran a best of 10 56 @ 126 mph
@ 3620 pounds.

Steve Cowan, that’s great to hear as I ordered a set today. Average CSA is going to be right at 2.08, but we may go bigger depending on what Extrude Hone tells me. The smallest part of the intake tract is the runners at 1.63” round. With the porting they do, they can use a light media and possibly trim that out to 1.66-1.68. The runners are only .060” so we’re still a bit unsure if this would be wise. They’re supposed to check with tech and call me back. The 165’s have an average CSA of 2.11 stock. So I need some help in the runners. If they can trim them out some to a 1.68, I believe that gives me a CSA of 2.21 and gives Charlie some breathing room.


I guess now is the time I mention Charlie is porting the heads, base and plenum. Cam will be chosen after all the porting is done.
I would like a slight taper in even if it still less than a degree from start to finish but it’s going to be tough. I just don’t want the airspeeds acting like they’re in a school zone mid manifold port.

The engine will be ran and tuned at CenTex Dyno after reseal and reassembly. I have no idea what it’ll make. As long as it’s fun, reliable and drives pretty good… I’ll be happy.

[RobZ28]

I have read that thread and I agree, they are excellent heads for many different engine needs. There is one thing about those heads I do not like, and its the water jackets in the heads arent very big. This can be a good thing to a porter who wants more area to create volume or a specific shape, but it most certainly is a bad thing to someone with a street car in hot climates that wants the best cooling you can get to prevent detonation with an iron head. Regardless, I am pretty sure I will just have to mitigate that with some porting in the water jackets for more flow and a cooling system that works better. In this video he explains how you can help the problem.

What's the cooling system like on your car? There's a lot to be said for the late model style high mounted header tanks that are plumbed to effectively eliminate bubbles and air locks. The one in my Aussie Falcon was particularly effective.

I see some people complaining about overheating with big engines in cars from the 60s/70s and blaming the engine when they don't even have a recovery cap, let alone a fan shroud or good airflow through the core.

Cooling system is bone stock 1987 IROC. Probably full of rust from sitting 40 years and never being driven. It’ll be inspected and checked over when I pull it apart.

[steve cowan]

I ran those heads in different configurations for a number of years from 10.6.1 - 11.65.1 compression in my 3620 pound streeter.
A few years ago on my dart 383 block those heads made 522 ftlbs @ 5300rpm and 570hp @ 6600rpm.
Average CSA was 2.15" still with 1.94" - 1.5" valves.
Ported strip dominator intake, 240 deg comp roller.
At the track I ran MS109,with a bigger cam it would of run pumpgas no problem I believe.
Drove that car alot including towing a box trailer to and from the track,never showed any signs of heat distress and it gets pretty warm where I live in summer.
That engine combination ran a best of 10 56 @ 126 mph
@ 3620 pounds.

Steve Cowan, that’s great to hear as I ordered a set today. Average CSA is going to be right at 2.08, but we may go bigger depending on what Extrude Hone tells me. The smallest part of the intake tract is the runners at 1.63” round. With the porting they do, they can use a light media and possibly trim that out to 1.66-1.68. The runners are only .060” so we’re still a bit unsure if this would be wise. They’re supposed to check with tech and call me back. The 165’s have an average CSA of 2.11 stock. So I need some help in the runners. If they can trim them out some to a 1.68, I believe that gives me a CSA of 2.21 and gives Charlie some breathing room.


I guess now is the time I mention Charlie is porting the heads, base and plenum. Cam will be chosen after all the porting is done.
I would like a slight taper in even if it still less than a degree from start to finish but it’s going to be tough. I just don’t want the airspeeds acting like they’re in a school zone mid manifold port.

The engine will be ran and tuned at CenTex Dyno after reseal and reassembly. I have no idea what it’ll make. As long as it’s fun, reliable and drives pretty good… I’ll be happy.

Early on with those heads -
383
10.6 comp
Heads were 173cc
Stck Vic Jr
Comp oval SFT
235 - 242 @ 0.050 "
500" lift
106 ICL - 106 LSA
1.6 - 1.5 rockers.
Car ran 11.70 @ 114 mph @ 3620 lbs.
Slide rule says 430 - 440 hp.
6000rpm shift points 6300rpm through the lights.
The biggest you will get at the pushrod pinch is around 1.90" - 1.95" max before you blow through.
With a 89% throat you will be 2.25" aprox with stem factored.
Try to keep CSA as consistent as possible, SSR is tall and can be shaped well,don't lay it down to nothing just to chase cfm.
When the 383 made 570 hp the heads flowed 252cfm with manifold bolted up @ 0.700 " lift @ 28" depression.
At 45 " depression the intake tract flowed 305cfm @ 0.700 ".
That's enough cfm to feed a 383 sbc at 6500rpm at max piston speed.

[RobZ28]

Any idea what these things flow stock? Dart has 2 numbers. Catalog says 238cfm, tech sheet says 210. Just curious if anyone has ever flowed a set.

[steve cowan]

Any idea what these things flow stock? Dart has 2 numbers. Catalog says 238cfm, tech sheet says 210. Just curious if anyone has ever flowed a set.

I went back through my notes
Intake 210cfm - 0.500" lift @ 28"
Exhaust 138cfm - 0.500" lift @ 28"
They are typical sbc ports that both go turbulent above 450 " - 500" lift.most of issue is the SSR is to abrupt.

[RobZ28]

Any idea what these things flow stock? Dart has 2 numbers. Catalog says 238cfm, tech sheet says 210. Just curious if anyone has ever flowed a set.

I went back through my notes
Intake 210cfm - 0.500" lift @ 28"
Exhaust 138cfm - 0.500" lift @ 28"
They are typical sbc ports that both go turbulent above 450 " - 500" lift.most of issue is the SSR is to abrupt.

Steve, for a limited RPM deal thatll lilkely peak in the 5000-5500rpm range, what do you think the PRP should be? I know were speculating a lot at this point, but for a head thatll probably flow 260cfm@300fps@.500" and peak at 5600rpm (hopefully) or more... I am curious to know what percentage the PRP should be. Ive heard up to 90% of the average port CSA.

Is it safe to assume the PRP sets up the SSR for the some of the airspeed it sees down the throat?

[steve cowan]

Any idea what these things flow stock? Dart has 2 numbers. Catalog says 238cfm, tech sheet says 210. Just curious if anyone has ever flowed a set.

I went back through my notes
Intake 210cfm - 0.500" lift @ 28"
Exhaust 138cfm - 0.500" lift @ 28"
They are typical sbc ports that both go turbulent above 450 " - 500" lift.most of issue is the SSR is to abrupt.

Steve, for a limited RPM deal thatll lilkely peak in the 5000-5500rpm range, what do you think the PRP should be? I know were speculating a lot at this point, but for a head thatll probably flow 260cfm@300fps@.500" and peak at 5600rpm (hopefully) or more... I am curious to know what percentage the PRP should be. Ive heard up to 90% of the average port CSA.

Is it safe to assume the PRP sets up the SSR for the some of the airspeed it sees down the throat?

Are your heads 1.94" intake or 2.02"??
I calculated for a 350 sbc @ 6000rpm minimum CSA will be 1.75" and that's the radius of the corners factored in.
If it's a 1.94" intake valve you won't get it to flow 260cfm @ 0.500" and that small of a port you won't slow the average velocity down to 300ft/ sec without making it big.
If I was doing those heads this is what I would do.
Proper valve job,change top cut to 40deg even if you are using a 45 deg seat.
Blend the valve job into the chamber and don't go de- shrouding chamber to much.
Open pinch to max 1.90" approx.
Set bowl to 95 - 100 % valve diameter.
Take height of SSR down to around 1.020" off deck at the apex and shape .
I have had airspeed on the floor at the base of SSR faster than 420 ft/ sec and run fine at 6000rpm.
Don't make exhaust port huge,it responds very well to shaping venturi, don't blow throat out either,intake will be 89% already I assume, exhaust around 86%.
If you are using stud mount rockers you might have to machine screw in stud pads down 0 0.050 " or so as I had clearance issues with rockers on the stud.

[RobZ28]

I went back through my notes
Intake 210cfm - 0.500" lift @ 28"
Exhaust 138cfm - 0.500" lift @ 28"
They are typical sbc ports that both go turbulent above 450 " - 500" lift.most of issue is the SSR is to abrupt.

Steve, for a limited RPM deal thatll lilkely peak in the 5000-5500rpm range, what do you think the PRP should be? I know were speculating a lot at this point, but for a head thatll probably flow 260cfm@300fps@.500" and peak at 5600rpm (hopefully) or more... I am curious to know what percentage the PRP should be. Ive heard up to 90% of the average port CSA.

Is it safe to assume the PRP sets up the SSR for the some of the airspeed it sees down the throat?

Are your heads 1.94" intake or 2.02"??
I calculated for a 350 sbc @ 6000rpm minimum CSA will be 1.75" and that's the radius of the corners factored in.
If it's a 1.94" intake valve you won't get it to flow 260cfm @ 0.500" and that small of a port you won't slow the average velocity down to 300ft/ sec without making it big.
If I was doing those heads this is what I would do.
Proper valve job,change top cut to 40deg even if you are using a 45 deg seat.
Blend the valve job into the chamber and don't go de- shrouding chamber to much.
Open pinch to max 1.90" approx.
Set bowl to 95 - 100 % valve diameter.
Take height of SSR down to around 1.020" off deck at the apex and shape .
I have had airspeed on the floor at the base of SSR faster than 420 ft/ sec and run fine at 6000rpm.
Don't make exhaust port huge,it responds very well to shaping venturi, don't blow throat out either,intake will be 89% already I assume, exhaust around 86%.
If you are using stud mount rockers you might have to machine screw in stud pads down 0 0.050 " or so as I had clearance issues with rockers on the stud.

Youre absolutely right about the airspeeds. The 300fps is the min. goal. Im sure they will be faster than that. They are .94's but were going to go 2.02/1.6's.

[gregsdart]

Several years ago i helped my son hop up his low compression 340 4 speed Duster. It had 3.21 gears, so we put headers on it, and i did some back yard butchery to the bowls in the heads, used an angle grinder and a drill press to back cut the valves, jetted the TQ, and it ran Much better with rhe 268h cam we put in. The cam is, as i recall, only .450 lift, so doing more rhan what we did to the heads wouldn't have helped much anyway.