Older Sonny's Dart 320 head program.

[rapidride2]

Its been decades..

Anyone know someone who has an awesome program or hand porting results on these heads?

I have a set of good condition late 90s, Sonny's Dart 320 "supermod" heads. Not fully ported... i believe just "heart shape" chamber work. Plus I had Ron's porting open them up for a 4.500 bore many years ago. They've got a 2.25x1.88 valve.

I know there is better heads out now but wanting to possibly bring these back to life...they are in good condition. Maybe 2.300 valve and full port to get the most out of them.

Trying to weigh out the costs vs newer heads...
Gonna be on a 540+ci, mostly drag car for now.

Thanks

[Alaskaracer]

You might hear different things, but with the availability of GOOD heads these days, you'd be money ahead just buying a new set. You'll likely spend less than having those ported and end up with a better part. Case in point: My buddy runs an alky funny car. He was running OLD dart 360 heads and swore up and down that he didn't need anything better....He wanted to upgrade and spent just under 5k getting them "updated and ported" for his stuff... He picked up ZERO mph and et.....Fast forward a couple of years, I talked him into finally getting a new set. He settled in on a pair of AFR 385 Magnums....Picked up right at .5 seconds in et and 10 MPH in the quarter......rest of the combo was the same, except that the AFR heads had bigger chambers and lowered his static compression by about a half point. He also noticed boost change. With old heads, at same drive ratio, he was making about 32lbs.....with new heads he was only making about 25lbs.....again, same drive ratio.....

[swampbuggy]

Hello Rapidride2, of all the parts that makeup the Engine, the Cylinder Heads or i should say ( The architecture / Design ) of them has More effect on Horsepower production than anything else, at least in a Naturally Aspirated Engine. In the last 25-30 years Cylinder Heads have improved a bunch. So the question is how much power does anybody want to make. Power cost money, and more power cost " More " money . Mark H.

[fordified]

Scratch my original post.

I just looked online and those heads don't flow very much air.

Sell them and buy something better.

[rapidride2]

Colorado, I understand his engine picked up a TON. Could it be he may have had a mismatched camshaft for the older 360 heads? .5 seconds is HUGE in my opinion. Maybe the blower and ALKY really liked the larger runner?

[rapidride2]

Well. That huge 1.880 valve isn't doing you any favors. PM Darin Morgan or Chad Speier.

I think I'd rather have the larger intake versus exhaust. I have no problem with a 1.900. If it would fit with a 2.300 intake.

[fordified]

Well. That huge 1.880 valve isn't doing you any favors. PM Darin Morgan or Chad Speier.

I think I'd rather have the larger intake versus exhaust. I have no problem with a 1.900. If it would fit with a 2.300 intake.

That's what I'm saying. That 1.880 is too big. Going down to 1.800 or smaller would be to your advantage.

Also, putting in a bigger intake valve isn't always the answer. With a 4.500 bore, the valve is 50% of the bore diameter. You could go larger for sure, but if those heads flow less than 400 cfm with 2.250 valve, then you're wasting your money going larger. The valve isn't your restriction. Many small block heads flow well over 400 CFM with a 2.150 valve. It's the port architecture and chamber shape that matters.

[fordified]

I'll give you an example. With a 2.250 valve at 110% efficiency per valve area, that valve will support 437 CFM. At 115% efficiency, which would be attainable with an excellent casting, the valve will support 457 CFM. It ain't the valve that's getting in the way.

Something else, if you want to build a 540 and have it make peak HP at 6200 rpm, the heads need to flow at least 410 CFM at the valve lift where max piston speed occurs (76ish crank degrees after TDC) to make good power. That's assuming you have a really good intake manifold.

Now, if you drop peak down to 5500 rpm, then you only need 363 cfm, which those heads should support.

[rapidride2]

Well. That huge 1.880 valve isn't doing you any favors. PM Darin Morgan or Chad Speier.

I think I'd rather have the larger intake versus exhaust. I have no problem with a 1.900. If it would fit with a 2.300 intake.

That's what I'm saying. That 1.880 is too big. Going down to 1.800 or smaller would be to your advantage.

Also, putting in a bigger intake valve isn't always the answer. With a 4.500 bore, the valve is 50% of the bore diameter. You could go larger for sure, but if those heads flow less than 400 cfm with 2.250 valve, then you're wasting your money going larger. The valve isn't your restriction. Many small block heads flow well over 400 CFM with a 2.150 valve. It's the port architecture and chamber shape that matters.

Ive never flowed the heads on a local bench. Sonny's flowed them at 370cfm at .800 or so bitd. I think 290 on exhaust. These numbers could be inflated for sure.
I have seen positive results of intake valve sizing over 50% may not be the rule but I believe Cboggs has proven this in some bbc conventional heads.

May be up for a new set of conventional bbc heads for a 540 to 555 ci... not sure what the hot head is these days...?

[fordified]

I think I'd rather have the larger intake versus exhaust. I have no problem with a 1.900. If it would fit with a 2.300 intake.

That's what I'm saying. That 1.880 is too big. Going down to 1.800 or smaller would be to your advantage.

Also, putting in a bigger intake valve isn't always the answer. With a 4.500 bore, the valve is 50% of the bore diameter. You could go larger for sure, but if those heads flow less than 400 cfm with 2.250 valve, then you're wasting your money going larger. The valve isn't your restriction. Many small block heads flow well over 400 CFM with a 2.150 valve. It's the port architecture and chamber shape that matters.

Ive never flowed the heads on a local bench. Sonny's flowed them at 370cfm at .800 or so bitd. I think 290 on exhaust. These numbers could be inflated for sure.
I have seen positive results of intake valve sizing over 50% may not be the rule but I believe Cboggs has proven this in some bbc conventional heads.

May be up for a new set of conventional bbc heads for a 540 to 555 ci... not sure what the hot head is these days...?

PM Darin or Chad. They can tune those heads up and give you some direction about the engine. They should be fine for a bracket engine.

[Alaskaracer]

Colorado, I understand his engine picked up a TON. Could it be he may have had a mismatched camshaft for the older 360 heads? .5 seconds is HUGE in my opinion. Maybe the blower and ALKY really liked the larger runner?

No, he runs a custom grind and it was ground for the older heads. Still running same grind with new heads....a new cam would net more gains as well....and yes, the larger running helped it breathe....

[rapidride2]

Colorado, I understand his engine picked up a TON. Could it be he may have had a mismatched camshaft for the older 360 heads? .5 seconds is HUGE in my opinion. Maybe the blower and ALKY really liked the larger runner?

No, he runs a custom grind and it was ground for the older heads. Still running same grind with new heads....a new cam would net more gains as well....and yes, the larger running helped it breathe....

Man, that's HUGE gains.

[fordified]

Colorado, I understand his engine picked up a TON. Could it be he may have had a mismatched camshaft for the older 360 heads? .5 seconds is HUGE in my opinion. Maybe the blower and ALKY really liked the larger runner?

No, he runs a custom grind and it was ground for the older heads. Still running same grind with new heads....a new cam would net more gains as well....and yes, the larger running helped it breathe....

Man, that's HUGE gains.

The gains come from better port architecture and casting thickness. CFM is one thing. CFM with the correct port velocity is another.

Creating a better head comes in large part from improvements in port architecture, whether intrinsic to the casting or the availability of adequate wall thickness to port them that way, including having the right cross sectional areas and at least 1/2" corner radii from flange to bowl. Chamber design is also huge, not only from the standpoint of burn but pressure recovery when the valve comes off the seat and air/fuel enters the cylinder.

Newer heads usually have better ports and chambers as cast, and more material on the deck and in the ports and bowls.

[mt-engines]

Colorado, I understand his engine picked up a TON. Could it be he may have had a mismatched camshaft for the older 360 heads? .5 seconds is HUGE in my opinion. Maybe the blower and ALKY really liked the larger runner?

If it ran 15s, .5s quicker isn't much power.

But a 7 second car gaining .5 is yuuuge.

[mt-engines]

No, he runs a custom grind and it was ground for the older heads. Still running same grind with new heads....a new cam would net more gains as well....and yes, the larger running helped it breathe....

Man, that's HUGE gains.

The gains come from better port architecture and casting thickness. CFM is one thing. CFM with the correct port velocity is another.

Creating a better head comes in large part from improvements in port architecture, whether intrinsic to the casting or the availability of adequate wall thickness to port them that way, including having the right cross sectional areas and at least 1/2" corner radii from flange to bowl. Chamber design is also huge, not only from the standpoint of burn but pressure recovery when the valve comes off the seat and air/fuel enters the cylinder.

Newer heads usually have better ports and chambers as cast, and more material on the deck and in the ports and bowls.

Cant °, valve °, valve placement, short turn height, roof thickness, rocker stud strength, valve pocket depth etc.... are all reasons to buy new castings.

The heads he has can make some power in the right hands. But depending on goal, even if I were to max port and epoxy them, the labor could buy him almost a pair of better bare castings to start with.

The real question is whats his realistic HP goal? 850? Tune them up. 900 plus, different head. Not that it cant be done.. just why would you