SM Head Modifications on a budget

[PRH]

Here's a test with the inside corner filled in with clay at a radius of 0.2".

Okay……..so no magic there.

Looks like the SSR is still ruling the roost from .500-up.

From my experiences, I would put it this way…….

The more potential you gain from various modifications to the port and valve seat & chamber area……..on a head where the as cast SSR isn’t capable of managing the volume of air flowing past it…….the more of a hinderance it becomes to further improvements.

 

[pittsburghracer]

Okay……..so no magic there.

Looks like the SSR is still ruling the roost from .500-up.

From my experiences, I would put it this way…….

The more potential you gain from various modifications to the port and valve seat & chamber area……..on a head where the as cast SSR isn’t capable of managing the volume of air flowing past it…….the more of a hinderance it becomes to further improvements.

For the little bit of work that he did his .300 number is golden. And that was early on.

 

[pittsburghracer]

.

 

[Earlie A]

I have a port mold drying now. I want to look at areas from the apex to the throat and see how much expansion is happening after the apex. I would like to try a much smaller throat with the same valve size. I think it will control the separation better and peak at higher cfm before falling off.

 

[PRH]

Is that throat/bowl shrinking going to be a clay or epoxy mod?

 

[PRH]

It would for sure. What I was hoping for was to see how close we could get to 285-290cfm with the least amount of work and cost for guys that can’t afford to pay for a full port job. Knowing what a 2.055 and 2.08 valve are capable of I can size the port accordingly. The shortside width and height is the biggest time factor on these heads. A 285-290cfm smooth flowing port would get most of our members the horsepower they are seeking. Doing it on a budget would be a bonus

Have we reached a point where the thinking is that the 285-290 number isn’t going to materialize by employing simple diyer friendly mods?

 

[Earlie A]

Is that bowl shrinking going to be a clay or epoxy mod?

It would have to be epoxy. I've tried raking the clay in a throat before and it didn't go well. Clay does not like a feather edge and doesn't do valve angles well. It would take some thinking about when to try it because it would obviously be the end of the step 1-5 process we are in.

I've done this once before and I was shocked at the improvements. Short side shape needs to stay unchanged with the throat reduction happening on the sides and the long side.

 

[Earlie A]

Have we reached a point where the thinking is that the 285-290 number isn’t going to materialize by employing simple diyer friendly mods?

Personally I think that number is not possible until the apex gets widened. I want to try different valve jobs as well. Trying to think through how that could be accomplished without using up 3-4 ports in a head. I think in the 270s are possible, especially if we start relieving the chamber a little. But then we're going to step 6. I'm not ready to leave 1-5 yet.

 

[PRH]

I like how you’re working your way thru the steps.

 

[pittsburghracer]

Have we reached a point where the thinking is that the 285-290 number isn’t going to materialize by employing simple diyer friendly mods?

I thought my target was 275-280 but I may be wrong. I don’t like a couple mods he made but that happens. I hope he learned a few things number one being save that one inch sanding roll for fab jobs in the shop. I don’t like how he did some slight short side shaping on the common wall side as it directs the airflow into the cylinder wall instead of bore center. This is one of the main reasons I attack the bolt bulge. It allows me room to stay wide and direct the airflow center bore. Laying down the corners of the short side floors corners allows you to shape things. You can see that on the chamber pictures I asked for. So yes I was hoping for higher numbers for those at home hoping to do a few mods to gain a few more horsepower. I would have really liked to see what a gasket matched single plane would have done but that’s not going to happen.

 

[PRH]

I think in the 270s are possible, especially if we start relieving the chamber a little.

I can tell you that with an RPM head, 270’s are possible without the 2.05 valve or any chamber mods.
Pinch at .970 and some pretty “safe” bolt bulge shaping.
But……..it did get some worthwhile SSR work.

Made 550+hp on a 416.

 

[pittsburghracer]

I can tell you that with an RPM head, 270’s are possible without the 2.05 valve or any chamber mods.
Pinch at .970 and some pretty “safe” bolt bulge shaping.
But……..it did get some worthwhile SSR work.

Made 550+hp on a 416.

You know it, I know it, and anyone that has ported heads seriously knows it. The short side is where the gold is hidden. But I know it and you know that the short side scares the be-jebies out of everyone that tries their hand at porting so we couldn’t go there.

 

[PRH]

Both you and Brian have done (way)more of these heads than I have, and have gotten far higher numbers from them than any I’ve had on my bench.
I thought the 285-290 numbers were extremely lofty goals for these heads without reworking the SSR.
I figured there was some area of the port that when tweaked in just the right way was going to unlock some magic, and I had never figured it out.
It doesn’t appear that secret area has been discovered in this thread quite yet.

Of course, the more telling test about the value of reworking the SSR, and the added flow it would bring would be……..
Do everything that goes into the 290cfm package…… except the SSR.
Put the heads on a suitable short block that could exploit them(600hp & 400+ cubes to use up the area), see what it makes.
Then pull the heads off, do nothing but rework the SSR and reinstall the heads, and retest.
See what the gains are.
That would basically be a test between flow vs area.
The flow would be noticeably higher, but the area would hardly change at all.

 

[pittsburghracer]

It would for sure. What I was hoping for was to see how close we could get to 285-290cfm with the least amount of work and cost for guys that can’t afford to pay for a full port job. Knowing what a 2.055 and 2.08 valve are capable of I can size the port accordingly. The shortside width and height is the biggest time factor on these heads. A 285-290cfm smooth flowing port would get most of our members the horsepower they are seeking. Doing it on a budget would be a bonus

Ok here’s the first time I mentioned a target that I would have loved to see which was 285-290 not 290-295.

 

[PRH]

285-290……. Yup.

 

[Earlie A]

Here's a question that occurred to me after reading you guys talking about porting the X & J heads back in the stone ages. What did you do about the short side then? Can't lower it very much because of water.

 

[pittsburghracer]

290 with a 2.02 valve is doable but lots of work and effort to get there. Pictures are out there on how to get there and I’ve given about every number that I port to, except the short side. Every valve size 2.02, 2.055, and 2.08 have a shortside size but I won’t give that number out. Way way to many hour’s getting there and I’m not done yet.

 

[pittsburghracer]

285-290……. Yup.

He’s five minutes away from getting there.

 

[pittsburghracer]

With a bur lol, not a sanding roll.

 

[PRH]

The most I’ve ever gotten out of a factory head is mid-270’s…….and that was an X head…….. which have a more sloping SSR than a J head.

I had some cnc ported J heads here that went 280-ish after some tweaking of the runner & VJ.
These heads had some fairly generously sized bowls.

Both of those heads had flow regression after the SSR gave up.

If I’m doing J heads myself, I’m done when they’re in the 260 range.

 

[Earlie A]

The most I’ve ever gotten out of a factory head is mid-270’s…….and that was an X head…….. which have a more sloping SSR than a J head.

I had some cnc ported J heads here that went 280-ish after some tweaking of the runner & VJ.
These heads had some fairly generously sized bowls.

Both of those heads had flow regression after the SSR gave up.

If I’m doing J heads myself, I’m done when they’re in the 260 range.

Never heard that before. Even the factory 2.02 J was different SSR than an X?

 

[PRH]

Yup.
I’ve had people argue with me about it, but when you have them sitting on the bench next to each other, and run your finger over the SSR…….. it’s quite obvious.
And I’ve had X and J heads in the shop at the same time on multiple occasions.

In my assessment, the X head has the better intake port as cast. The SSR apex is shaped and placed in the correct location for a 2.02 valve, because that’s all they came with.
The apex of the J head is moved towards the guide to be able to work with a 1.88 valve.
When the 2.02 is installed, the corresponding bowl cut ends up making the final approach of the SSR into the bowl much more abrupt and steep.
Which is why an untouched X head outflows an untouched J head.

 

[Earlie A]

Been on the lookout for a set of untouched X heads. I'll pay more attention now.

 

[PRH]

The shape of the SSR on a X head is similar to(but still better than) a J head that’s machined for the 1.88 valve.

 

[Newbomb Turk]

You know it, I know it, and anyone that has ported heads seriously knows it. The short side is where the gold is hidden. But I know it and you know that the short side scares the be-jebies out of everyone that tries their hand at porting so we couldn’t go there.

That’s because it was beat into the head of every potential head porter that if you even look at a short turn wrong the casting is junk and you should never try again.

I didn’t get the fear gene.

Guys that are motivated by fear (or I suppose unmotivated by fear too) will never make a go of it no matter what.

I **** on all those authors and talking head bastards who spent the 1960’s and onward telling guys what not to do rather than what to do.

And when they did do some articles no porting they bought some sorry assed paper roll kit and maybe a couple of burrs and they say just remove the casting flash but don’t move any metal and never touch the short turn unless Ernie Elliott or Smokey Yunick are standing there, holding your hand.

You’ll never learn to port unless you do it. If you live in fear of killing a short turn or poking a hole in something you’re in the same boat.

To learn to port the guy MUST learn to pick his own tools and such so that HE can make the shapes HE wants.

No two guys see things the exact same so it takes different guys different tools to make the same shape.

There isn’t one way to port. What matters is the end result.

I’ve always said if someone chopped a short turn down to almost hitting water and you went out and set a national record with them, as soon as it was spread about what you did every swinging dick with a grinder would be chopping down their short turns, not considering as to WHY it was done in the first place.

Eventually you have to stop copying what other people do and learn for yourself.