Port match intake/gaskets/heads or not

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1badfish67

1badfish67

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Received new Promaxx 171/65cc heads a few days ago. Promaxx recommended Fel Pro 1213 intake gasket. Measured intake ports on heads a few minutes ago at 1.125" x 2.250". Looking at using a Edlebrock RPM AirGap intake (port: 0.98" x 2.16") on website. Fel Pro 1213 port size is (1.160" x 2.270") according to website.

Head ports are larger than the intake ports and gasket ports are larger than the head ports. Gearing this build for performance street application, at least what I think of as performance street. It's all relative right. Plan is to shoot for about 8.5:1 DCR or little less with SCR ~ 10.75:1, if possible. Looking right now at Comp XE274H cam 230/236 duration @ 0.050", 0.487"/0.491" lift with 1.5 ratio rockers.

Would it be worth the time/money to have a port/gasket matching job done here? Anyone attempted port/gasket matching themselves?

Appreciate any wisdom/insight.
 
What's to lose? ....and you WILL gain with a good job.
 
A bit of a reversion dam wouldn't hurt on an unported head. If the head ports were bigger than the intake ports that would be a problem. Port matched or gasket match would be better for flow, especially if the heads were ported.

I am not a porter but I have had several heads and intakes ported. Just going off the information I have come to understand.
 
If you're trying to squeeze all the power you can, yes.
The intake smaller than the head port if anything would stop reversion, not induce it . Why would there be reversion though, we arent designing flaws here.
 
Fel-Pro

intake2.JPG.jpg
 
1badfish67 said:
Received new Promaxx 171/65cc heads a few days ago. Promaxx recommended Fel Pro 1213 intake gasket. Measured intake ports on heads a few minutes ago at 1.125" x 2.250". Looking at using a Edlebrock RPM AirGap intake (port: 0.98" x 2.16") on website. Fel Pro 1213 port size is (1.160" x 2.270") according to website.

Head ports are larger than the intake ports and gasket ports are larger than the head ports. Gearing this build for performance street application, at least what I think of as performance street. It's all relative right. Plan is to shoot for about 8.5:1 DCR or little less with SCR ~ 10.75:1, if possible. Looking right now at Comp XE274H cam 230/236 duration @ 0.050", 0.487"/0.491" lift with 1.5 ratio rockers.

Would it be worth the time/money to have a port/gasket matching job done here? Anyone attempted port/gasket matching themselves?

Appreciate any wisdom/insight.
Click to expand...

If I were spending money I would do it having the valve job double checked and done right if needed first, then go from there. Best bang for the buck.
 
Port matching is a plus in the power department. Not doing so isn’t the end of the world but there would be some power left on the table. The mismatch from a smaller intake window to the larger head window would be OK. The reverse is bad. It would help to port match since the air and fuel would have a smoother uninterrupted path. The quality of the air and fuel into the head and cylinder would improve only slightly. But this is where the little things come into play for just a simply better running and more efficient engine. That’s what I’d be doing it for. Not so much the power. Just a nicer running engine.

Some will say this is small potatoes. I’d agree on that. It’s just these things are up after awhile. Keep adding on the small potatoes!
 
Like RRR said, there's not much to lose. In general, more unobstructed air flow = more power.

The only thing you need to try and verify as best as you can is how the ports between the two parts line up. Obviously you need to be able to see both mating surfaces with the intake on but since it's almost impossible to do that 100% accurately you need to make some sort of reference mark or impression on either side so you can see where things are.

This is an old Holley Strip Dominator I "gasket matched" several years ago. Don't know if my handiwork helped or not but it looks cool in the pictures. I went as far up into the runner as the burr shank would allow. YRMV.

IMG_2324.JPG
 
My opinion, it's not something you will ever notice a difference, and it's not something that will repeatably show up on a time slip, unless you have a very consistent car. Note that the heads being larger is the key here. If the intake was larger that's more of an issue.

If you are having a full port job that's one thing. But barring that I'd spend the time, effort, and money on the bowl and short side areas, and a quality valve job and valves. Also the chamber side. Getting rid of ridges and deshrouding while you are having the valve job done.
 
On the head side I found the 1213 gasket to be a near perfect match on my 171's. Looks like there is a RCH at the bottom in this photo, but the gasket moves up that much with the hardware installed.

20220725_095424.jpg
 
It will help, how much it helps is all in how you do it.
I try not to "gasket match", I attempt to "port match".
Why? As rmchrgr said, there's always going to be a bit of a discrepancy between laying the gasket on the surfaces, and how the parts (and ports) actually line up when assembled. Remember, we're talking thousandths here.
It's somewhat unconventional, and far from perfect, but here's how I go about it:
I pre-assemble the long block using USED gaskets- before bolting on the intake I make a thin paper "gasket" that I sandwich between the used intake gasket and the surface of whichever has the larger port- head or manifold. In your case, the head. Use the gasket as a template to cut the paper one, leaving the ports uncut. Use a bit of your favorite tack adhesive (or a couple dabs of grease) to hold the paper to the head surfaces and gasket, and bolt the manifold on. This will shift the gaskets into their installed positions. Then remove the manifold, leaving the gaskets stuck in place on the heads.
Now with the gaskets in place, pierce the paper gaskets with a sharp X-Acto knife and cut out the ports, without disturbing the gasket position. This makes the gasket match your head port size and shape. Coat the manifold flanges with blue machinist's dye. Now spray some spray adhesive on the intake manifold flanges and reinstall. Remove the intake again, this time being careful to remove the gaskets as a unit with the manifold, still attached. Set the manifold upside down on your workbench. You now have a template to scribe the manifold to the exact size and location of your head ports when installed. The actual port alignment between the two may surprise you. Scribe, remove the gaskets from the manifold and grind.
Not perfect, but darn close.
So, why go to all this trouble and not just use a gasket and grind both ports to match the gasket? Well, are you sure the gasket is orienting itself the same on both mating surfaces, and side to side? And when ported out to the full gasket port size, what happens to the gasket when you torque the manifold to the heads? It compresses the gasket. The gasket displaces and bulges into your newly "matched" ports. Same issue if your gasket doesn't perfectly re-align with where it was situated when you did your "gasket match". It may not be a lot, but we're talking thousandths here. So much for a smooth transition.
Allowing the gasket to remain larger than the ports gives it a bit of leeway for the gasket squeeze. You may have a bit of a gap at the mating surfaces, but at least the ports will be aligned.
Again, not perfect; but it's as close as I can get it.
 
Also keep the roof and floor straight don't funnel the entrance. You could put it all together with intake gaskets partially glued 'to the heads only'...next set the intake on and using 4 end bolts...center it end to end as best you can 'centering all bolt holes'..then 'snug' it down...install the rest of the intake bolts and torque it down the 30 lbs from center outward 'I torque them by feel'...then take drill and a 1/8 inch bit..at the ends just outside the no.1,2,7,8 runners between intake bolts.."where there's no water'...drill a hole through the intake flange and into the head flange. You don't have to drill all the way through, just drill partially enough to hold a drill bit in other words.. because you're going to need three more eighth in drill bits ..and I let you know where I'm going with this...this is going to tell you when you take it apart where everything ends up ...the intake gasket when it shifts and settles during torque , , the head versus the intake alignment. 'Also why you align gasket n glue it to the head to start after port matching head to gasket size 1st.'
When you put it together after you port match everything and or do some intake end to end adjusting which isn't unheard of to align the common walls... you can use four 1/8-in drill bits to align the gasket to the intake & to the head just as it was when you had it torqued and it will go back together the same for sure. It makes it full proof and when you do your Port matching to the intake you use those 1/8-in drill bits to locate the gasket and use a little tape as well and go to town
 
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I always port match, my method is similar to Moparofficials. I use a small dab of contact cement on each end of the head to hold the gasket, then install the intake. Then I use a sharp scribe and trace along the top of the intake (on the gasket), this is my guide for aligning the gasket to the intake. I mark around the port openings on the intake with a black sharpie, then attach the gasket to the intake using bolts with large flat washers. Scribe the intake, remove the gasket and start grinding. I like to blend as deep as I can reach in the head and intake. Sneak up on the line with a rotary file and finish sandpaper drums. My preference is to just remove the scribe line on the head and leave about half of it on the intake.
 
I have port matched by taping bolts for a perfectly tight fit to the gasket and then scribing the head and intake
with the gasket.But i have also read a tiny bit of inversion with the head ports being smaller greatly improves air fuel mixing and increases velocity. I also read some tests using different intakes and oddly enough the best flowing intakes did not make the most power in dyno results.I'm not convinced it could be noticed in a street driven car through full exhaust
 
Here is a beautiful port match job:

AA5E5BA6-F78C-46D1-BA0A-ABCE87F53CCE.png
:lol:
 
MOPAROFFICIAL said:
When you put it together after you port match everything and or do some intake end to end adjusting which isn't unheard of to align the common walls... you can use four 1/8-in drill bits to align the gasket to the intake & to the head just as it was when you had it torqued and it will go back together the same for sure. It makes it full proof and when you do your Port matching to the intake you use those 1/8-in drill bits to locate the gasket and use a little tape as well and go to town
Click to expand...
the drill bit idea as you say is fool proof, just like the dowels on the head to block or block to bellhousing joins :thumbsup:
 
I personally wouldn't bother. I know of 2 well known engine builders known for making serious power that say don't bother porting manifolds. One stated that he saw a manifold murder intake flow once bolted on but didn't affect power like he thought it should. I remember Larry Widmar saying to keep the intake manifold smaller by a millimeter and I can only assume that that helps the fuel that's on the walls get re entrained into the airflow.

Large intake tracts encourage reversion messing up carb signal and ultimately cylinder filling.
 
added eddy heads. Ported polished gasket matched. Same with M1 intake. Made ZERO difference. What a waste of money.....
 
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