Port Match or Not

4spd67

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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 matching job done here? Anyone attempted port matching themselves?

Appreciate any wisdom/insight.

Thanks
 

Runcharger

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I wouldn't bother, the overlap is going the right way on that deal.
 

4spd67

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I was think the mismatch was in the right direction of flow. How about the void created by the larger intake gasket ports between head and intake and the void creating eddie currents and possible turbulent vs laminar air flow to the cylinders? Just thinking out loud.

Thanks
 

1 Wild R/T

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Yup, minimal gain & an opportunity to make it worse... If the intake port was bigger I would definitely open the port in the head but your good IMO
 

INTMD8

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Anyone attempted port matching themselves?

Appreciate any wisdom/insight.

Thanks

I did it on my engine, not sure if it's worth it as I didn't do a before/after test.

I think I would do it on yours given the difference in dimensions but can't imagine it hurting much if you didn't.

(and as mentioned you could make it worse as well)

What I did was get gaskets slightly smaller than the port. Tape them in place with painters tape and cut the gasket to match the head port with a razor.

After milling the intake to get it closer I put a few drops of glue on the intake side of the gaskets, install intake and torque down, leave overnight.

Removed the next day and gaskets stuck to the intake of course, then used a sharp pick to scribe the gasket ID to the intake face.

IMG_9200.jpgIMG_9221.jpgIMG_9222.jpg
 

68Moparmaniac

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Port matching is time consuming for sure and the dividends you see will mostly be in the upper RPM range where flow makes the magic. Making these stock BB heads breathe a little better takes time and patience but it will give you an edge over a stock cast iron head. The 906's above have major port & bowl work done, took a little over 40 hours for both heads. LOL still taste the cast iron in my mouth when I look at them
 

66Satellite47

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I'm guessing this a small block, but you didn't say. Matching the intake to the head is always a good idea. Not sure what your gasket is. On my BB heads I match the intake gasket size, intake port, and intake manifold. Just my opinion.
 

4spd67

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Yup, minimal gain & an opportunity to make it worse... If the intake port was bigger I would definitely open the port in the head but your good IMO
Head ports are larger than intake ports.
 

4spd67

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Yes it is a SB 340.

Appreciate everyone sharing your experience.
 

33 IMP

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I would have said that the gains would not be worth the effort in the o.p's situation, but....
I did see an episode of EM where the did a test of this (port matching) and I was surprised how much it helped. I don't have access to the episode right now, but I seem to remember 15hp.
 

66Satellite47

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My bet is the amount of mismatch makes a big difference. If you do your own head porting like I did, not much effort. On the 360 I did for my tow van, the Fel-Pro 360 gaskets were the dimension I matched to. Made the heads match the gasket dimensions and the LD4 intake match both. Worked great, lots of towing power.
 

4spd67

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My bet is the amount of mismatch makes a big difference. If you do your own head porting like I did, not much effort. On the 360 I did for my tow van, the Fel-Pro 360 gaskets were the dimension I matched to. Made the heads match the gasket dimensions and the LD4 intake match both. Worked great, lots of towing power.
As a future thought, does it make selling a gasket/head matched intake more difficult to sell later if you decide to go with different setup later?
 

66Satellite47

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As a future thought, does it make selling a gasket/head matched intake more difficult to sell later if you decide to go with different setup later?
My guess is that the gasket manufacturers have not considered that for cost reasons. I just know what I did for many, many years.
 

33 IMP

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As a future thought, does it make selling a gasket/head matched intake more difficult to sell later if you decide to go with different setup later?
If the port match is to a common intake gasket, I wouldn't think it would be a problem, however......
Before edelbrock re-released the TM7, the used prices for them were very high, around $200. I found one, that a guy couldn't get rid of, because it had been modified for max heads (EXACTLY what I wanted!) and I got it for $75. (Probably should have negotiated down, but it was what I needed)
So that mod basically lowered the value about 60%.
 

66Satellite47

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I still consider the TM7 a really good manifold for ported iron heads (906 & 915).

EDIT: A TM7 works very well with mildly modified, medium to large FTP cams with some gear. I would use one with a 800 or 850 DP. May not be the best manifold, but darn close for an iron head motor.
 
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1 Wild R/T

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So we've quit talking about gasket matches & started talking about Tarantulas......
 

HawkRod

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If it were my engine (and I just built a 416 stroker out of a 340), I would port match them. It won't take long at all to open up the aluminum intake manifold ports and blend them back about 1.5 to 2 inches.

Yes, the performance gains will likely not be huge, but any rapid step in port size will cause fuel to more easily drop out of suspension and flow through the engine unburned. Look, I know we don't build these engines for economy, but why burn more fuel that you need?
 

33 IMP

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I still consider the TM7 a really good manifold for ported iron heads (906 & 915).

EDIT: A TM7 works very well with mildly modified, medium to large FTP cams with some gear. I would use one with a 800 or 850 DP. May not be the best manifold, but darn close for an iron head motor.
Your edit described my motor to a "t". Except I'm using a team G, cause the TM7 is modified for bigger heads.
 

66Satellite47

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Back in the day I looked at the Weiand manifolds. Never got one used at a reasonable price. The TM7 worked for me. Intakes, like cams, are in the eye of the beholder.
 

4spd67

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Thanks everyone for sharing experience and tech insight. Much appreciated.
 
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