Intake port matching to heads - Do I need it?

[Dignlif]

Hey guys, I'm looking for some advice from those with real world experience (Bill, Jeff, others)...not opinions based on articles found googling please. ( )

Based on recommendations during DW last year, I'm in the process of swapping intakes on my 427W from the Super Victor to a Performer RPM Air Gap. This is because I'm shifting at 6000 and not the Victor upper limit of 8500. Reason for shift point is specifics of the engine build which I can't/ won't change at this point so don't need to discuss the intake choice again.

I'm wondering about the difference in port size between the N351 heads and the new Performer RPM intake. The Victor size was close but the Performer is significantly smaller. Since it's not the head port that is smaller, there won't be a blockage situation.

Port openings:
N351 - 1.23"
Performer RPM - 1.10"
Super Victor - 1.20"

My 'simple' question is, should I have the ports on the intake opened up to at least 1.20 so they're closer to the head opening? Will it even make a difference since it is dual plane and the rest of the runner length isn't ported? Do you think spending the money for this work is worthwhile for my particular situation?


cam - solid roller .670 lift 262*/ 268* @.050 LSA 106

[BOSSMAN]

Yes, open it up to match the port. Most manifolds are left small to fit various heads and port match from there. I generally go 1 inch up the runner to blend the transitions into the as cast port.

[Dignlif]

Perfect! answered by one of our subject matter experts...thanks for taking the time to answer my question.

[TheSilverBuick]

Win!

[TC]

All match porting does is move the powerband higher up the RPM range, as an example if your powerband runs from 2000 to 6000 rpm, it'll be more like 2500-6500 rpm with the match porting.....

Also IMO swapping to a dual plane with that type of camshaft is a big mistake, don't be surprised if you lose ET...... Also IMO a 195cc intake runner like your heads have is to small for 427 cubic inches....... You'd be better off saving your money on the intake and swapping to a better set of heads.......

[MR P-BODY]

I always port match the intake to the head... I dont like the turbulence
that can be created .... it really doesnt increase the power much but it
sure doesnt hurt it either... the higher the rpm it seems to help more

[Deaf Bob]

Turbulance is the main reason to do it... Create a smooth flow/shot into the head.
As for his port runners.. He will get velocity.. That helps on the street, and since he does not want to go over 6000 rpms..should be ok.
I think he will get more grunt out of his motor with the Performer RPM ... More driveability.. Thus possibly quicker than faster..

This is what I understand to happen... For all I know.. I am way off! But I do think he will be happier..

[TC]

It doesn't matter how smooth things are or how gentle the transition is, his heads are the limiting factor, a 2.02 valve is only good for about 550hp, his heads at .650 lift only flow 240 cfm which is good for about 500hp... So knowing that, in a perfect world with his motor fully optimized it is only going to make 500hp due to his heads not being able to support more than that..... Also the intake manifold port being smaller than the port in the head really isn't that big of a deal, the shearing effect from the lip could actually be beneficial in keeping the fuel from puddling on the walls of the intake runner......

Also you have a cam that is way to big to be shifting at 6000rpm, stick a smaller cam in it with the dual plane and watch it go faster......

[kyhunter89]

Do you think spending the money for this work is worthwhile for my particular situation?

I vote for you doing it yourself. It's port matching, not redesigning the flow of the heads. I can agree with everyone in the thread so far. Cam too big etc. But gotta do what you can with what you got.

Why not a victor jr?

[A/Fuel]

David Freiberger says there's no such thing is to to big of cam

[Scott Liggett]

I have debating this with my newly aquired Victor Jr.

[MR P-BODY]

I vote for you doing it yourself. It's port matching, not redesigning the flow of the heads. I can agree with everyone in the thread so far. Cam too big etc. But gotta do what you can with what you got.

Why not a victor jr?

I agree.... I do it all myself(being a cheap bastard, but I love doing this sh!t)...if your
only gonna shift at 6000 if might help a little... but thats no more than a stock shift point...
you have plenty of cam so you need to move the rpm up which would take some port work

[Deaf Bob]

I agree.... I do it all myself(being a cheap bastard, but I love doing this sh!t)...if your
only gonna shift at 6000 if might help a little... but thats no more than a stock shift point...
you have plenty of cam so you need to move the rpm up which would take some port work

In your opinion... Would you change intakes? Or keep this one and use a smaller carb?

[Dignlif]

real world experience not opinion from articles read...

I didn't want to but I'll explain this again. I picked up this engine 'complete' from a friend. It definitely had some problems but it was all I had to work with before DW '11. Hence the choice of heads. The reason for the low shift point is the crank. It's an old school stroke...400M crank offset ground and it has a ton of mallory in it so it's not the most substantial piece. It was also recommended that I not use the trans brake due to the crank, so I don't. I had the new cam spec'd by Cam Research in Colorado who only deals with Fords. They know the heads and I told them my desired rpm range. And what A/Fuel said.

These heads are regularly underated by online folks who only look at numbers but the dirt track guys do great things with them in the real world on both 302 and 351 based stock stroke and strokers. Will I use them forever? No, but I cannot afford to spend $5000 on a new set of heads and complete shaft rocker system that I want. Nor do I want to for this engine with it's potentially weak crank and factory block. The shaft rockers I'm using now only work on these heads so can't transfer them to another set. Then there's the $1000 worth of headers in the car that only fit these heads, I can't see tossing them just yet either.

I need this to last for awhile until I can afford to build a new bigger, better, faster engine. Like Barney Fife, I've only got one bullet so if I hurt this one, it will be parked again. This engine already made it through 2 Drag Weeks so it's not a complete pile, just running slower than it seems it should. Part of that is likely my lack of tuning knowledge as well but I'm hoping that a season of bracket racing this year will help with that. I just wanna get this combo optimized as best as my wallet/ bartering will allow. I trust the experience of the folks that recommended the smaller intake during DW and I stand by the decision to change. Besides, I'm not selling the Super Victor, maybe I can get Jeff to convert it for EFI.

I spoke with Rich at TEM Performance in Napa today and he's going to do some work on the intake. He agreed that I had way too much intake for my self imposed shift point. We're not expecting much from the intake work but it should help some. It will be similar to what Nick suggested with just an inch or so up into the runner.

He's also going to take a look at some slightly damaged heads I had laying around and see what he can do to get them together and I'll try to sell them. If so, then I may use the cash to have him do some work on the heads I'm running now. I asked Rich if it would even make a difference shifting so low and he believes he can get more out of them. He won't mess with the runners since that moves the power band in rpm, focus will be on the bowls and valves/ valve seats. He has some incredible training and experience so I fully trust his word and abilities. Folks with a butt load more money and performance requirements on the line trust him so I'm on the bandwagon too.

Deaf Bobs assumptions of what will happen with the change of intake are similar to what I was told and convinced me to change.

Mr P-Body - Rich mentioned the turbulence you speak of in explaining it to me. It would probably be ok for most street driving but WOT likes the smoothness.

KYHunter89 - I actually would like to do some stuff like this myself but I don't want to F' it up. There are just certain things I defer to professionals for. When a shop owner/ specialist on BS said it was a good idea to port match, I went to see Rich at TEM.

The Victor Jr is still a single plane with power band of 3500 - 7500. That was fine for my 347 that I was shifting at 7200 but still alot of intake for my restricted rpm range.

[BOSSMAN]

I was wondering about the rest of the details, thanks for posting this. The N351 head can be made pretty good with port work and is a pretty decent iron head for a SBF. I now understand the reasoning for your change and agree with it (especially because of the crankshaft strength- makes sense). The dual plane intake has a longer runner length and will make more torque for your combination. I think its a good move to broaden the power at your lower peak RPM. The camshaft size doesn't bother me for the cubic inch. Alot of people don't give dual plane intakes a chance. The true power potential of a dual plane? Well we made 615+ hp on an unported one for a test with our 385ci Early Hemi! You will be just fine.