Looking for a few tips on porting 351c 4v heads

[RL]

Just buy them and put them in.



Where are you, because I know places where you can get them done.

[mag2555]

And then how does one deal with the overtly large exh port at the flange?

[groberts101]

And then how does one deal with the overtly large exh port at the flange?

http://www.mpgheads.com/port_plates_a.php

I've used them.. the stingers.. not the cheap ass stamped steel plates you could just make yourself.. they work decent enough. Also changes the exhaust note slightly too.

http://www.pricemotorsport.com/html/bod ... _plat.html

More work and costs more.. but is the proper way to really fix this exhaust port.

And price motorsports also has the port stuffer style inserts as well.

http://www.pricemotorsport.com/html/bod ... 1c_4v.html

[mag2555]

I think I would lean more towards using Cotronics 904ht ceramic epoxy to build up the exh port floor as I have used it many times to block off exh cross overs!

[BobbyB]

Does anyone have any flow numbers or performance numbers using the port stuffers?

[Daniel Jones]

We (Dave McLain and I) dyno tested the MPG MPG Head Service "Stinger" exhaust port inserts (the individually flanged bronze inserts with the a rounded tongue, not the stamped sheet metal ones):

http://www.mpgheads.com/port_plates_a.php

They bolt between the header and the head. Feedback from some of the Mustang drag racers suggested they might not do anything positive. However, one of the Pantera guys had drag tested them on an engine similar to ours and found they made some additional power. Pantera headers have several inches of straight pipe at the exhaust port exit before turning down unlike most Mustang 351C headers that have to turn down sharply down at the port exit to clear the shock towers. My expectations were that they might work with the Pantera shorty headers but not with the Mustang long tubes. Surprisingly, the exhaust port stuffers worked on both the Pantera headers and the 1 3/4" primary diameter Hooker long tubes to the tune of approximately 5 HP and 10 ft-lbs on a 400 HP 351C.

> this is the 4V usa pricemotorsport int stuffer, its better than any of the overly thick aussie import version/s.

The Parker inserts are meant to match his reduced cross-sectional area Funnelweb intake.



They size and position the intake port more like a CHI 3V. The Roush and PME only raise the floor and are closer to an A3 port (A3 has a little higher roof as well as the filled floor). Has any tested an unmodified 4V intake manifold on a stuffed 4V head port against one filled to match? I've wondered how much of a difference it makes to go from a larger to smaller port area abruptly. In subsonic flow, there's a pressure wave that travels ahead of the flow that might minimize the effect of an abrupt contraction.


Dan Jones

[thomas butt]

It seems that a 4v cleveland in the 375-575 hp range would benefit with stuffers but the 675 and up builds benefit with minor fill on the side and bottom and that's it along with bowl and SS work.

I am gonna have to think this out a while and see what's feasable. I would sure love to take a 4v build to 700hp but might not be able to for a few years because of $. Definately at 425+ ci.

[wyrmrider]

All depends on your rpm and engine size
I've had good luck raising the intake floor and filling wall down to the pushrod
filling on the bowl side of the pushrod pinch is a lot trickier
exhaust is easier and needed

[RL]

this is the 4V usa pricemotorsport int stuffer, its better than any of the overly thick aussie import version/s.

These are the right ones, don't fill the sides.

All those side fill photos are very old (maybe 80's), and stopped being used decades ago when people realised they were too small. People are doing Google searches now and thinking we use them, but we don't.

The trap that people fell into was that you can fill them that much without loosing flow, but back then no one knew about velocity so those ports would make no power after 5000rpm.

[user-23911]

Converting to EFI would eliminate some of the problems.

Adding a turbo or two would eliminate more problems?

But then again, the headgaskets will still leak.

[RL]

Don't know if they are American but I know they aren't new.

We had a floor and side filled 351C come in about 1991 making 550hp, and I came up with casting my own tongues - no one made them back then -, like in the picture, and screwing them in. The engine dynod at 601hp with no other changes, and that was without any exh filling. I have never seen a cast tongue filler until they started selling them recently - maybe 10 years ago -.

2005 I did a int filled, no exh mods except porting, simple street engine that did 596hp at 6850 on pump gas with a simple solid cam and nothing special.

Have had 2 sets of 4V come in with the full exh plate added - a popular mod in the 90's -, and no inlet fillers - people weren't bright back then - and when I flowed them they flowed the same as a ported 2V exh.

So I made plates that actually flowed well. From memory they flow 250@28"

[BobbyB]

Hey RL,
When you said... "2005 I did a int filled, no exh mods except porting, simple street engine that did 596hp at 6850 on pump gas with a simple solid cam and nothing special. "

How many CID was that?
Was the cam a flat tappet or roller solid?
Any idea on the cam spec?
Thanks, those sound like real good numbers to me.

[thomas butt]

I still think a race motor properly built and cammed whether it's a 358 at 8,500 or 434 at 7,000 the stock ports should be ok with minor filling. The exhuast a different story. FYI this is my amateur opinion.

[RL]

Thought the idea came from PS. There wasn't much info around when we did our first one, and we were having big problems with epoxies, so I came up with cast alum after doing a casting course during mech eng.
We tried epoxy 3 times with 3 different brands, and each time it separated from the head. The only way we got it to stay put was to put bolts in the head to anchor it, but even then it swelled and separated and was only held by the bolts.

Hey RL,
When you said... "2005 I did a int filled, no exh mods except porting, simple street engine that did 596hp at 6850 on pump gas with a simple solid cam and nothing special. "

How many CID was that?
Was the cam a flat tappet or roller solid?
Any idea on the cam spec?
Thanks, those sound like real good numbers to me.

408, flat, 268-ish

I still think a race motor properly built and cammed whether it's a 358 at 8,500 or 434 at 7,000 the stock ports should be ok with minor filling. The exhuast a different story. FYI this is my amateur opinion.

Exactly. Buy the int tongues and bolt them in, and if you're inclined buy the exh flange plates.

[thomas butt]

Thought the idea came from PS. There wasn't much info around when we did our first one, and we were having big problems with epoxies, so I came up with cast alum after doing a casting course during mech eng.
We tried epoxy 3 times with 3 different brands, and each time it separated from the head. The only way we got it to stay put was to put bolts in the head to anchor it, but even then it swelled and separated and was only held by the bolts.

Hey RL,
When you said... "2005 I did a int filled, no exh mods except porting, simple street engine that did 596hp at 6850 on pump gas with a simple solid cam and nothing special. "

How many CID was that?
Was the cam a flat tappet or roller solid?
Any idea on the cam spec?
Thanks, those sound like real good numbers to me.

408, flat, 268-ish

I still think a race motor properly built and cammed whether it's a 358 at 8,500 or 434 at 7,000 the stock ports should be ok with minor filling. The exhuast a different story. FYI this is my amateur opinion.

Exactly. Buy the int tongues and bolt them in, and if you're inclined buy the exh flange plates.

Did late 70's pro stock teams use exhaust port plates or epoxy?