Dyno 351C 2v vs 4v Heads

[rocket366]

Port Plates... Way Cool that is new to me!

Photo...

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

I've been out of the hot rod game for some time due to the local drag strip closing

and the smog requirements here in CA. Now pre 76 cars = smog exempt.

What I remember is in the late 70s when i had a 69 302 Mustang I was hankerin to

have a 351c 4v engine but I didn't have the coin.

My 351 2v engine has a boatload of torque and wants to spin the 10 inch wide tires so easily

I have to be careful.

My 73 is bare bones under the hood and the engine only has the necessary stuff Carb, Cam, Intake, and headers no smog no extra crap or hoses.

 

[will e]

Well technically it doesn't pull air in. It lowers the air pressure below outside pressure and the result is air is pushed in.

 

[Dave72Rcode]

i decided to sell my MPG port plates... $45 (50% off reg price) + shipping. if anyone wants them, PM me. i can't seem to seal them correctly with my Sanderson headers, due to their raised flange design, but if you have stock exhaust manifolds or Hooker headers, they should work just fine..

FYI, my near-stock O/C 4V 351C (280HP/286TQ REAR WHEELS) is making #s at the rear wheels, similar to modern Mach 1s with all motor 4.6

http://www.dynoperformance.com/article_details.php?article_id=27



and our 351 4Vs seem to be as strong as or slightly stronger than our fellow 1971 429 Big Block brethren (370HP fty rating = 255HP rear)...

http://www.429mustangcougarinfo.50megs.com/new_page_39.htm

 

[Butch65]

Dave-

Thanks for the post, as I was about to ask about headers and the port plates. ( we are running Sanderson's, too)

I checked out the MPG website and didn't see any tech talk regarding whether the intake plates would still yield benefit if paired with a set of headers. Maybe I missed it? Thoughts?

 

[Dave72Rcode]

Dave-

Thanks for the post, as I was about to ask about headers and the port plates. ( we are running Sanderson's, too)

I checked out the MPG website and didn't see any tech talk regarding whether the intake plates would still yield benefit if paired with a set of headers. Maybe I missed it? Thoughts?

Butch, welcome. i think MPG will say that they yield the most benefit and i'm sure they will be happy to sell you a set.

honestly, i felt a little more grunt down low when i had them in. but that is subjective. no hard #s. but a couple weeks ago, i dyno'd at 286 rwTQ (est 425-450 TQ-gross) without them and i'm ok with that since the orig fty spec was 286 tq-net at the flywheel. The ONLY 3 things I've done that deviates from STOCK that probably contributes to the huge increase, seem to be 030 overbore adding 6 cubic inches, slightly higher lift cam (0.030+) over stock (0.491-.505ish), and the sanderson shorties. everything else is bone stock or near stock.

the intake tongues & port plates are a "bolt on" solution to turn a 4V into a 2V or 3V more or less, but with a lot more velocity (pushing same amount of air but thru a smaller hole?) than a 2V.

i think people with LONG TUBE headers on a stock stroke 351C might benefit the most since long tubes seem to reduce the HP and TQ #s down low while raising the HP's up higher... the port plates might help to move the power band back down a little... stroker motors can forget about the port plates, they solved the TQ problem with displacement.

comparing my original Boss 351 exh manifolds (headers) to the Sanderson shorties, i don't see much difference in "packaging" (space used). The only real difference are the longer individual tubes and 3" collector vs the Boss's 2-1/4" collector. Standard 351C 4V had 2" collectors, as i recall. on street motors, i think larger collectors reduce TQ at lower RPM but helps HP at higher RPMs.

sorry for writing another book... ugh...

 

[hyena429]

I do not think it is fair, how can you use the same cam for the diff heads ? "Sure you can" but even Ford had to stick a "special" dual pattern cam in the 4v cleveland for good reason. 2v cleveland has more equal airflow potential on the intake and exhaust sides, a single-pattern cam is sufficient. When the airflow differs between the intake and exhaust," Like in a 4v cleveland" a dual-pattern cam needs to be used to balance flow through the engine. To be a fair test, they needed to switch to a dual pattern cam with the same lift. 4v cleveland will never flow quite right with a single pat cam.

And if i remmeber this build right, they used a single profile cam for both engines..I cannot find on there site the build part anymore..They use to have it all last year. Unless some one knocked them around for using the same cam on both heads ..lol

http://www.7173mustangs.com/thread-the-amazing-351c-4v <~~ from this classic tread..Cleveland 4v heads stock intake port was optimized for 0.600 inch valve lift.

 

[Dave72Rcode]

http://www.7173mustangs.com/thread-the-amazing-351c-4v <~~ from this classic tread..Cleveland 4v heads stock intake port was optimized for 0.600 inch valve lift.

thanks for that link! bookmarked. that's a lot of history in one gulp. not sure how much of it is true and it seems Pence is an evangelist for the 4V, but a lot of it does make sense... optimized for .600" lift, 7000 RPM, Nascar racing, iron crank vs steel, bottom end built to handle 7000+ rpm, drag racers vs nascar, rousch v hank the crank...lol

to handle 600 lift and 7000 rpm, the top end components (non-R code) for most 351C probably needed to be beefed up with conversion to studs & guide plates, dual springs, single groove valves needed to matched up a higher lift cam

 

[Jeff73Mach1]

to handle 600 lift and 7000 rpm, the top end components (non-R code) for most 351C probably needed to be beefed up with conversion to studs & guide plates, dual springs, single groove valves needed to matched up a higher lift cam

Yes on all of those and a stud girdle is good insurance along with a set of Roller rockers

My cam has .641 lift intake and exhaust, everything mentioned above and a rather beefy set of pushrods and solid roller lifters.

Valve stems are undercut to improve flow, but nothing else dramatic.

Drag racing requires a little different set up than oval track racing, but Clevelands did pretty well in both arenas.

 

[4Vforever]

Wow the port plates we've always used down here in Australia look nothing like those things offered from MPG. The intake ones are a solid alloy piece that is shaped and not flat like those ones and are held in with grub screws from underneath the port. Even the exhaust ones look a fair bit different, the ones we used to use we made of thicker material and the floor would shape into the port beautifully. I'll see if I have any pics around to show the differences, because to me those ones just look like they cheaply made, and made so anybody with simple mechanical skills can just bolt them in and think they're going to make a ton of more power. Also I notice they say with their product that they will give you an extra 20hp. Whereas the ones we used to use would lift flow and airspeed well over 30% over standard 4V. A guy I know, when he had his XY GT, that was all he'd done to his heads + new Ferrea valves and associated parts for his top end rebuild. No porting, no fancy valve seat multi angling, just a good 3 angle job, and it made a massive difference to his car compared to running the standard 4V heads on the exact same bottom end. All I remember was the next time I ran into him, he was ecstatic how well it went and how his car showed up all his "chevy's are the best" mates cars and blew them off the track. He thanked me so much for all my advice, and said he wished he had listened to me years ago when I was still doing it for a living instead of listening to know it alls who told him that port plates don't work, etc.

 

[Jeff73Mach1]

It sounds like you are describing what I have heard called port fillers as opposed to port plates and if so, I tend to believe they are the best mod for a 4v head, short of building a stroker motor.