MightyMach

I thought that in order for the "quench" effect to properly work the piston had to be as close to the head as possible, and the 3.5" stroke of the 351 and the deckheight made it just right? With the 400 you are cramming an extra .5" of stroke driving the CR up higher. The Deck is also taller moving the piston away from the head??

With a 64 cc head and a flattop wont you be well over 11:1?? With 60cc heads, and flat tops MonsterMach is getting 11:1 CR.

The only way that I have heard of this working is with dished pistons. The extra stroke with Dished pistons can still get you close to 11:1 CR and the outter rim of the piston retains the, "Quench" affect.

I am not sure if this is all true or not, but just what I have heard. Guess I will go over to the 335 series board and post there

 

DynoTom

I was really quite surprised when I started posting on this board how popular the 351-Cs were here?

Around here it's very uncommon to see a built 351-C in a car?

It's mostley 351-Ws and 429-460s that are used.

I'm not saying the 351-Cs are bad or anything it's just that the only time I really see alot of stuff about them is at this board?

I guess different areas have different tastes in what motors are common to that area?

Polar68

Hey DT, well there were a couple of things that really spurred my curiosity regarding the Cleveland. One I just met someone in passing at work who had one and then I just happened to check out "MONSTERMACHS" homepage which I felt gave a pretty cool history of his Buildup..."The Beast". I thought it was pretty interesting and nicely done. Anyway I just got interested in them but you are right, don't here too much about them up here either, but when I do, nothing negative, only the same stuff that has been brought up here .....lack of parts including aftermarket options. Different stokes for different folks I guess

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jmobley

MightyMach,

I'm not going to lay out some BS here as I cannot fully explain quench. The Pantera guys that I talk to quite often say that the Aussie heads with 2.19 intakes valves and some minor unshrouding of the cc's around intake valve will yield about 62.5cc. When used on a 400, this works out to 10.8-11.0:1. These guys run 93 octane with out problems. I'd think high air temps and a heavy load would cause knock. BTW, why would stroke affect quench or compression? Wouldn't that be dependent on deck hieght, chamber volume, dome hieght, and pin location?

--J

brianfulwood

On building a 400, Summit offers a rebuild kit that gives 8.33:1 CR with 76cc heads. I calculate that you would get about 9.3:1 if you used an Aussie head with a 62cc chamber. I think that would be a nice engine in my 79 F150 four-wheel drive.

XR9UTE,
What alloy Cleveland heads are you referring to?

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\'65 Fairlane 351C/C4; \'31 Model A Coupe 460/C4 in progress, \'01 F150 4WD, 2003 Expedition (wife\'s)

MightyMach

First, let me start off with saying I am NOT A BUILDER, OR A GENIUS!!

Secondly, I am not saying that you are BSing us.

That said: From what I understand The deck height is important because the piston needs to be near the head for the "Quench effect". With the higher deck height, the piston does not get close enough to the head. The "Quench effect" is gone now. To solve this, you must mill the deck. Milling the deck raises the Compression ratio. To lower the Compression ratio, you get a dished piston (summits rebuild kit is a 14.5 cc dish) and according to FM's Compression calculator this figures to be a 10.5:1 compression with 0 deck volume. The outside rim of the dished piston is still close to the head keeping the "Quench effect". Anyone wanna tell me how I did? I think I will post at the 335 series board as well.

Jeff Given

qtrhors

No other W head stock or otherwise will out flow a stock C head? Lets not get carried away. The available and soon to come aftermarket inline valve W heads will kill a stock C motor head any day. Remember that peak flow is not the only determing factor of the power making capabilties of a cyl head....this has been pointed out many times on this forum. Also dont forget the lame dog leg exhaust on the C motor head that required being cut off and exhaust port plates used to raise and straighten it.(the common practice started in the 70's by Pro Stock Ford racers). To say the stock C motor will kill a stock W motor is no great revelation. Ford never developed the W for racing or performance as the Boss cyl head(351C 4V quench chamber) was Fords answer to the small block chevy in 69(1969 was the 1st appearance of the Boss 302/351 cyl head). In some respects it still is when you look at the Ford nascar engine...in many ways it is the C motor in its most modern developed state. In the end the canted valve layout seems to be the better power maker over the inline valve layout for all out racing...although this will probably be debated by many from boths sides. It just depends on what you are trying to build. For all out high rpm racing the C motor is very capable and it should be as it was designed for it. But for a strong midrange torque street motor in the 3000-6000 rpm range a W motor with the "right" aftermarket head will waste the 351C 4V and its way to large intake ports. This is why the 351C 4V motor was only around for 4 years, it was a terrible low rpm engine(idle-5000 rpm) for moving big ford cars around and also why it was never installed in pickups.

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Tim

qtrhors

I guess I wasnt finished yet

After all that being said the Boss 351 is still the King of ALL smallblocks as no other factory assembly line smallblock has the potential of that engine. Ford did well 30+ years ago when they released that monster on GM and the rest

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Tim

DynoTom

You got that right!

I have never been a fan on the 351-C engines but,I definatly respect that motor and I'm sure glad that Ford made it!

393Clevor

Just build a Clevor and get the best of both worlds

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Whipple Survivor..............

XR9UTE

The heads are by Cylinder Head Innovators(CHI). They call them the 3V. I can't seem to find anything about them on the net except this picture;
http://www.pim.net/3v1113b.jpg
I have a magazine article somewhere. I'll see if I can dig it out. From memory they built an engine which made 525hp @6400 with these heads. They switched to a set of port filled and high ported CC 4V's which made less power and nowhere near the torque and average power that the 3V's made. I think they used 2.1" Intakes and 1.65" exhausts. 2.19" intakes are known to shroud themselves on the cylinder wall as is the case with stock heads.

Pete.

kens6t7mustang

EWWWW. why waste time on a 351M? a TRUCK motor...............way better engines out there.

dbu8554

hey there we try not to dig up posts from 5 years ago but with a 400 crank in a 351m and a good set of heads you can get 400 HP alot cheaper then you can with a windsor

gordon

Why not a 351 windsor with CHI heads. Best of both.

dacofa

Clevor has may vote, we need more of them to make it known that it's a beast to be reckon with.