1996/1979 Ford Ronco

[baddad457]

I don't have a calculator handy, but those pistons would have to be domed and the rods bushed or the piston pin bore opened up to use em (they'd have to be 351C pistons)on the 351M rods, to yeild a 12.5 to 1 ratio. Even then I question them as the pin height would be wrong for the deck height of the block. I built a 400 using 351C pistons and they weren't tall enough with the 400's 1/2" longer stroke to reach zero deck. They were still .100 or less shy of that. With the open chambered 2 bbl heads milled .030 and the block decked .010, the ratio was only 9.7 to 1.

 

[baddad457]

I looked up Speed Pro L2466F and there's no such part number. There IS an L2446F but it's a 351W piston with a 1.772 pin height which puts it .200 below the deck with a 351M block, crank, and rods. And to add to that, there's a 13.2 cc dish in the top. NO way you're going to get 12.5 to 1 with em.

 

[fleetbob1]

Another way to increase your CR is to install a set of high CR pistons. Unfortunately, there are not may choices available for the 351M/400 engines. One option is to have a custom set of pistons made for your engine. There are many companies, such as J & E and Keith Black, that will make a custom set for your engine in any CR you want, but be prepared to pay a minimum of $700.00 for a set of eight and to wait for 4 to 6 weeks for them to be made. However, there are a couple of other much less expensive options available for the 351M.



351M -- The only production high CR piston for the 351M is the TRW 8.6 to 1 CR piston (P/N L2466F). This is a forged aluminum piston that is available in both standard and 0.030" sizes. This piston will give a 351M with stock heads a 8.6 to 1 CR in the standard size and a 8.7 to 1 CR in the 0.030 size.


Many owners of Ford trucks that were originally equipped with M-block engines have chosen to upgrade their vehicles' performance by replacing the M-block with a 429/460 big block. In fact, this particular engine swap is so popular that an aftermarket industry has emerged to cater to it. (L&L Products in Dallas, Texas was originally founded specifically to manufacture and market components for Ford 385 series big block engine swaps.)

On the other hand, an M-block engine in factory trim has vast, untapped power potential. It is smaller and lighter than a big block (which is why it was developed in the first place), and when properly built, the M-block's power output is comparable to most big blocks.

 

[fleetbob1]

There are open and closed chamber versions of the Aussie 2V heads.

The open chamber Aussie 2V heads are, for all practical purposes, identical

to U.S. open chamber 2V heads that can be picked up in the junkyard for

$75 per pair. The rare (at least in the States) heads are the closed chamber

versions. These heads combine a quench combustion chamber, similar to

that found on U.S. closed chamber 4V heads, with 2V ports. One thing to

note is, that while the chambers are similar in shape, they are not identical

due to the smaller valve size of the 2V heads. I have not CC'd my heads

yet but I expect the Aussie quench heads to have a smaller volume than

the big valve U.S 4V versions. Also, pop up pistons meant for U.S. 4V

quench heads may not fit the Aussie heads without some relieving.



If I remember correctly, the Australian sourced 351's (like Paul Timko's),

are truck motors and used the low compression, open chamber, heads. Interestingly

enough, the closed chamber Aussie 2V heads sold by vendors like Mike Fielder

are sourced from Australian *302* Clevelands. Note that Aussie 302C's

are just de-stroked 351C's (like a 351M is de-stroked 400) and are not

Windsor-based like Boss 302's.

 

[fleetbob1]

About the Heads
Note that heads are interchangeable between all Cleveland and 400, 351M engines. All 335 series engines use the same camshafts as well.

All US made 2V Clevelands have open-chamber heads with about 76cc combustion space. 351M/400 heads, while similar in design to 351C-2V heads, had larger 78-78.5cc open combustion chambers.



Closed chamber head (open chamber heads have a circular bore rather than a chamber curved tightly around the valve and spark plug.)
The "Aussie" 351C-2V heads are highly sought after due to their closed chamber design, and resulting 60-62cc chambers. On a late 70's 400 motor these heads will increase compression ratio from 8.4:1 to a thumping 10.5:1. The challenge is finding a set!


In 1970-1971 the 4V Cleveland heads were all closed chamber (aka "CJ" heads)-highly desirable due to the increase in compression ratio (63cc chamber) and more efficient (read powerful) burn characteristics. In 1972 some 4V engines had closed chamber heads, while others had open chamber 4V heads to reduce compression. By 1973 all 4V heads were open chamber. Open chamber 4V heads had 75-76cc combustion chambers.

The chart below sums up the differences in the US 335 engine series heads:




Everyone knows that 4V heads are for "high rpm" use. Designed for NASCAR, the ports on these heads were large, perhaps too large to be offered in heavy cars which never saw the high side of 5000rpm.
The port on the left is a 4V intake port, while the right pic is a 2V. A 4V port measures 2.47" x 1.47". A 2V port measures 2.05" x 1.37". Now consider that the Fel Pro 1228 intake manifold gasket for 4V heads allows porting to 2.65"x1.88"....yeah, you can just about stick your hand down in there!


One solution to maintain velocity in the 4V intake port is to either build up the floor with epoxy or install "port plates" (aka tongues) made by places such as MPG head service. Similar plates are available for the exhaust ports on the 4V heads.

For a 351M or 400 motor, the 4V heads offer a double edged sword. If they are closed chamber, they can raise compression significantly, however this comes at the expense of large ports and poor atomization and velocity.


--------------------------------------------------------------------------------

Contrary to popular belief it is possible to use a 351C manifold on a 400 or 351M, despite the wider deck. This is made possible with Holleys 351C to 400 intake adapters (pn: 8205), shown below:




--------------------------------------------------------------------------------

Finally, what exactly does "M" stand for? Ford says it has no official meaning. Some think it means "modified" -due to the new 351 being modified from the 400. Others think it signifies the Michigan foundry where the block was cast, however the 400 and 351M were cast at both the Michigan (code MCC) and Cleveland (CF) plants. The casting codes can be found at the rear of the block, behind the intake seal ridge (MCC shown in picture.)


--------------------------------------------------------------------------------
Remember that the 351M and 400 were designed to bolt up to Fords existing big-block (385 series) transmissions. However in '73 Ford produced a small number of 400 engines with a small-block (Windsor) bellhousing pattern, such as the one shown right. Rumor is this was done for the Panteras in case 351C supply fell short. Casting number is D3AE-B, if you think you've got one.

 

[Barber]

Ok dude... Your starting to freak me out here..... You don't answer any questions... instead you copy and paste from different websites.... WTF??

 

[baddad457]

He's talking without saying anything. Must be a Politician

 

[fordwheelinman]

Maybe he should be elected president. it seems to be all the condidates strong point.

 

[fleetbob1]

All Im trying to say is using the parts i used,
I should have alot of HP & torque.

 

[baddad457]

Yea, but you claimed to have a 12.5 to 1 compression ratio with pistons that at best only yeild 8.5 to 1. Plus the piston numbers you gave didn't come up in a search for them. And I doubt TRW made domed pistons for a 351M anyway. The only way to get to the numbers you claimed would be to "stroke it & poke it" in which case it wouldn't be a 351M any longer.

 

[fleetbob1]

Pistons------------------------------------ 8.6
The aussie heads alone raise the c/r 2.1 points 10.7
After milling .030 off the heads add.6 11.3
using Felpro racing head gaskets.045 add .3 =11.6 c/r
I added wrong

PS. those pistons are no longer available/Obsolete

 

[baddad457]

Going from an open chambered Cleveland head to quench doesn't get you 2 points. I know, I've done the math too many times. Not even on a 400 does it get 2 points. After milling you might get 2 points. the head gaskets add nothing. .045 is the std Ford head gasket thickness. The volume for it is 9.5 ccs. And all this is moot anyway, unless you can prove TRW made such a piston for the 351M. There was never a market for any such piston, not even for the 400. And using 351C forged units wasn't an option, the pin height is wrong in addition to the pin diameter. You're trying to blow smoke up someone's butt, but it ain't mine.

 

[fleetbob1]

Ok whatever ---the engine subject is closed (i will take pix of the box i got the pistons in)

Todays progress :
All cab mounts --done
Twin stick --done
B&M ratchet shifter--done
Brakes--done

Next: Bed crop & mount,Gas tank & shakle flip

 

[Sunk]

Sweet, sounds like its coming along nicely.

 

[fleetbob1]

Thanks --still alot of work to do