451 low deck

Click on the books page and you'll find plenty of information covering stroker motors.

http://www.moparts.org/moparts/books/index.html

The mains need turned down to 400 size and the counterweights need turned down to 7.25 ish diameter. Then you can run a 6.76 rod and a 1.32 ch piston which is a popular piston for many combos. I'm doing a 3.9 offset stroke with a chevy 6.70 rod and 1.32 piston. It seems people are always very happy with the 451 combo.

Some background on the 451 "B". I think much of the success of the 451 combination was from articles in Chrysler Power magazine in the late 1980's.
They were putting turned down 440 cranks in with stock cast pistons milled for the compression height. Because of the shorter deck height the pistons weighed less than a 440 so the engines would RPM good and were cheap to build, considering no one wanted 400 blocks, they were much cheaper than buying a 440. One of the first failures was the piston pin pulling out of the stock cast piston at sustained high rpm. So custom (at the time) forged pistons were used and I think the custom pistons also allowed running the longer 440 rods. At this point 451 "B" had the same stroke and rod length (and about the same bore size as a 0.060" over 440), but with pistons that weighed about 1/2 as much as the 440 piston.
The lighter weight pistons also reduced the stress on the crank and rods. So at the time the big deal was the low cost of the 400 block and light weight pistons. The "B" engine may also have some strength advantages over the 440 "RB" with shorter cylinders they should be stiffer, the shorter deck height uses shorter pushrods (stiffer and weigh less),the smaller main bearing size reduces friction and allows more material in the main webbing and caps, but that's usually not a problem on a 440, but the difference is usually mentioned.
Another issue is the shorter deck height "B" engine at 9.98" compared to a 440 "RB" at 10.725" results in the "B" engine being slightly narrower so it fits easier in A-Body cars.
Anyhow, 500 HP is easy with decent flowing heads and a mild cam. With better heads, and some cam 600 HP is not too hard to make. 700+HP is possible with good aftermarket heads and a bigger roller cam, but at this level you will want a stronger than stock crank and rods, so larger strokers are usually built. The 500" "B" stroker with 4.15" crank still uses the longer 6.768" rods and a pretty short compression height piston requiring oil ring supports. This is a nice combination for a higher winding 7,000+ RPM engine. The 4.25" stroker 512" kits use a shorter rod, and are really nice for a street engine that does not need to spin 7,000 RPM.

I have seen friends Duster go 9.70s with 451, stock eddie rpm
w/452 heads ran 10.2/10-30s stock rods, (aries pistons tho.)
430 gear 33 tall tire,, oo the motor stayed together some 10 years

this is all sounding sweet to me thanks for the info guy's ur awesome....

have one sitting on the stand ready to go in my customers duster 451 11 to 1 comp comp solid cam 565 lift 242 duration out of the box eddys team g intake and 850 quick fuel carb dynoed at 538 hp and568 torque 3100 pounds we figure 10.80 to 10.90 no problem i like low deck strokers because they make good torque down low in the rpm range this motor made 500 torque at 4000 rpm!

awesome seems a no brainer they seem to be rather cheap to build an make awesome power seems like a win win

I built mine for just over 5 grand. Mine's a .040 over block for 452", in a 3780 lb. street B-Body, and it has gone 12.0's in street trim with plenty more to find. Take a ride in it here: https://board.moparts.org/ubbthreads/show...e=1#Post6920806

Watch the tach when I hit the throttle a few times. RPM's on demand, baby!

sweet sattelite i had a belvedere wagon 67 loved her till some ass rear ended her....

I like mine alot, I built it at home, and it does pretty much what I wanted it to do.

PM me if you have any kind of specific questions you don't want to post, but it's all be covered pretty well.

The way I look at it is:
If you like 440s, then you will love the 451 low deck.

It acts similar to a bored out 440 in some ways, but seems to like RPM maybe slightly little more...it is smaller on the outside...gives more room for big headers, and more room for taller intake manifolds.

No better use for an old steel 440 crank with trashed mains

All the work is in the crankshaft.

Mine makes 525hp 500tq at the rear wheels and is street driven on a regular basis.

I believe it all clears the block but I'm not there yet with my build.

that would be great talking after the couter balance been cut down

Here is one I recently did....you'll notice the chamfer on the inner crank throws. This must be done to clear some block casting in those areas. You can also gring the block to help clearance this. It is also possible to put a 440 crank in with no or minimal crank work, but a lot of grinding in the upper saddle areas. A poor mans stroker is possible this way, but its not the best way in my opinion. I did one with a cast 440 crank to see what it involved, and didnt care for it much myself.

2

440 crank with no turned counterweights, only clearanced block, but needed chamfered counterweights

Also a 451...

I built several 431's (383 based) and 451 B's long before they were cool and long before they were overshadowed by the (now more easily affordable) 496-511; I think of them more as lighter (both in weight and rotating mass) and more compact 440 where everything seems to work just a little bit better. If you already have a 440 RB in a B/E body, I think nowadays the couple extra $100 it cost to machine the crank for a 451B could probably better invested in (in terms of more HP per $$) in improving your cylinder head flow. Simply stated, a 440RB is still a very formidable motor and when you go with aftermarket rods and lighter pistons for either build anyway (which 20yrs ago was seldom used in the apples to apples 451RB vs 451B build comparisons back then) 20 yrs ago, a 4.25" stroker crank was at least 1200-1500 so not many 511's were running around on the street....so when you take those considerations into account I think today the 451B's 'real world' advantage diminishes quite a bit. Of course I'm the first to say that the 451 is still a great motor....but with todays' affordable stroker cranks vs machining the mains CW's and sometimes opting for an offset grind 3.90/ 2.200 rods) on a 40yr old crank, it's much harder to make the case for not doing a 4.15-4.30" 2.20 journal 496-511-517; compared to a 451 it's like getting more than a whole extra 440 cylinder's worth of cubes/power and torque for really (as pistons and rods are a wash) not much more coin.

Yer wise, Wizeman. No need to pay for machine work on a used crank when new ones are so readily available. And as Chuck Senatore says, "Build the biggest shortblock you can afford."
We are living in a golden age where everything we wished for in 1975 (in terms of engines and transmissions) is available for much less than the only equivalent parts cost then.
Example: In my hometown in 1975 the local serious hot rodder built a 427 with Carillo rods and aluminum heads. The rods cost $500 and the heads cost something like $1500. In 1975 a new car cost around $5000. Now a new car costs $25000.
So if the prices were converted on the same scale a complete set of aluminum heads would cost $7500 and a set of aftermarket forged rods would cost $2500. Also, in 1975 there were no aftermarket hard parts for Mopars. None. I guess Arias or Venolia would make you a set of pistons but that was about it.
Enjoy it while it lasts!

R.

Dog,

Yeah I remember Arias would make you a 451 slug, with a .990 pin and you had to bronze bush your LY (or my prefered 383) rods. The undersize of the slug had "427" (chevy BB) cast into it.

You're right Arias and Venolia were about the only 2 Piston players that would make you one back then.

It was expensive but fun times, very 'hush-hush' back then in the pre F.A.S.T. days when we had a few very quick '383's trawling around

Everyone ( the customer ) has different needs,wants,expectations and especially budgets . I would love to sell every single customer a new crankshaft,rods and pistons.

That would be a perfect World indeed. The reality is that simply isnt going to happen. When you build enough engines as a business, and not a hobby, you find out you deal with an incredible cross section of " personalities". They have many many different requirements. This is where a builder needs to put himself in the customers shoes as if it was their money and build.

I agree that its always best to use new parts whenever possible. I recently did a 451 with stock crank and stock 400 rods. There was no need for this guy to buy a new aftermarket

crank and h beam rods. He took that money and put it into a set of Edelbrock heads. He wanted a torquey,simple drive it anywhere street car. Thats what he got.

The original poster asked some specific questions obviously so he knew more about how to make 451. Does he need a new crank? I dont know. None of us know his budget or needs at this point.

Good info here, but be careful of simply broadbrushing everyone into the same picture.

Bobby, i do agree on the 4.250 crank motors much of the time. Usually just makes sense, but again, not everyone wants or needs maximum torque and horsepower. What did thoseu 431's go in amd how did they run? What heads and cams?
I like the availability of the 383 blocks for the street/strip guys.

My first 431 went into a black 69 road runner with a 4 speed hacked trans tunnel for an e body shifter and 4.30 gears and epoxied 915 heads and that little '383' took 4x what it cost to build playin possum ( long odds) against some pretty serious street iron and trailered race cars with 'borrowed' plates.

I agree whole- heartedly and I'll always have a soft spot for 431-451's cause I cut my teeth on them after switching fromw2 small blocks.

sounds great u guy's are awesome with all this info thanks.

ok guy's who wants to grind a crank? lol but on a serious note i will pay as long as it's a reasonable price. thanks buck

Please pm me your phone number

Some good info posted. I built a low deck 451 in a 400 block back in 2001. I liked it. The main bearing journals on a 440 crank are 2.750" (nominal), and the 400 block used 2.625" (nominal).

In general, cutting the counter weights down to 7.25" diameter will clear the block. The bigger the bevel on the counterweights, like CompetitionWedge posted, the larger the counterweight diameter can be. A typical factory 440 steel crank has counterweights about 7.50-7.55" dia.

This picture shows where the 400 block interferes with the factory 440 counterweights. You can grind clearance here as an alternative.

With typical 6.76" long connecting rods, a piston with a compression height about 1.32" puts the piston near zero deck. Some specific rod lengths, pistons, and block deck heights may result in the piston down the hole (low compression ratio); so check the details (especially the machined deck block height) of the parts you plan to use:

+9.980 Block deck height (could be 9.97x after machining)
-1.875 Crank stroke divided by 2 (3.75/2)
-6.768 Connecting rod length (many H-beams are 6.760")
-1.320 Piston compression height
------
0.017" below the deck

And be sure the pistons you buy use the pin diameter to match the connecting rods you use (1.094", 0.990" common)

Examples of pistons:
Bore___CH__weight_ring pack sizes__piston pin size_ part no.
4.375, 1.320, 510g, 1/16, 1/16, 3/16, 1.094 x 2.930, 99494 Ross
4.375, 1.320, 527g, 1/16, 1/16, 3/16, 0.990 x 2.930, 99495 Ross
4.375, 1.313, 524g, 1/16, 1/16, 3/16, 1.094 x 2.930,131175 JE
4.375, 1.313, 525g, 1/16, 1/16, 3/16, 0.990 x 2.930,131174 JE
4.375, 1.300, 515g, 1/16, 1/16, 3/16, 0.990 x 2.930,K296A35 Wiseco

Check KB also. I don't know if all the above are still available, but they were stocking parts back then.

My 451 is low 700 hp, pushes my 3600lbs car 9.73to 9.85 all day. and the best news is its FOR SALE for way less than you could build it.

whats the specs if you don't mind.....

I have a 451 for sale . . . 3.45 x 4.560

im gathering parts hopefully kinda excited