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351 Modified stroked to 444

hdsadey

Well-known member
So on another post I let it be know we were working on a 351 Modified for a 78 Bronco. The customer ordered a 4.350 Molnar stroker crank along with rods and pistons to produce a total of 444 cubic inches. Bore is 4.030. Stock iron 2V heads, Edelbrock intake, Bullet hydraulic roller cam, Scorpion 1.73 roller rockers and a 650 Holley double pumper. Final numbers after the dyno tuning is 448 hp at 4700 and 547 tq at 3800. Crane scaled the engine at 520 lbs. Thought this would make a contender for a direct drive power plant. Bolt on a set of aluminum heads and lose another 40 lbs. Whatcha all think? Here's the link to the dyno pull.
https://www.facebook.com/1384552318518946/posts/2281029972204505/
 

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Unfortunately the dyno doesn't wanna let us pull down that far with effective results. Plus since we weren't building it for an airboat, max numbers is what we were concerned with. I would love to experiment but I don't own the business so can't play the way I would like! I'd be dragging it down low out of curiosity.
 
My parents had those motors, he had th 400 m in the 78 bronco and a 351 in 77 f150 and put a rebuid 400 back in the truck. I always thought they were a pig of a motor, but you could pull a boat or trailer and it didn,t really know it was there. I always wondered how it would swing a prop, but motor was heavy. :bounce:
 
The web says in 1978 the 351m in a truck made a whopping 155 hp @ 4000 rpm. Significant power can be brought out of these but it is expensive. 480 lbs. with aluminum heads. Might be an alternative.
 
john1edwards said:
My parents had those motors, he had th 400 m in the 78 bronco and a 351 in 77 f150 and put a rebuid 400 back in the truck. I always thought they were a pig of a motor, but you could pull a boat or trailer and it didn,t really know it was there. I always wondered how it would swing a prop, but motor was heavy. :bounce:


The 400M made decent torque vs the 351M, was a pretty good engine for towing or 4X4
 
hdsadey said:
Crane scaled the engine at 520 lbs. Thought this would make a contender for a direct drive power plant. Bolt on a set of aluminum heads and lose another 40 lbs. Whatcha all think? Here's the link to the dyno pull.
https://www.facebook.com/1384552318518946/posts/2281029972204505/

Wow, that's surprisingly light. I thought they were heavy like a Cleveland? That number is lighter than a SBC?
 
Weight can be confusing as some is fully dressed and other is bare block. This site has some data to compare of various power plants.
It's data does support the Fords being light. This may be why they do not handle boring well and tend to run hot above a .060 bore in some platforms. Hope it helps

https://www.gomog.com/allmorgan/engineweights2.html
 
So this is the way we weighed it. Less distributor, coil, headers, flexplate, and pulleys. 5 qts. of oil but no coolant. 520 lbs. Assume 40 lbs less for aluminum heads. Fully dressed I would put it at 500 to 520 lbs.

351m and 400 are the same block. Basically a tall deck Cleveland.
351m is 4.00 bore x 3.50 stroke
400 is 4.00 bore x 4.00 stroke
Our configuration is 444.... 4.030 bore x 4.350 stroke

Neither Chevys or Fords small blocks do well .060 over on stock blocks. Other than Dart or World Products I wouldn't try it on anything other than big blocks.
 

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hd,

So now you have done a Cleveland (Modified) engine here and a Windsor previously, what are they all about, how do they compare, Windsor, Cleveland and Modified? In my mind, Cleveland is a big block and Windsor is a small block :?:
I have built a couple of 302's that jumped. :bigsmurf:


Reference your Windsor:
hdsadey said:
So I got my Chinese crane scale today capable of 1100 lbs. After I tested it for accuracy by weighing myself using a short lifting strap and making a swing off of my engine hoist (lol), I hooked up the engine. The weight as dynoed minus carb and headers it comes in at 439 lbs. Assuming the cradle weighs maybe 10 lbs, it should be 429. Pretty lean for a Windsor considering they are 510 in stock iron! I will weigh the 302 coming off shortly. Time now to build the stainless headers.

file.php

https://southernairboat.com/phpBB3/viewtopic.php?f=48&t=71651&start=75
 
At this point I'm not sure I would trade. I would have liked to more testing at lower rpms but since this wasn't an airboat build and I just work there not owning the shop, not much leverage on what goes on as far as dynoing. I believe the 335 series engines are capable of swinging a good size prop in a direct drive application. Lighter than a Caddy but not able to support the cubic inches. The 4.350 stroke is longer than a 500. We picked up power going from a 750 carb to a 650. Cam selection would be critical. This Bullet cam was ground specific for a 78 Bronco with a C6 trans. Having a grind made to move the power down further might be the key. 444 cubic inches with 448 hp and 547 tq and 520 lbs. is hard to rule out the possibility. My 408 weighed 439 made 426 hp and 516 tq at the same rpms. Is it worth the extra weight? With the right cam who knows. Other than a massive head difference the only other big factor is the stroke. If I had the dough I would certainly like to try it!!!!
 
Branch is taking the Caddy platform to 570 inches with a factory crank, just not for everyone...lol

There will be a 570 DD on his Jimmy White boat with 3 Q blades.

Several 542 DD engines out there now holding up good so far.
 
What kind of numbers is Mr Branch getting out of those big Caddys? Nothing against gearbox guys but I believe there's a real art to making an automotive engine work well with a direct drive. I'm certainly no artist by any stretch. Mr. Branch I think deserves that title.
 
It's about the prop with him HD he built a 514 roller motor for me in 2013-2014. It was a pump gas build but nothing left undone.

It would spin a 2 blade (76) inch NGQ pitched around 3 ya don't see many of the 540 gang doing that. Generally they are 72 inch blades.

The DD engines in the 542 roller family spin 3 blade props with authority.

A buddy had a high compression 509 non roller it spun a 74 at 3050 with a pitch of 3 hard.

After putting a big inch Cadillac on a gear drive it is hard to go back to DD
 
No dyno time? How do you know if the tune is correct or what kind of numbers it produces? Seat of the pants tuning is wonderful but can leave power on the table.
 
I get that you trust him. It would be nice if the rest of the world got to see what kind of power he's makin. Don't want to know the man's secrets just curious of hp and tq. Prop is just an air dyno but can't give hard numbers.
 
I get that you trust him. It would be nice if the rest of the world got to see what kind of power he's makin. Don't want to know the man's secrets just curious of hp and tq. Prop is just an air dyno but can't give hard numbers.
 
SWAMPHUNTER45 said:
As far as numbers go well PROOF IS IN THE PROP
Swamp,
Ya'll's Camaro must be putting too many smiles on your face, I mean that's a LS Slogan :fishing :stirpot:

SWAMPHUNTER45 said:
It would spin a 2 blade (76) inch NGQ pitched around 3 ya don't see many of the 540 gang doing that. Generally they are 72 inch blades.

My AV spins a 72" NGQ pitched on 2 and I will take on your whatever caddy any day of the week, usually I have to go in, make a few passes to mash the grass down (laugh a bit :bom: ). Next I have to get all the women off the damn overloaded thing and drop off my rider to shake the grass rake so my stern heavy buddy can get back to the main trail. :slap:

So let's talk Torkey.

The measure of spins "X prop at Y pitch" is only a measure at one point and that is it. Further, that measure is only valid for a specific boat or as a stand alone on a test stand with no boat. Prop Inlet conditions mean a lot more than outlet conditions, but that is a different discussion.

HD,
There is no doubt that a dyno run gives a whole bunch of useful data for many applications, but at the end of the day, the prop is the dyno of interest. Take two engines, both identical except one has less rotating mass (inertia). Standard dyno runs, slowly increasing the engine load, basically steady state, are not going to show a difference, but the low inertia motor will throw the prop better hands down. Most people would say the low inertia motor makes more torque. I would say they both make the same Pork, but one is more Torkey.

The slow grow dyno run gives a PORK curve. The Pork curve measures Pork vs. RPM for the engine at WOT. That's a max PORK curve, but its also a Hp curve in disguise (seriously, what's the difference? RPM is already part of the curve??). Throw Hp through a gear box (or axle gears)and you got Pork. Pork is most useful towin my airboat to the launch. Towin that big sail down the highway while cussin yankees, well my turbos are gonna be spinnin and the diesel is gonna make Pork, the only way you know you are making more pork is watching the boost gauge. That's some damn Pork :violent1:

For an airboat application, you definitely want Hp/Pork, start there. But everything below max Hp/RPM is response. Torkey is a measure of how the engine responds instantaneously. Torkey is torque vs time (in milliseconds) as opposed to torque vs. RPM. Torkey is taking flight in an instant. How much torque does the mill make flat off the bat in the first 2 seconds when you mash the gas? That's Torkey.

So mull that over and figure out a way to compare/tune Airboat mills. If you think about it, you will understand why the dedicated airboat builders don't waste money on dyno runs or publish data, who would understand it :dontknow:
 
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