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Building a 451.

3

383man

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We have been building a 451 for my sons Dart. It will be getting supercharged with a Pro Charger also. They are Diamond piston with a Scat crank and rods. We just got the cam in and degreed yesterday and checked all the cam timing which was right on the money. It calls for a 108 ICL and we have it at 109. Its also getting a girdle and we ill be finishing the shortblock this week. It came out at 9.2 comp right what we wanted. Ron

414415678.jpg


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One thing is for sure, you're one who knows what they're doing. Bet it will be a monster when done. Looks good!
 
451.Best damn engine I ever had. Built one in 2002. Has been in 2 cars and at least 50K miles on it now.Raced it for several years too.Still going strong.
 
Is it a low deck block and what heads are you going to be using, also what headers


Good luck with the build
 
The heart of Lemonwedge is a low-deck 451. Mines .040 over, so it actually measures 452”. It’s been a great engine for me. Built it on a tight budget over 10 years ago. It runs a craigslist sourced ‘64 413 crank, CAT 6.76 rods, and Iconn pistons. inbuilt it with the goal of going 11.50’s; it’s now approaching the 10-second door. Can’t wait to see how RonJr’s runs! Have fun Ron!
 
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67MPRFAN said:
Is it a low deck block and what heads are you going to be using, also what headers


Good luck with the build
Click to expand...

Yes its a low deck that 4.375 bore and for now we are using Eddy RPM heads. And its getting TTI 2" headers. Also the crank got a second 1/4" keyway they highly recommend when supercharging it. Ron
 
got 2 451's one I built in 2000 that I have to this day another that came in a car I bought in 06 currently on engine stand in line for rebuild.1st one has 426 crank 400 rods and venolia dome pistons 4.375 bore stage 6 heads and .625 roller cam.My other one is a 440 crank 440 rods wiseco flat tops so two variations of motors.I rebuilt 1st motor after 16yrs of service and hundreds of runs only rods started to show a little copper mains I could've reused and car would trap 6800 cant wait to put in my new project 67 belvedere.
 
LemonWedge said:
The heart of Lemonwedge is a low-deck 451. Mines .040 over, so it actually measures 452”. It’s been a great engine for me. Built it on a tight budget over 10 years ago. It runs a craigslist sourced ‘64 413 crank, CAT 6.76 rods, and Iconn pistons. inbuilt it with the goal of going 11.50’s; it’s now approaching the 10-second door. Can’t wait to see how RonJr’s runs! Have fun Ron!
Click to expand...


I remember the first time you ran your car and ran in the low 12's. Look at it now pushing 10's !!!! That's great. Ron
 
I am a believer of the 451. I have one I built for my '74 bracket Duster. I went the route of higher compression (about 12.4:1) on E-85 fuel. B1/BS Brodex heads. It pulls the 3000lb A-body to low 10s. I describe the 451 as "A big block that thinks it's a small block."

Recycler.JPG
 
my 451 has been in 3 cars a tube chassis 86 Daytona with iron heads ran 9.80 142mph in my 70 cuda it ran 10.40 last car 70 Dart with stage 6 heads it went 10 teens just under 134mph depending on track 1 or 2 mph slower its been a good engine and will see service in a 4th car.My other one I hope to be together by end of summer.
 
The 451 exposes why Chevy's 396 was so successful. Even shorter deck. My GTX has a 375 horse 440. And it does get beat from a friend of mines '55 chev 375 horse 396. Both very similar builds. Cars are close in weight. But the 396 just raps faster. (The GTX will run him down at the 1 mile mark)

And that's because the 396 has less rotating weight. Smaller mains. Like the Chrysler 400. Marry that with the 3.75" crank? And you have a even better 396. More cubes. And certainly better head flow. (And more options.) The failing's of the 396 was not a lot of head porting room. With less "Bolt on" aftermarket options.

Just my observations and opinion.
 
My 1st low deck 452 (400 block, turned steel 440 crank, low deck rods, 12.5 CR, home ported 906, 650+/- mushroom or roller). [email protected] in 3500#, 9.3@147 in 2350 Arrow. 7200+ RPM too much for the main caps & crank. Discovered end of season teardown, still running good.
 
66Satellite47 said:
My 1st low deck 452 (400 block, turned steel 440 crank, low deck rods, 12.5 CR, home ported 906, 650+/- mushroom or roller). [email protected] in 3500#, 9.3@147 in 2350 Arrow. 7200+ RPM too much for the main caps & crank. Discovered end of season teardown, still running good.
Click to expand...

what made you go with the shorter rod? I would think that the longer 6.76 rod version would create less rod angle / side loading. This would seem to be especially helpful in a 7k+ RPM application. Not questioning the build, just looking to discuss and learn.
 
The short rod kept piston pin was well below the oil ring, short rod works the intake harder for the tunnel ram, didn't think the rod angle was excessive. Still better than a 4" stroke short rod Chev. That 400+.040/3.75 spun up fast, I just didn't have the right gears in the car & the motor was enough faster than the previous one and over extended past the reasonable RPM range. The second 451 low deck I built used the LY rods. It was not quite as fast as the short rod version. Don't know why.
 
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In the '70's the L/R ratio (rod length/stroke) was a big deal. Grumpy Jenkins said lots about it. The L/R is one factor, combined with heads, cam, induction, block/cylinder strength. The weak link in both my low 451/452 was the stock crank. It had durability issues at 7000+ RPM. They were only good for about 350/400 runs. Never broke one though. Never saw any issues with side loading.
 
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