400 to 512

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oktire

oktire
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has anybody ran the stroker kit 400 to a 512? looking to put something together in a 71 duster bracket car and i like big cubes and their are lots of 400s around yet. any help!! good bad
 
One of my friends did this for a 1969 Dart. He sourced his whole stroked balaned rotating assembly from 440 Source. He also used their stroker windage tray and other valve train parts. 8)
 
As it's a strong performer and a great foundation for a bracket car. The bore is the largest you can get which means less to impede flow into the cylinder. The mains are the strongest possible from Mopar. The pistons are very short and light... I think it's a good idea. But there will be issues with headers depending on what he runs for a head package and what he needs for exhaust.
 
moper said:
As it's a strong performer and a great foundation for a bracket car. The bore is the largest you can get which means less to impede flow into the cylinder. The mains are the strongest possible from Mopar. The pistons are very short and light... I think it's a good idea. But there will be issues with headers depending on what he runs for a head package and what he needs for exhaust.
Click to expand...

One other thing about a 400 block is that it has more material around the main bearing bosses that makes it stronger. People used to laugh about my smaller 904 transmission but it had a riveted sprag unit from the factory and was a lot lighter than a 727. I was never able to break it. According to 440 souce and some other sources a 400 block is the best one to stroke.
 
you will love it I also used 440 source 512 kit, indy sr max wedge heads indy intake, hughes solid cam 578/260 850 demon tti 2 headers put in 72 demon for street use made 520hp at rear tires on street exh.
 
Just a note: If you install any stroker kit in a B engine yourself, be prepaired to champher your own main bearings. It isn't hard but it must be done or atleast checked. It's stupid that they make bearings for the RB engine factory clearanced for the wide radius that is on a race crank but they don't make them for a B engine. I built a 473 using a 440 source kit. The first crank I got had too much runout. They took it back reballanced another crank and sent it to me. Just alittle FYI:read2:
 
hemijoejr said:
Just a note: If you install any stroker kit in a B engine yourself, be prepaired to champher your own main bearings. I built a 473 using a 440 source kit. The first crank I got had too much runout. They took it back reballanced another crank and sent it to me. Just alittle FYI:read2:
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This is more of a function of 440Source product than representative of everyone... It's because the radius of the fillet is .250 and not smaller like others'. So the bearings don't fit it well. It's also a problem on the RBs when the narrow bearings ARE used...
 
moper said:
This is more of a function of 440Source product than representative of everyone... It's because the radius of the fillet is .250 and not smaller like others'. So the bearings don't fit it well. It's also a problem on the RBs when the narrow bearings ARE used...
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Thanks!! I thought it was just a B engine problem. I'd rather have the large radius and have to cut the bearings than have a weak crank. I hate it when that happens.=P~
 
i asked the same question in mopartech since im going to stroke a 400 , the responses were that for street&strip the best stroker kit was 470 , for drag race 500ci because of the oil ring support not so good for the street , and that the 512ci had a bad rod radio ... so im going with the 470ci since the car is going to be a dayli driver :snakeman:

hope this info helps you
 
oktire said:
has anybody ran the stroker kit 400 to a 512? looking to put something together in a 71 duster bracket car and i like big cubes and their are lots of 400s around yet. any help!! good bad
Click to expand...

You can use a 440 crank to stroke it and 440 pistons watch your heads
you may get into quench problems.
This set up makes for a real torque monster.
 
DODGESTRIKE said:
i asked the same question in mopartech since im going to stroke a 400 , the responses were that for street&strip the best stroker kit was 470 , for drag race 500ci because of the oil ring support not so good for the street , and that the 512ci had a bad rod radio ... so im going with the 470ci since the car is going to be a dayli driver :snakeman:

hope this info helps you
Click to expand...

I'd have to agree here. Although, the rod ratio in a 512 with 6.535" rods is 1.538 which is still better than the ever so popular 383 Chevy with 5.7 rods (1.520). The disadvantage to the weak rod ratio is the side loading on the piston and less piston dwell at TDC.

Oh yeah, I just pulled the trigger on a 512 for my Barracuda. The 451 that's in the car, for some strange reason, was built with a cast 440 crank. Basically a grenade.
 
There's a lot of debate on rod ratio. Personally my feeling is on a drag car, bigger's better and the shortcoming of short piston and short life and increased friction is trumped by the power possible with it. If it has to last, the longest crank I'd use would be the 3.915 using the RB rod and taller piston.
 
IMHO, I wouldn't be concerned one bit with rod ratio when using most of the current B block stroker kits. Changing the ratio sure won't help or hurt performance in any noticeable way.

If it's a street strip car, find a piston that has at least 1.25-1.3" compression height and get whatever rod length/stroke combo that fits your deck height. Find the lightest piston for the combo too. Sometimes the taller compression height pistons weigh less than a shorter because of the piston blanks that are used.

Full on race car, then the shorter pistons are OK. I still prefer something more stable. The 500" B block uses pistons that look like hockey puck, ~1.122 CH, which have been known to be a bit unstable in the bores.

Building a 512 cu in, 4.25", 6.535 rod, 1.32 piston is not an issue in the B block. Strong proven engine, make sure you have a set of heads to feed it.

And to carry on mopers comment re: 3.915.... You can put together a really strong combo using a 3.915 crank, 6.7 rod and 1.32" CH piston (same piston used in a 451 or 512). It won't be as hard on the block (ratio), stable/taller piston.
 
We have indy sr heads (ported but nowhere near maxwedge size intake ports) on a 12-1 499 with a sft cam with mid 600s lift and a bunch of 050 dur. runs mid 9s going solid roller this yr and we should see some gain.
Good luck
Jr.
Been three seasons on this engine with no issues,sometimes back to back hotlaps...no issues.
 
IMHO,the 470 has to be one of the best overall stroker combo's around. A race on sunday,drive on monday setup that has the reliabilty of factory engineered 440 bottom end dimensions combined with a very light piston. Makes for a torquey quick revving big block. We shall see how it responds to max wedge size ports...8)
 
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