BB stroker 440 or 400 block?

[V8punch]

Friends, I have a challenger with a 383 hp and think of-changing him by a stroker. I ask the help of you for decide between a 440 (up 1971) or a 400 (1971) for the project. It will be a motor that permit me good please upon driving but nedd to be well strong. I think of a kit 440 souce, performer rpm or victor heads and a camshaft 240 to 250@. 50 down the lifth of. 600. It Will be better use a block rb or a b (400) ???
Thanks.

[JVMopar]

b better bore to stroke ratio

[machinist 48]

I aggee on the B motor am building 383/438 stoker to go into 70 D100 the tq-hp # are interesting

[rumblefish360]

I'm on board with the low deck even though it has a smaller bore.

[JVMopar]

400 had the largest bore of all big blocks.

[DartGT66]

In my opinion, depends of the stroke and the purpose you want. B engine has got a lot of advantages, but I would not build a 4.15" stroke 6.76" rod combo, because the 1.1" compression height is just too small. In a street engine you want soem piston height to keep it more stabile in the bore, and personally I don't like the idea of oil rings in the piston pin bore.

[jelsr]

Like DartGT, I would go for the 440 for the 4.15 crank unless it was a balls to the wall strip rig. The 400/451 is a nearly perfect engine and with RB rods and 3.75 crank the oil ring is nearly in the pin hole but still has a fair skirt ratio. The 440/500 setup has a half inch more comp ht than a 451 and weighs only 619 gr. (Ross)

[Steve DeTar]

B block....it has smaller mains, and a shorter, stiffer cylinder wall.

[Steve DeTar]

I forgot, what kind of horsepower and expectations are you looking for?

[DartGT66]

The B-block is definitely better, it's a more compact package and shorter unsupported cylinder walls, making them stiffer than RB cylinders with the same thickness. However, the combo is also a dictating factor, like I said earlier the 4.15" stroke and 6.76" rod makes the piston too low for anything sensible outside all out racing, but a 400 block with 4.25" stroke and 6.535" rod uses the same pistons as 400 based 6.76" rod '451's. If you go with that much displacement, you definitely want good heads. The port window in the stock mopar BB heads is pretty small even for a 440, and in a 500 it will keep the power level down compared to bigger ports. Personally, having some experience with the Victors, I would avoid them and take some Indys instead. Many people do not like dealing with Indy directly, but they have a lot of good vendors that can be used for the purchase. Buying any aftermarket head, it's actually better to buy them from a reputable engine or cylinder head shop, or at least have them gome through by one. The quality of for example the deck surfaces, valve jobs and guide clearances may be questionable. Most aftermarket heads really wake up with even minor pocket porting, money well spent (except with Edelbrocks that have the bowls blended out of the box, and work reasonably well without additional port work) .

[rampage_82]

I'm soo jealous, all you guys get to play with aftermarket heads...

[DartGT66]

If ordered now, 440 sources aluminum heads should be 899$ complete and avaialble early 2008. The Edelbrocks are int eh 1400$ range; I'm jealous, that someone can still afford to prep old factory castings!

[V8punch]

Thanks guys, I dont now yet whitch block I'll buy... I am thinking to use my 383hp block with 440 crank and rods, maybe BB chevy rods, but did not I find yet pistons for this application. ... as alone I will go to america buy the pieces in 6to8 weeks, I will appreciate continue pass myself information. If I'll use 400 block and 440 cranks and rods, witch pistons can i buy?

[pishta]

Look into KB "251" pistons: 440 crank, 440 rods into a 400 block. Check the throws in the 400 block to make sure there is clearance in the block, should not be a problem with a built stroker crank, but an issue with a turned down 440 crank. The Holley Street Dominator is a great intake for its low hood lines and good street performance.

[V8punch]

I am thinking of an 3,915" crank, connecting rods 6,535" and pintons kb 784 (bb chevy, bore 4,250 to use with my 383 block) with work in the top for lower .06"... probably be a very cheap configuration to be done....

[RacerHog]

Build the big one.......

[rampage_82]

The only problem that I know of, when using the BB Chebby rods, is that they are a little narrow. The only real thing this hurts, is that you are slinging a lotta oil around your motor.

[RacerHog]

Just use the Callus Stuff.......It will serve you well.....

[djswwg]

It depends on how many cubic inches you want to end up with. Bigger always makes more power, everything else being equal. If you use the B block, it's more of an "efficient" engine, size-wise. More header clearance, easier to change the spark plugs, lighter weight, shorter and therefore stiffer cylinder walls and pushrods. The problem is that if you make over 470 cubes, the deck height requires really short rods and the rod ratio suffers accordingly. Still, a very nice motor. For anything bigger, use the RB block. They really make a great engine with a 4.15, 4.25, 4.375, or 4.5" stroke. You can use up to a 7.1" rod with any of these cranks and the piston compression height is determined according to the stroke used. An RB block is really a waste if you don't use the long cylinders to their full advantage. The stock stroke and rod length of a 440 mandates the use of a very long piston, (over a 2" compression height) which makes them very heavy, that in turn hurts performance and is harder on rod bearings and con rods. Having said all that, a stock stroke 440 is still an excellant engine, but they get way better in a hurry when you stroke them using the design parameters mentioned above. One more thing, don't be afraid of short pistons. First of all they weigh less than their longer counterparts and therefore accelerate and decelerate quicker, and are much easier on the rest of the rotating assembly. I have built several engines with VERY short pistons with no issues. Stop and think about it for a second. The pistons are manufactured with a skirt long enough to prevent excessive piston rock as long as the bores are clearanced properly by the machine shop. Always warm up the engine properly before using heavy amounts of throttle and use a good quality oil, preferably a synthetic. Best of luck on your project, let us know what you decide to build and how it works!.........djs

[DartGT66]

I have experienced problems with very short pistons, and would like to have at least 1.3" compression height in a street & strip engine with the oil rings above the pin hole. I wouldnät be too worried about the rod ratio, in my opinion it's a matter of lesser importance. Both the 400 based 3.915" stroke and 4.25" stroke engines commonly use +0.4" long BB chevy rods, 6.535". Both still with better rod ratios than for example stock 454 chevys, which seem to work somehow despite of their rod ratios

[djswwg]

You are right DartGT, those engines do work well, but the fact remains that the longer the rod, the less cylinder side load you have, resulting in more power and less rapid cylinder/piston wear. What exactly are the problems you have had with short (less than 1.3") pistons?..............djs

[DartGT66]

Our problem really wasn't because of the height, I have just heard that in the long run there might be some because of the lesser piston stability, but we really haven't driven a lot with our lowest pistons (with 1.12" compression height). Our problems were because of the ring position; for some reason something "foreign" got from the pin hole to the oil ring grooves, and locked a couple of them up. We used support rails, most likely using pin buttons instaead would prevent this problem.

[V8punch]

Thanks guys... I thinking to buy a 400 block and a 440source 4.150 complete and balanced kit.... I'll need 2 or 3 days more to decide it.... I eas thinkink about 3.915, but hensley said to me...use 4.150!!!! I think its an order!!! hehe...

[djswwg]

DartGT you really shouldn't have any problem unless the assembly wasn't done right or there was dirt or other junk in there when it was put together. I talked to the tech guys at Ross and JE about potential rocking or stability issues before I bought my first set and they both said if there was a problem it would be corrected before the pistons were released for sale or they would not make/sell them. JE makes a big block Chev piston with only 1.06" compression height and to my knowledge(I've never used them) there are no issues with them .......djs

[DartGT66]

During the assembly, there was no dirt, we are pretty strict with cleaning and have good possibilties to do that well, but from somewhere something foreign still got in to the oil ring grooves. We replaced the pistons because of changing cylinder head type, and haven't had problems with the new ones. With the 451 and 1.32" compression height we run about 30000 miles hard in an engine that evolved from about 550 hp to 713 hp during those ten years, before replacing them. There seemed to be no problems. I think it may be more like "I feel, that" kind of thing, but I wouldn't use pistons with extremely low compression heights in my street engines.