450 stroker thoughts

[qkcuda]

Due to my cam failure, I will have to pull the engine apart and rebuild it.  I was never entirely happy about the 440 pistons because a) they were heavy, and b) they had no valve reliefs.  I looked at the 440 source kits, and they look like a good deal, but the max piston size is .040 over.  My block is already at 4.38.  I already have a steel 440 crank I could have ground.  I have been looking at the KB hypereutectic pistons, which are avilable in .040 and .060 over.  I still don't have the engine apart to have the cylinder walls checked out, but I am leaning towards doing the 450 stroker as a good compromise between power and cost.  My question is using the 400 or 440 rod lengths?  The short rod pistons are about 700-750 grams while the long rod pistons are about 550 grams.  I like the lighter weight, but they also have short skirts with the pin in the oil ring groove.  Anybody have any thoughts one way or the other?

[satellite65]

I don't have any actual "hands on" experience with strokers but I never really liked the idea of the pin in the oil ring groove. I think short skirts look great on girls but as far as pistons go they may lead to piston slap sooner than a taller piston. The short piston is lighter but the longer connecting rod weighs more and would probably negate any benefit. You could try calling 440 source and see if they can get a set of .060" over pistons. Their kits seem to be a great value.

[daniel_depetro]

While gather parts for a 440 crank400 block based stroker myself I too was just wondering about this very question. I have read of guys using both and having great success.
I didn't realize the long rods needed pistons with the pin in the oil ring groove. Knowing this (thanks guys) I personally am staying away from the short skirt pistons. My engine is no super high performance/racing engine either. Currently I have a of brand new (re-man) low compression ~8.0:1 1977 400 (+.030") in my Dart Sport and am going to swap out the short block when it gets finished. I am currently running the 1967 915 casting 78.5cc closed chamber heads (when I sell the '68 GTX 4-speed I'll get a set of aluminum heads from 440 Source) Mopar .020" steel shim head gaskets, Mopar .484" lift camshaft, Edelbrock Performer RPM intake, Holley 770cfm carb, Mopar windage tray, 7 qt. pan & pick-up, Melling Hp oil pump, Holley 110 gph mechanical fuel pump, MSD performance digital HEI distributor...
I am hoping it'll be ~8.5:1 compression so it has some sense of power to it.

[bOb shingler]

there is nothing wrong with the short skirt pistons. that's the way i built my 512" motor. 4.250" stroke and 7.230" rods with a 1.320" compression distance but that's not the real reason. the short skirt long 440 rod will give you a broader torque curve than the 383/400 rod motor which will be pretty much done with torque at a very low rpm to be real useful. i guess if you use 3.23 gears that would spread the torque curve out little for you.

[qkcuda]

That's interesting bOb.  The KB 280's actually have a 1.327 compression distance, almost the same as yours.  The rod ratio with the long rods works out to about 1.8 (same as a stock 440) while the short rods come out to 1.7.  Is that enough to make a difference?  I calculated yours to be 1.7 also.  The 440 Source 400>512 comes in at 1.537.  I've heard rod ratios argued both ways in the past, and I'm still somewhat fuzzy on the theory behind it.  I'm also concerned about the weight.  The thing that used to bother me when running the old engine up to 6000 RPM, was that each piston weighed slightly over 2 pounds.   

[Dcuda69]

It can be done. I have a 3.900 crank in a 400 block,6.76 Manley rod,1.270 CH Diamond piston,.990 pin and the pin is not in the oil ring! Sorry I don't have the part#(can't find paperwork) all I have is some notes I wrote during assy. Maybe call Diamond and talk to them. I know not the cheapest way to go,but it is a whole lot of fun! Pulls like a freight train through the whole rpm range. I'll keep looking for a part number and post it if I find it! Good luck with your build!

[Crazy68Dart]

I am almost positive a low deck 451 build can be done with the longer RB rod and a piston that does not have the oil ring into the pin area.  Did you check Ross and JE?

[dusterdarryl]

a B block 440 crank and rod 451 does NOT have the pin in the oil ring lands, KB, JE, wiseco, etc etc all have off the shelf slugs for them,  take your pick on compression,  pin size will more likly have to be a .990,  put it together with good heads and buy a rev limiter these little B blocks scream & love it, to hear one scream click onto to youtube and dail in "prosport norwalk"  thats a 9sec footbrake car, yes read that again... only 451 cubes,  FOOTBRAKE, high 9s natural asp,  pretty dam good I say.  the B block 451 is the forgoten stroker since everyone thinks they need 500 cubes etc etc to go fast, if your on a budget then think 451 B block, all the torque of a 440 & a piston that weighs below 550grams,  a block that weighs less than a 440 block & is stiffer because its shorter, more room for headers,  its a win win situation, can you imagine the look on your chebby mates face when you beat his 454 camaro & say oh it's a old 400 I tuned up, its runs ok

[chargerbr549]

I know when you talk rod ratios you will get alot of different thought and opnions so here is mine, if you are staying with a stock flowing type head cast iron head l would lean towards the long rod set-up they seem to work better together whereas if you are putting good flowing heads on it you should be fine with the short rod set-up also if you go with the long rod setup bush the ends of the rods down to .990 to reduce weight and helps keep the wrist pin out of the oil ring groove. My two cents.

Kevin

[qkcuda]

The KB hypers do have the pin in the oil ring area, but they use stock type 1.094 pins.  Their forged pistons use .990 pins and are not in the pin area.  I have not made any final decisions yet.  Alot depends on what I find with the block, and also if I can get a deal on some aftermarket rods.  I'm thinking 3.75 stroke, aftermarket rods, 550 gram pistons, and a mechanical roller valve train would be good for some decent revs.

[bOb shingler]

That's interesting bOb.  The KB 280's actually have a 1.327 compression distance, almost the same as yours.  The rod ratio with the long rods works out to about 1.8 (same as a stock 440) while the short rods come out to 1.7.  Is that enough to make a difference?  I calculated yours to be 1.7 also.  The 440 Source 400>512 comes in at 1.537.  I've heard rod ratios argued both ways in the past, and I'm still somewhat fuzzy on the theory behind it.  I'm also concerned about the weight.  The thing that used to bother me when running the old engine up to 6000 RPM, was that each piston weighed slightly over 2 pounds.   

the point i'm trying to make is try to keep as long a rod as you can get in the motor reguardless if the pin is in the oil ring to have a broader torque curve. look at the rod ratio on a 383/400 motor, it's 1.88-1 and you know these make good power through out the band and still at the high revs too. can anyone explain why they feel it's a no no to have the pin in the oil ring.

[Crazy68Dart]

That's interesting bOb.  The KB 280's actually have a 1.327 compression distance, almost the same as yours.  The rod ratio with the long rods works out to about 1.8 (same as a stock 440) while the short rods come out to 1.7.  Is that enough to make a difference?  I calculated yours to be 1.7 also.  The 440 Source 400>512 comes in at 1.537.  I've heard rod ratios argued both ways in the past, and I'm still somewhat fuzzy on the theory behind it.  I'm also concerned about the weight.  The thing that used to bother me when running the old engine up to 6000 RPM, was that each piston weighed slightly over 2 pounds.   

the point i'm trying to make is try to keep as long a rod as you can get in the motor reguardless if the pin is in the oil ring to have a broader torque curve. look at the rod ratio on a 383/400 motor, it's 1.88-1 and you know these make good power through out the band and still at the high revs too. can anyone explain why they feel it's a no no to have the pin in the oil ring.

I think everyone's biggest complaint is longevity, but considering these cars, and generally low miles per year, I'm not sure how big of an issue that is.  I guess the other might be a contaminant in the oil making its way into the pin area since it is no longer protected by the ring, but not sure how probable that is either.

An RB rod 383/400 would be interesting.

[ksdartguy]

I have a 400/500 kit with the pin in the oil ring. I have run a few thousand and dont see what the problem is.
The higher the pin the less piston rock you will have. As far as oil ring controll, the oil ring is a wiper ring,
not a compression ring.Maybe Im just not hard enougth on mine, but Ive run 150hp of N2O along with well over
600 on motor. Plenty of street use and a few trips to the track. NO Problems.
Its 1.120 CH.

Rick

[qkcuda]

Well, I went to Moparfest today and talked with some buddies I saw there.  I think the 450 stroker is a go, with the long rods and KB hypereutectic pistons.  I already have a 440 steel crank, and I am getting a virgin set of 440 rods.  I may also have a line on some adjustable rockers.  I came home with some enthusiasm again and pulled the heads off the motor. (It is possible to pull the heads in the car with Hedmans!)  The heads look great, no piston to valve interference.  The cylinder walls have some light score marks which you can see if you shine a light on them, but cannot feel with a fingernail.  I'll have to have it miked to be sure, but it looks like it would clean up with a light hone, so I may be able to get away with .040 over pistons.