low buck rb stroker

[dave571]

OK

I was pondering this earlier. I have a 76 440, from a 3/4 ton. I was planning on re ringing it, and using it as is. Upon taking some measurements, Ive discovered that the pistons are .150" down the hole. That makes it about 7.6:1 compression.

I want it for towing, but that still seems too low.

I was thinking this. By offset grinding the crank to a stroke of 3.90, I can still use the same pistons. That reduces the deck clearance to .075". It also increases the displacement to 457 cid. The combo works out to 8.97:1 compression. Big displacement and medium compression.

Good for towing, and future bolt-on upgrades

All for the cost of a crank grind, rod resize, and an engine ring and gasket kit.

Am I mental??

[DartGT66]

So you mean rezising the rods to chevy size? I wouldn't do it. The rods will become shorter and weaker, bolt length will be different etc. Iwould just change in to higher compression height pistons, or if willing to make a stroker, use a CAT 4.125" crank. 'It's unde 400$, and you could propably use low compression 400 pistons.

[dewme5]

well, it's a good plan, and is actually pretty common. if you can get a good shop to do it, for a good price, great, other wise it might be better to just get a stroker crank.

When you do the offset grind, are you going to weld up journals, and keep the same bearing size, or just grind it to a smaller size. I've heard of some using acura rods I believe, = smaller bearings, and therefor more power. I don't know which rods, but a little research shouldn't be hard.

Dont forget that you are going to need a balance job too! You are going to change the balance alot with this setup, and you might end up needing a new harmonic balancer (a good idea anyway), and move the weights on your TQ converter if you have any external balancing.

I say, for the money involed, rebuild it stock, keep the pathetic compression ratio, and then put about 15 pounds of boost on it.!! that'll really pick up the power.!

[panic]

Acura rods? They're 5.4" long.

[rumblefish360]

Muscle motors has that deal I think. That offset crank and chevy thing is common to do with B/RB engines. They also have other stroker kits.
http://www.musclemotorsracing.com/mu...sh/intomm.html

[dirty dan]

econemy was the key word.
Get diferant pistons and have it ballanced.
remember the simpler it is the longer it will last.
Well most of the time any way.

[dewme5]

panic.

Originally posted by dewme5
acura rods I believe, = smaller bearings, and therefor more power. I don't know which rods, but a little research shouldn't be hard.

yep... "don't know which rods, but a little research shouldn't be hard."

[djswwg]

Or if you can score a set of '67 GTX heads (916) that would be faster and perhaps cheaper....djs

[Slingshot383]

You can turn the rod journals down to 2.200" and get rods the length you need fairly cheaply. You will need to rebalance the rotating assembly, and balance it internally so you don't need the oddball balancer and flywheel weight. The motor will be plenty strong, and will rev quicker due to less mass. Mopar over engineered their crank and rods, giving us a lot of options when changing things.

Another, even cheaper fix would be to get Hemi NASCAR rods. They are longer than a 440 rod and will get the piston up to 0.0 deck, or nearly so. You will still need to rebalance the motor though.

[dave571]

Where would I get Hemi Nascar rods?

They sound expensive.

[b-1ken]

You're going to all this trouble to raise the compression ratio of a tow motor? First it was a re-ring and now you're contemplating buying special rods and you want to use the old pistons? Your priorities seem way out of whack. Why don't you bore the thing out so you have fresh cylinder walls and get the correct pistons?

[dave571]

Thanks for the advice b-1ken

I guess I thought that this was a discussion board, and I was just thinking about ideas.

It was ideas like this one, that lead to the popular stroker motor we all hear so much about, the 451.

The first versions of the "B" stroker engines were 400's with stock pistons, and a 440 crank. The difference in stroke meant that the piston came up .185 more in the cylinder. Since the pistons were over .100 down the hole to begin with, the pistons only needed to be turned down the extra .085 to be flat tops.

I supposed those guys could have just bought taller pistons to beef up the compression in the 400's and skipped the stroker idea. Or, they could have built .060 over 440's to have an engine with the same stroke, and bigger bore, than what has become known as the 451.

But since they didn't, the rest of us can benefit from the thought process they went through.

As for my engine, since the bores are true, I will probably just re-ring it, as planned, and live with the lower compression. I have driven this engine, when it was still in the truck it came out of. It had torque, torque, and more torque. It didn't care if the truck was full of gravel or empty, it pulled like mad. Besides, the lower compression will also mean I can run regular gas. That is something currently not possible, in my 400.

Hey dart gt66, where can a guy get info on that crank??

djswwg, do you mean 915 casting heads, or 516 casting heads? Since you said 67, I'm assuming 915, but the 516 was still in use, that year too. I'd like too do that(like you said it's quicker), but both of those are "leaded fuel" heads, and won't stand up to the hauling without hardened seats. I had hardened seats installed in the 516's I'm using now, and it was a fairly pricey procedure.

Lot's of interesting ideas turning up on this thread.

[Slingshot383]

The Hemi's have a longer rod than a 440, and the Hemi NASCAR rod is longer than a stock Hemi rod. They both cost the same, it's just a matter of finding them. Hemi rods are heavier than 440 rods, so that is why it's a good idea to rebalance the rotating assembly .

[dirty dan]

Originally posted by dave571
Thanks for the advice b-1ken

I guess I thought that this was a discussion board, and I was just thinking about ideas.

It was ideas like this one, that lead to the popular stroker motor we all hear so much about, the 451.

The first versions of the "B" stroker engines were 400's with stock pistons, and a 440 crank. The difference in stroke meant that the piston came up .185 more in the cylinder. Since the pistons were over .100 down the hole to begin with, the pistons only needed to be turned down the extra .085 to be flat tops.

I supposed those guys could have just bought taller pistons to beef up the compression in the 400's and skipped the stroker idea. Or, they could have built .060 over 440's to have an engine with the same stroke, and bigger bore, than what has become known as the 451.

But since they didn't, the rest of us can benefit from the thought process they went through.
Lot's of interesting ideas turning up on this thread.

Thats right

[djswwg]

dave571, you are right; I hit the 6 instead of 5! happy head hunting!!......djs

[DartGT66]

Info about cat cranks (and other cat parts) http://www.catpep.com/Products/Produ..._Category_ID=5

[jelsr]

The Nascar Hemi rods are hard to find and weigh a ton (1/2" rod bolts & over 7"). The offset grind to 2.2 is popular but the 2.2 Chev rods are in-between the B and RB rods at a little over 6.5' so you will be lower in the bore than before. Aftermarket 2.2 rods are available in lengths to 7"+ but then you are starting to lose the bargain aspect. The std Hemi rod is 6.86, just shy of being .100 longer than the RB but uses a 1.03 floating pin. Just a FYI post.