340 "the hard way"...318 w 3.55 crank...thoughts

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Streetwize

Streetwize

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New here but not new to the Mopar web scene....

I read with great interest of Bobby in Georgia's 349" 318 stroker....here's something similar I'm putting together with "swap meet" parts


1988 318 Roller block, 30K original miles, bores look new, just a good clean up, square deck and a quickie hone.

3.55" MP P4529711 crank ($225 bucks)
MP P5249784 6" Aluminum Rods, standard SB big & little ends ($250 a set)
KB167 9.5:1 318 pistons 1.81 CH, standard width ring pack, floating pins ($ 238 @ summit)

Bowl ported closed chamber (63cc)E-heads with VJ, heads and Perf RPM intake were $1100 off E-bag

With this combo I calc right around 10.4:1 and 341 cubic inches.

Cam 236/240 @.050 Hydraulic roller (comp XE grind) .520"/.540" 112 centers in at 108, with 1.6 intake rockers shes at .554 lift

Perfromer RPM with an 830 Annular holley (might be a touch big but it's the one I have
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)

1 5/8" headers 3" collectors with 18" collector extentions

To be honest the temptation is there to throw a solid roller in her with a Victor 340 and really spin her up but I'm really looking to limit the fun to around 6500-6700RPM with the Hyper slugs (pretty light @ 507 grams) so the rods ought to last and last, the last Aluminum rod solid cammed 340 I built was a W2 that peaked ~7300 and went through the traps at 7800+ with much heavier slugs. (~20 yrs ago)

what do you think of this one???

Bobby, How far is Dallas Ga from Charlotte, NC?....I might need a new machine shop for my Mopar projects.
 
Streetwize,
I'm about 300 miles from Charlotte, but I have a nephew that lives just north of Charlotte in Huntersville.
 
Welcome Wize. I bought your manual a few years ago. Good tech info in it. Unfortunately it was on my old computer that took a dump, LOL
 
Rob,
According to your map I would be in New Georgia, and really I'm 1 mile from there just off Hwy 61. But I have a Dallas mailing address.
 
LOL, waaaada yankee kno....

I'll just drop you a line when I'm in the general hood......
 
Thanks Bobby.

Have you ever worked with one of those MP 3.55 cranks? The counterweights are pretty fat on them so It''ll need to be trimmed down from ~3.625 Radius to ~3.475 just to clear the rod....I'm thinking as an option I could use a cut down main 360 instead and come in at 9.600 in an uncut block.

If you have a good 360 crank core that'll work I could ship you the pistons, rods and B&M 360 flexplate (I need a balalncer) that would be cheap to ship.

I just want to get this motor built and done and back in the car....here's the car by the way....85" wheelbase 2750 pounds. Almost hikes the wheels with a stock 318!!

ROCKY VMP.jpg


Rockyside.jpg
 
Are you sure your thinking correctly on the crank width? The width isn't the issue, but the height from the rod journal to the edge of the counterweight is. I removed .150 but really only needed to go .080-.100 to make the pistons clear. Then I radiused the counterweight edges. I have a core here but it's a regular 360 crank and for the price of the Scat cranks you come out cheaper going this route then balancing to your parts.

Shipping is higher than you think. It would cost less if I met you half way or just came and picked up the parts. But it's your call.
 
I've always considered Crank WIDTH as the Centerline to the outside of the counterweights...IE 1/2 the crank Diameter.

I think we're talking the same language...just different "dailects" 8)

I think the 3.55 will be a good crank, the Aluminum rods are thicker on the small end and they have a clearance"cheek" which is roughly the same dim as the very bottom of the piston pin and that dimension is roughly 5.25" from the big end crank throw centerline....that's where my concern is. The dim from the B/E C/L to the bottom of the pin is 5.508". With 1/2 the stroke being 1.775" I think the factory CW (approx 3.625" from the CL) will clear but we can't be sure until we mock it up so I think some, but hopefully not much will need to be trimmed and possibly a chamfer will get us to .060" clear with out a lot of work.

Bobby, I gotta get the crank shipped to me from the west coast...if we can get something set up maybe I can just get him to ship it to your shop??? The Slugs and rods we can figure out how to get there....I'll be in Greenvilles SC for about 4 days next week (week of the 30th) , maybe we can meet up somewhere?

Originally, I was gonna put an 11:1 360 short from a buddy in it but it fell through, I figure since this is a 30K mile 318 roller block I might as well use it.

BTW, my name's Bobby too, some of the Moparts guys around here prolly know me.
 
Smaller bore and longer stroke than 340, I would think it will be torquey, and not as top-endish as the 340. Watch out for valve-to-cylinder bore interference.
 
I've already run with the E-heads, it's tight but it clears the 3.91 bore (or else Edelbrock couldn't sell them for 318's)

3.91 is still a decent bore size (plenty of stock block 5.7 LS1s running really fast with 3,90" bores), from the seat I don't think I'll tell much difference from a stock 340 bottom end...for one thing my rotating mass is gonna be a whole lot lighter.
 
When I did my crank I measured it a bit different, and yes I think that were talking the same thing. On my crank I went from the counterweight to the rod brg. surface and I cut it to 4" total length and I could have left .050 more on the crank and then it wouldn't have had to have so much mallory added to make it internally balanced. But this shouldn't be as critical on yours as your going with aluminum rods and lighter weight pistons. I will need the rings for 1 piston and 1 set of rod brgs. besides the rods and pistons w/pins. Plus the dampner and flywheel because of external balance.
 
Streetwize said:
I've already run with the E-heads, it's tight but it clears the 3.91 bore (or else Edelbrock couldn't sell them for 318's)

3.91 is still a decent bore size (plenty of stock block 5.7 LS1s running really fast with 3,90" bores), from the seat I don't think I'll tell much difference from a stock 340 bottom end...for one thing my rotating mass is gonna be a whole lot lighter.
Click to expand...

You should be able to tell a big difference from the engine your doing and a stock 340 engine, even in Tq.
 
Gotcha!

The mp crank (I think I'll go that way) should balance internal as it's the good 8053 (?) steel one, not the cast one. But It does have that PITA 8 bolt hemi register though. Assuming we work it out I might just let you sell me the rings and bearings (if you will/want) because I think if we use std bearings they need to both be fitted to the Alum cap allignment dowell and chamfered for the big radius fillet on the MP crank.

The rods are about 680G , not much lighter (if at all) than a factory 318 rod, the pistons are 507 with I think a 109 pin... I see you've run the KB167's before...nice piston for the $$$ but kinda unusual that they use a 'universal' (non siamese left and right) eyebrow.

Thanks!!!

Bobby
 
Sounds like a good combo to me. Should go pretty good in that little box. My father has a few Samuris, All ways wanted to stuff in a GN turbo 6.
 
The Rocky is a pretty stout well built little toy. it has torsion bars up front just like an A Body so it's real easy to drop in a V8
 
Wize, Nice to see you here. The environment here might be a little more friendly than some other spots for these ideas....lol. I think it would be a fun little package, especially in that truck. (Ok, maybe not truck.. rather... cart, box, whatever...lol)
 
Streetwize said:
Gotcha!

The mp crank (I think I'll go that way) should balance internal as it's the good 8053 (?) steel one, not the cast one. But It does have that PITA 8 bolt hemi register though. Assuming we work it out I might just let you sell me the rings and bearings (if you will/want) because I think if we use std bearings they need to both be fitted to the Alum cap allignment dowell and chamfered for the big radius fillet on the MP crank.

The rods are about 680G , not much lighter (if at all) than a factory 318 rod, the pistons are 507 with I think a 109 pin... I see you've run the KB167's before...nice piston for the $$$ but kinda unusual that they use a 'universal' (non siamese left and right) eyebrow.

Thanks!!!

Bobby
Click to expand...


Bobby,
No problem on getting the parts, as for the rod beargings I like the King engine brgs. as they are machined and fit the best without any further work. They may be a bit more but well worth it, and there made here in the USA.

The pin on a small block should be .984, the 1.09 that you stated would be a big block. Unless your rods need to be bushed.
 
LOL, 109 is the Grams of the pin!:-D

Gonna make arrangements to get this crank, I had the guy check it for starightness before I bought it, just got the green light.

Where can I reach you?

Never mind, found your website info! I just sent you a PM!

B
 
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