Mopar crank deal

[355 racer]

I don't know if you guys can use , but the crank I am using has been put on clearence sale by MOPAR .It is an 'A' engine crankshaft, surface hardened, forged 1053 steel small block crank,featuring radiused fillets at main and rod journals, eight bolt flanges,straightness checked (318 mains).This is Part # P4120312. This is a 3.45" stroke.This crank listed for $ 960.00 two years ago. I paid $ 760 at dealer cost +5% .It is now on sale at $312.00 .There are a total of 10 cranks in this series in catalog, including 340 6bolt,and 340 8 bolt. Don't know if these other cranks are "ON SALE". They only had like 13 of my type left.
Harry

[DYNO360]

Who is selling these cranks? Can you run them in both 318 and 360 blocks?

[crackerg]

355:

Thanks for the info, I have been wanting an afordable steel crank, I have a block thats prepped and now and the crank will go nicely. The cast crank just wont cut it as long I got 3 seasons out of the last one and then the cracking started. I think with the steel crank and the oil prep the small block will be healthy for many a race.

[355 racer]

Cranks are available from Mopar Performance dealers. I buy locally from BERGEY'S DODGE in Franconia,Pa. All parts are cost + 5% and available in 2-5 days from time of order. Talk to Russ at parts dept. E-mail me for phone #.
Harry

[isky3x]

Using this steel crank what rods and pistons will work with the 360 block. Can you use the stock rods and KB 191 pistons in a 360 block ?

Please let me know.

[Rich33]

It has 318 main journal size. Wont work in a 360. Stroke's shorter, too.

[isky3x]

SO I guess unless you plan on running a 340 block with some sort of storker set up these cranks are not good for much. thanks again mopar performance for nothing, lol

[355 racer]

There are 10 different cranks available with a series of different strokes and main combinations. 318 main just happens to be what I run. A 340 main is also available . I suggest you spend the $5.00 for the catalog and check with your MOPAR dealer. Sanborn may also be able to shed some light on what exactly to use. He is the MOTOR GURU. The 360 race billet crankshafts offer 4 different strokes from 3.55" to 3.79". I don't know weather these are on sale or not. Please check your dealer.
Harry

[POWER]

The 4120312 crank is the only one on sale. Good price, i just bought three of them. Only 8 left in warehouse.

[isky3x]

355 and POWER,
Thanks for the info. The price for the crank thats on sale is a good deal, however without a 340 block its not a lot of good, would yall disagree ? Or tell me what can you build other than a 318 or 340 with that crank ?

Then when you talk 340 or 318 NO ONE makes a high compression out of the box, so there is still another issue to deal with.

All those other cranks in the mopar book are $900 bucks. And the other cranks are of course the ones you need because they can be run in the 360 block.

There are pistons available for the 360 off the shelf with good compression numbers.

This is a sad state of affairs, heck you can buy a 38lbs ultralight steel billet crank from SCAT for a chevy for about $960.

So meanwhile we are having to get buy with cast cranks that are a lot heavier and wont last as long, or spend about the same and still have a heavier piece.

Weight is really key to carrying corner speed I know my competition is running all lightweight stuff and MOpar offers none of this for us.

[355 racer]

I use the crank in the R3 355CI block. The motor is 33# heavier than the 358CI chevy that I had been running. If you use the old 59deg.design,than your 360 parts will all be usable. A new block is $1960 plus crank for $2300.00 total. The up side is that you have more torque and HP . Since I had nothing to start with,and the other guys were breaking cranks, I went with new,including the 48deg.valve train. Just finished the 2nd.year,all positive. Run about 700 laps between freshening, bearings all like new.
Harry

[Racedude_5]

355 are you saying that your motor with the new heavy block is only 33 pounds heavier than the chebby? I have never got anyone to tell me exactly what a chevy weighs. (steel block aluminum heads aluminum intake w/oilpan w/water pump no starter) If anyone really knows (not a guess) please let me know

[sanborn]

My reply is not going to be an answer but is intended to add information only. There is no absolute answer as to weight of engines. For example, mid 70s GM 4 bolt main blocks weigh about 166-170 lbs depending on bore, etc. But, those blocks are very HP sensitive and most LM engines use the Bowtie blocks, they weigh about 188 lbs. Since GM stopped producing the Nascar Bowtie in 1999, your only option for a serious GM block is a Dart/World and they weigh about 205 lbs. All the blocks can be lightened to some degree(milling machine).

The same story applies to Mopar blocks, stock 2 bolt 340 blocks weigh 170-175 lbs and are as strong as a 4 bolt GM. X blocks weighed 210 (2 bolt versions, 7-10 more as 4 bolt) and the R blocks weigh between 210 to 235 depending on which series. And all can be lightened to some degree. How much can you lighten a Mopar safely? I have an early R block, 9" deck that weighs 176 lbs and it is as light as a lightened Nascar Bowtie.

Other components all weigh about the same given the same $ spent-cranks, cams, rods, pistons, pans, etc.

Cylinder heads are much the same story- it depends on which GM and Mopar units you want to compare. Stock cast iron heads for both are about the same, W2s and GM Dart units are about the same. Aluminum heads are different; Early GM 23 degree heads are 22-23 each but they are not as good as 18 degree raised port heads (30 lbs. each). Mopar W7s weigh 38(can be lightened to 32), W8s weigh 30(can be lightened to 27) and W9s weigh 22 each(don't try to lighten).

What's the bottom line? We have a good friend that has an lightened Bowtie block, 18 degree aluminum headed Dirt Late model engine. It weighs 458 lbs complete, our lightened R block, lightened W7 head engine weighs 462 lbs. Same steel pans, carb, etc. Both engines are essentially the same weight. The biggest disadvantage for Mopar is the added compression height thus the added block weight. Of course, the R block is available as 9.6", 9.2", 9.0" and they can go as low as 8.8". X blocks came as 9.6" but can go down as far as 9.2". Can't do much with stock blocks.

[crackerg]

Sanborn;
Thanks for all the knowledge. I guess when you step up to the R block world it seems to even the playing field a lot with the chevy guys.

But back on the crank deal just like Isky 3x is saying in his post there is no good answer that I know of as far as a crank for the old stock blocks and I cant see guys that run modifieds buying up a bunch of R blocks at $1900 a shot.

But when you compare $1900 to the cost of the Dart or Bowtie block you are not too far off I must admit.

As I have said before though there desperately needs to be a solution in the crank area for the mopar guys. I know I have had my cast cranks ion nitrated and this helps but when its all said and done I have spent about $400 on a cast crank.

THe bowtie crowd can buy a good forged crank for the same money and thats reality.

I am not gonna run the R block because of costs and I cant see paying $1000 for a forged crank so I guess I have painted myself into the corner until I am willing or able to peel off some more cash.

That being said it takes a lot off work to make a stock block oil correctly and live at the rpms needed for circle tracking and then to watch that work go to waste with a cast crank that may crack at any time is no fun.

I avoid this some by trying to keep the rpms down and not running the cast cranks more than about 15 nights before installing a different crank or having the one in the motor checked for cracks.

[sanborn]

Crackerg, just a few thoughts. Most of the open wheel modifieds(front runners anyway) around here are using the GM Bowtie or the Dart blocks ($2000). If I was going to build one I would use the R block so I could forget about that potential problem. And the R block has the small main journals(2.500") and that really opens up crank availability. I understand the crank problem. I went through that several years ago.

Another thought, have you checked with Moldex up in your area? 2-3 years ago they had a sale on Mopar cranks, rough billets, finished to your desired stroke, for slightly under $1K. If you had one of those you could forget about crank problems as well.

[speedway]

I had a terrible time of finding a crankshaft for my 359ci Super modified motor. I originally purchased a steel unit,3.38" stroke from mopar, when it arrived my engine builder almost got a hernia trying to lift it. (62lbs) I then ordered one from scat, seings how this is where ole Karl advertises that he gets his for the sprint car. This was also a disaster, as scat could not fill the order in a timely manner, and i probably would still be waiting for those idiots to grind me one. The problem is that we don't run a transmission and most of the open wheel stuff is designed for the chevrolet flange. I finally bought one from Stanton, which he had on the shelf, a Sonny Bryant masterpiece for about 2800.00. Yes this is a lot of money but you should see this piece, it is a work of art. Now if I could just get rid of this brand new 3.38 stroke steel crank, still in the box never been used.

[sanborn]

Speedway, did you get my e-mail yesterday?

[355 racer]

I just picked up a set of cam bearings from our Mopar dealer, he said the crank deal has been expanded to at least 5 more #s.
' The old man'

[mr_340]

I ordered one of the 3.55" stroke cranks (P4529711) yesterday. It is a little more expensive than the 3.45" stroke crank. My dealers cost is $347.20, so I'll pay around $415 TTL. The stroke is close to the 360, so I can use the 360 pistons in my 340 block. I'll lose a little compression, but I can deck the block .015" to get it back if I need it. I'll end up with essentially a 360 but with a forged crank. MP needs to make cranks like this with the 360 mains.

[DYNO360]

Help me out here Mr 340, how are you going to use 360 pistons in a 340? Won't they wobble around a little? I thought the 340 had a bigger bore than the 360. Do you have special pistons or what?

[mr_340]

You can get 360 pistons in a +.060" over size (4.06" bore). This is only +.020" on a 340 block however. I think most of the KB pistons can be gotten in a 4.070" bore size when running in a +.030" 340 block. For a race engine, you can get them almost any way you want if you pay the price.