About 10 years ago, I built a 400 for my 4X4. At that time, I had an article that talked about offset turning a 400 crank and using a Chrysler Rod. I think that the rod was from a Mopar 360, but I don't remember for sure. I ended up getting some pieces and building the motor so I didn't pursue it any more. At the time, however, I talked to a very good crankshaft and machine shop that I know and we discussed it. We came up with a recipe that would work.

The math involved doing an offset turning on a 400 crankshaft and giving it the rod journal size of the Mopar rod. The rod length was such that a particular M or 400 piston would work together with the rod and the stroke change to work out. As I remember, the rods had to be machined for thickness so that a pair of them fit the journal.

I can do the research for the dimensions, but I thought that maybe someone here had also seen the recipe or had done this before. If I can come up with this recipe such that I can do this stroking, I plan on tackling the project after I finish painting the truck. I have another block and crankshaft, so I would build the short block and then have it ready to go in the truck so that it won't be down for long. My heads are in great shape, so I could short block the truck in pretty short order.

Thanks for your help.

 

remember how much displacement it nets?

 

Like I said, I don't remember the details. If memory serves me correctly, the crank could be offset ground for about another .200" stroke. The math on that would give you about 422 cubes with a standard bore and about 430 cubes with a .040 overbore.

The good news for me would be that all of these cubes would result from additional stroke which would help most in the form of low to mid range torque.

 

i would think very hard before offset grinding a 400 crank...

offset grinding is risky business and in many cases can severly weaken a crank.

if ground enough, the oil passage can be close enough to the journal's surface that cracks can form.


Nick

 

Try to PM TMI. He can fix you up.

 

i was under the impression that the 400 crank design overcame the offsett grind issue...whereas other cranks like the cleveland - it's a big issue....can't remember where i heard or read that.

 

Yes Roger, when I read that article ten years ago, they discussed the weakening issue and explained the reason that it would work with the 400 crank. I will continue to look for the article.

I do know that Tim has a stroker kit and I would love to purchase one, but I can't justify the expense for the purpose of the truck. I no longer use the truck to tow and feed as I once did. I am fixing it up just as a Saturday night cruiser. I won't be racing it, so a forged crank and H beam rods are extreme overkill for my purposes. If I can do a poor boy stroker engine, I don't mind putting time into the project. I have more time than money to put into it.

 

On one of the other 335 related boards a guy built a stroker using 300 6cyl rods. The stroke was 4.15" I think. The motor was around 425ci. He used an off the shelf piston also to keep the costs down.

 

The 351C forum on Yahoo has a link to a stroker design that uses a 240 I6 rod. It will yield about 424 to 434 cu inches, depending on the cylinder bore.

http://www.bacomatic.org/~dw/engine/km434/km434.htm

This uses a crankshaft offset grind to get a 4.150 stroke.

I think that the parts are cheap, but there is a lot of labor involved. If you are paying a shop $50.00/hr or more to do the labor, it may be better to buy the whole rotating assembly from Tim and get a steel crank etc.

 

yup danlee, that came from a guy that doesnt live too far from my house, this guy has some truly artistic abilities when it comes to doing machine work, mostly on a small budget too, thing is he doesnt have all the high tech cnc stuff that alot of places do, just an ordinary guy working out of his shop in the back yard, his name is dave williams http://www.bacomatic.org/~dw/index.htm

 

$2343.69 seems like a bargain to me for the stroker crank, H beam rods, oversize pistons, rings, timing set, etc. from Tim:

http://www.tmeyerinc.com/cart434kit.htm

Not to mention the peace of mind that this has been done before many times... You will get a stout engine that should last a very long time, and quality parts that can likely be reused (if not involved in catastrophic failure)

 

Yes Tims stroker kit is worth the money if you are building a severe use engine that will see lots of RPM's or for any other reason requiring a forged crank and H beam rods. My project does NOT, however, require such exotic pieces and my budget doesn't allow it anyway.

If I can make the Chrysler rod work, I can get the crankshaft made for VERY reasonable money by someone who I know well and trust to the n'th degree. The other necessary components being off the shelf would make for a poor boy motor that would be of my own creation and up to the task that I have in store for it.

I am in NO WAY belittling Tims kit. It is a great package that can be used to build a great engine and I'm sure that it is fairly priced for what's in the kit.

If some time between now and the time I finish painting my truck and am then starting to build a motor I win the lottery or enjoy some other wind fall, I will most certainly use his kit for building the next phase of my 400 engine.

 

Me thinks me likes overkill 400! Even for the street...
But wouldn't all the machining costs offset a kit? Or is your friend giving you a killer deal on the work?

 

The offset turning doesn't cost much. I already have the core that he would start with. If it works out, I will be using 351M pistons, so they're off the shelf as are the Chrysler B motor rods. There will be a little machining to the rods, but nothing drastically expensive. This will be a lot less than $1,000 for everything that I don't already have. In fact if I wanted to get silly thrifty about it, I have a very low mileage 351M that I could use the original pistons and block, saving the piston and boring cost. Of course that would result in about 6 or 8 less cubic inches than an overbore.

Yes, overkill would be nice, but overkill costs money, money that I can't justify for this truck for the purpose it will serve. Maybe that wind fall will come along and this will all be a non issue.

 

Okay, this thread appears to be paying off big time.

I started looking into the 300 rod and it appears that it is perfect. The 300 rod is 6.2 inches. With an offset grind which appears to gain .095 in arm length, netting a 4.19" stroke, a 351M piston will be .015" higher in the bore than a 400 piston with stock stroke and rod.

There are several side benefits to the 300 rod; same pin diameter and the bearing does not have to be machined, only the big end thickness has to be milled. It's perfect.

The extra .015" piston height works out fine, since the 400 piston is buried so deep in the bore anyway.

Now I have to determine the compression ratio, but my initial SWAG, puts it at about 9.3 with my .040 milled heads. That's .6 more than my current engine which is at about 8.7 with it's milled heads.

Thanks to all,