crank and rod info needed

[gremlinsteve]

what is the crank pin diameter on the 4.2 crank. what is the crank pin diameter on the 4.0 rod?
drumming up some recipe for a stroker for myself and i do not have that info yet.

steve

[gremlinsteve]

my thoughts as of today...for the short block


4.00 stroke
6.250 rod
4.00 bore
0 deck custom piston
looking at a 9.0 compression

301 inch displacement long rod motor...


just a thought right now. no mock ups have been done so i do not know how the rod/block fitment will be


steve

[yuppiexj]

the 4.0 and 258 share the same crank pin diameter, (from the 1988 FSM) all hail fair use.

Connecting Rod
Crankshaft Bore ................ 2.2080-2.2085 (56.083-56.095)
Pin Bore ......................... .9288-.9298 (23.591-23.616)
Cylinder Bore
Diameter
4.0L ......................... 3.8751-3.8775 (98.427-98.488)
4.2L ......................... 3.7501-3.7533 (95.252-95.334)
Out-of-Round ...................................... .001 (.02)
Taper ............................................. .001 (.02)
Piston Pin Bore Diameter ........... .9308-.9313 (23.642-23.655)
Piston Pin Diameter ................ .9304-.9309 (23.632-23.644)
Piston-to-Cylinder Clearance ..... .0009-.0017 (.022-.043)

[Plechtan]

I went with a 6.2" rod on My 4" bore stroker. You will need a rod for a 2" journal or smaller. In order to get enough stroke out of the jeep crank, you will have to have the journals offset ground. If you were going with a 3.95 stroke, you could probably use oversize bearings, but for a 4" stroke you will have to reduce the Journal diameter.

With a smaller journal diameter you will need special rods, Custom rods go for $200.00 or more each. If you send your crank to Castillo Crankshaft ( 714) 523 0321 , they can offset grind it and narrow the journals so you can use a Chevy rod. The crank work will cost about $500.00 but you will save major dollars on buying of the shelf chevy rods.

[gremlinsteve]

already have the rod. 1.88 honda journal is what i am looking at. offset ground of course. i have the crank shop local that will do the crank work.
curious what the big end width of the 4.0 rod is tho. have not measured one yet. i am also assuming that the block will accept a overbore of that much and retain a decent service life...

any one run a 4.0 inch bore on a 4.0 block yet? how long and what if any power adder..

steve

[yuppiexj]

This kit uses Honda rods (according to the internet rumor mill)

http://www.rpmmachine.com/amc-stroker-kit-258.shtml

The vendor says it won't fit in a 4.0 block, I'm not buying it. The crank will bolt in(according to my awesome FSM reading skills).
The pistons may pull too far out of the cylinders at BDC though...

I think it was Mike at the now shut down Accurate Power had an MJ with a 4.0" bored stroker.
He said something about there was a need to sonic check the block on the thrust side and a really good core was needed.

[YJason]

This kit uses Honda rods (according to the internet rumor mill)

http://www.rpmmachine.com/amc-stroker-kit-258.shtml

The vendor says it won't fit in a 4.0 block, I'm not buying it. The crank will bolt in(according to my awesome FSM reading skills).
The pistons may pull too far out of the cylinders at BDC though...

Sorry for the Hi jack, but what crank are they using to get 4.145" stroke (.250 more than 4.2L)? Is it a custom casting? or are they welding them up and offset grinding with a smaller rod journal?

Just curious for a future build.

[yuppiexj]

They offset grind the 258 crank to 1.88 for the Honda size (pure speculation on my part)
for the price they were charging I don't think welding was done. (<$2000 range)

[SilverXJ]

I don't see why it wouldn't fit a 4.0L block unless they are saying it won't fit unless you ground the block a bit. I.e. not a drop in fit.

[Plechtan]

Am i missing somthing? the honda rods do not have the right BE with to work with the Jeep crank, and you cannot get stock rods anywhere near 6.250" long. You must be talking about custom rods.

I did a 4" bore for the Bonneville truck, I would suggest a 2000 + block and sonic test the walls. The thrust side is much thicker n these blocks, but the accessory mounts are different and everything is metric on the outside of the block.

Below is a quote from the 5.0L Stroker post from eariler this year.

According to Lee at Hesco, the later 4.0 blocks can be bored to 4" without a problem. Well i thought i would give it a try, i had 2 blocks and here are some of the sonic test numbers 0 is the front of the cylinder, 90 is the passenger side, 180 is the rear, and 270 is drivers side. First number is is top, second is middle third is bottom.

Casting 53010328AB

Cylinder# 0 90 180 270
1 .281 .306 .154 .291
mid .195 .315 .108 .269
bottom .814 .334 .115 .295


2 .198 .325 .180 .252
mid .182 .288 .150 . 250
bottom .189 .318 . 170 .281

3 .166 .342 .188 .295
mid .144 .309 . 158 .275
bottom .169 .511 .172 .305

4 . 188 .325 .148 .305
mid .177 .301 .136 .281
bottom .200 .388 .159 .313

5 .190 .327 .180 .285
mid .171 .301 .163 .254
Bottom .176 .622 .190 .280

6 .189 .350 .263 .280
mid .146 .321 .223 .238
bottom .182 .576 .313 .272


Casting number Casting 53010327 AB

1 .223 .226 .173 .261
mid .186 .236 .144 .227
Bottom .242 .268 .159 .285

2 .162 .284 .147 .308
mid .163 .284 .122 .244
bottom .145 .262 .201 .269

3 .152 .176 .185 .314
mid .133 .255 .141 .269
bottom .245 .260 .163 .274

4 .140 .202 .218 .360
mid .141 .202 .155 .272
bottom .169 .318 .169 .361

5 .161 .227 .182 .303
mid .134 .231 .155 .247
bottom .154 .261 .169 .275

6 .144 .225 .278 .284
mid .136 .258 .203 .242
bottom .178 .249 .231 .276


we wanted to have a .09-.10 minimum cylinder wall at the thinnest point. It looks like both castings have plenty of meat on the sides of the cylinders, but are a little thin front to back. The 328 casting is generally thicker, but has a thin spot in the center rear of the #1 cylinder. To get to 4" we have to remove about .062 per sides of the cylinder ( .125 on the diameter) We ended up using the 328 casting and sleeving the #1 cylinder, we did break through a little, but i think the sleeve has plenty of support. Both blocks had almost no wear on the cylinders, you could still see the hone marks.

I will look for another 328 block to see if i can bore it to 4" without sleeving it.Peter Lechtanski
The worlds Fastest Comanche Prroject
Plechtan
Donator


Posts: 478
Joined: August 28th, 2008, 12:00 pm
Location: Woodstock, IL
Thanks Given: 4
Thanks Received: 8
RSS

--------------------------------------------------------------------------------

Private messageE-mail PlechtanWebsiteTop
--------------------------------------------------------------------------------

Report this postReply with quoteThank Alex22's postRe: 5.0 Stroker
by Alex22 » December 27th, 2008, 12:30 am

[SilverXJ]

Am i missing somthing? the honda rods do not have the right BE with to work with the Jeep crank, and you cannot get stock rods anywhere near 6.250" long. You must be talking about custom rods.

The Jeep crank has to be reground smaller on the rod journals to fit the smaller Honda rods. When the crank is reground it can be offset ground. I'm not a Honda expert but going off of these Honda rods: http://crower.com/cat/import/honda/rods/rods.shtml their big end measurement is all under the Jeep 2.208" BE measurement. I have also heard of Chevy guys utilizing Honda rods.

[Plechtan]

My statment was correct, but i used the word "with" Instead of the word "width" The BE width for a Jeep rod is about 1.060" The honda rods are all under 1" The maximum side clearance on the rod is .010 Using the Honda rod you will end up with about 10 times that.

Nissan L-16 rods are close with a 1.054 BE width, but the rods are only aboyt 5.25" long. The Toyoda 3s-GE rods are a little longer at 5.433" these rods have a 2.008" BE bore.
Carillo makes a rod, for a Spridget 1275 ( part # SP-1275>-55750S) which has the proper BE width (1.059), a 1.7707 be diameter, but the rod is only 5.75" long, and they probably cost $200 each or more.

I got custom rods from R&R Racing products for about $200.00 each. took 2 months to get them.

[gremlinsteve]

the rod i have uses the 1.88 rod journal and honda rod bearings. the rod is for a sbc application.
this will use a custom piston of course..

steve

[yuppiexj]

the rod i have uses the 1.88 rod journal and honda rod bearings. the rod is for a sbc application.
this will use a custom piston of course..

steve

Eagle makes ones like that part no CRS6000HJ for example.

[Plechtan]

the rod i have uses the 1.88 rod journal and honda rod bearings. the rod is for a sbc application.
this will use a custom piston of course..

steve

How do you handle the issue of the Bottom End Width not being correct?