jsawduste wrote:There are ways to do it and ways to do it right, your choice.
I'd rephrase that by saying there are ways to do it and ways to do it better, and I agree that 4.0L rods with IC944 pistons would be better than 4.2L rods with stock replacement pistons mainly for the lower quench height.
I built my engine more than a decade ago when IC944 pistons didn't even exist and if you wanted to reuse your 4.0L rods, the only option was $600+ custom forged pistons. Times, of course, have changed.
You can get the forged IC944 pistons for $402 from RPM machine, that's a decent price. I found them for $360 a few years ago. http://www.rpmmachine.com/shop/index.ph ... ail&p=5972
Recommended piston-to-bore clearance is only 0.0025" to 0.0035" for normal street use, so they're not really loose and noisy compared to stock type pistons.
I mentioned the 'later' stock cam being decent. I believe they used it starting in 1996? .. and till at least 2001. Dino can give better details.
Walt K
Eastern Pa
2001 Cherokee 4.6 stroker 90 day build
Buick GS's and Saab turbos for other days...
jsawduste wrote:There are ways to do it and ways to do it right, your choice.
I'd rephrase that by saying there are ways to do it and ways to do it better, and I agree that 4.0L rods with IC944 pistons would be better than 4.2L rods with stock replacement pistons mainly for the lower quench height.
I built my engine more than a decade ago when IC944 pistons didn't even exist and if you wanted to reuse your 4.0L rods, the only option was $600+ custom forged pistons. Times, of course, have changed.
I`ll go along with that comment, Dino.
Just hate to see things get put together in an less then optimum way. Especially when there are several venues to follow that ultimately will serve the intended purpose best. Do it right or don`t do it all.
Retlaw01XJ wrote:You can get the forged IC944 pistons for $402 from RPM machine, that's a decent price.
Yes indeed. That's only slightly more than the combined cost of a set of 4.2L rods and H825CP pistons so unless you already have a set of 4.2L rods, there's no real reason to use them in a stroker these days.
I really appreciate everyone's input, but money is really holding me back and I need my jeep as soon as possible. I figure since I need to do a rebuild, I might as well do a poor man's stroker style engine. Has there ever been a bad experience with using 4.2 rods? I'm asking sincerely.
Now is it necessary to deck the block with the 4.2 rods if the block doesn't need it? I found this video where the machinist decked the block .009 and compensated for the 4.2 rods, i just don't know if he did it on purpose or if it had to be done anyways. Thanks again.
Retlaw01XJ wrote:You can get the forged IC944 pistons for $402 from RPM machine, that's a decent price.
Yes indeed. That's only slightly more than the combined cost of a set of 4.2L rods and H825CP pistons so unless you already have a set of 4.2L rods, there's no real reason to use them in a stroker these days.
Yeah, I had some time today to add up some numbers and I think I might go with the IC944 pistons then. My block is still at the machine shop and when I called them a few days ago, the told me that the bore was 0.010 and that I can order standard size pistons. The thing is that RPM machine only has 0.020 as the smallest option to order, and I'm kind of wondering what to do. Should I call the shop and tell them to bore it to .020?
optmaxx wrote: the bore was 0.010 and that I can order standard size pistons.
That doesn't make sense.
Should I call the shop and tell them to bore it to .020?
The machine shop will need the pistons first to size the bore.
It doesn't? Man I was afraid of that. I probably misheard, or my memory is failing me cause I can't remember if he said ten thousandths or one thousandth, but I do remember him saying to get standard size pistons. Either way I'll have to call them tomorrow to let them know I'll be ordering pistons and to hold off on the block. Thanks, it's been a crazy week and sourcing parts does seem to be the toughest part of making a stroker.
Take it 20 and start the rebuild with fresh bores.
Have the machine shop bore AFTER they have the pistons.
Comparatively speaking, before you buy the 944`s I would talk to Diamond and see what they will sell you a set for. The advantage here is that the piston will be made so that you will have a 0000 deck. Then using the typical .043 compressed head gasket you will now be in the enviable position of having a good foundation for a well running stroker.
Last set I bought from Diamond worked out to be cheaper then off the shelf 944`s.
optmaxx wrote: Has there ever been a bad experience with using 4.2 rods? I'm asking sincerely.
I love my setup using the 4.2 rods
The 4.2 rods will run long and hard for you. The 258 was known to be a long lasting engine. It ran in jeeps from around 1975 to around 1987 and it is said by some (Novac Conversations) that "The AMC 258 is probably the most recognizable and longest-running Jeep powerplant in the brand's history."
The 258 used the shorter rods and it created the same geometry we see today in our short rod strokers. I just can't find any FACTS that support the claim that the long rods will last longer.
It is my humble opinion that you could save yourself a couple hundred bucks and go with the shorter rods without sacrificing ANY durability issues and end up with a tighter fitting piston.
Bore it .020 and go with Sealed Power Hypereutectics
optmaxx wrote: Has there ever been a bad experience with using 4.2 rods? I'm asking sincerely.
I love my setup using the 4.2 rods
The 4.2 rods will run long and hard for you. The 258 was known to be a long lasting engine. It ran in jeeps from around 1975 to around 1987 and it is said by some (Novac Conversations) that "The AMC 258 is probably the most recognizable and longest-running Jeep powerplant in the brand's history."
The 258 used the shorter rods and it created the same geometry we see today in our short rod strokers. I just can't find any FACTS that support the claim that the long rods will last longer.
It is my humble opinion that you could save yourself a couple hundred bucks and go with the shorter rods without sacrificing ANY durability issues and end up with a tighter fitting piston.
Bore it .020 and go with Sealed Power Hypereutectics
It makes perfect sense if you already have a set of 4.2 rods sitting around. But when you have to purchase rods and pistons its a wash as far as money goes. I haven't found the 4.2 rods anywhere super cheap.
Try looking at the long vs. short rod with an advanced eye. Considering things such as dwell angles, rod angularity, bore to engagement, compression and quench, effects of volumetric efficiency for starters. There are more but this is a start.
There are basic fundamentals that "should" be adhered to if you want to "optimize" your investment in time and money.
Unfortunately someone reads it on the internet or perhaps even builds there own engine and they become experts without fully understanding the dynamics.
For kicks, do research on detonation. You will find that EGT and combustion temps actually go DOWN. Imagine that !!
jsawduste wrote:Try looking at the long vs. short rod with an advanced eye. Considering things such as dwell angles, rod angularity, bore to engagement, compression and quench, effects of volumetric efficiency for starters. There are more but this is a start.
There are basic fundamentals that "should" be adhered to if you want to "optimize" your investment in time and money.
Unfortunately someone reads it on the internet or perhaps even builds there own engine and they become experts without fully understanding the dynamics.
For kicks, do research on detonation. You will find that EGT and combustion temps actually go DOWN. Imagine that !!
Im not trying to argue but I'm board so here goes.
I did consider these things, WITH an "advanced" eye. My diploma in auto mechanics says that my eye is advanced enough.
Riddle me this. How does rod length effect volumetric efficiency if the deck clearances are equal? The FACT is that the 258, with its higher "dwell angle" and greater "rod angularity" was/is still a very long lasting durable engine.
I am not for or against the different rods. If I would have had the extra ~300 dollars laying around then I would have went that way as well, and then I would also have thrown a blower on it too.
P.S. I have an extra set of short rods in Denver if you want them.
Last edited by akadeutsch on December 8th, 2014, 9:17 am, edited 2 times in total.
