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Build a long rod motor or sell a set of 198 rods?
https://slantsix.org/forum/viewtopic.php?t=56803		 Page 1 of 2
Author:  Reed [ Sat Dec 27, 2014 7:10 pm ]
Post subject:  Build a long rod motor or sell a set of 198 rods?
I am about 99% certain that I scored a 198 motor, complete with connecting rods. This has me contemplating building a long rod motor.

The 198 was rebuilt by Jasper an unknown number of years and miles ago. It lost oil pressure and the #3 con rod bearing appears to be gone (I haven't pulled the pan yet, but there is slack on #3 when I turn the crank). The engine was rebuilt and bored .060 over. The bores look nice and clean and the pistons aren't even carboned up (too bad).

So, my understanding is that building a long rod motor requires:

(1) a forged 225 crank (because the cast crank is incompatible with the 198 con rods)
(2) a 225/198 forged crank block with cylinders bored to at least 3.5 inches (got it, but it is only overbored .060)
(3) a set of 2.2 or 2.5 pistons (preferably 2.2), or some other "modern" metric piston

Then the head, cam, and manifolds of my choice.

I don't have a forged 225 crank (I do have two 225 cast cranks :wink: ) and I would need to send this block out to get over bored and get new pistons.

I guess I am looking for a rough ballpark price estimate of the cost of building a long rod motor from the people who have actually built one. I am on the fence about actually saving up to build a long rod motor or making some quick cash and selling the 198 rods I got.

Any input is appreacited. Thanks!
Author:  DusterIdiot [ Sat Dec 27, 2014 11:32 pm ]
Post subject:  The option...
Quote:
So, my understanding is that building a long rod motor requires:

(1) a forged 225 crank (because the cast crank is incompatible with the 198 con rods)
(2) a 225/198 forged crank block with cylinders bored to at least 3.5 inches (got it, but it is only overbored .060)
(3) a set of 2.2 or 2.5 pistons (preferably 2.2), or some other "modern" metric piston

1)I would research the cost of a 225 crank kit, that will save you some cost since it has the 225 crank and the bearings for the block you are working with....I built my last 12:1 225 engine with a fed-mog forged crank kit from autozone and all the journals came 10/10 and it came with all the bearings saving me the price of the main and rod kits.
2) Look for the known pistons for the long rod in the 0.5 mm over bore kits which should be close to an .080 over bore...
3) while researching #2 your research should turn up a set of pistons and Hastings rings in that range...

Note, you will have added cost to fly cut the piston dishes/ valve reliefs which you will need to research who can do it in your locale....last year I had 5 shops in 60 miles that could do the service, as of now, 4 of them sold their tooling or went out of business due to the slump in our economy (I lost 2 good machine shops as well..one due to the old school owner passing away...)

Make sure to pull your knocked piston and rod assembly to check the rod part number to verify the conn rod part number with the 198 rod number, juts to be 100% sure.

:wink:
Author:  SlantSixDan [ Sat Dec 27, 2014 11:33 pm ]
Post subject:  Re: Build a long rod motor or sell a set of 198 rods?
Quote:
a 225/198 forged crank block with cylinders bored to at least 3.5 inches
What would make it mandatory for you to bore to at least 3.5"?
Author:  Reed [ Sun Dec 28, 2014 12:31 am ]
Post subject: 
Answer questions backwards:

From reading the stroking article and searching through old posts from Doctor Dodge, my understanding was that the metric sized pistons (or at least the "good" metric sized pistons) were a 3.5 inch bore at the smallest. I know that there are smaller pistons, but I know so little about building non-stock performance motors that I am trying to follow known recipes for now. Of course, maybe I was misunderstanding Doc's instructions. Now that I think about it, since he is building race motors he may have been talking about stuffing the maximum sized piston possible into the cylinder. Hmmm.

I was looking at the cost of pistons and crank kits, and I think my enthusiasm has been dampened. $400-$500 for pistons, another $300 for a crank kit, and then you add all the machining and incidental costs. I may cheap out and try and fix this 198 and leave it as is. I don't race and don't have the disposable income to build a custom motor just because. If I can salvage the 198 crank I think I will. The money I made selling the con rods would be quickly eclipsed by the cost of getting a forged 225 crank and rods.

I hope to pull the pan tomorrow and get a better look at the #3 con rod, con rod bearing, and crank journal. If I can get away with replacing the bearings and cleaning up the 198 crank I think I will just do that. I already have a rebuilt head, and a custom ground cam, and a bunch of other goodies. I will still be happy if I can get a low-mile rebuilt motor for almost nothing, even if it is a 198. Maybe I will build an economy minded 198 for my brother's Duster.
Author:  ceej [ Sun Dec 28, 2014 5:44 am ]
Post subject:  Opinions : 198 Rods
The 100 over bore is not necessary Reed.

The Hooptie engine is .045 over, and other than I needed to clean up the bores from a 0.030" over bit of damage, even that wouldn't have been necessary, strictly speaking. The rest of that build is tucked away somewhere in the Engine Matrix thread.

There are of course custom pistons, which make it possible to do some pretty crazy things. I've got those 7.400" rods out in the shop. Doc's got a build on tap that's using longer rods still.

198 rods are pretty nifty for a long rod build. I found a Toyota V6 that over the counter stock replacement pistons and rings would work pretty well, without having to buy a couple sets. They are metrics, so you get a nice reduction is friction. the compression height was a bit taller than the four banger pistons I chose. They were slightly heavier though. With the huge stroke I used, every gram was my enemy.

Before anybody gets their panties in a bunch, using Sealed Power pistons that were intended for a Toyota rebuild is not grounds for a military strike on the west coast! :lol:

I'd like to point out, the Hooptie was built a year or two before the K1/Molner rods became available. Before anybody discounts the Molner rods based on up front cost, keep in mind that if something goes wrong with one, you will be able to readily find a replacement, and if your going to do any mods to the 198 rods, the cost of getting them ready to go can match or exceed the price of the aftermarket rod. (Which is stronger, lighter, and all around nicer than the stock forged piece.)
If the Molner rods had been available, they would have been my choice for my long-rod build.

Having a 198 long-rod engine is pretty neat. It's not universally accepted as the "Way to go" when it comes to performance configurations. I'm sure you've heard the arguments both ways.
Forged customs would be a nice improvement for serious racing applications, but a good HE Casting is fine for most. For a street engine, perhaps in a van or pickup, the Hyper Eutectic will be ready to drive much more quickly. Forgings are heavier, and need more warm-up consideration for like configuration.

Just a few thoughts that may help.

CJ

Edit: A quick add to the Metric thing; I had to bush the small end to install those pistons. The pin is not the same diameter. That adds cost to the reconditioning of the 198 rod.
Author:  Doctor Dodge [ Sun Dec 28, 2014 8:03 am ]
Post subject: 
The "3.5 bore" stated in the stroker article is based on limited piston availability way back then.
Today, you can find the metric 2.2 pistons in the factory 87.5 mm (3.45) and in .25mm oversize increments. (3.465, 3.475, 3.85, etc)

Many new offerings are available in the 87 to 89mm size range but be sure to look at the pin size to avoid extra cost & time needed to address a different size.
DD
Author:  Reed [ Sun Dec 28, 2014 8:12 am ]
Post subject: 
Thanks guys! I think short term I will keep this 198 motor as is and try and repair the cause of the connecting rod bearing failure and repair any damage caused by the failure. I don't have the money to build an exotic slant right now, and if I can spend $200 or less to get what would effectively a be low mileage rebuilt short block I would be ahead of the game.

At some point in the future I might try combining the crank out of the original 225 that is in my brother's Duster right now with the 198 motor and make a true long rod motor using the .060 pistons that are in the 198 right now. But short term I will leave the 225 as is and try and fix the 198 as a spare engine.

EDIT: But just putting the 225 crank into the 198 engine won't work either, because the long rod motor needs pistons with the pin closer to the top of the piston than stock slant pistons. OK, so repairing the stock 198 is the plan for now.
Author:  slantzilla [ Sun Dec 28, 2014 9:25 am ]
Post subject: 
Be aware that if it took out a rod bearing you may only have 5 rods. If the rod has discolored from heat it is junk. :(
Author:  Reed [ Sun Dec 28, 2014 9:49 am ]
Post subject: 
Thanks for the heads up. I hope to pull the pan today and inspect the damage. There is definitely a problem with cylinder #3. At TDC or BDC there is about 5-10 degrees of crank rotation before the piston stats moving. From TDC #3 is visibly higher than #4 on the downward stroke. I am hoping that the bearing failed and fell out of the con rod and no damage occurred to the crank or the con rod. We'll have to see. If I find catastrophic failure, I may be selling 5 198 rods and getting a 225 crank kit and connecting rods. :wink:
Author:  Reed [ Sun Dec 28, 2014 3:28 pm ]
Post subject:  Panning for silver.....
After spending some time working on the rear axle in my brother's Duster, I pulled the pan off the 198 to inspect the #3 con rod. I did confirm that the connecting rods are about 7 inches center to center.

Here is what I saw:

Image

Hey, where's the bearing? Oh! There it is!

Image

I think the crank might be salvageable, even though I can feel bumps if I drag a fingernail across it. What worries me more is the blue discoloration on the bottom of the connecting rod. Dennis said that discoloration means a junk rod. Is this the discoloration he was talking about? If you look close you can see the metal changes color right where the connecting rod opens up for the crank bearing:

Image

I would like to salvage the rebuilt block and pistons, and if I could find on e 198 connecting rod and get the crank cleaned up I think that would be the cheapest option.

What do you guys think? Am I: (a) in the market for 1 198 rod; or (b) selling a 198 crank and 5 con rods and looking for a 225 crank and rods?

Thanks!
Author:  SlantSixDan [ Sun Dec 28, 2014 5:25 pm ]
Post subject: 
Bottom end of that rod got hot, no question. But did it get hot enough to ruin the metal's strength? Or just hot enough to clean off a minor layer of oil? I'm not enough of a metallurgist to answer that question; I think step one would be a good, thorough cleandown of the entire rod to see if the "discoloration" disappears when there's no oil film on the rest of the rod.
Author:  Reed [ Sun Dec 28, 2014 6:14 pm ]
Post subject: 
Excellent questions Dan! However, I have a possible source for a reconditioned 198. If I can get it cheap enough, I will just replace the rod for peace of mind. However, I will still pull the current overheated rod and inspect it once I get a clean workbench in my garage. I am in the middle of end of the year cleaning, which explains why I just picked up a second spare engine and a second and third spare 904. :wink: :lol:
Author:  slantzilla [ Mon Dec 29, 2014 2:12 am ]
Post subject: 
You may be able to save that one getting it resized if it hasn't been done too many times already. Hard to tell from the pic how hot it got.
Author:  Reed [ Tue Jan 06, 2015 4:34 am ]
Post subject: 
I found a single NOS 198 rod on eBay for $42 with shipping. Yay.

So, do you guys think that crank will polish out or do you think I will need to get the con rod journals ground undersize?
Author:  slantzilla [ Tue Jan 06, 2015 9:58 am ]
Post subject: 
General rule of thumb is if it has scores/boo-boos you can catch a fingernail on, it needs ground. Not very scientific, but fairly accurate. :D
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