Am I suppose to use the OEM clearances for the rods and mains?

[DarkStarMenace]

So I am assembling my motor currently. Its a 2G 7 bolt. Machine work has already been done. I am dropping in an Eagle 88mm crank, Eagle rods and Wiseco pistons. I know I have to send out the rods to accommodate the Wiseco pistons. I also purchased the ACL race bearings for the mains and rods, thrust bearing kit and the MBCAD Kit.

Couple of questions:
1. Am I suppose to use the OEM clearances for the rods and mains?
2. The MBCAD Kit can only be used with ARP Studs?
3. The original thrust bearing is 1-piece, the one I have is a 3-piece. Am I gonna even need this? I know the thrust bearing was redesigned but is it required for the Eagle crank?

I have searched for the last week on this topic and cannot find the answer to save my life. Eagle doesn't supply any directions or a spec sheet. I went to their website and its "Coming Soon". I have sent an email and called, no response thru email and long wait on the phone.

I put the crank in and measured with plastigauge. I placed strips on the block side bearings and set the crank in. Then placed strips on the crank and set the main cap girdle in. Did not use the MBCAD kit due to the fact I have not received my ARP studs. I torqued to OEM specs and ended up with different measurements on the block side and girdle side bearings. These are in inches and OEM specs are 0.0008-0.002 with a Max Limit of 0.004. My reading went like this: Block side bearings a hair over 0.0015, Girdle side bearings a hair over 0.002. These were mostly across all mains with some right on the dot. I know plastigauge isn't the best measuring tool, and there is 0.0005+/- correction factor. I spoke to one of the engine builders at RRE and he said they run their motors at 0.0025. That seemed kind of strange to me, I know you want a certain amount of spacing for oil but running that much over spec and 1/4 closer to Max Limit. If these measurements were right on the button I wold have to cut the crank or Line-hone the mains. I am going to borrow a dial bore gauge to get exact measurements and see how much they truly are. Just strange how the top was different than the bottom, unless that's the correctional factor.

Any help is greatly appreciated. Anyone that has put together this setup or builders that do these a dime a dozen chime in please.

So thru some digging and waiting, I have found some useful info.

Stock Clearances for the Main bearings call for 0.0008-0.0020". The limit is 0.0040". Since the Eagle cranks are identical measurements, these would still work. After talking with some engine builders they have stated running 0.0025" as their clearance on these 2G 7 bolt motors. This is obviously with the new ACL bearings.

Now I have also been waiting for some tools from my local Snap-on dealer. Only took a week, so not too bad. I have taken most the measurements with a set of Telescopic Gauges and a Dial Caliper. The only thing I didn't get to measure were the Eagle Connecting Rod bearings clearance due to not having a 12 point socket handy.

The following post will have all measurements.

Crank Main Journals from front to back: 2.2435", 2.2434", 2.2435", 2.2434", and 2.2435". Now the 4th decimal point is an estimation on placement of the needle within that measurement.

Main Bearings from front to back: 2.245", 2.246", 2.245", 2.245", and 2.245".

Which gives me my clearance @ .0015", .0026", .0015", .0016" and .0015". These look very decent except for that second clearance. Any machinist have some advice? Should I have them all cut to be equal? Leave it as is?

Now I have a set of Standard Wiseco pistons. When I took the measurement, I was taken a bit. 2 pistons measured 3.345", 1 measured 3.344" and the last measured 3.343".

All cylinders measured 3.347". Wiseco calls for a .0025 oil gap. This puts 1 cylinder over the threshold and another that's questionable. My clearance ranges from .002-.004". I could either sleeve the cylinder and rehone, or replace all pistons with .020" bored over and bore all cylinders. Any recommendations?

So here is where I am @ currently:

Sending the block out to get bored .020" over and reorder new pistons. I think I'll measure pistons before I send block out so I can have it cut to what I want for any compensation.

Here are my measurements for the rods & rod journals:
From nose of crank to end, 1.771", 1.770", 1.770" & 1.770"
Rod bearings, 3 of them measured 1.774" and the 4th measured 1.773".
Eagle calls for .002-.003". My clearances range from .002-.004". Not much I can do but retake measurements and verify.

With 130-something views and not one response or advice. I find this sad for this size of forum. I don't know if its the wrong people looking @ this thread or what. But out of that many not one that could come up with an idea. So to the posters that having something to add that contains useful info and advice, thank you.

 

[donniekak]

First off what did you use to measure, and how did you do the measurements? Second, i never have a block bored without sending the pistons with it to be used for the measurements instead of a set bore size. Most of the mitsu blocks i've used, 4, and 6 cyl, have had different size mains and used a select fit bearing from the factory. Usually i have the block line honed. For the rods a good machine shop can resize them to get the clearance you want, if you send the crank, bearings, and rods. When i do anything more than a stock rebuild/ freshen up, i have the entire rotating assembly machined on every surface that contacts another surface. Decked, bored, line honed, rods sized, balanced. When the machine shop has all of the parts at the same time they can machine the specs to what you want instead of what is listed as ok in their manual. This costs more, usually an hourly rate instead of what they charge as a flat fee for each operation. Af for the question on specs, I don't run oem specs on anything except a stock rebuild. .0025" is a good number, you get more oil cushion, but it's not so much as to get excessive wear on cold starts. I have built engines with as much as .0035".

 

[DarkStarMenace]

First off what did you use to measure, and how did you do the measurements? Second, i never have a block bored without sending the pistons with it to be used for the measurements instead of a set bore size. Most of the mitsu blocks i've used, 4, and 6 cyl, have had different size mains and used a select fit bearing from the factory. Usually i have the block line honed. For the rods a good machine shop can resize them to get the clearance you want, if you send the crank, bearings, and rods. When i do anything more than a stock rebuild/ freshen up, i have the entire rotating assembly machined on every surface that contacts another surface. Decked, bored, line honed, rods sized, balanced. When the machine shop has all of the parts at the same time they can machine the specs to what you want instead of what is listed as ok in their manual. This costs more, usually an hourly rate instead of what they charge as a flat fee for each operation. Af for the question on specs, I don't run oem specs on anything except a stock rebuild. .0025" is a good number, you get more oil cushion, but it's not so much as to get excessive wear on cold starts. I have built engines with as much as .0035".

Thank you for an informative post. And your advice/recommendations. The measurements I took were with a set of Snap-on Telescopic gauges, which I then measured using a micrometer. I dropped my motor off at a machine I trust. I am going to have him deck, bore and line bore the block. Also going to have him resize the rods. It will be a week til he gets to it, which doesn't bother me as I am waiting for my new pistons. I told him not to bore until I have these so that I can get the clearance I want and not go thru this again.
I knew I shouldn't use OEM clearances for a build that won't be stock but figured the limits would still account for something and should be avoided. But I guess I am no expert and I have not being doing this for decades. This is my 3rd motor that I have built since I have been working on cars, which was about a decade ago. First was a Chevy 350 that I did some bolt on upgrades to, then followed by a tear down. Then which led to a complete build of a stroker 350, which I love and still have but had to part with the car. Now it came time for an import and Mitsu Eclipse have always impressed me. Every car has there misfortune, just got deal with and find a way around them. Once again, thanks for your post.