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Stroker Rod Side Clearance

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ob1murry

10+ Year Contributor
111
11
Jan 27, 2010
Glen Burnie, Maryland
I have a short block currently being built at a local machine shop, but there seems to be a problem with the rod side clearance being way out of spec.

The parts being used are as follows:

6 bolt block
G4CS 100mm crank
Manley 6 bolt rods
Wiseco stroker pistons
King Bearings
ARP main studs
Kiggly Girdle

The machine shop says that everything is in spec, but that the rod side clearance is WAY out of spec at .065. I'm wondering if this is normal? The shop called Manley who had him measure the rods, and all checked out just fine, which would suggest that if a problem exists, it is with the crank.

He and some of his local mitsu customers and enthusiasts that he called in to look at it and give him a second opinion all agree that the play is excessive, but seem to think that running it would still be fine, but with concern for the oil pressure.

What's the general consensus here? Is this normal clearance for this rod/crank combo? Is the crank trash? Can it be run?
 
This might be a long shot but it seems like you may have gotten Manley 7-bolt rods by accident as they are 1.038" wide on the big end, where as the 6-bolt rods are a bit wider at 1.115".

Have the machine shop mic the big end of the rod and see how wide they are.


For reference, these are spec from the FSM...
Standard Value: 0.1 mm- 0.25mm (.0039-.0098 in)
Limit value: .4mm (.16in)​
 
This might be a long shot but it seems like you may have gotten Manley 7-bolt rods by accident as they are 1.038" wide on the big end, where as the 6-bolt rods are a bit wider at 1.115".

Have the machine shop mic the big end of the rod and see how wide they are.


For reference, these are spec from the FSM...
Standard Value: 0.1 mm- 0.25mm (.0039-.0098 in)
Limit value: .4mm (.16in)​

Well, I had that thought as well, and I asked the shop to verify that the rods measured as above to confirm we had 6 bolt rods, he said he had already thought of that as well, and that he had an OEM 7 bolt rod there that he checked as well, and that it was closer to 1 clearance, which makes sense given the .077 width difference.

The problem is that I seriously have no idea if the clearance as measured on a stock 88mm crank transfer over to a 100mm G4CS the same, or if the rod journals are wider, and I couldn't seem to find any info to answer my question online.

Seems like given the numbers out of the FSM, that the clearance is within the serviceable limit, but clearly not ideal?

At this point, it seems like my options are:

1. Run it as is and hope for the best.
2. Try and find a replacement G4CS or 6 bolt 4G64 crank, which seems unlikely.
3. Buy an aftermarket 100mm Eagle crank.

Suggestions?
 
Rod journals should be the same 4G63 to 4G64 cranks for rod side clearance specifications.
 
I know it doesn't help but, may I ask who the shop is? How are they measuring side clearances?
Funny this should pop up now. I have oem 6-bolt 88 and 100mm cranks here in boxes. I opened them up and measured to verify, they do in fact have identical journals.

I also grabbed an oem 6-bolt rod to verify what I've seen a million times. Every rod side clearance I've ever checked was way on the tight side of spec.

If they are using a snap gauge and mic, or caliper to measure the inside thrust face on the crank, and subtracting the rod width to get clearance they are probably measuring the wrong place on the crank, or suck at math. A feeler gauge will measure the right areas. Even .0065" would be looser that what I normally see though.
 
I know it doesn't help but, may I ask who the shop is? How are they measuring side clearances?

I'd prefer not to name the shop publicly, as the guy has been pretty cool about everything so far, when he could have just given the motor back and gone "not my problem", but if you really want to know, I'll gladly let you know through PM the name of the shop. It's not a large local shop, but it is one that I have seen mentioned a once or twice on the site, and one that I know for a fact at least one other local guy has work for his stroker done at that is still running strong.

As for how he is measuring the clearance, I don't know, I never asked.
 
I'd prefer not to name the shop publicly, as the guy has been pretty cool about everything so far, when he could have just given the motor back and gone "not my problem", but if you really want to know, I'll gladly let you know through PM the name of the shop. It's not a large local shop, but it is one that I have seen mentioned a once or twice on the site, and one that I know for a fact at least one other local guy has work for his stroker done at that is still running strong.

As for how he is measuring the clearance, I don't know, I never asked.
Well, if it isn't too far of a drive, maybe pop in their shop and see how their coming up with the side clearance measurement. Like Donnie said, a feeler gauge is the proper way to measure it.

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I asked because I shipped my own 2.3L parts/block to a shop a few miles down the road from you in Hanover, MD and was wondering if it was the same place or a shop that doesn't typically build 4g's. Not trying to blast anyone, we all make mistakes, even the guys that have done it hundreds of times.
 
No, I assumed the same thing, called him back and specifically asked "oh oh six five or oh six five?" to which he responded "no, oh six five".
 
Well, if it isn't too far of a drive, maybe pop in their shop and see how their coming up with the side clearance measurement. Like Donnie said, a feeler gauge is the proper way to measure it.

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I asked because I shipped my own 2.3L parts/block to a shop a few miles down the road from you in Hanover, MD and was wondering if it was the same place or a shop that doesn't typically build 4g's. Not trying to blast anyone, we all make mistakes, even the guys that have done it hundreds of times.

Nope, the shop that I believe you are referring to refused to build the motor unless I purchased only the parts they wanted me to use, and only if I purchased through them.

At this point, I'm just going to go by the shop tomorrow, and bring it home. It either gets run or needs a crank, no sense in it just sitting there in the shop either way.
 
That's too bad about them not letting you use your own parts.


I've only ever helped clearance/assemble friends motors and I think I've got 2 under my belt so take this with a grain of salt but it just seems too convenient that all 4 rods have a 0.065" side clearance, the limit is 0.016" difference between them so I would expect there would be some variance. Or is there a single rod showing out of spec at 0.065"?

If it were my block I'd do a sanity check and mic the width of every rod to verify they are all 6-bolt Manley's (1.115") and verify side clearance is being checked with a feeler gauge.
 
That's too bad about them not letting you use your own parts.

Yeah, it's easy to think that, but I'm sure that if they see this post, they will think "That is exactly why I don't let people bring it their own junk." Not everyone would accept that the shop isn't to blame, and someone running around talking about how the shop screwed your motor up when the reality was that you supplied shit parts is bad for business.

Regardless, I went and picked up the motor today, I'm still going to check the rod ends tomorrow, but I don't need feeler gauges or a micrometer to tell me that the clearance is way beyond what it should be.

http://sendvid.com/l4nsk1dj
 
Yeah, that's a no go there. Did you buy the rods new?

Yes, brand new from ExtremePSI. The crank however, I did buy from another member.

When I got them though, the only way I had checked to see if they were correct was by checking the wrist pin size, which was correct.

On the plus side, the shop gave me a hell of a price on the motor. I would have paid more just for the clearancing of the block and the line hone at most other shops. So, even if the rods are junk are need to be pulled to be replaced later, it's not as if I wasted a bunch of money on assembly.
 
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