How big of an issue is this gonna be

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1930

1930

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Had I known better I would have taken some general measurements before disassembly, now Im putting some things together and I notice the connecting rod clearance is real wide on the front and rear 2 apposing cylinders, ( #1 n 2 and 7 n 8 ) I can slip a .030 feeler gauge in there pretty easily and thats the largest I have.

Its already all been balanced, new ARP rod bolts installed ect so buying new rods cause these have been ground isnt something Id like to do but if I must.

Supposed to be 7-17 according to the book I have.

Picture 481.jpg
 
I was going to say .018 is the number in my head. I'm sure some of the real engine builders will chime in as to what their max allowable is. Seems pretty loose to me...
 
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Just extra oil on the cylinder walls, is my understanding. Might overload your rings a bit, but I'd be surprised.
 
Stock, my other 440 ( the one that hasnt had any machine work done to it is much tighter. Oh well, I dont like it but like the man said dont worry, be happy
 
The only thing "WE" run 25-30 on is circle track engines that run 50 wt oil.
BUT...an observation...you need to be checking clearance on BOTH sides of the journals. As in.. If you think you have .030..you need to be able to get .015 on both sides, with TWO feeler gauges. hopefully when you check it with 2...you can only get a 9 on both sides?

If you just stick a single .030 in the middle, thats not how we do them. you can rock the rods a few thou "triangularly?" lol and give a falsely high reading. worth trying.
 
I've run .080 on steel rods.

Side clearance is overblown, much like quench distance.


Much better to have too much side clearance than too little.

RUN IT.
 
Wow 0.80

I like Johnny Pace rendition and stick two in from each end.
 
1930 said:
Wow 0.80

I like Johnny Pace rendition and stick two in from each end.
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It's what the rods measured. The big ends were a bit narrow. The point is it didn't do anything. The oil rings didn't get overloaded (what a bunch of horseshit that is...the amount of oil getting by the rods is NOT controlled by side clearance but by how much rod bearing clearance you have...think about it....how can a rod with .0025 leak more oil with the rod side clearance at .080 than at .017???? It can't) nor was there any other issue with it.

Some guys can choke to death trying to swallow a gnat.
 
In the small-engine world, this clearance isn't even talked about.
I've put 8000 rpm snowmobile engines together with clearance enough nearly for another rod in there. Well that's a bit of an exaggeration.
Outboard marine engines too, with vertical cranks, and needle-roller rods.
I have to agree with YR, as to the absolute number.
And also with Pace as to getting the rods parallel.

But I do wonder about what the oil does as it leaves the crank. I mean it is spraying all around as the spinning crank flings it in every direction. I mean some of it is going up, and some is going sideways and some is bouncing off the windage tray and some/most of it is going around for a second trip; man that crankcase is a busy place. Hyup I'd like to see a slo-mo of that action!
 
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yellow rose said:
It's what the rods measured. The big ends were a bit narrow. The point is it didn't do anything. The oil rings didn't get overloaded (what a bunch of horseshit that is...the amount of oil getting by the rods is NOT controlled by side clearance but by how much rod bearing clearance you have...think about it....how can a rod with .0025 leak more oil with the rod side clearance at .080 than at .017???? It can't) nor was there any other issue with it.

Some guys can choke to death trying to swallow a gnat.
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Stupid question but I had ARP rod bolts installed, it looks like the machine shop machined the edge of the rods ( the edge where the side clearance is measured from ) is that typical to machine that edge and why?
 
1930 said:
Stupid question but I had ARP rod bolts installed, it looks like the machine shop machined the edge of the rods ( the edge where the side clearance is measured from ) is that typical to machine that edge and why?
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Yes. It's done to remove any burrs before grinding the cap and rod to rebuild them.
 
bOb shingler said:
AJ, that's what windage trays, screens and scrapers are for.
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Yeah the tray is in mine. But that don't stop that oil from going round and round before it exits the tray. The tray is just the final thing it hits before it maybe escapes through the little slots. That oil may go round and round for who knows how long before that happens. In the mean time it is joined by the top-end oil trying to find a way back to the pan. And the oil from the cam journals. And the mains. That oilpan has got to be a very busy place at 7200! Hyup I'd sure like to see a slo-mo of that action!
 
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