resized rods. face has dings

[twostick]

For a stock application, those nicks are not an issue.

If this was a full tilt race application, theoretically, a crack could start at one of those nicks and cause a failure. Odds on the Lottery are probably better than that scenario tho.

Some machinists as has been commented on here, are hung up on too much side clearance being a problem and are reluctant to increase it to clean up stuff like you are seeing.

The only side clearance spec that you need to worry about, is minimum clearance. Without going to silly extremes, there is no such thing as too much.

Kevin

 

[Big_John]

Some machinists as has been commented on here, are hung up on too much side clearance being a problem and are reluctant to increase it to clean up stuff like you are seeing.

There's a lot of years of engine builders warning against too much side clearance. I had always heard and read that too much clearance would drop oil pressure and spray more oil on the cylinder walls.

I've seen that has been dismissed as not that important as we all used to think it was and I can tell you from personal experience that I've run engines with more side clearance than spec'd with no problems.

As you say, as long as it's not "silly extremes". Cleaning up the sides of the con rod shouldn't be enough to worry about, but if I had a rod that needed a lot of the side faces machined off to get it straight, I'd probably toss that rod and find another that didn't need that much. Of course, IMHO, that is just common sense for any engine build.

Of course, there's a lot of schools of thought on con rods and engine rebuilds in general... Some guys wouldn't go to the expense of rebuilding the con rods for a street engine and some guys will replace rather than rebuild. I've seen engines tossed together in a dirt floor garage from odds and ends that ran as well as something a pro built in a clean room from the best parts, so I'm a bit cynical about a lot of it.

I wanted a good source of info on this and googling came up with this. I like that they quote my favorite engine building book, written by Bill Jenkins. The Great Rod Side Clearance Imbroglio: Clearing Up the Confusion

This is really interesting stuff (at least to me LOL) but I can't help but think that in this particular engine build, since it's his first, it's probably best to keep everything close to stock specs that we know will work in the long term.

 

[twostick]

The reason excessive side clearance causes oil pressure and windage issues is a myth is because the bearing clearance is what dictates the amount of oil "leaking".

You have a .0015" - .002" gap feeding a .030" - .040" gap. That's like feeding your garden hose into a fire hose. It's not making you fill a bucket any sooner.

Kevin

 

[Big_John]

The reason excessive side clearance causes oil pressure and windage issues is a myth is because the bearing clearance is what dictates the amount of oil "leaking".

You have a .0015" - .002" gap feeding a .030" - .040" gap. That's like feeding your garden hose into a fire hose. It's not making you fill a bucket any sooner.

Kevin

The question that I haven't found an answer for is "how much is too much for a stock type piston with a pressed pin?". Or with a floating pin for that matter. And I'm not talking about oil control, just how much excessive side clearance could affect bearings or pin bores. I guess you could say it's more of a geometry question that looks at side loading more than anything else.... and it may not come into play at all.

I know that race engines will use a piston guided con rod where the side to side clearance of the rod in the piston is limited. That would keep it all from rattling around too much... But I don't know as that's practical in the old design street engines we run or cost effective for that matter.

Interesting stuff!

 

[twostick]

The question that I haven't found an answer for is "how much is too much for a stock type piston with a pressed pin?". Or with a floating pin for that matter. And I'm not talking about oil control, just how much excessive side clearance could affect bearings or pin bores. I guess you could say it's more of a geometry question that looks at side loading more than anything else.... and it may not come into play at all.

I know that race engines will use a piston guided con rod where the side to side clearance of the rod in the piston is limited. That would keep it all from rattling around too much... But I don't know as that's practical in the old design street engines we run or cost effective for that matter.

Interesting stuff!

BBC rods were used for BBM strokers when there weren't any reasonably priced Mopar rods to be had. A BBC rod is .025 thinner than an LY rod.

I believe that would increase side clearance by .025" unless I'm seeing it wrong, and untold numbers of those combos ran/run just fine.

.017" max published spec plus .025" would be .042"

Kevin

 

[Cartel]

I think 1 figure 8 on 400 will show any high spots. I will lightly and carefully file them off probably 1 stroke. Thank you for the replies I feel a bit better now.

 

[wyrmrider]

my 2 cents side clearance makes no difference, brg clearance controls oil
you can sand those sides on a flat surface and see if there are any shiny spots, divitos are no big deal
wtf is that crack on that one rod side above the bolt
were these rods magged?
If you are going to balance you can grind the sides
LY rods are tough if there are no stress points, you can grind these out better than a scratch

 

[Cartel]

my 2 cents side clearance makes no difference, brg clearance controls oil
you can sand those sides on a flat surface and see if there are any shiny spots, divitos are no big deal
wtf is that crack on that one rod side above the bolt
were these rods magged?
If you are going to balance you can grind the sides
LY rods are tough if there are no stress points, you can grind these out better than a scratch

which one looks cracked please

 

[Cartel]

I gave all the face to face surfaces a rub. they were all not bad but 2. the highspots scratched the paper. 1 was easily rubbed away but 1 is the esge of the cap catching. Not sure how to take care of that....I wonder if that number 3 rod cap is the mate to the rod? thats quite a edge poking out there

 

[Toolmanmike]

Casting flash

I gave all the face to face surfaces a rub. they were all not bad but 2. the highspots scratched the paper. 1 was easily rubbed away but 1 is the esge of the cap catching. Not sure how to take care of that....

View attachment 692210View attachment 692211

 

[Cartel]

Casting flash

I made it easies to see now sorry. It looks like it came from the factory like that. that lighter gray area looks to been rubbing.
I think I will take the cap off and massage that edge a bit so it isnt a sharp step. not much else I can do really
What do you make of that?

 

[Just Carbs]

I would want to know the finished inside diameter of those rods.

 

[Cartel]

I would want to know the finished inside diameter of those rods.

says 2.5002 but the sheet looks incomplete. I only see a bore gauge mark on a few rods but thats why I paid someone $2800 to take care of all that....now I'm unsure if it was really checked thoroughly.
I didnt get a balance sheet from the guy he sent it to either. He said he's old and grumpy and doesn't do that...

 

[Big_John]

the sheet looks incomplete

Nothing incomplete about that sheet.

You didn't have them assemble the short block, so most of the measurements listed would not be able to be taken.

Example: "Oil Clearance" can't be measured because you didn't give them the bearings. Same for crank end play, ring gap, main and rod torque etc.

I would have marked that stuff "NA" myself, but that's me being used to having my paperwork audited from my work years.

 

[Big_John]

I gave all the face to face surfaces a rub. they were all not bad but 2. the highspots scratched the paper. 1 was easily rubbed away but 1 is the esge of the cap catching. Not sure how to take care of that....I wonder if that number 3 rod cap is the mate to the rod? thats quite a edge poking out there

View attachment 692211
View attachment 692212
View attachment 692216
View attachment 692214
View attachment 692215

That is nothing to worry about and massaging that stuff should have been done before they were reworked and balanced.

 

[Cartel]

Nothing incomplete about that sheet.

You didn't have them assemble the short block, so most of the measurements listed would not be able to be taken.

Example: "Oil Clearance" can't be measured because you didn't give them the bearings. Same for crank end play, ring gap, main and rod torque etc.

I would have marked that stuff "NA" myself, but that's me being used to having my paperwork audited from my work years.

I did give the rod bearings.
I dont know if every rod and crank was exactly 2.5002 2.3740
I'm just gonna lightly chamfer that edge so its not scraping.
Ill hose the bigends down and blow them off too

 

[Big_John]

I dont know if every rod and crank was exactly 2.5002 2.3740

According to the sheet they are. Not surprising.

 

[fury fan]

Although I'm not an engine machinist, or a high-precision machinist of anything, I would be skeptical of a set of measurements where each measurement of a set is the same to 4 decimal places. That means each measurement was within the same rounding direction in the 5th decimal. A spec of dust can alter that.

 

[Big_John]

Although I'm not an engine machinist, or a high-precision machinist of anything, I would be skeptical of a set of measurements where each measurement of a set is the same to 4 decimal places. That means each measurement was within the same rounding direction in the 5th decimal. A spec of dust can alter that.

Well... I spent a lot of years as a Journeyman Tool & Diemaker and then spent more years doing tool & gauge calibration, including being an owner in an A2LA accredited calibration lab. During those times, I not only machined and built many things to high precision, I also measured and worked on many very high precision tools and gauges. Just to illustrate, in our calibration lab, we had one room that I set up to measure gauge blocks. I could easily write several pages about how that was set up. We had a listed calculated measurement uncertainty of 2 millionths of an inch, but to get to that point, we were into what is called "sub-millionths" in actual measurements.

I will say I've never worked in an automotive machine shop, but I've been in them many times.... Many years ago, I was offered a job in a shop that did everyday work along with race engines, but there wasn't enough cash or benefits to make me want to lift heavy stuff and work with that nasty cast iron. That sign that says "no customers allowed" has never applied to me when I've been to automotive machine shops where I knew the owners. I've also repaired and calibrated measuring tools for several automotive machine shops over the years. I'm somewhat familiar with things like crank grinders and the honing machines that are used for rod work.

So much for what I've done... I think that qualifies me to say "Not surprised".

With a good crank grinder and an experienced machinist, holding .0001" accuracy and repeatability is a walk in the park. Measuring that crank journal to .0001" is also very easy. Again, you have to use the right tools and have some experience. Honing and measuring the big end of the rods is more fussy, but again using the correct tools and gauges, .0001" accuracy is just part of the day's work.

I understand the process, understand the tooling, and understand the gauges along with the limitations without bragging or exaggerating. I've also built a few engines in my time.

 

[73Coupe]

Well... I spent a lot of years as a Journeyman Tool & Diemaker and then spent more years doing tool & gauge calibration, including being an owner in an A2LA accredited calibration lab. During those times, I not only machined and built many things to high precision, I also measured and worked on many very high precision tools and gauges. Just to illustrate, in our calibration lab, we had one room that I set up to measure gauge blocks. I could easily write several pages about how that was set up. We had a listed calculated measurement uncertainty of 2 millionths of an inch, but to get to that point, we were into what is called "sub-millionths" in actual measurements.

I will say I've never worked in an automotive machine shop, but I've been in them many times.... Many years ago, I was offered a job in a shop that did everyday work along with race engines, but there wasn't enough cash or benefits to make me want to lift heavy stuff and work with that nasty cast iron. That sign that says "no customers allowed" has never applied to me when I've been to automotive machine shops where I knew the owners. I've also repaired and calibrated measuring tools for several automotive machine shops over the years. I'm somewhat familiar with things like crank grinders and the honing machines that are used for rod work.

So much for what I've done... I think that qualifies me to say "Not surprised".

With a good crank grinder and an experienced machinist, holding .0001" accuracy and repeatability is a walk in the park. Measuring that crank journal to .0001" is also very easy. Again, you have to use the right tools and have some experience. Honing and measuring the big end of the rods is more fussy, but again using the correct tools and gauges, .0001" accuracy is just part of the day's work.

I understand the process, understand the tooling, and understand the gauges along with the limitations without bragging or exaggerating. I've also built a few engines in my time.

The 0.0001" (ten thousandth) is usually the decimal place where the machining "limit" is specified, on automotive engines, as in low or high limit.

Yes, standard procedure for all journals and rod bores to be exactly the same, the entire width of each. I had a problem with rods being "bell ended" in one engine that I had machined long ago. They honed them bigger on one side than the other. That machinist I dealt with at the time was a bellend himself, lol.

On a Sunnen hone for example there is a dial gauge on the machine to check the bore diameter as you're honing it. They can then be measured after with a handheld diel bore indicator.