Rod bearings?

Putting the motor together and the rods are a little to tight .002 wanting .003 . The bearing I have are a ACL 8B743H. So the only thing I can find in town was a CB743HN001( clevite?). I this a narrow bearing than the one listed? Cant fine a clevite book to look them up


Ace

The ACL are chamfered....the clevite are narowed.

Lem Evans wrote:The ACL are chamfered....the clevite are narowed.

So i should not use them?

Ace

Both will work.

Ok called them back as the correct number should be cb743hxn001. So they had to ordered and be here by Friday .


Ace

the ACL number you were looking for is 8b743hx-std it is std + .001

Larry T wrote: the ACL number you were looking for is 8b743hx-std  it is std + .001

I need a minus .001 the bearings are too tight.

Ace

powerstrokeace wrote:

Larry T wrote: the ACL number you were looking for is 8b743hx-std  it is std + .001

I need a minus .001 the bearings are too tight.

Ace

I understand that what you have is too tight the way the number is lettered etc is misleading.i use this number to get my clearance @.003 the X means it is .001 oversize.

X2

If you are looking for an extra thou clearance you will want part number CB743HXN. Do not use a 001 or 1. Part number CB743HN001 will tighten your clearance up a thou.

Bret

Yes,the X bearing is what you want.I just tell Lem what I have and he gets . Me what I need.

The machine shop did not do their part in measuring the big end of the rid with the bearing installed and gave my crank grinder a bogus number. Missed by .001

Ace

The machine shop did not do their part in measuring the big end of the rid with the bearing installed and gave my crank grinder a bogus number. Missed by .001

Ace

let me correct this the clearance with a standard bearing is less than .002 but more than .0015. and with the x-tra clearance bearing its .002???? ok the crank is out and back to the grinder to have .0012 removed....

Ace

I hope you have a very good machinist...

Hitting .0012 is not easy to do.

Easy to make a mess and end up with a bunch of out of round tapered journals ...

dkp

How are you checking your clearance?

cool40 wrote:How are you checking your clearance?

I have no idea? THE MACHINE SHOP WAS COMMUNICATING THAT WITH THE CRANK GRINDER. I was using the plastigage method. the mains are fine at .003. I have a racing buddy that bought out a old friends machine shop and does limited stuff for other people and his own. We will take the rods over there and remeasure them before we touch the crank.


Ace

powerstrokeace wrote:

cool40 wrote:How are you checking your clearance?

I have no idea ? I have a racing buddy that bought out a old friendsachine shop and does limited stuff for other people and his own. We will take the rods over there and remora sure th before we touch the crank.


Ace

well... how do you know what it needs?    you may be much better off letting someone who can check things out put the bottom end together.

x2

If your using plastigauge you could be off by .002" or more and not know it. Dial bore gauge and mics are necessary tools.

cool40 wrote:

powerstrokeace wrote:

cool40 wrote:How are you checking your clearance?

I have no idea ? I have a racing buddy that bought out a old friendsachine shop and does limited stuff for other people and his own. We will take the rods over there and remora sure th before we touch the crank.


Ace

well... how do you know what it needs?    you may be much better off letting someone who can check things out put the bottom end together.

     

powerstrokeace wrote:

Larry T wrote: the ACL number you were looking for is 8b743hx-std  it is std + .001

I need a minus .001 the bearings are too tight.

Ace

You are looking for "X"tra clearance NOT a 1 for the bearings.  If it is a good quality crank and you are not making +750 horsepower then .002" clearance vertical with the rods would be fine.

rmcomprandy wrote:

powerstrokeace wrote:

Larry T wrote: the ACL number you were looking for is 8b743hx-std  it is std + .001

I need a minus .001 the bearings are too tight.

Ace

You are looking for "X"tra clearance NOT a 1 for the bearings.  If it is a good quality crank and you are not making +750 horsepower then .002" clearance vertical with the rods would be fine.

Let me first clear some thing up. I was using a maching shop for the second time in 14 years as a good friend has recommend them to me. The current owner is a long time top fuel mechanic as his dad was a driver for many years from this area. 12 years ago i needed there resources to save a new build on a block as the guy preping the block installed one of the cam bearing wrong and that resulted in 10-15 second if run time before is stop. So the have a tooling to bore out the cam tunnel and install roller bearings. And they only charged me $200. It was a life saver at that time. So I have this same block and took it to them and asked them to see if they can check the cylinders to save the block and if we can to replace a lifter bushing( i had the lifter bored bushed) the roller cam bearing and align hone as well IF the cylinders were good. Well they did the cylinders last and we ended up at 4.450 bore. F*#@ers!!!! I then had them Bore and hone the last DOVE block i own to a 4.440 bore and Oakley got me a set of pistons. At this same time i had a set of H-beam rods that needed to be finished on both ends as these were brand new never ran. So they were to finish sizing these and then install the bearing and measure the big end of the rods and like wise with the block for the crank to be checked as well with the bearings installed. This information was then relayed to my crank grinder to finish the 4.5 stroke cranks that was on the fat side. The crank grinder did his job with the specs given. The crank grinder thought from the beging the rods were a little smaller than what he normally see's.
So i get everything measured out with the plastic gauge and the mains are fine but the rods are tight. So i call the crank guy and talk to him and he then infomed me he thought the rods size given was a little small ( the crank grinder does all these guy's stuff as well as they are 3 blocks away). So he offer to fix the crank at no charge or i could try the extra clearance bearings.
So i went to the speed shop and we ordered up a set of bearings. When i got home I noticed the part number was +.001. So this is where  i started this fourm as i spent an hour searching part numbers and asking question to make sure i had my fact right and called the speed shop back and inform him he ordered the wrong bearings. Which he said he did. So the order was corrected and I got the X bearings I wanted to remeasure the rods

So using the plasti-gauge I re checked the rods using the X bearing and only gained maybe .005-.008 clearance. The standard bearing was more than .0015 but less than .002. The x bearing was .002. i checked these 3 time and everytime was the same results. So the crank guy mentioned this to a 30 + year racing buddy and he contacted me and has offered his service's as he has a small machine shop at his house and is 2 miles away.
Now i'm not a professionally builder but i have been a mechanis for a 35 years and have built all my own motors for the 35 years i have raced. The only enigne failure i have had was the motor i destructed last April and it was together for 11 years with just normal maintenace. Then the heads (Motorsports A460's) went to Phillip to be Corrected as a local ford guy thought he knew what he was doing and messed them up. Phillip picked up almost 60 CFM on the flow bench on the intake side and I can't remember what he said on the exhaust side.
I'm sure evey one of our fourm members at one time or nother has had to deal with the Machine shop that are CHEVY guy's and really could careless about your ford junk. Well that the same for here in Colorado.
Last example Scott Main at MPG head service has screwed 90% of his local customer and he could careless. However Scott is a smart man and his engine master motors show that. But he's a jerk to deal with. I happen to have a 557 A headed motor that i bought from a friend to run this last year and it has one of his cams. I often wonder why he ground this cam and then told the owner to change the rocker ratio from 1.73 to 1.75 on the exhaust and 1.85 intake and leave the lash loose (.030) and start there. Sorry for the rant as i only trust what I see with my own eyes and what i build with my own hands or the guy's on this fourm that i have talked with.


Ace

All's good. checked them out tonight on an older Sunnen rod machine and we have .0035 on the rods. so nothing will be done to the crank and the short block will be built this saturday...

Ace

scap the plastiguage !! even a cheap dialbore guage is more accuate !!
Frank