52 replies to this topic

[ClassicAlex]

Hi everyone!

I am in the process of rebuilding my engine, and I was checking my end flots between the crank against the main bearings and the crank against the thrust bearings, and this is what I got
Crank End Float - .34mm
Main Bearing - .57mm
And these were with std sized bearings.
I have tried to look for the oversized bearings that with bring the end floats to an acceptable tolerance, but couldn't find any on minispares etc. As I've only seen some go up to +020 when I need something that will cover +030 and +050!

What are your suggestions?

Thanks!

[Spider]

Can we just take a step back here?

 

These engines are Imperial and IMO, it's always best to work in Imperial and Measure in Imperial when working with them.

 

The numbers you've posted up are a mix of Imperial and Metric, which I've found is the first ingredient for a recipe for disaster (and errors).

 

Also, in regards to the Main Bearing, what is it you've measured in regards to the Main Bearing and how have you measured it?

 

What Block is it and what crankshaft?

[ClassicAlex]

Can we just take a step back here?

 

These engines are Imperial and IMO, it's always best to work in Imperial and Measure in Imperial when working with them.

 

The numbers you've posted up are a mix of Imperial and Metric, which I've found is the first ingredient for a recipe for disaster (and errors).

 

Also, in regards to the Main Bearing, what is it you've measured in regards to the Main Bearing and how have you measured it?

 

What Block is it and what crankshaft?

 

Sorry, it's just been a long day ha!

 

I'm following the set measurements from the haynes manual, which are in mm. I am using the DTi to measure the end floats.

 

I have used the dti to measure the main bearing by place the gauge sensor on the top of the crank shaft and have the engine hanging from the crankshaft to measure the displacement. 

 

The block is 1275 rebored to 1293, its the standard crankshaft that came with the engine.

Edited by ClassicAlex, 15 December 2016 - 08:24 PM.

[Carlos W]

When I measured my end float I bought a set of new standard thrust washers. 

 

http://www.minispare...ic/AEW2136.aspx

 

This gave me an end float which was too big so I bought a set of these and fitted them to one half

http://www.minispare...41.aspx|Back to

[Spider]

Sorry, still not much help there in understanding that of the Main Bearings.

 

by the way to highlight the Imperial / Metric issue that I've mentioned, 0.34 mm = 0.0133", so I think your end float is is actually 13.3 thousands of an inch. The Factory specs are 0.002 to 0.003" though I prefer to have the engines 'free turning', so I aim for 0,005".

 

The crank will have some numbers forged in to one of the webs. There's a number of 'standard' 1275 cranks and they are all different. These numbers may help us identify what crank you have.

 

Have you also measured the OD of the crank Journals?  Have you checked them for roundness?

 

<EDIT: The over and undersizes of the bearings and thrusts is expressed in thousands of an inch, not in any metric numbers. >

Edited by Moke Spider, 15 December 2016 - 08:34 PM.

[panky]

Cant figure out how you are trying to measure it, have a look at this vid.

 

[ClassicAlex]

It's all very confusing, but starting to make sense of it now.

The crank is CAM6232, and the crank has been polished.

[ClassicAlex]

Cant figure out how you are trying to measure it, have a look at this vid.
 

I did my thrust end float the same way as the video, I was talking about measuring the main bearings end float, where I measured the displacement using the dti whilst lifting the crankshaft up to work out the end float. Hope this makes sense

[Cooperman]

Let's just work in inches here.
The crankshaft end float after installation should be between 0.002" and 0.005". If outside this there are thicker thrust bearings available which reduce the actual float by 0.003" or 0.006" depending on whether you fit a single oversize pair or 2 pairs, one pair each side of the main bearing.

I am lost regarding what you mean about main bearing float. All shell bearings are sized to match the journal ground sizes either standard, 0.010" undersize, 0.020" undersize, or whatever it has been ground to.

[Coxie]

Are we talking about measuring main bearing clearance not crank shaft end float.
If so measure the main bearing clearances with plastigauge not by lifting the crank up.

Or am I reading this wrong

[Cooperman]

I don't have a manual to hand this minute, but the bearing to journal running clearances should be 0.001" to 0.0025" from memory. This is not called 'float - the float is the longitudinal movement of the installed crankshaft, Measure the crankshaft journals for both big-ends and mains with a micrometer screw gauge and establish the sizes. They will be either standard, -0.010", -0.020", -0.030" or -0.040". Then appropriate undersize bearings can be bought. You can finally check with Plastigauge. If you have 0-57 mm that would be a 20 thou undersize journal.

 

To convert mm to inches, divide the mm reading by 25.4. You must have all dimensions in inches.

[ClassicAlex]

Are we talking about measuring main bearing clearance not crank shaft end float.
If so measure the main bearing clearances with plastigauge not by lifting the crank up.

Or am I reading this wrong

Ah I think that's were I went wrong! I will order some plastigauge and measure the clearances in the main bearings.

[Carlos W]

How far are you from Dartford?

You could take it to Dartford rebore and get it properly looked at.

Otherwise you won't know if the wear is the crank or the bearings

[ClassicAlex]

I don't have a manual to hand this minute, but the bearing to journal running clearances should be 0.001" to 0.0025" from memory. This is not called 'float - the float is the longitudinal movement of the installed crankshaft, Measure the crankshaft journals for both big-ends and mains with a micrometer screw gauge and establish the sizes. They will be either standard, -0.010", -0.020", -0.030" or -0.040". Then appropriate undersize bearings can be bought. You can finally check with Plastigauge. If you have 0-57 mm that would be a 20 thou undersize journal.
 
To convert mm to inches, divide the mm reading by 25.4. You must have all dimensions in inches.

Yeah I think that's what I am going to do from now on, concert all metric measurements to imperial.

Ah I think that's where the confusion started, it was longitudal movement that I was measuring, as I think I may have measured it wrong, so I have ordered some plastigauge to take the measurements and will report back here with the findings.

In terms with the thrust bearing, I have noticed that the oversized bearings are 10 thou or 20 thou each side, not a total oversize of 20 thou, so this should be able to cover the end float.

[ClassicAlex]

How far are you from Dartford?

You could take it to Dartford rebore and get it properly looked at.

Otherwise you won't know if the wear is the crank or the bearings

The block has been rebored and the crank has been polished. It's the bearings that's causing the problem and these are new std bearings so I need to find the correct oversized bearings to fix the issue.