Small end bush / Gudgeon pin clearance

[AceOfHearts]

I am getting an engine rebuilt (not totally standard) which is requiring new small end bushes to be manufactured, and its for an engine where build manuals are not generally available and closely guarded.

Having been doing some reading on the subject, the bushes should be reamed after fitting to give clearance to the gudgeon pin of about half a thou (0.0005" / 0.012mm)

Does this sound about right? It is for a fairly high revving V8 not that I think that should make much difference, The pins are 18mm diameter.

Some input from the experienced builders on here would be much appreciated

[stevieturbo]

If possible, I'd be sending them back to the rod manufacturer to do it, or seeking info from them

And for a "high revving V8"....those are pretty small pins !

[AceOfHearts]

stevieturbo said:

If possible, I'd be sending them back to the rod manufacturer to do it, or seeking info from them

And for a "high revving V8"....those are pretty small pins !

Thanks, yes thats a good shout getting onto the rod manufacturer about it

Its a 3.4 litre Ferrari engine

[Evoluzione]

Whoever is doing the job should know, you don't own a machine like a rod hone and not know what the clearances are.

[AceOfHearts]

Evoluzione said:

Whoever is doing the job should know, you don't own a machine like a rod hone and not know what the clearances are.

Its something I would like to know myself though hence asking on here, as I know there are a lot of experienced engine builders on the forum. I just like to learn and gain as much knowledge on a subject before starting the project.

[Boosted LS1]

I'd be happy with .0005". Robson's could do the bushes I imagine and hone them for you.

[stevieturbo]

Evoluzione said:

Whoever is doing the job should know, you don't own a machine like a rod hone and not know what the clearances are.

A local shop fitted new bushes to some aftermarket rods here for a friend some time ago......and later a rod broke, destroying most of the engine.
The aholes didnt fit the bushes correctly, nor even hone them perpendicular to the rod.

So yes they "should" know......but I would trust very few to actually know or be capable.

Hence saying the best people are the rod manufacturer ! lol