[Mgs] Project 74.5, valve guide options

[Max Heim]

In the past, I have had machinists explain this choice as follows:

Knurling is a temporary solution to keep the car on the road at minimal
expense. It will more or less rapidly wear and resume doing whatever it was
doing before (leaking oil through the guides, etc.). One way to describe the
process is that it deforms the iron around the hole to reduce the
clearances.

Bronze guides are a more permanent fix. This involves inserting a new guide
with the proper tolerance. Bronze, like cast iron, is softer than the valve
stem material. Bronze also has some self-lubricating properties, I believe.

I have had both done at various times on various vehicles.


--

Max Heim
'66 MGB GHN3L76149
If you're near Mountain View, CA,
it's the primer red one with chrome wires


on 3/17/08 11:28 PM, cyberemp at comcast.net at cyberemp at comcast.net wrote:

> Greetings 0 list.
> Head for 74.5 needs guides. Machinist is offering to put bronze sleeves into
> existing cast iron guides,(after reaming current guides, of course) but I'm
> curious to know if anyone has any experience with this technique.
> 
> Back when I rebuilt the engine on my first car, (1967 Cortina GT) the shop
> "gnurled" the guides.
> Of course they also rebuilt the short block which threw a con rod through
> the side of the block within a year. Ouch.
> warantee not much good when your speedometer doesn't work. At least that's
> what 
> they claimed.
> But wait, I'm yammering bitterly. Blame the pain meds I'm on.
>    
> $ is a factor, as I'm still on disability, but even though I'm selling the
> car, 
> partly to fund next project.
> I just feel that if your going to do a job, do it right.
> 
> machinist is checking valves to see if they're okay.
> 
> My second option is looking at Northwest pacific parts flyer I got in mail,
> (sorry Ed ;-)  package deal for valves, guides and springs. (can't find flyer
> right now) I'll send them an email asking what kind of guides. Cast iron or
>  bronze, and the valve material.
>   Total package was around $108 if I remember right. That might hint at what
> kind of materials are used.
> Apparently valves can be stainless steel, stellite treated and who knows what
> else. 
> guides can be cast iron, bronze, possibly others.
> 
> I just visited Barneys site. Got some good ideas there.Thanks Barney!
>     Any one have experience with the bronze guide inserts? this would save
> cost 
> of buying and r/r of guides.
> Eric
> 
> 46 MGTC
> 59 MGA
> 70 MGB
> 71 MGB
> 74.5 MGB
> 00 Nissan X-Terra
> So many cars, so little parking
> _______________________________________________