Worn valve guides

[englishmaninwales]

My TC has started to blow blue smoke at idle, but exhaust is clear on acceleration and over run, so I suspect worn guides and valves.

I have heard of problems with the removal of guides damaging the head casting. Is there a way around this? I have heard of the guides being bored and sleeved back to original size - is this possible?


Thanks
Malcolm

[rgh0]

Guides can be lined but getting the required tight clearances for a twin cam is not easy.
https://klineind.com/k-line-service-too ... s-cat.html

Removing and replacing guides is a routine operation in a twin cam head. if necessary oversize OD guides can be fitted.

cheers
Rohan

[Chancer]

Way back when there were companies that could bring worn valve guides back into tolerance by an internal knurling process, always seemed like a bodge to me and not likely to reduce o?l consumption unless seals were fitted.

Might be worth a Google though.

[john.p.clegg]

Malcolm
Best to put the head in the oven when the wifes out shopping , or for the weekend , and have a suitable sized drift to knock them out , and if you plan ahead have the new guides in the freezer , don't forget to check the valves / seats , reface ? and grind in.
An enjoyable afternoons work...

John

[Craven]

The engineering company I use favour the lining process using a Phosphor Bronze liner they reason far less disturbance to the head. Often replacement of the complete guide requires the valve seats to be centralised with the new guide resulting in greater metal removal and therefore deepening of the seat this of course means loss of valve clearance ( tappet ) and no concern about oversize guides. The liner can be reamed after fitting to fine limits and if a Colsibro liner is used should run for many many miles before needing replacement again.
You pay your money and make your choice.
FWIW.

[types26/36]

I had some guide replaced by two different engineering company's, first time the valves had more play then when I took the head in. I complained and he "knurled" the guides, the valves became tighter but the the car smoked like a chimney.

Had them replaced by another company and the valves felt good.......a couple of hundred miles later it was smoking again.

Got fed up with this so fitted new guides myself and reamed them but modified the guides to take seals, since then no smoke even when first started and plugs and exhaust are clean even at idle.

Takes a fair amount of measuring and checking to prevent the seals being crushed but it works for me.

PS. dont think the wife would appreciate a head in the oven and doubt it would fit anyway so heated it in the BBQ.

[john.p.clegg]

More details about the seals please....

I tapered the top of my guides after fitting to " scrape " the oil from the stems..

John

[Grizzly]

I had two bad exhaust guides so i had four new oversize valves made and reamed the exhaust guides to match.

Short term fix as i planned to have a set of guides modified for oil seals but haven't got round to it.

[types26/36]

More details about the seals please....

The valve seals were VW mk1/2 Golf but I machined them shorter, the guides as well as cotters and retainers were also shortened and I think I had to slightly modify the lower metal spring platform hole.

[john.p.clegg]

Many thanks....will ponder.

John

[elancoupe]

If you have access to Dave Bean's parts book, read his thoughts on seals.

[englishmaninwales]

Thanks for the advice.
Malcolm