Valve guide removal and replacement

[MyhreMade]

I have a 1953 Pontiac chieftain with a straight 8 I’m working on the valves on. A few of the guides are broken and need to be replaced. Does anyone have experience doing this? The manual says to use tool j-2542. I’m guessing I won’t be able to find that tool. Can anyone recommend the correct tool I can find to get the old guides out and put in the new ones? I found a lot of drift tools online but I’m not sure which one is correct.

[RussJagoau]

I have replaced guides in these engines numerous times. One method i successfuly used ( without knowing which tools / drifts you have looked at)  is to measure the Guide ID and OD and have a tool made on a lathe that has a step shoulder on the tool. 

I have done this for numerous guides that were an interference fit in various heads or blocks that Ive restored over the years. Just ensure the tool ID is long enough to be the length of the guide so it acts a a good pilot whilst you are removing the guides. Any machine shop should be able to make this for you at a reasonable cost. 

I have used standard Grade 8 engine bolts with the nut screwed on to sometimes start the removal of the guides if they were tight as I didnt want to damage the shouldered tools that I manufactured.  Some of the guides removed took a lot of pounding to start the removal process so only use hi-grade bolts that will withstand the impacts.

 

If the protruding section of the guide is broken - i would suggest you square that off before commencing the removal process to have a uniform surface area to act upon when you are removing the guide. If not you can skew the guide sideways somewhat as well making life more difficult than it needs to be.  

 

For what its worth many manufacturers make guide removal tools for British motorcycles - to which i have a BSA engine guide tool that comes very close to the  original dimensions of Pontiac guides.

However its a selective fit that you can only try at the time before you purchase or manufacture the tool.

 

Hope this helps

 

 

[MyhreMade]

Great! Thank you for the help. I ordered a new guide today. I think once I get it I’ll do as you recommended and use it to measure the id and od and make a drift on my lathe.

[RussJagoau]

No probs - if you get the time when you get the new guide and fabricate the drift - pls post a few pics as would be interested to see what it looks like and how it performed. Ive tried numerous combinations over the years and some work better in some applications than others. In cast blocks like you have there, removal is generally straightforward. In alloy heads where steel / bronze guides are fitted, when the guide is being taken out, it can damage the head and make the counterbore loose even when the head is heated in the oven to assist with the removal and installation process. Good luck ! 

[Teddy]

I have a 1948 Pontiac Silver Streak 6 cyl flathead. It had been in storage for many years and I just want to get it running. I took the head off along with the manifolds, and I removed all of the valves since some were stuck. The cylinders look good and the valve seats are good. I bought new valves, and was thinking of just lapping and installing. I was not planning to replace the valve guides because I assumed that it would be too difficult to do with the engine in the car. But the ID of the exhaust guides are significantly eroded near the top although reasonably good further down. How hard is it to replace the guides, if possible at all, with the the engine in the car?  Since I have not seen a new guide, not clear whether they go in from the top or bottom and if there is a shoulder on one end to seat it at the proper point. If they have to be driven or pressed in from the bottom, that appears to be a difficult situation because of the limited working room. And I also saw in the shop manual that the new guides are undersized and are supposed to be reamed with a special tool. Any comments would be appreciated.

[RussJagoau]

Teddy

Exhaust valve guides have a counterbore inside the valve guide to allow for expansion. This is near the top of the guide and if you have access to a workshop manual the dimensions of the counterbores is stated as its different for 6 cyl vs 8 cylinder engines. This may well be what you are seeing as the eroded section you refer to,  in the 6 cylinder engine application, the counterbore is approx 0.750" depth according to the Pontiac workshop manual

The guides are driven out downwards and the new guide is installed the same way, ie from the top of the block downwards. Before installation, i place them in the freezer overnight to minimise the OD of the guide insert before its driven into the block. Never had any issues with this method in the engines i  have done.
Prior to removal - suggest you   measure the  heights of the guides protrusion  in the block under the valve head  before you drive them out,  and then  replace to an identical height . They  dont have to be within 0.010" of one another as some of the Pontiacs I have dis-assembled had significant assembled height variations for years and were running well, as the engine simply wore out over time. 

Depending on the manufacturer of the replacement guide, and the dimensions of the  valve stems, some guides will  require precision reaming to obtain the correct radial clearances, whereas others dont.  So its a condition based approach based on the measurements of the  guide ID vs Stem OD. To do this you will need a good small hole bore gauge and a micrometer to accurately measure the dimensions .

 

Some of the old guides can be difficult to remove given the time they have been installed. A good soaking with release fluid sometimes helps as does some local heat application using a paint stripper hot air gun. If you try to rush the job, then generally something wil invariably end up damaged, generally its the operator applying the removal techniques.  Good luck