I removed my 455 heads to change intake and heads gasket, also take the opportunity to lap the valves but found that two valves has worn guides. The machine shop that I trust can't receive orders until next February so I'm pretty much like stuck and my unique two options are assemble the heads by this way and use the car like this until next year or change the guides by myself. I've done this job in the past on a bike engine but it was a very straightforward work, just push the old guide out and press the new guide in so I'm sure like isn't so simple on my 455. I checked on Rockauto and guides are available: https://www.rockauto.com/en/catalog/buick,1970,gs+455,7.5l+455cid+v8,1379763,engine,valve+guide,5776 What can you recommend me about this ? the 455 guides can be pushed out or needs to be reamed? also what's the most easy way of aligning the guide and the seat without very specialized high tech machine shop tools?
Are these aftermarket heads? If they are stock cast iron they probably dont have press out guides.even if they are I wouldn't trust that they would be centered enough to lap the valve in. I would think you could ship them to a reliable machine shop.
They are the stock cast iron of my 455, I lapped all 16 valves and tested them and the sealing is fine but my big concern are the worn guides maybe Will affect the valve sealing with the heads on engine
Let's Say that original guides were replaced a time ago (the engine looks like has been previously rebuilt and current guides doesn't look like cast), new guides could be "press in" type?
Find a good machinist that can do this and put them on the Pony Express. The time and money you spend to get them done right, vs the time and money you think you will save (and might see going down the toilet) will be well worth it. Cheap is for those Chevy guys...
Ive seen them removed with air hammer and attachment of correct size. I then seen them put in by hand and hammer with installer tool. Like a bushing installer. Then you have to reem it. With a tool sized to the valve. Engine manuals by Motor , from the 50 and early 60ies have good info on this since doing tbis by hand is the origional technique. Ive not done it but have read how.
I know the feeling of wanting to do it yourself and save money, But as Joe said, they are cast/machined with the rest of the head, you cannot press them out if they are original. They have to be reamed/removed, then new guides pressed in.
First off how was the motor running? Are the guides loose enough that they where making for valve stem to valve seal issues and you where seing blue smoke out the tail pipe during deceleration? If your not smoking then the thing about running loose guides the most in regards to making power is the width of the 45 degree valve seat. The valve will still seal pretty good if the valve sets is wide enough to deal with the side to side valve movements, but of course this type of movement will make for faster valve seat ware to a degree ! You can likley just run them as is , of course you will not get peak performance, but at least you can use the car until the shop can take the heads in. Also note that many times the valves are worn too and for me anything over .001" of ware on the stems high load area calls for new valves also, not just new guides! One thing is for sure you will never have issues / motor failures with loose guides like you will from guides that are too tight!!
If they have been replaced then you can swap them at home. They could have had liners cut in during the first rebuild.
I've never had smoking issues on cold start, idling or hard accelerations. What I did after lap is a 4 hours leak test and all the valves sealed right, then I did repeat the test with compressed air with the same result I'm going to take a picture of the guides that I think has been replaced, I'm mostly sure they aren't stock guides but want some additional opinions
Even if your able to replace a 1/2" od guide or a guide liner at home your still going to need to get the valve job touched up by a shop unless you are able to do this yourself also.
The wall thickness on those is 0.064". It would be considered a sleeve. It's listed for hundreds of applications including Ford, GM, Mopar, AMC and Jeep. Pretty much a generic 3/8" guide insert. Your heads will have to be machined and these guides pressed in.
Ok guy As I promise I'm attaching some pics of my heads guides which I'm not sure if are the stock cast or are replacement guides. Note that the valves shown on these pictures has considerably wear due to the shaft was improperly mounted and the head suffered of lack of lubrication so I'm planning to replace the wore out valves too
Just what I though, so now the big question is, can be "easily" home made changed? tomorrow I'm going to talk to another shop that a Mopar friend used a time ago but want to have a couple options on the table
They look like .500" OD liners to me. The good news is they can be replaced as the head has already been bored/ reamed for them, the bad news is they will need finish sizing once installed and you will want the seats cut once done. Get a competent machinist to do the job and have it done once
Josehf, do yourself a HUGE favor, have a machine shop do those for you. I know the feeling of wanting to learn and do myself, but there are some things that require experience, knowledge, and skill, not to mention EXPENSIVE tools to do the job properly. I concede and have my machine shop do my engine machining. Im sure the guides are pressed in, not beat in with a carpenters hammer. Sometimes yah just gotta pay
Those look like iron guides to me and they usually last a good long time if your not running used valves that will beat them up, or if the heads where not cleaned up well before assembly. Are you sure the guides need to go? Have you measured the stems of your valves ? You can maybe save save your self 15 bucks in labor cost if you drive them out yourself before taking the heads to a shop.
I haven't measured the stems, I'm sure at least three guides needs to go because the valve have play, the other guides looks like they're "fine" but I'm not sure if could be a good practice just go ahead and change all of them. I'm going to talk to the machine shop and see what can they do for me
