351C factory heads, can valve guide cracks be repaired by complete removal of the iron guides and pressing in thick-wall bronze guides?

Spring side

Seat side

I've got a much better valve guide for you that will save these heads. I'm checking with the supplier now to see if he still carries them.

I'll update as soon as I get an answer.

You will like LOVE these.

They really made a mess of them.

I hate to think where all the fragments of cast iron went.

Is the cracking on the top of the heads a serious issue? Couldn't he press / machine out the guides, and then remove the thin cast material? I can't see how that cast housing adds A LOT of strength.

I would be worried about the cracks inside the port, though. I wouldn't want a chunk coming off the intake side.

I'm just asking, to trying to learn.

Thanks.

Rocky

Best guess- the P.O hammered new guides in from the top down, at room temp. The very thin flashing left from boring out the oem guides then cracked. Very hard to avoid if flashing is left behind. Disregard- does nothing for strength but remove broken bits as much as possible. FWIW- I drive them in from the chamber side using an air gun while castings are hot. Cut for .502 guide seals, sometimes the guides crack as well if driven from the top.

quote:

Originally posted by Rocky:
Is the cracking on the top of the heads a serious issue? Couldn't he press / machine out the guides, and then remove the thin cast material? I can't see how that cast housing adds A LOT of strength.

I would be worried about the cracks inside the port, though. I wouldn't want a chunk coming off the intake side.

I'm just asking, to trying to learn.

Thanks.

Rocky

The person who did these guides has no idea what is required to do them right.

What I am trying to get is current availability of the solid manganese-bronze guide.

It is .502" od. To install them, you machine off the rest of the top of the cast iron guide that "the other guy" left. (Must be a Community College shop class graduate?)

Then you bore the guide hole to .497 and then hone it to .499. Then you press these in from the top until the shoulder stops it.

The top has a ridge so it can't slip through. The seal sits on top and you trim the length in the port to where you want them.

Easy-peesy!

The guy who sells them is Ted Standhope, I believe and email him at

engnbldr@engnbldr.com

Here's a picture of one of my spares.

This one is for a 427 Ford. The one for the sb Ford is the same except for the valve stem hole of 5/16". This one is a 3/8 stem.

These are the same guides that Edelbrock and Trick Flow use. As far as I know, he supplies them from what I understand but it's been awhile since I bought these?

If he doesn't have them, TFS has the same ones. You can get them there or even from Edelbrock.

They are so simple to do you can do them yourself in your own shop.

These are the guides that you want. They are so easy a retard, a Chevy guy, a potential xxx candidate could do them?

Now - don't go "full retard" on us, Doug, or you'll need more cowbell.

Thanks for the info.

On the intake side the answer is definitely yes. I've seen guys do it intentionally. There's very little risk.

On the exhaust side I'm a little hesitant about complete removal of the iron guide inside the exhaust port, exposing the bronze guide to the exhaust gases which can run up to 1000 degrees F. I have no experience however.

Press in iron guides could be used on the exhaust.

I would suggest removal of the cracked metal is paramount, a crack in the exhaust port could run anywhere and do who knows what damage eventually.

Ok guys, thanks for your answers.

In fact we are on the same line, I was thinking the same remove the thin stuffs on the top and have a basic guide with a shoulder and the other side have a tapper which come gently to my valve diameter, I have EPN valves and the portion supposed to be outside of the guide has a smaller diameter for flow I guess. So in order to avoid sharp cross section changes I would see a tapper here. If I go in porting I will take all opportunities to do the best flow.

Panteradoug, thanks for your help I will email your guy see what he proposes to which price.

But I am pessimistic, first I don't find what I want and when I find it it is pretty expensive. So if the part is so simple I was wondering about asking my machinist to do them I would just need to buy a 11/32 reamer. I just need to confirm that I can go with bronze.

Another problem I found, if you look to the guides they are driven to far in the direction of the top, so when the valve is opened there's nearly no room for the valve seal which almost all cracked and felt as small pieces into the oil pan.

And I am nearly sure the drove the guides from the bottom to the top because it would have been to complicated to do from the top with the thin casting lips. And as they probably were not exactly aligned they've cracked everything, when they start driving it.

I have made few measurement this morning, the intake press fit length with a "flat roof" would remain as 21 mm on intake side and 27 mm on exhaust side. If I assume the 0.502 guide this gives a 1.75 ratio on intake (press fit length = 1.75 diameters) and around 2 for the exhaust.

Last thing, about the sealing, there is an option which is using some modern valve seals, as you advised to me, but, with old one and broken one my engine managed to get very worn guide with I guess plenty of lube, two questions : is there a break-in procedure with new valves + new guides, and isn't it better to stick with old style seals ?

Some more pictures :

Look to this disaster :

Casting top (just need to be cut away and do a little chamfer) :

Measurement :

Intake press-fit length :

Exhaust press-fit length :

Have you considered the price differential between the cost to machine your old heads with new parts vs a set of upgraded modern aluminum heads?...Mark

Hi Mark, I'm in France, I can look but things cost twice the price when arrived here (customs .. shipment … ) …