Valve/valve seat questions, 308 heads

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Snaggletooth

Snaggletooth

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Stockholm, Sweden
Hi!
"Rebuild season" is closing in here in sweden and it's time to get some work on my 360 Valiant. Found a pair of 308 heads for cheap in pretty bad order (donor engine had water in cylinders) so I'll have to do some valve work.

Found out that 2.02 valves aren't that expensive on summit so why not go for it? My concern is the valve seats. Haven't done anything like this before so I wouldn't know. But how much material can you mill of the seats? Is it possible for standard 308 heads(is it 1.88 intake valves?) to house a 2.02 with some additional milling? Valves and seats looks pretty rough so some work will be needed anyway.

The goal for the engine is an early power curve. Good bottom end power and rising to a peak diminishing between 4800-5500RPM.

Best regard
Carl
 
Snaggletooth said:
Hi!
"Rebuild season" is closing in here in sweden and it's time to get some work on my 360 Valiant. Found a pair of 308 heads for cheap in pretty bad order (donor engine had water in cylinders) so I'll have to do some valve work.

Found out that 2.02 valves aren't that expensive on summit so why not go for it? My concern is the valve seats. Haven't done anything like this before so I wouldn't know. But how much material can you mill of the seats? Is it possible for standard 308 heads(is it 1.88 intake valves?) to house a 2.02 with some additional milling? Valves and seats looks pretty rough so some work will be needed anyway.

The goal for the engine is an early power curve. Good bottom end power and rising to a peak diminishing between 4800-5500RPM.

Best regard
Carl
Click to expand...


Leave the 1.88 valves in there and use the best valve job you can find. Unless you want to do more than just bowl porting its not worth the trouble of the bigger valve.
 
I had 2.02/1.60 valves installed in the 308 heads I have on my 340. It's a pretty basic process, the heads are opened up for larger valves and then cut to take the larger valve seats. These are my heads after the larger valves were installed. This set also got what amounts to a stage II port job, ended up flowing 264 cfm @ 0.500"

IMG_4409.JPG


Here's the basic process. This is an old ford y-block, but you get the idea. You would want hardened seats installed afterward.
 
sure beats the old days of cutting new seats using a stone on a drill with a pilot shaft coming up through the guide to keep you centered....that is the way we used to do it in the 70s and 80s....then hand lap them in with lapping compound and the wooden dowel with the suction cups on the end...and a 3 or 5 angle valve job??? what was that....your stone had one angle...I think 45 degrees and that was it......well there was no such thing as a cnc back then until mid to late 80s
 
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bbrroowwnn said:
sure beats the old days of cutting new seats using a stone on a drill with a pilot shaft coming up through the guide to keep you centered....that is the way we used to do it in the 70s and 80s....then hand lap them in with lapping compound and the wooden dowel with the suction cups on the end...and a 3 or 5 angle valve job??? what was that....your stone had one angle...I think 45 degrees and that was it......well there was no such thing as a cnc back then until mid to late 80s
Click to expand...
Why you dress 'stones' different angles, to switch and grind 3. It still centers from guides to cut for hard seats and to grind seats to 70, 45, and what ever the master stone slinger likes for a top grind. Seri, souix...all need a good guide to pilot the tool... hence not much has changed.
 
So milling the existing seats is a no-no for bigger valves? In that case I might settle with a dingleball rebuild with my existing parts. Plan is to be as cheap as possible. With upgrades each year rather than everything at once!
 
in addition with a porting burr you might open up the chambers on the ends to unschroud the larger diameter valves for more flow. Dulcich has some good iron head porting info if desired (Google it)
 
If you are using stones, you're still in the stone age for valve jobs and valve size won't really make a difference. Find a place that does cutter valve jobs using a modern head machine. If you find that equipment, then have the existing seats cut for OS valves, and the throat cut that's part of any performance deal will do 80% of the template type work.
 
moper said:
If you are using stones, you're still in the stone age for valve jobs and valve size won't really make a difference. Find a place that does cutter valve jobs using a modern head machine. If you find that equipment, then have the existing seats cut for OS valves, and the throat cut that's part of any performance deal will do 80% of the template type work.
Click to expand...
No stones for me! I will take the heads to a machine shop that's really experienced with headwork, it'll be exciting to see the result!
 
Dissasembled the heads this weekend. Looked rough even with clean-up!

I consider the intake valves unusable (maby 3-4 of them looked OK) So they will be replaced. Waiting for the heads to be acid-bathed at a shop to get all rust and gunk out.
It was really obvious that water had come in the motor from the intake, since intake valves were pretty eaten and the exhaust valves pretty much only had surface rust...

20171021_213112.jpg
 
Snaggletooth said:
Dissasembled the heads this weekend. Looked rough even with clean-up!

I consider the intake valves unusable (maby 3-4 of them looked OK) So they will be replaced. Waiting for the heads to be acid-bathed at a shop to get all rust and gunk out.
It was really obvious that water had come in the motor from the intake, since intake valves were pretty eaten and the exhaust valves pretty much only had surface rust...

View attachment 1715103657
Click to expand...
I don't know what prices are like there, but I wouldn't be using any of those valves over, get a quality set of stainless replacements whether stock or oversize.
 
Do yourself a favor... replace the exhaust valves too, and get new retainers and locks for them. Those rotators are not going to work in any performance application.
 
Since I'm switching over for a flat tappet most of the valvetrain will be changed - including retainers, since they wont fit the new springs. Haven't posted any pics of the exhaust valves yet but both stems and dishes looks good. They'll be milled if needed!

Heads and headers are back from the acid bath too!

received_10155055050846662.jpeg
 
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