Marine 351

[scotts90ranger]

Next dumb question, what's the stock small block valve stem diameter? The rusty valve stem is .355" in the clean spot before the rust...

I'd search for things but google and everything blows anymore and you guys know your shiznit... I'm expecting I'll need to visit a machine shop to put guides in the dumb thing so I can use stock valves or find new heads...

Ok, I'd mentioned there's a D8 casting number on the heads but there's also F3 stampings on one end of at least the head with issues... we'll see if I have the energy to take pics of both tomorrow...

 

[19Walt93]

We used to ream out new valve guides to .343", I'd recheck thar .355 number. I've seen valve with oversized stems before.
What's the rest of your casting numbers? D8AZ-6009-A is an example of a block ID.
If you want to build power, those compression killing pistons won't help.

 

[scotts90ranger]

There's steps on the stems just under the keepers so I'm thinking they're oversized valves... I checked it with my calipers half a dozen times and got the same number.

I'm not too worried about power, the marine cam has a power peak of like 4500rpm from what I'm hearing at work (they sold Ford's back in the day and the salesman has been there since '81 so he remembers lol). It does everything I want it to do other than uses too dang much gas but that's what boats do... once I get it back going I'll probably go through the steps to rejet the carb to help some... On a jet boat the prop curve gets exponential over a certain point so it takes more power to get faster depending on the pitch, the old ways of the '80's was to have a top rpm of around 4k and cruise around 3k, still a decent rule of thumb depending on the use but with modern engines you get more power around 5k without losing too much prop efficiency and still can cruise around 3500 and use less gas than I'm using now being in closed loop at cruise instead of having roughly 10% more fuel than needed just to stay safe without oxygen sensors.

I'll get the numbers off the heads later today

 

[scotts90ranger]

The casting number on the heads are D8OE with AE below it. The stamped number on the end is F388 3002 I think, that's what it looks like on one head at least...

 

[19Walt93]

The casting number on the heads are D8OE with AE below it. The stamped number on the end is F388 3002 I think, that's what it looks like on one head at least...

That's a head originally used in a 1978, most likely an LTD II or T Bird. It would have pedestal rockers so that's good but the ports are probably restrictive. The other number is likely a date code.