one more pic...

 

From what I also know this is a normal apperance... The exhaust does have a thicker head so it will not "tulip" under the intense heat it has to survive...

 

Same here. Looks normal to me.
A 3 angle valve job is pretty standard. The seat area is cut at 45*. Then you use a 30* to cut the top angle and a 60* to cut the inside. By cutting the top and inside you set the seat angle thickness and location on the valve head. You can add a 15* and a 75* to taper the seat more...a 5 angle valve job. When you "lap" the valve in you are actualy confirming the seat width and location on the valve.

 

Just a reminder.....Dont forget to recheck that geometry. It will be different.

 

What is the process for lapping the valves?

 

Forget lapping the valves.. On an aluminum head motor. The cold pattern you see is not even close to where the actual "running" seat will be. The exhaust valve runs at or near red hot (read expand) the aluminum head and the valve seat insert run much cooler.

As a novice there is a good chance of you screwing up a good valve job. If you MUST see where the cold seat is get a "Majik" marker. Ink up the seat, then insert valve and spin it against the seat with light pressure. Remove. You will see where seat edge contacts valve.

If you see only a knife edge line, don't worry, as most valve jobs are done with 1/2 degree interference fit and only the edge will show contact under light checking pressure.

The thicker exh valve margin should not be a problem unless you are using a long duration, high lift, aftermkt cam and the heads have been excessively shaved.

You did have these heads resurfaced didn't you??? They are famous for being warped or Brinnelled badly!!!

 

This is not a huge cam at all, 212/220 .531/.539, I also did have the heads surfaced.

Thanks all!

 

That's a fair amount of valve lift. You will want to check valve to piston clearance anyway. You will want to check your stem height, this will tell the story if the seats are cut properly for the valves that you have. I'm not sure what the factory stem height is on a 3.8 Ford, but they should all be equal. Is this converted to a fully adjustable rocker arm?

 

That's a fair amount of valve lift. You will want to check valve to piston clearance anyway. You will want to check your stem height, this will tell the story if the seats are cut properly for the valves that you have. I'm not sure what the factory stem height is on a 3.8 Ford, but they should all be equal. Is this converted to a fully adjustable rocker arm?

I will have to check the clearance just incase, but I'm told that other guys running the SBC valves running even more lift don;t have probelms. But I guess I'll check just in case. They were suppose to deck the block to zero hight, so I guess I'll hv to check. What is a safe piston to valve clearance? How would I measure that? Do I do the putty on the piston thing, then see how deep it is? I don't know how accurate that would be...

The rocker arms are stockers, non-adjustable, but can't they be shimmed up if necessary right?

Thanks!

 

Forget lapping the valves.. On an aluminum head motor. The cold pattern you see is not even close to where the actual "running" seat will be. The exhaust valve runs at or near red hot (read expand) the aluminum head and the valve seat insert run much cooler.

I don't quite get what you're saying, are you saying aluminum heads run igher temps in comparison with iron heads?

I don't see how that would make any difference for the valve seats...

 

The aluminum heads expand and contract moreso than iron heads do, it will change the shape of the seat when the engine is running. That's why checking the exhaust valveseat contact area is almost pointless as it will change a good deal after the engine is running and up to temperature.

As for the valve-to-piston clearance, It's not only the size of the valve that makes checking the clearance necessary, it's the increased lift from the new camshaft along with zero decking the block and milling the heads. All three of those conspire to decrease you valve clearance a great deal, it's a good idea to verify there's enough space between the valve and piston when that many changes are made that affect that particular specification.

Larry

 

But the seat is not aluminum, so how would that make a differnce on the seat?

And what is a safe piston to valve clearance to run?

I am told, even with a .580 lift cam, their is no issue, but I'll check it anyways...

 

But the seat is not aluminum, so how would that make a differnce on the seat?

And what is a safe piston to valve clearance to run?

I am told, even with a .580 lift cam, their is no issue, but I'll check it anyways...

The seat itself is pressed into a large chunk of aluminum that will expand and contract, anything connected to it will move with it. The seat will distort with heat applied to the head. It is a fact.

I prefer 0.125" valve clearance, you can get by with 0.100".

Maybe those folks didn't mill the heads and block?

Larry

 

Any competent machine shop should have confirmed the seat contact and used a vacuum set up that checks the seal of the valves immediately after the seat is cut. No lapping is necessary.

Most competent machine shops cut 3 "angles" and a 4th 75* throat cut, and often a 5th top 15* cut as he explained.

Any competent machine shop will have set the valve stem height and valve spring height when installing the valves. If the same shop did all the work, then the valve stem height should be compatible with the milling they did on the block and the head...... hopefully....

Most machine shops are stuck in the 70s still doing 50s technology, and believe they are OK.