Another 87 octane/aluminum heads question
Did you measure the ID of the seat ring before you assembled the heads?
The “recommended” replacement ex seat for those heads is 1.6875 OD/1.4375 ID.
These will usually leave a noticeable step where the seat ends and the casting starts.
If they were installed with a normal amount of press(about .005-.006), you could still open the ID up a bit and not have issues with them coming out.
In operation, the hot exhaust gasses blowing past the seat actually make the seat tighter in the head.
Here’s an old J head(actual T/A head) that someone installed the wrong size ex seats in(1.750 OD), and you can see the cross section is fairly thin.
They’d been in there for years, so I left well enough alone, I just blended that nasty step at the bottom of the seat away.
Did you measure the ID of the seat ring before you assembled the heads?
The “recommended” replacement ex seat for those heads is 1.6875 OD/1.4375 ID.
These will usually leave a noticeable step where the seat ends and the casting starts.
If they were installed with a normal amount of press(about .005-.006), you could still open the ID up a bit and not have issues with them coming out.
In operation, the hot exhaust gasses blowing past the seat actually make the seat tighter in the head.
Here’s an old J head(actual T/A head) that someone installed the wrong size ex seats in(1.750 OD), and you can see the cross section is fairly thin.
They’d been in there for years, so I left well enough alone, I just blended that nasty step at the bottom of the seat away.
