What happens if you don't get hardened seats....

[1 Wild R/T]

This is the worst cylinder, exhaust valve has sunk badly.... Valves were sunk in seven cylinders..

Apparently somebody patched this head close to thirty years ago they installed one exhaust seat..... Looks like they didn't do a very good job of cutting the pocket for the seat... Just hammered it in a rolled the dice... Got their moneys worth out of it...

 

[Ray70Chrg]

if you were to do a compression test on that engine, what would be your guess on the outcome?

 

[1 Wild R/T]

if you were to do a compression test on that engine, what would be your guess on the outcome?

I don't need to guess... I took a compression test....

1) 180 2) 180
3) 175 4) 180
5) 180 6) 100
7) 20 8) 175

Then I did a cylinder leakage test on 7 It was obvious that the exhaust wasn't sealing..
I tore it down & was shocked how good the compression was with the valves looking as bad as they did....

Heads went to the machine shop & I measured the lobes of the cam, didn't want to put it back together & find out it has a lobe going away... Cam is fine...

 

[Ray70Chrg]

I don't need to guess... I took a compression test....

1) 180 2) 180
3) 175 4) 180
5) 180 6) 100
7) 20 7) 175

Then I did a cylinder leakage test on 7 It was obvious that the exhaust wasn't sealing..
I tore it down & was shocked how good the compression was with the valves looking as bad as they did....

Heads went to the machine shop & I measured the lobes of the cam, didn't want to put it back together & find out it has a lobe going away... Cam is fine...

except for the obvious valve seats that you pointed out, the camber looks new. The pressure readings, except for 2 of them, are like new readings.

 

[eldubb440]

does this not affect valve lash? or not enough to make a difference?

 

[1 Wild R/T]

does this not affect valve lash? or not enough to make a difference?

In this case it has hydraulic lifters & they have enough range to handle it...

 

[RemCharger]

does this not affect valve lash? or not enough to make a difference?

Certainly. It Increases the preload of the lifter. As the valve sinks into the head. But also, the valve doesn't flow any air until it comes out of that pocket that sunk into the head. Performance motors have proud valve seats and heights.

 

[sr71mopar]

A lot of that can be prevented with an eye on the tune. Probably had a bad valve job in the first place.

 

[RemCharger]

I don't need to guess... I took a compression test....

1) 180 2) 180
3) 175 4) 180
5) 180 6) 100
7) 20 7) 175

Then I did a cylinder leakage test on 7 It was obvious that the exhaust wasn't sealing..
I tore it down & was shocked how good the compression was with the valves looking as bad as they did....

Heads went to the machine shop & I measured the lobes of the cam, didn't want to put it back together & find out it has a lobe going away... Cam is fine...

Was this a previously built motor? I've had several 76-77 400 2bbls that all looked like they were parked from burnt exhaust valves.. seemed like a common theme

 

[1 Wild R/T]

Was this a previously built motor? I've had several 76-77 400 2bbls that all looked like they were parked from burnt exhaust valves.. seemed like a common theme

70 340, built back around 92-93, bought by a friend as a fresh rebuild & bolted in... Driven probably 50K miles & feeling soft for the last few years...



It's got 68-70 style forged Speed Pro's & a Comp 270H.... It use to run pretty well, Hopefully having the heads done will bring it back to how it ran years ago...

 

[1 Wild R/T]

A lot of that can be prevented with an eye on the tune. Probably had a bad valve job in the first place.

Yeah, the tune was pretty good, but I think they cheaped out on the heads & it shows... Then again he got thirty years out of it, can't bitch to loudly...

 

[Kern Dog]

Is that for Mikes car?

 

[1 Wild R/T]

Is that for Mikes car?

Like Shultz, I know nothing....

 

[Geoff 2]

I think any seats [ inserts ] you get today would be hardened, if that is the question.

 

[1 Wild R/T]

I think any seats [ inserts ] you get today would be hardened, if that is the question.

There is no question... Just a post to show what happens over time with standard seats... It will be getting 16 new valves, guides, & hardened seats.... There was discussion of Aluminum heads but the decision was to stick with iron heads...

 

[bm02tj]

The flame hardening from factory is gone on first valve grind and with no lead gas that will happen

 

[BSB67]

I did a street performance build in the early 1990s. 915 heads, non-hardened seats. Competition valve grind with the typical narrow seats and a single spring W/ damper for a performance hydraulic cam.

R&R’d them three years later with less than 10,000 miles. The seats were toast.

 

[70 sublime]

1) 180 2) 180
3) 175 4) 180
5) 180 6) 100
7) 20 7) 175

I will guess cylinder 8 had 175 as you wrote 7 twice

What cylinder had the newer seat ?

 

[Runcharger]

My D100 had a 383 that ran a bit rough. You'll know it when you pull the valvecovers and you have uneven heights between your intake and exhaust valve tips. All of the exhausts were sunk on that 383. I was amazed it ran at all.

 

[dadsbee]

Why I run lead..