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MOPAR Cylinder Head Issue

For a mild street build I would put lash caps on the exhaust and call it a day
 
1968rt said:
For a mild street build I would put lash caps on the exhaust and call it a day
Click to expand...
He still needs to check assembled height as the short ones might be correct or not
 
Charged440 said:
I had the exact same thing on a set of 915s I have. I couldn't run them that way at all, had the tips of the taller ones cut down. Geometry was right on the money after that.
Click to expand...

Problem with that is the valve stem tip is hardened to take the constant beating... But that hardening only goes so deep...
 
Mike is right..... they aren’t great, but they aren’t disastrous either.

Everyone likes to have the tip heights even and correct, sometimes it just doesn’t work out that way.

Since these heads have had ex seats installed, the tip height disparity could be from the intake seats being cut excessively, or the ex seats haven’t been cut enough to provide the correct tip height.

If the ex tip height is actually “correct”, you could have the intake valve tips cut down some, but keep in mind the tip of the valve is hardened so it’s best to not get carried away with that.

It’s really not something that will affect the way the motor runs if the tip heights can be kept within about .030 of each other.
With stock rockers, this will only affect lifter preload by .020”.

If they’re farther off than a mild tip trimming will solve, depending on exactly how the intake seats were cut, the two options for remedying the situation are:
-Have intake seats installed
-recut intake seats for oversized valves(2.14). This will only work if the seats aren’t currently “fubar’d”.

FWIW..... the current valve seat work(valve job) doesn’t look great.
It costs money to correctly recondition these old heads, and if you’re trying to do it on the cheap so you can sell the heads at a low-ish price.......corners will be cut....... and one of the side affects of that can be uneven tip heights.

In a nutshell...... if you’re not looking for “perfection”, if the tip heights are within .030”, or can be brought to with .030” by just doing some minor tip grinding...... then I’d do that and run them.
The tips need to be done on a proper fixture with coolant so they remain straight and square, and don’t get overheated and annealed.
Most valve grinders have the capability of doing this operation.

If you have a decent shop near you, it might be worth having them assess the quality of the valve job.
It doesn’t look great in the pics, but from purely a functionality standpoint, it might be fine.
 
Keep in mind I’m looking at a pic on my phone...... and there’s blue dykem on the seat area...... but I’m not seeing a hardened ex seat.

Take some carb cleaner and clean the dykem off the ex seat area and get a couple more up close pics there.

The way the valve job is done, particularly on the intake side....... at least on the one shown....... the flow will be down compared to what it was when it was new.
A little bowl work...... and I do mean “little”...... would be worthwhile imo........ if the build is at least somewhat “performance oriented”.
 
Last edited:
What about just using flash caps on the exhaust valves to correct the height difference as previously mentioned? 440'
PRHeads said:
Mike is right..... they aren’t great, but they aren’t disastrous either.

Everyone likes to have the tip heights even and correct, sometimes it just doesn’t work out that way.

Since these heads have had ex seats installed, the tip height disparity could be from the intake seats being cut excessively, or the ex seats haven’t been cut enough to provide the correct tip height.

If the ex tip height is actually “correct”, you could have the intake valve tips cut down some, but keep in mind the tip of the valve is hardened so it’s best to not get carried away with that.

It’s really not something that will affect the way the motor runs if the tip heights can be kept within about .030 of each other.
With stock rockers, this will only affect lifter preload by .020”.

If they’re farther off than a mild tip trimming will solve, depending on exactly how the intake seats were cut, the two options for remedying the situation are:
-Have intake seats installed
-recut intake seats for oversized valves(2.14). This will only work if the seats aren’t currently “fubar’d”.

FWIW..... the current valve seat work(valve job) doesn’t look great.
It costs money to correctly recondition these old heads, and if you’re trying to do it on the cheap so you can sell the heads at a low-ish price.......corners will be cut....... and one of the side affects of that can be uneven tip heights.

In a nutshell...... if you’re not looking for “perfection”, if the tip heights are within .030”, or can be brought to with .030” by just doing some minor tip grinding...... then I’d do that and run them.
The tips need to be done on a proper fixture with coolant so they remain straight and square, and don’t get overheated and annealed.
Most valve grinders have the capability of doing this operation.

If you have a decent shop near you, it might be worth having them assess the quality of the valve job.
It doesn’t look great in the pics, but from purely a functionality standpoint, it might be fine.
Click to expand...
 
440Coronet500 said:
What about just using flash caps on the exhaust valves to correct the height difference as previously mentioned? 440'
Click to expand...

It would be allot better knowing if the shorter valve stems are to short or the taller valve stems are to tall don't ya think???
 
Exactly! Which valve has the right height. There is a measurement and acceptable specs.

What about the idea of not using lash caps with a hydraulic cam? Is they still a factor? They can come off the valve tip and travel inside your engine.
 
1 Wild R/T said:
It would be allot better knowing if the shorter valve stems are to short or the taller valve stems are to tall don't ya think???
Click to expand...

I wouldn’t be surprised If it were a case where both the intake is “too high” and the exhaust is “too low”.

That being said, judging by the looks of that intake seat, I think it’s a pretty safe guess that the intake seat being sunk is the bigger offender here.

Several years ago I went through a set of 346’s that were the original heads off the 383 in a 71 Challenger.
The motor had already been rebuilt by a performance engine shop, that the owner of the car had worked at.
The motor basically ran fine, but used a lot of oil and would foul plugs regularly, and it smoked pretty bad too.
He’d go to car shows with it(super nice car) and was embarrassed by how bad it smoked, along with the burned oil smell and oily residue on the rear of the car.

He pulled the heads off and brought them to me.
They had nice quality parts throughout, and had ex seats installed and poor attention to detail was employed when they were installed and machined.
Additionally, several of the intake seats were noticeably sunk.
As a result, the tip heights were all over the place.
In particular one really sunk intake was in the same chamber as one of the new ex seats that hadn’t been machined deep enough..... to the point where the tip heights for those two valves were .125” different from each other. Nice!!

I tried to get him to just get some different castings, but he wanted to fix the originals....... so I installed 8 intake seats.
Seat installation can result in a loss of flow, so I did some minor blending to make sure they were at least a little better than they would have ever been new.

The oil consumption issue was mostly the seals.
It had the white Teflon seals on the heads, and there was a period of time after Perfect Circle stopped making them..... and someone else was...... where they were very problematic.
The oil consumption problem went away after the heads were redone and the seals got upgraded to the steel jacketed Viton pieces.

The thing here is....... even with the valve tip heights varying by at least .125”....... it still ran fine.
If the motor hadn’t been an oil burner...... it never would have been taken back apart.

I had some previously reworked SBC DZ-302 heads in here last year for some updating.

It looks like there was possibly an issue with these similar to the OP’s where the tip heights varied, and it was resolved by grinding, what appears to be too much, off the tall ones.
And then you get this:

17BDD60E-B2BD-46D8-A8C0-C35DA992C1DE.jpeg
 
Last edited:
Thanks for all of the advice. I haven't had a chance to get back to this forum or to look at the heads again until now. Unfortunately, there are new issues. Please see pics and let me know your thoughts on if these usable or not. Thanks.

DSCN5401.JPG DSCN5403.JPG View attachment 952466 View attachment 952467
 
Last edited:
Well, that’s a curiosity for sure.

Why someone thought there was a need to grind that area of the original seat away is the question.

Or, was it merely an “oops” moment?

As long as there is still some material back by the perimeter of the insert for it to sit on in that area where the grinding was done, it should be fine.

I highly suggest you have a qualified shop give those heads a thorough looking over before putting them into service.
 
U are not that far from PRH
road trip
another cure for sunken seats are 2.14 intakes and some bowl work
 
Update Cylinder heads back from machine shop, Ok to use but with shims under rocker arm shaft. Now what head gasket to use I have Mr. gasket 1135g and Superformance 5983. which one can I spray VHT copper sealant on? Thanks
 
880598-fe054290cc13ab77a11282249729b89f.jpg


Did you fix this? Looks like a jacket leak about to happen.
 
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