66-67 273 Cylinder Head Part Number and Identification?

[Bossanova5]

The Machinist ruined my heads and I'm trying to find a different set from a 66-67 273

The part number I found in the 66 Factory Parts Catalog is # 2536-176

The casting number on my 67 273 heads are # 2658920-5

I have a gentleman on here who might have a set of heads.

What is the best way to identify the correct heads using the numbers cast into the heads?

Thank you

 

[Plymouth 65]

920 castings.

 

[Dana67Dart]

Bring an intake manifold bolt too

If it's a set of 65 and earlier the 66 67 intake bolts will not fit

 

[Dana67Dart]

What did the machinist do?

 

[Bossanova5]

What size are the bolts for the intake manifold for a 66-67?

He installed too large of a hardened exhaust valve seats. The new machinist believes the heads will eventually leak (Coolant into the combustion chamber) from all the material removed and the pressure exerted to install the hardened seats. He is going to pressure test them, but he still recommends I get different heads and start over. The first machine shop also installed the wrong valve springs, he put hydraulic valve lifters springs in instead of solid lifter springs. The worst machine shop nightmare........

 

[Dana67Dart]

What size are the bolts for the intake manifold for a 66-67?

I don't know of the top of my head but that are larger then 65 and older

 

[cosgig]

I don't know of the top of my head but that are larger then 65 and older

66-69 273 engines use 3/8”/16 for intake, the 64-65 uses 5/16”/18

 

[JDMopar]

@GTX JOHN was selling a big bunch of heads 6 months or so ago. He may have some 920's. He's not too far away from you either. Good luck in your search.

 

[GTX JOHN]

I still do have about 100 heads or more. Mostly from
my Friend and Machinist Gregg Luneak (RIP).

 

[Two7T3Dart]

You could always step up to a set of xxxx302's....hardened seats already installed.

Just a thought.....

 

[GTX JOHN]

I think there are a lot of 318 heads that would
perform as well or even better that would be a
bolt on.

 

[Dana67Dart]

The 273 heads have a very small chamber so unless the pistons are changed the compression ratio will be very low

The flat top 273 piston only gets 8.8 iirc and the domed gets 10.5 iirc

 

[eekvonzipper]

The first machine shop also installed the wrong valve springs, he put hydraulic valve lifters springs in instead of solid lifter springs?

Is This really a Thing? I did a 273 with a Solid Lifter but I used Springs from a 340...
I'm pretty sure that 340's are hydraulic valve lifter springs instead of solid lifter springs.
So, is there a mismatch there?

 

[junkyardhero]

The 273 heads have a very small chamber so unless the pistons are changed the compression ratio will be very low

The flat top 273 piston only gets 8.8 iirc and the domed gets 10.5 iirc

he's building a commando, so it'll have more squeeze.

 

[PRH]

Aside from whatever other issues might be present….
As far as the ex seats go…….if the heads pressure test good, I think they’d be fine.

As for the springs, they don’t know what the cam is.
They either have adequate force for the task at hand or they don’t……simple as that.

 

[cudamark]

If you're using the '64-6 LH exhaust manifold, using a later "smog" head would require extra clearance at the left rear (#7) exhaust port to keep from breaking the manifold. Best done by a thicker exhaust manifold gasket rather than grinding on the head. Best just to get the correct head.

 

[GTX JOHN]

I believe any of the 66 to 69 year heads will perfectly fit
the exhaust manifold. The mid 70s to 80s would need the
thicker exhaust gasket.

 

[cudamark]

Yup, up to 1974 when they changed to the casting with the A.I.R. provision. The open chamber heads starting in 1968 will reduce the compression ratio a bit though. '66 and '67 920 castings were closed chamber.

 

[GTX JOHN]

There is only 3 CCs difference between the two part
number heads and sometimes different castings CC
a couple CC different than another pair the same number.
In our testing at low 300 to 400 lift the 675 flowed better.
Plus, I prefer the open chamber heads myself as they seem
to have less detonation and better tolerance for bad gas issues.


Just my .02 = For Free

 

[Two7T3Dart]

If you're using the '64-6 LH exhaust manifold, using a later "smog" head would require extra clearance at the left rear (#7) exhaust port to keep from breaking the manifold. Best done by a thicker exhaust manifold gasket rather than grinding on the head. Best just to get the correct head.

It's not that much...a little off the head...a little off the manifold...you're good.

 

[GTX JOHN]

I believe only a problem IF you are using a 70s something up
Smog head and not any of the early heads.

 

[toolmanmike]

920's Shipping would probably be $50-75 each now days.