273 Engine with Frankenheads Setup

[64 SRT8 Dart]

After pulling the 273 to put the 318 in it's place I finally pulled the 273 apart.

If I'm correct, the 66 273 has a normal intake bolt mounting angle and the 64 and 65 have the different angle?

The casting year on the block is 65 which would've been correct for the 66 year.

Well, I checked the head casting numbers and one is a 920 which when I look up, shows for a 67 273. The other one is a 315 which is for a 64-65 year.

I find this weird as all the intake bolts were fine and all the bolts were seated as they should be. The intake sealed as well.
I checked the threads in the heads and all are as they should be from the factory.

Anyone have any ideas on this??? Explanations.

Also, the main and rods were .010 under. It had a factory timing chain set and original steel shim head gaskets.

So, either this thing was a cluster from the factory or someone put a crank and two different heads on it at some point early in it's life??

Wonder if the 65 block was used later, possibly in 66 and two different heads put on it??

 

[bmw88rider]

Sounds to me like the motor was opened at one time. It would be a royal FUBAR if they mixed heads at the factory. The .10 under crack could be factory.

 

[coryw]

I have an engine that is supposed to be a 66 273, that has the early (65) casting number heads but the heads have the larger bolts and late bolt angle and no sign of modification. Only thing I can figure is that they machined some of the early heads with the late bolt angle at the beginning of the 66 production run. Yours with mis-matched heads sounds like it has probably been worked on.