1964 Impala SS 427 Mystery

[UK Racer]

Hi guys,
I have a copy of an application from GM to the International Automotive Federation (FIA) to approve for competition the 1964 MY Impala SS 2dr HT with a 427 motor. The homologation paperwork was signed by the Chief Special Products Engineer and the Manager, Technical Projects, Public Relations though I can't make out their names from the signatures (Buawell?). However, as far as I can tell, this is a combination that was never actually officially manufactured by GM even as an option. More than this, I have also found records of people taking part in races in Europe with vehicles identified as '64 Impala SS 427.
Anyway, because of this document, I believe that I'm going to be allowed to race in Historic Racing events run under FIA regulations with a '64 427 Impala SS with which I hope to take on Galaxies and Falcons.
Can anyone shed any light on this mystery?:dunno :scratch

Thanks
Adam

'58 Corvette Cunningham Le Mans Racing Clone
'64 Impala SS 427 Project

[models916]

Car and papework pics would be nice. Sounds very interesting.

[UK Racer]

These are some of the pages from the homologation document. I'm sorry they are poor scans of poor photo copies.
Looking closer I almost wonder if this is a Mystery Engine rather than Z-11 427? Though the intake looks to be a 2x4.
Anyway, more to puzzle over!

Adam
'58 Corvette Cunningham Le Mans Racing Clone
'64 Impala SS 427 Project

[UK Racer]

Actually, I realise that once down sized to fit those scans are almost unreadable. :doh If anyone wants a closer look then let me knowand I'll email them to you.
Adam

[SS425HP]

The only thing I can see that might give an idea is the combustion chambers in the head picture. Sure looks like the BBC head to me. Or the 427 mystery motor? Don't think I ever saw one of those heads upside down. But the placement of the valves and the runners you can make out are BBC style. Could make out 11-1 comp ratio. Couldn't really read the valve sizes, but looked to be 2.06 which is smaller than the BBC.
Looks like you might have some good history there. Too bad it can't be redone to come out better. I sure would do eveything I could to protect them.

Fred

[MK IISS]

Adam: What is the date is on the application?

[UK Racer]

From the bigger pictures I have I can make out the following:
427Cu In
4.313In Bore x 3.65 In Stroke
Distance from Crank Centreline to block deck 10.218in
Combustion Chamber vol 10.3cc
Compression Ratio 11,0:1
Bearings 2.5/2.2 Main/Rod
Crankshaft 66.25lbs
Valves 2.195/1.725 Inlet/Exhaust
2x Carter Carbs #3815403 / #3815405
Intake port 2.4x1.25
Exhaust port 2.04x1.56 (ends) 1.78x1.72 (centre)
Any help?:dunno
Adam

[UK Racer]

The main document has no dates (but gives '64 VIN numbers for ID)
An attachement clarifying wheel sizes is dated March 18, 1964.
The wheel sizes they have got approved by the way were 14x5, 14x6, 15.5x5??, 15x5.5, 15x6 and 15x7.
Regards
Adam:scratch

[UK Racer]

Fred,
Is this any help?

[MK IISS]

I believe that is a MkII engine, not a MkIV. Bore (should be 4.312 not 4.313 ?) and stroke (3.65) is MkI/MkII 427...intake is not MkI. There was some documentation that Winters cast some MkII 2X4bbl intakes.

[SS425HP]

Richard, there appears to be 4 seperate exhaust ports. Looks to be a regular combustion chamber. The cc number is more Z-11, though. Piston appears to have a dome on it. The Z-11 has the exhaust valves paired in the center. These combustion chambers look to be aligned on the same angle all the way across, not like the 409 04 Z-11, which are turned to each other on the ends to get the exhaust valves side by side in the center. That's the way I see it, anyway. But, my eyes are a little old!

Fred

The exhaust port sizes look to be Z-11 sizes, though. Just read the numbers. Oblong ends, almost square in the center.

Heck, What do I know?

[MK IISS]

Fred: The crank has 2.50 mains so it is a MkI 427 (Z11) and/or MkII 427 (Mystery Engine) crank. As we all know, both engines used the same crank. The intake has a thermostat housing so it's not a MkI/Z11 plus the front runner isn't squared off so it's not a 409/409-425. The photos are still too fuzzy for me....I believe your eyes are better than mine but the head appears to have the MkII combustion chamber. But then again whata I know. Another mystery to add to the Mystery Engine legend. I bet they made more MKII Mystery Engines than we thought.

[UK Racer]

I forgot to mention that to add to my confusion, the first page of the paper-work identifes that the vehicle is an Impala SS but then quotes a VIN prefix of 1847 which is for a non-SS 2dr coupe! :scratch
I have no idea what they were thinking!
:dunno

Anyone have insight into GM Special Projects around this time?

Adam