Engine capacity conundrum

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mustangandy

Well-known member
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Sep 5, 2018
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Location
France
My Car
1971 Cobra Jet 429 Ram Air C6 auto 3.50 traction loc
[url=https://ibb.co/Wtx4kTW][img]https://i.ibb.co/dgWwPh0/mine1.jpg[/img][/url]
I've gotten around to registering my 429 CJ in my name and on checking the registration document find the engine size is listed at 7850cc (rather than 7000cc). On looking back over old paperwork the earliest reference I have is from the 1988 registration papers with this capacity. OK this could just be a mistake (most likely reason?) when the car was re-registered with the 3rd owner (bought in 1987 and kept mainly as part of a static classic car collection) but it's got me wondering if any work might have been done on the engine in the past? 

The car was first registered in the UK in 1972 and covered some 35,000 miles in the first 6 years so it was quite well used in its early life. Its only covered some 2,000 miles over the last 20 years. I've been checking out web sites etc to see if it's possible for this engine to actually be at that capacity. Seems like a 460 with a 0.08" overbore gets there but is this just a bit fanciful? What do you think?

Are there any easy ways of telling if the engine has been apart, or worse, replaced? I gather that with the engine in situ you can't check the block ID and I certainly don't want to pull the engine or even lift it up and pull the pan to check the internals. I have a inspection borescope so should be able to look all around the engine for any tell tale signs - if I know what to look for. I don't want to stress, too much, about this but can't help wondering.

Any advice or thoughts gratefully received!

 
This link may be helpful. Chuck   http://429mustangcougarinfo.50megs.com/decoding.htm

 
This link may be helpful. Chuck   http://429mustangcougarinfo.50megs.com/decoding.htm
Thanks Chuck. I did have a look at that site and noted that it says it's almost impossible to see the partial vin number when the engine is in the car. I'll have a look of course just in case.

 
If you can see the casting number and date code on the block they may give you a starting place.

Other than that, the easiest way is to pull a head and measure bore and stroke.

 
If you can see the casting number and date code on the block they may give you a starting place.

Other than that, the easiest way is to pull a head and measure bore and stroke.
hopefully I'll be able to see something but, if not, I reckon I'll leave the engine alone as she runs OK though certainly needs a tune up :)

 
This link may be helpful. Chuck   http://429mustangcougarinfo.50megs.com/decoding.htm
Thanks Chuck. I did have a look at that site and noted that it says it's almost impossible to see the partial vin number when the engine is in the car. I'll have a look of course just in case.
Mirrors and a camera can be helpful.
Sent from my SAMSUNG-SM-G930A using Tapatalk

 
If you can see the casting number and date code on the block they may give you a starting place.

Other than that, the easiest way is to pull a head and measure bore and stroke.
Its been a while since i took these pics when i had the 351C engine out





 
If you can see the casting number and date code on the block they may give you a starting place.

Other than that, the easiest way is to pull a head and measure bore and stroke.
Its been a while since i took these pics when i had the 351C engine out



Cheers. I'll update with what I can find out.

 
Unless the 429 is different from the 351....I believe the partial VIN is stamped n the driver's side of the block in the rear by the firewall below the head. Camera or mirror work well but I cleaned the area and then took some clay and pressed it on the VIN and got an imprint. Play Doh or SIlly Putty work very well!

 
Smartphone camera using flash and a bit of trial and error should work. Silly Putty is a excellent idea!

 
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