How can you tell if a 429 is a

super cobra jet, a cobra jet, or just a 4v. I am looking at buying a early 1970s merc and it says ‘429 4v’ on the air cleaner. (it is the origonal air cleaner). could it be a cobra jet or did they put them in the four door mercs?

A 1970 4 door Mecury could be bought with a 429 Thunder Jet engine. This was a two bolt main block and could come with a 2 bbl or 4 bbl carburator. So it’s not a 429 Cobra or Cobra Jet engine.


Ok. Still, How can you tell if it is a thunder jet?

If it’s a 429, and it’s sitting inside a 1970’s 4 door Mercury, it’s a Thunder Jet.


The 429 is A completely different motor that replaced the 332 introduced in 1958, then 352, 390, 406 428. The 427 was really a special racing engine. The 429 was the “new” big block, a completely different engine that evolved into the 460…

If you want to learn about Ford engines, read this.


It’s interesting that the bore and stroke of the 427 engines is not mentioned…

The 289 enjoyed a 2.87" stroke…
The 427, 3.78
The 428, 3.98

Now, lets talk about piston speed and how it relates to stroke, horsepower and engine reliability at high RPM…

If the price is right, I’d say jump on that car and stash it back for the engine and drivetrain even if you don’t use it.
If sheer size is important then what about a 460 with a 557 C.I. stroker kit? That would make you king of the 'hood for sure!

Remember the prior comments about the Modular motors? We’ve got a local boy here who does very well with them.