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engine ?

New User
Posts: 15
Joined: 09/13
Posted: 09/24/13 09:50 PM

I have a 1970 thunderbird with a 429 thunder jet.What is the difference in the 429 thunder jet and the 429 cobra jet? Would the thunder jet be a good replacement engine for my 1969 mach 1 "s"code mustang? Confused  

Post Reply
Posts: 223
Joined: 04/13
Posted: 09/24/13 10:03 PM

Types of 429s
(Thanks to Dan Davis)

First was the base 429, known as the Thunder Jet (TJ). It came in T-birds and full size Fords in the late 60's and early 70's. Typically 360 horsepower. By far and away the most common -- they made 100,000+ of these. Can be ID'd be block casting numbers of C8SE, C9VE, D0VE, D1VE among others and head casting numbers of C8SE, C9VE, D0VE among others.

Then there was the 429 Cobra Jet (CJ). It was built only in 1970-71. It was only installed in mid-size (1970-71) and pony cars (1971 only). 370 HP (likely underrated), thick strong blocks and massive ports int he heads. ID'd by D0VE-A and D1VE-AA casting numbers on the block and D0OE-R on the heads. No other numbers are CJ. Not too common, maybe a total production of 15,000.

The 429 SCJ was a stronger version on the CJ. The difference was forged pistons, solid lifter cam and four bolt mains*. The rest of the info is the same. Even less common with a production of maybe 3,000.

cobra jets and super cobra jets have a MUCH taller exhaust outlet.. perhaps 3/8" taller.. so much that if you use conventional 429/460 exhaust gaskets on it.. there will be tremendous exhaust leaks.

you can see on the left port in this 429CJ exhaust manifold image that the gasket just barely covered the port...

Exhaustmanifoldbefore Zps71bfc6eb

to get rid of the nasty exhaust leaks i used a piece of plywood with a belt sander belt glued to it..

Exhaustmanifoldafter Zps2270e7d6

it took 3 techs holding onto that manifold to get it properly surfaced and true so i could use the felpro performance 429 CJ exhaust gaskets on it.

this is what the outlet looked like..  ugly...

Exhaustflangebefore Zpsfba5c149

this is what it looked like after i fitted the new rings to it.. i used a 1/4" die grinder to cobble the mating area smooth..

Exhaustflangeafter Zps5e3c7504

and a huge hint.. when doing manifolds in chassis...

use rubber bands to hold the bolts in place..  there is only room like that because there is a engine support bar going across the top of the inner fenders with the far side motor mount bolt loose but still there.. so this side tilted up..


.. i missed out as i was really tired and posting to stay awake...

that you have a 69 mustang with a 390 motor..

1969 S code:

Sportroof (Mach 1 / GT / Plain)
Converible (Standard / GT)
Hardtop ( Standard / GT / Grande)

Total 1969 S code Mustangs (all body styles/all models) - 10,464

Total 1969 S code Mustang Sportroof (All Models) - 9.440
Total 1969 S code Mustangs Hardtop (All Models) - 772
Total 1969 S code Mustang Convertible (All models) - 252

(these are for

Sportroof (All Models) Auto Trans - 5,549
Sportroof (All Models) Manual Trans - 3,891
Hardtop (All Models) Auto Trans - 629
Hardtop (All Models) Manual trans - 143
Convertible (All Models) Auto Trans - 146
Convertible (All Models) Manual W/R - 86
Convertible (All Models) Manual C/R - 20

(Sportroof - no breakdown between GT, Mach 1, standard sportroof) yet
(Hardtop - no breakdown between standard HT , GT, Grande ) yet
(Convertible - no breakdown between standard, GT) yet

being wayne... i don't think i would go to the massive amount of work.. to yank a 390 out of a mustang to drop in a 429TJ..

end edit..  

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New User
Posts: 15
Joined: 09/13
Posted: 09/25/13 07:16 AM

ok thank you  

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New User
Posts: 15
Joined: 09/13
Posted: 09/25/13 10:16 AM

The "S" code mustang was found as a shell.There was no engine or trany in it(or any other parts on it)I have the 70 t-bird which is a non molested unrestored survivor with no rust and only one repaint even the hose clamps are original and it is the 2 door fast back t-bird.Alot of the parts will go a long way to restore my stang ( i think).I have acquired a 1969 model 390 engine and trany form a 1969 galaxy but I heard that the 390 engine was not all that good so that is why I was looking to the thunder jet.I think my car might be a K.A.R.429 car but I am not sure..Please read my other post titled K.A.R.???? it will explain my situation...thanks  

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