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428 PI vs. CJ

4K views 12 replies 8 participants last post by  Mekanikbob 
#1 ·
What are the diffrences between the 69 428 cj and the 69 428 PI. I have the opportunity to buy a 69 428 PI, but would like to put it into an original R code car. Is it worth it?
 
#2 · (Edited)
The heads are main difference they are of the garden varitey. The short block is the same. I would just value it as a short block myself.

Also do your homework and use this as a componet identification guide. A lot of dressed up 390's have been sold as 428's over the years.
http://www.428cobrajet.org/id-main.html
 
#3 ·
I didn't think they made a 428 PI in 69 but I've been wrong before. I know the earlier PI's didn't have the webbing in the block for the extra main support. If it has the aluminum intake on it that is better to have than the CJ intake. You can always buy better heads to put on it if you want. They are very worthwhile unless you wanted a CJ specific engine for a CJ car.
 
#4 ·
If you have an original R code car and are going through all the effort to do it up I would spend the extra money to get the correct engine. At a minimum get a correct date coded block and perhaps the heads. You could do the rest (carb, fan, dist, etc) later if you choose.

A.J.
 
#5 ·
The 428 PI was used through the 1970 model year. California appears to have made a large order of 1970 full size Mercury police cars in 1970 with the 428 PI engine. Engine code is "P" in the VIN.

The aluminum intake on 428PI engines was discontinued around January 1968. After that the CJ type cast iron intake was used. Cylinder heads on the 428PI are the same as 352 / 360 and 390 low performance units.
 
#7 ·
Thanks for the help!

Thanks of the help. You guys are really great! It is nice to be able to tap the wealth of knowledge here! If I may ask one more question. Would the C6 tranny that would be mated to the 428 PI be the same as the 428 CJ or are there differences there as well?
 
#8 ·
The tranny for a PI has a shifter arm that is upside down for a floor shifter since the cop cars all had column shift. It is not as beefy as the CJ transmission either and does not necessarily have a cast iron tail shaft although I am told some cop transmissions had them either by design or accident. You should be able to tell by looking.
 
#9 ·
Carroll Shelby SEZ>>

NO DIFFERENCE.......a quote from the man himself comparing how the KR car's where bringing so much more money than a GT-500. Mustang Monthly even rounded up a field of different FE powered cars for a chassis dyno----put-up or shut-up. The result's verified what Shelby stated! I have learned first hand from own expierence that "testing" and "tuned" can easily mean a 40-50 rwhp difference, so I think you would have to curve the result's. I don't think the CJ Block will give you anymore HP than the same component's on a passenger car block but it will certainly cost much more. From what I have learned unless you are going for a "numbers matching" trophy car put you're money into selecting good components, dynamic balancing and good tuning. I have CJ heads on a pass car block with FPA headers, an old F-427 intake topped with the original 735 cfm carb and it puts 318/385 to the rear wheels. The key here is the 385 ft lbs.......what fun! Mercinary....out
 
#10 ·
I had read what Shelby said about not being able to tell the difference between the 428CJ and the 428 PI. The block is not going to give you any more power but it is supposed to be stronger. I figured that the heads would flow better though.



Royce or anybody else that knows; Did the PI blocks that were cast at the same time the CJ blocks were have the main webbing or did they continue to use the early style castings?
 
#11 ·
Late 68, 69, and 70 PI blocks are the same as CJ blocks as are the cranks, rods and intakes. Most of the smog equipment is the same as a CJ as well as the air cleaner (except it does not have a chrome top) and snorkel. Most of the pulleys are the same as are all of the brackets. The pistons are different as are the heads, exhaust, ignition, carb. the heat stove and stube are different. Hawkrod
 
#13 ·
I ran a 428 pi engine in a 75 f100 4x4 with 427 medium risers many years ago,pulled great,but had to put a 361-391 truck 8 quart pan on it,as it used to suck the pan dry.Surprised many chickenhawk firebirds light to light with that truck.Would set c6 in second,put transfer case in low range,light up the 34 inch tires ,back off,ramm transfer case into hi and blast it to 75 mph in second before catching 3rd.at old airport strip in ft st john BC it ran 14.2/92 mph,which was pretty good for the mid seventies,and aerodynamics of a garbage truck.
 
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