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455 Question

3K views 12 replies 4 participants last post by  Josh.AZ.GTO 
#1 ·
If the engine was originally set up from factory as an automatic.....will it directly bolt up to a muncie 4 spd? My car was originally a 4spd and was converted over to an automatic. I want to change it back, and found a year matching 455 block for sale that was from an automatic car.

I've always assumed they could easily accept either or..but I'm not sure and that is why I'm asking.

Thank you in advance.

JR
 
#2 ·
The bolt pattern on the rear of the engine is the same, so no worries there. I've heard, but never personally verified, that occasionally you might find a block from an automatic car that doesn't have the driver's side "socket" for the clutch Z-bar drilled, and also - on occasion - you might find a crank that isn't drilled to accept the transmission pilot bushing. Both of those are at least worth checking before you plunk down your cash.

Bear
 
#9 ·
Well all-righty then. It's probably model year 1970 and therefore a 370 horse 455 out of a Grand Prix, but I 'spose also could be very late 69 and a 428 (both used XF). Go back to the same web site, see if you can get the 7-digit block casting number off the top rear passenger side - that'll clinch it. Also if it's a 455 you should find "455" cast into the side above the oil pan rail.
Next assignment is to ID the heads. You should be able to find antoher 4-character date code on the sides, similar format to the date code on the block. Then get the two (sometimes 3) character code from the tops of the center two exhaust ports.

Bear
 
#10 ·
Unfortunately the motor is a block only with no heads. The guy who has it did say it was from a Grand Prix though. That being said I have a Pontiac 350 (1970) carb to pan. I plan on reusing the Q-Jet. Were the heads mostly interchangeable?
 
#11 ·
That is the 1970 XF 455 H.O. block for a Grand Prix. They are rare. The block alone can bring good money for the right guy. Ask him if he can get the heads or has them. They should be 64 heads. They are worth a good amount of money also. Some Pontiac guy consider that set up to be the best to buy. The drivers side of the block toward the front should say 455 vertically, or 428 if it is older. I would bet on 455.
 
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