Engine codes

I was told I bought a pontiac 428 which I believe is correct but the problem I have is I can not find a flex plate that the bolt holes line up? The codes on my engine as good as I can read them are by the distributor on top there is a clock picture with arrow in 9 position under that there is a plug and beside that it looks like 6135 and a screw and below that between 2 screws J216 and on the front of the block stamped vertically on on the left side of timing chain cover is 153330 and beside that YH, it has 2 hole motor mounts and 3 frost plugs above the motor mounts, any help on what my engine is or what flex plate I need would be great the old flex plate was cracked around the bolt holes otherwise the engine runs great can email you pics if needed, or let me know if more information is needed, thanks, Brad  

Year Engine HP Engine code Trans CR Cam Head Code BBL Carb No. Misc
1965 421 338 HP YH A 10.5 067 76 / 9778776 1-4 3898S Block Casting # 9778791 Should have full head production number under valve cover - 9778776
1966 421 338 HP YH A 10.5 067 092 1-4 4037S 4-bolt main Block Casting # 9778791/9782611
1967 428 360 HP YH A 10.5 067 670 1-4 7027262 Block Casting # 9786135
1968 428 375 HP YH A 10.5 067 16 1-4 7028268 GP Block Casting # 9792968
1969 428 360 HP YH A 10.5 066 46 1-4 7029268 45 deg int. Bonneville Block Casting # 9792968
1970 455 360 HP YH A 10.0 067 15 1-4 7040262 Big Car /1970 - only year hi comp 455 Block Casting # 9799140
1972 455 185/200 HP YH A 8.2 066 7D4 1-2 7042064 Early head no center exhaust divider Block Casting # 485428
1972 455 185/200 HP YH A 8.2 066 7L4 1-2 7042064 Block Casting # 485428
1974 400 190 HP YH A 8.0 255 4X 1-2 7044066 Block Casting # 481988
1975 400 170 HP YH A 7.6 266 5C 1-2 7045160 Block Casting # 481988/500557
1977 301 135 HP YH A 8.2 868 01 1-2 17057172 Block Casting # 525934
1978 400 180 HP YH A 7.7 471 6X 1-4 17058264 Block Casting # 568557/500557  
Engine builder,self taught auto body guy.
Horsepower sells engines and torque wins races

What I have seen on the Internet the J216 code is october(j) day 21(21)year 1966or 1976(6) and beginning in 1967 they had 3 freeze plugs? My question is mainly on the flex plate  

What's the block casting number on the back of the block where it meets the bellhousing?
Based on the YH stamping and the date code provided, you have one of the following:

1977 301 135 HP YH A 8.2 868 01 1-2 17057172 Block Casting # 525934

1967 428 360 HP YH A 10.5 067 670 1-4 7027262 Block Casting # 9786135

You need to determine what you have so you can find the correct parts.  
A little help... 'cause we don't all have to learn the hard way!

1967 428 360 HP YH A 10.5 067 670 1-4 7027262 Block Casting # 9786135

This is probably what you have.  
Engine builder,self taught auto body guy.
Horsepower sells engines and torque wins races

+1
The 301 has 3 bolt engine mounts, the 428 only has 2

 
When The Flag Drops,,,



The Bull Chit Stops,,,


P. Engineer, Engine Builder

Good point guys, I missed his mention of the motor mounts!  
A little help... 'cause we don't all have to learn the hard way!

I think also, in mid 1968.. possibly 1969, Pontiac started casting the CID of the block in the side by the freeze plugs. If the CID isn't cast in, then it was most likely made before 68..  
Jim,

It looks like it is 9786135 but there is a round plug with a square indented Allen wrench type of head installed over the 978 maybe? but the last four are 6135  

So what does all this mean?
1967 428 360 HP YH A 10.5 067 670 1-4 7027262 Block Casting # 9786135
1967 year
428 engine size
360 hp horsepower
YH ? Automatic transmission
A?
10.5 ? Compression
067 ?
1-4 one four barrel carb
7027262?

Thanks for all the help by the way I should be able to find the right parts now!
My car is currently in a million pieces to get restored and painted and I am in the process of putting it back together now definitely easier to take apart than to put back together! Again thank you  

Br,
YH is the 2 letter engine code. Auto trans type of that year had a "Y" in the code. Manual trans usualy had a "W" or possibly an "X"
A=transmission type
10.5 is CR (10.5:1)
067 is the factory cam designation
7027262 is the Q-jet carb numbering for the style/type of Q-jet carb.
You've got a darn good motor there!  
Jim,

Ok got my new flex plate today fit perfect! Thanks to everyone for there help my car should be ready to go this spring! Also if anyone lives around the Sioux city, Iowa area there is a huge car show, legal drag races on city streets, and cruise night July 19-21, 2013 it is the 3 rd year for this and it is awesome! Just google rocknrods Sioux city I will be driving my dark blue 70 gto hope to see ya there.

Thanks again
Brad  

One more question what does the 153330  YH stand for on the left of the timing chain cover is it just a serial number for the engine?  

yes for the number. yh = automatic.  i know some pontiac people that live in farnhamville, fort dodge, rockwell city and omaha neb.  
76 455/4spd TRANS AM
69 GRAND PRIX 406/5SPD