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I own a 1970 GTO, I am having a hard time identifying the engine. The block stamp on the front has a WD which according to what I have is either a 1967- 326, 1968- 350 or a 1973- 350. The block mold number is 9799914, making it a 1970 400 or a 400 RA III. The date code by the distributor is 0815. All numbers sheets I have come from YEAR ONE Pontiac so not sure if they are accurate. So my problem is I want to rebuild the engine but I'm not sure what engine I have, can anyone help.
 

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Block code WD 9799914 Is a 1970 400ci 2V 290 hp turbo 400 originally in a B body RPO L65. Should have a 400 stamped on the block on the drivers side above the motor mount. You might be looking at the date code upside down. It should be a letter followed by 2 or 3 numbers. If it was A180 it would be Jan 18, 1970. Letters A-L Represent Jan thru Dec First or first and second numbers are the day, last number is the year. 0=1970. Google Pontiac Engine Block Codes and you can find all the info.
 

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Perhaps one of you guys can help me. I've been trying to de-code a Pontiac motor that came in a 1968 GTO that I purchased in 1989. The motor was removed in 1992 and is in storage. I'm quite certain it isn't origional to that car, but haven't found any luck de-coding it on any of the de-coding sites.
I can tell you that with a aluminum intake and a Holley 750 this car was fast...13.00 with no other mods, and the worn out suspension that came on the car, with a 4 spd. Perhaps i got a # wrong somewhere but this is what i have written down.

front bank of motor: YA 175570

by distributor: 36138

Date Code (this is the confusing part) L026 ???

Heads (again confusing) 142 B

Any help would be greatly appreciated...
 

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L026 is going to be a year model 1967 block (factory switched over to the next year about mid-year), the YA and the 142 head code both further ID it as a 1967 400, 2-bbl, originally rated at 265 HP. The block casting number (passenger side rear, down "below" the head, next to where the tranny bolts up) is probably going to be 9786133.
This engine would have originally been in a full size Pontiac with an automatic transmission.

Bear
 

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L026 is going to be a year model 1967 block (factory switched over to the next year about mid-year), the YA and the 142 head code both further ID it as a 1967 400, 2-bbl, originally rated at 265 HP. The block casting number (passenger side rear, down "below" the head, next to where the tranny bolts up) is probably going to be 9786133.
This engine would have originally been in a full size Pontiac with an automatic transmission.

Bear
That makes sense about the mid-year switch over. And clears up my confusion.
Would the aluminum intake, 750 Holley, headers, and possibly a cam wake that motor up enough to drag that car down the 1/4 mile at a 13?
 

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Well.. I suppose an aftermarket aluminum intake and Holley carb are reasonable substitutes if you can't find a factory iron 4bbl intake and QJet :D --- Fact is, on a street engine nothing will out perform those factory pieces until you start making some big league power and spinning the motor past 6000 rpm. Those heads have 72cc (nominal) chambers, same as the performance D-port heads, but they have smaller valves (and probably pressed in rocker studs instead of screw-in studs). You could go with a little "more" cam but pretty quickly you'll reach the point where the spring seats need to be cut down for taller springs and the stresses would make me very nervous about those pressed-in studs. Then too the valve size is going to become a limiting factor. All of that is fixable - the heads can be machined for screw-in studs and also have the larger 2.11/1.77 valves fitted - all for a price of course :D You'd probably be a-"head" (ar ar ar) financially by replacing them with different heads that already have screw-in studs and the larger valves.

If you want to go fast.... there are definitely ways depending on how much you want to invest in the effort.

Bear
 

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I had a hot cam in my engine when I had it rebuilt. About a month after I started driving it one of the pressed in stud backed out. The rocker turned sideways hitting the one next to it breaking that stud and bending the pushrod.

Luckily I used a reputable machine shop. He paid to have a mechanic to remove the heads. He repaired them, put in screw in studs, and had the mechanic re-assemble it. No problems since then.

If I was to do it again I would have bought after market heads.

My two cents. But at a minimum get screw in studs.
 
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