# Pontiac 1969 YD Block



## Phil Hoyle (May 27, 2018)

Hi All, I'm wondering if anyone can assist? I have a 70 YD block in my 69 model GTO which I understand would have been a 290hp 2 barrel motor but please correct me if I'm incorrect. I believe previous owner may have swapped the original 69 heads (date code H269) and 4 barrel intake (date code A089) from the original motor but not entirely sure. 

So the question is, how would this motor vary from a YS block which I believe would have been original? What are the differences apart from the 4 barrel carb between a YD and YS motor? I'm guesing different cam and valves? 

Regards, Phil


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## O52 (Jan 27, 2019)

The engine is from a full size Pontiac. 10:1 compression, small cam (9777254-269*/277* duration, 376"/412" lift), small valve heads. Since the heads and intake have already been changed it may just need a cam to bring it up to the same specs as original. 
Previous owner may have already swapped the cam (??)


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## PontiacJim (Dec 29, 2012)

The date code on the heads is August 1969 when 1970 engines start to come out, so they may be the correct heads for that block. The 2-digit number cast on the center exhaust port is the quickest clue. Original heads will have screw-in rocker arm studs, easily ID'd as the base of the stud will have what looks like a nut.

The intake is January 1969 and too far off to match the heads - so it could be original to the car if you know when the cat was built. The Q-jet also has a part number that can be used to ID it as original or not.


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## Phil Hoyle (May 27, 2018)

Thanks for the responses. The 2 digit number on the center exhaust port is 16, not sure what this means? I noted that the engine date code is B39 (3 Feb 69) but it is stamped as 70 so I'm a bit confused about that.

I'm unsure how to determine the build date from the cowl tag? I do have the PHS form which has shipped date as 30 Sep 68 so it would seem to me that the heads (Aug 69) and intake (Jan 69) are much later. Carb has been replaced with Holley.

So to sum up I guess nothing of the original engine that came with the car remains.

Regards,
Phil


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## O52 (Jan 27, 2019)

Those are the 78 cc small valve heads from 1970. Probably the originals from th engine you have.

This page describes how to read the data plate for 69 GM cars. Although slanted towards Chevelle the data is the same.





1969 Chevelle Trim Tags


Decoding Chevrolet VIN, trim tags, cowl tags, engine, engine block casting numbers, cylinder head casting numbers, intake manifold casting numbers, transmission, interior codes, and paint codes.




www.chevellestuff.net


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