My GS400 convertible is currently for sale and has a 462 in it, I have the original engine for the car. A prospective buyer asked me for the numbers off the original engine verifiy it's the numbers correct engine. It appears to me that it's a factory stage 1 motor. What is throwing me off is that from everything I've read the block deck stamping should be "RR" for a stage motor, this block is stamped "IOI" what gives here? The head casting number is 1231109 and the block casting number is 400 over 233790. The VIN stamp on the block deck is correct and matches the VIN and title. Pictures can be viewed here. https://photos.app.goo.gl/eEHWLZnH823oShvC9 Thank you for any help offered. PS. I do have the build sheet found above the gas tank but most of it is unreadable.
Check to the left of the I0I (one zero one) stamp to see if there is an "R" on the left hand side of your picture. Use a scotch pad there.
The 101 looks like a date code. The 2 letter code should be opposite that, like below (SP). Can't really see that side in your picture.
The block is a '69 400 1383790 not 233790 1231109 are heads on a '69 And as stated IOI is 101 and the RR will be stamped to the left.
Ok I found the other stamp, it is RR , so this would make it a standard 400 engine and not a stage 1 motor correct? what numbers would signify stage 1 heads for 1969 ? Thanks everyone. Jay
69 Stage 1 heads have the same casting numbers as 69 non stage 1 heads. RR = 69 400 non stage 1 engine
In 69 there is no stage 1 head, it's exactly the same as a standard head, larger valves didn't come out till the 455
Oh well , guess I still have a GS400 for sale just not a stage1. Thanks for all your help. We will buy a 2 seater convertible when the gs sells. Anyone have opinions on the 2 seater Buick convertible made years ago? What was it called? Regatta or something like that?
