#1  
Old 06-23-2019, 11:53 AM
jhnichols2 jhnichols2 is offline
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Location: Apopka, Florida
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Default 1966 GTO 389 YS STORY AND BUILD ADVICE

A couple of months ago I was searching my local Craigslist for Pontiac parts as I usually do and ran across a listing for a Pontiac engine block for sale for $100.00. It caught my interest as I am looking to swap out the 326 engine for a larger motor in my project 64 Lemans Convertible. Clicked on it and all it showed was a picture of a block in a large wooden crate. I called the guy to see if he still had it and get a few details. He said he had it but did not know much about it as it was something he had collected over the years from someone.

So I made arrangements to check it out. To my surprise not only was there a Pontiac block but there were oil pumps, pistons, a cam shaft, a crank shaft, and a pair of cylinder heads laying in the crate too. After a few minutes I got some id information off the parts and ltd. the guy I would let him know. With the information in hand I found out that the block was a late 65 dated 66 YS 389 with the original crank, pistons, cam, and 093 heads!
I tried not to appear too excited and knowing that the engine had been sitting apart for years raised caution about why it was torn apart and had been left sitting. I told the guy I was interested in everything, but hesitant not knowing the condition. I said I would take a chance and we made a deal, everything for $200.

The next order of business was to have the engine block checked out. I have been in the Pontiac hobby for over 20 years and I don’t know about your area, but in Orlando Florida I have yet to hear about a good Pontiac engine shop. I asked around and was recommended to a guy just 3 miles from my house so I loaded up the block and took it him.

Much to my surprise again, I learned he was restoring a 66 Lemans and was building himself a monster 400 for his car. I told him I wanted the block checked out. A week or so later he told me the block was good and in fact had never ever been bored out. He said the cylinder walls just need honed. I then took him the crank and pistons to check. Again he said the crank was good and just polished the journals. He ran into a small problem with the pistons and cannot get the old rings out on several of the pistons. He is recommending new pistons.

My question is what kind of pistons should I purchase? Stock bore, .10, or .20 over? I want to build a basically stock motor for street driving. Also which cam should I consider? A stock 067 grind or maybe a 068? I have not decided as to what stock intake to use, a 4bbl or a tri-power. I have a friend, who has both a 66 4bbl and a 66 tri-power intake he will sell me. The carbs on the tri power intake are not correct and I am not sure I want to go to that expense. Your input, opinions, advice and experience are appreciated.

I have not had the heads checked yet but that will happen soon. I will update as things progress.

  #2  
Old 06-23-2019, 12:28 PM
BOB VIDAN BOB VIDAN is offline
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Not everyone is old and needs 2 grade size block letters.

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  #3  
Old 06-30-2019, 08:12 PM
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GT182 GT182 is offline
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That hurts the eyes.

If it's ok and still stock keep it that way. Why do the added expense of boring it out.

Personally a 4bbl is good enough. If the tri-power isn't correct... again, why the added expense.

I have a good Carter AFB "Competition Series" I could part with it if you're interested. It's built by Weber and has an electric choke on it. I have one on my 66 now with a manual choke and wouldn't use any other brand. So I don't really have to sell it. Send me a PM if you are really interested..... if not, don't bother.

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