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Jwlemmerman
Joined: 22 Sep 2021 Posts: 1 Location:
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Posted: Wed Sep 22, 2021 9:36 pm Post subject: Convert 389 intake on 1965 GTO |
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Am looking to buy a 1965 GTO, and have spotted a few problems:
1. Can you swap a 4bbl intake and carb for a Tri-power setup on a 389 - or is there more modification to be done (cams, etc.)?
2. If you do, is the 335 hp now increased to 360 hp?
3. Several sites say that the serial number portion of the vin (1965 GTO) must start with a 1 for V8 or a 6 for a 6 cylinder engine. But I have seen two examples where the serial number begins with a 2 (?)
4. Any foolproof way to quickly spot a GTO clone (again for 1965j? _________________ |
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Larry Site Admin
Joined: 01 Jun 2006 Posts: 4773
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Posted: Thu Sep 23, 2021 12:01 pm Post subject: 1965 GTO Questions |
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1) Yes. That swap is made all the time, but I would make sure the manifold you want to use is from a '65 or '66 as some places I see note that not all '65s had interchangeable bold patters to the heads. I could not find any specific info, just that note. Obviously fuel lines and throttle need to be addressed. Cams and other engine parts (heads, etc.) will all work. I have done swaps the other direction (2-bbl to tri-power) and even the smaller 2-bbl. heads will work fine. Not as high of performance, but no issues.
2) No. As a matter of fact, the only 360hp shown in my references is the tri-power engine (code WS with standard trans. and code YR for auto trans. The 4-bbl engine is shown as 335hp (WT with standard and YS for auto). What the internal differences are, I can't tell, but they are there. Compression ratios are the same between the two blocks, so it is probably heads and cam. What I can tell you is that tests of the tri-power against the 4-bbl usually showed the 4-bbl to be as good or even better.
3) the code (VIN) breaks down as follows:
2= PMD
35= Tempest (GTO was an option on Tempest, not a style)
27 (2-dr. coupe), 37 (2-dr. hardtop), or 67 (2-dr. convertible)
5= 1965
LETTER= which plant built the car
6 Digits= each plant for V-8 cars started at 100,001 and went up; each plant for 6-cyl. cars started at 600,001 and went up
4) The one and ONLY "foolproof" way to know if it is a real GTO is to buy the report(s) from PHS (Pontiac Historical Services) in Michigan. You can google them on-line. Note that they do charge for their services, but it is a small price to pay to avoid and expensive mistake-- we have seen them, and the buyer is never happy! _________________ PontiacRegistry.com... building the single largest source of Pontiac information, services, and entertainment in the world! |
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