# 1965 GTO Convertible restoration



## JMR (Apr 8, 2012)

I'm restoring my 1965 GTO convertible. It's a numbers matching 389 4 bbl 4 speed car. I'm trying to do a top notch resto on the car to make it as valuable as possible. I'm wanting to do a few mods to the engine like adding a tripower, steel crank, forged pistons, h beam rods and screw in studs and guide plates to the heads and a set of ram air manifolds but I don't know if this will increase or decrease the value of my car beings that I have the original motor or should I just build it back to stock specs. Also the car has drum brakes should I keep them original or upgrade to disc brakes. I'm not going to drive the car much just take it to car shows as I'm anticipating it being nice enough when I'm finished that no one would want to drive it far and it only has 52000 original miles. Thanks for any help I can get.


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## Instg8ter (Sep 28, 2010)

for best value with 52K miles all #'s matching i would keep it as original as possible, as far as engine internals i would have it built with the forged parts and 9.5:1 or lower compression for pump gas (judges will never know). welcome and lets see a few pics....:cheers


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## geeteeohguy (Feb 2, 2008)

I agree 100%. Modifications will decrease the value of the car. As you stated, you want it to be as "valuable as possible", so that means virtually no changes, which will be fine. The dished pistons used in the engine overhaul, and a cam change to an XE262H would be the only changes I would perform. I have drum brakes on both my GTO's and have driven them that way for 30 years with no issues. Not much stopping power at 120-130 mph, but around town and in normal driving, you can't tell them from disc brakes. If you're not used to driving these old cars, you'd be surprised at how well they actually drive compared to today's front drive "appliances".


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## 05GTO (Oct 6, 2004)

As far as adding a tri-power, if you keep and restore the original Carter AFB the value should not be hurt. I've seen 64-66 GTOs for sale with the original Carter AFB included with the deal and they sold for top prices.


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## JMR (Apr 8, 2012)

I'm going to restore the original Carter carbuerator and also the intake and sell it with the car when I decide to sell. :cheers


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## Pierre (Mar 5, 2021)

Hello,
I have a GTO 1965 tripower with four speed manual 

The Trim Tag Info of my goat 1965 indicate
L (4 speed floor shift)
G (console)
P (radio)

N (option GTO) 


but my block code is WT which normally correspond to 335 three manual speeds.....

Would my tag be wrong ?
Thank


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## O52 (Jan 27, 2019)

Hi Pierre

It would be highly unlikely that the trim tag is wrong.
It is highly likely that the Tri-Power was added to your engine either by the selling dealer or by a previous owner in the last 56 years 

You need to obtain the PHS documents for your car. They will tell you exactly what you have.





PHS Historic Services


The source of historic information for Pontiac owners, restorers, collectors, enthusiasts and car buffs, who are looking for specific information on their Pontiac Firebird, GTO, and more.



www.phs-online.com


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## Pierre (Mar 5, 2021)

Thank you for your answer
But why on my block there is WT and no WS ? On my trim tag is indicated L (four speed floor shift) the block should be indicated normally WS ? What do you think ?

Pierre from ANGOULEME near BORDEAUX and COGNAC


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## O52 (Jan 27, 2019)

WT and WS were both manual transmission engines. Does not matter if it was a three speed or four.
The difference is single four barrel (WT) or Tri-Power (WS) 

This is why you need to verify what your car was built as. PHS documents will indicate that.

Since the WT and WS codes were used over several years, there is also a chance you may have a different year engine. Verify the engine block casting date near the distributor











*Year **Engine**HP**Engine code**Trans**CR**Cam**Head Code**BBL**Carb No.**Misc*1965389360 HPWSM10.7506877 /97787773-2(F)7025178 (C)7025175 (R)7025179Block Casting # 9778789 Should have full head production number under valve cover - 97787771966389360 HPWSM10.750680933-2(F)7025178 (C)7026075 (R)7025179Block Casting # 97787891967400360 HPWSM10.750686701-47027263Block Casting # 97861331968400360 HPWSM10.75744161-47028267HO Block Casting # 97900711969400366 HPWSM10.75068/744481-47028273/7029273RA III Block Casting # 97900711970400366 HPWSM10.5068121-47040273RA III Block Casting 97999141971400265 HPWSM8.2555991-27041171Block Casting # 4819881972400250 HPWSM8.20677K31-47042263Block Casting # 4819881973400200/230 HPWSM8.00674X1-47043263Block Casting # 481988



*Year **Engine**HP**Engine code**Trans**CR**Cam**Head Code**BBL**Carb No.**Misc*1965389335 HPWTM10.7506777 / 97787771-43895SBlock Casting # 9778789 Should have full head production number under valve cover - 97787771966389335 HPWTM10.750670931-44043SBlock Casting # 97787891967400335 HPWTM10.750676701-47027063Block Casting # 97861331968400350 HPWTM10.75067161-47028263Service Manual shows 360 HP; Block Casting # 97900711969400350 HPWTM10.75068481-47029263non-RA Block Casting # 97900711970400350 HPWTM10.25067121-47040263Block Casting 97999141971400300 HPWTM8.2067961-47041263Block Casting # 4819881973455215/250 HPWTM8.00674X1-47043265Block Casting # 485428 Unitized Dist1974400225 HPWTM8.00674X1-47043263Block Casting # 4819881975400185 HPWTM7.60675C1-47045263Block Casting # 481988/late 500557?1976400185 HP (Early)WTM7.60676X1-417056263Block Casting # 500557


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## Pierre-Marie (Mar 6, 2021)

Thank you for all theses details you are very kind
The engine casting date of my goat is right.
But I thought that the option four speed floor shift was matching only with tripower and not four barrels
But is it possible to replace the four barrels with a triple carburetor without changing the engine ?


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## O52 (Jan 27, 2019)

Yes, very common modification. Can be done with the engine in the car.


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