# 1966 GTO Barn Find - WA Engine Rebuilder / Machinest for 389 Recommendation



## kkosche (Dec 13, 2021)

A friend and I just purchased a 1966 GTO barn find . . been in a garage in WA since 1980. West coast car. 86K miles. Fully documented. Original owner. Factory 4 speed, factor A/C car. It is a freaking time capsule.

Started on it this week . . . removed belts, fan, fan shroud. Pulled plugs (all looked great). . . . put 100ml of Mystery Oil intro 4 of the holes, and 20-40ml in other 4 until full . . . . let soak for two days. Breaker bar . . . and we get only 3/8 - 1/2" of rock out of the harmonic balancer. . . . Rotor on distributor doesn't move at all. My guess is we are able to move the crank, at least to the point that the slack is up in the timing chain. Something on the upper end is stopping further movement. At this point, I don't think it matters what is stopping us . . . as even if we get it broken free fully . . . there will be enough rust / debris where it would chew up bearings, etc if it ran any length of time.

Two questions:

1. Based on the above, do you agree with our diagnosis?

2. Does anyone have a recommended engine rebuilder and/or machinist who specializes the 389 (or at least has done one before) ?

My tentative plan would be to pull the motor . . . have someone take responsibility for the rebuild of the long block . .. and then I would reinstall. While the motor is out I can go through Starter, Alt, A/C, Heater Core, Brakes, Fuel Delivery, etc. . . 

Thank you in advance for any wisdom (or opinions) you may be willing to share.


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## armyadarkness (Dec 7, 2020)

There's no chance that a barn find engine would be serviceable, so personally Id immediately abandon any more in car diagnosis. Even if it only had 30 miles on it when stored, rust and dried seals have long since mandated a strip down.

Any notable engine builder should be able to do a Pontiac engine. Their unique properties are mostly external. 

Depending on your plans for the car, you might consider buyinfg a replacement motor and storing that original for another day.


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## Scott06 (May 6, 2020)

Transmission could be locked up as well. If you want to see if it is top end pull valve covers and loosen the rockers move them out of the way. If that works you may want to tap the valves with a deadblow. 

I had a 65 389 that sat in a field for years, couldn't get it to budge pulled heads still locked. Pulled the motor and found throw out bearing was locking against pressure plate and bell housing. Someone had janked the trans and disloged the throw out bearing and or fork locking the engine. I was amazed how clean this was as it had probably sat at least 15 years.


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## kkosche (Dec 13, 2021)

armyadarkness said:


> There's no chance that a barn find engine would be serviceable, so personally Id immediately abandon any more in car diagnosis. Even if it only had 30 miles on it when stored, rust and dried seals have long since mandated a strip down.
> 
> Any notable engine builder should be able to do a Pontiac engine. Their unique properties are mostly external.
> 
> Depending on your plans for the car, you might consider buyinfg a replacement motor and storing that original for another day.


Thank you. Appreciated.


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## kkosche (Dec 13, 2021)

I can put the trans in first gear (4 speed) put clutch in, and roll the car just fine. Car also rolls just fine in neutral, with clutch out.


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## 67ventwindow (Mar 3, 2020)

I would probably try to unstick the engine if it was a old beater grain truck with a straight six. It has 86K miles on it. Are you going to get many miles on if you get it unstuck? 1 in 100 you get it running well with out taking it apart. For me it would take 15000 attempts to get that one. I know guys it will work every time they try.


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## PontiacJim (Dec 29, 2012)

kkosche said:


> I can put the trans in first gear (4 speed) put clutch in, and roll the car just fine. Car also rolls just fine in neutral, with clutch out.


You can still have a clutch disc stick to the pressure plate and it lifts when you depress the clutch. You won't actually know until you move the inspection cover down/out and have someone push in the clutch. Even at that, I would not trust the disc after all the years.

The engine is stuck, and you may break it loose, or you may damage it. The chain will have slack at that mileage as they are usually in need of a replacement when you start going past 60,000.

No doubt several of the valves were open when parked. Moisture WILL get down into those ports. The valves could be frozen stuck and the cylinders rusty. A bore scope to look into each cylinder will give you a peek at their condition.

Sitting so long also means no oil in the engine. The oil will have turned bad or dried up. Spinning it over is only asking for trouble. All rubber gas lines will be bad and dried out. Fuel pump diaphragm and gas lines are not ethanol friendly and you are only asking for a problem/fire. The carb gaskets and accelerator pump have dried out by this time.

All rubber brake parts will need replacing. The lists goes on if you want?

Trying to fire it up after all this time will be a mistake in my book, regardless of what else you may hear.


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## kkosche (Dec 13, 2021)

PontiacJim said:


> You can still have a clutch disc stick to the pressure plate and it lifts when you depress the clutch. You won't actually know until you move the inspection cover down/out and have someone push in the clutch. Even at that, I would not trust the disc after all the years.
> 
> The engine is stuck, and you may break it loose, or you may damage it. The chain will have slack at that mileage as they are usually in need of a replacement when you start going past 60,000.
> 
> ...


Thank you.


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## kkosche (Dec 13, 2021)

67ventwindow said:


> I would probably try to unstick the engine if it was a old beater grain truck with a straight six. It has 86K miles on it. Are you going to get many miles on if you get it unstuck? 1 in 100 you get it running well with out taking it apart. For me it would take 15000 attempts to get that one. I know guys it will work every time they try.


Appreciated.


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## kkosche (Dec 13, 2021)

Thank you all, for the advice.

Net / net: engine is coming out.

I believe these motors have 10.75:1 CR, seems a bit steep for iron headed motor with todays pump gas. Any council here?

Given the cars history, I think we will build back to stock to the extent possible, or that I am advised otherwise (hardened valve seats, etc).


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## Scott06 (May 6, 2020)

kkosche said:


> Thank you all, for the advice.
> 
> Net / net: engine is coming out.
> 
> ...


I have stock set up with my 65 389, I run 93 with a lead substitute on non hardened seats. I limited my advance to about 36 total, and carbs are a tad on the rich side. I don't drive it a lot, but seems to have no issue with detonation. I just switched from a 160 stat to 180 to see if it makes any drivability difference so that could be part of it??

Bottom line if you are goin through and doing a complete overhaul new pistons etc yes go back in with hardened seats and lower compression. But for an engine I did a valve, ring, and bearing job ( basically a $500 backyard overhaul) on in 1990 this still works ok.


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## armyadarkness (Dec 7, 2020)

"Barn Find" was definitely a term (unjustly) glorified by reality TV. But with elbow grease and check books, it'll be back to where it belongs!


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## kkosche (Dec 13, 2021)

armyadarkness said:


> "Barn Find" was definitely a term (unjustly) glorified by reality TV. But with elbow grease and check books, it'll be back to where it belongs!


I am fairly certain this project will be like many others I have leaned into . . . "solid deal" up front . . . followed by over investment . . . followed by a market value of something 25-50% less than invested. But as my dad says .. . . it is a better investment than hookers and blow.


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## armyadarkness (Dec 7, 2020)

kkosche said:


> I am fairly certain this project will be like many others I have leaned into . . . "solid deal" up front . . . followed by over investment . . . followed by a market value of something 25-50% less than invested. But as my dad says .. . . it is a better investment than hookers and blow.


GTO's, Hookers, Blow... I'll help out however I can


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## O52 (Jan 27, 2019)

kkosche said:


> I believe these motors have 10.75:1 CR, seems a bit steep for iron headed motor with todays pump gas. Any council here?


10.75 was a bit of advertising hype. 10-10.25 is closer to reality


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## PontiacJim (Dec 29, 2012)

kkosche said:


> Thank you all, for the advice.
> 
> Net / net: engine is coming out.
> 
> ...


My suggestion. As pointed out by O52, the advertised and actual compressions are different. The 10.75 was for NHRA purposes when the Super Stock racers blueprinted their engines. They were allowed certain specs that they could play with, but had to still be pretty darn close to stock. So actual compression is generally lower at 10.0 - 10.25. The GTO will have "093" heads used for 1966 which are a "closed" chamber head that can get away with a little more compression than the 1968 and up "open" chamber heads.

First things, have the block/heads hot tanked and then magnafluxed for cracks. Then go from there.

BUT, I would still lower the compression just to save some grief in the future so you can run pump gas without issue. I would shoot for 9.25-9.5 compression. You are going to lose a little HP with the lowered compression, but not much, AND you can make it up.

Since you are going to rebuild the engine, figure a budget plan. Pontiac's are not inexpensive like a Chevy or Ford. But, you can go economy, or you can go best. 86K is not real high mileage, so you could use the crank & cast iron rods - having the rods resized and fitted with the better ARP rod bolts. You will still have cast rods which are OK if you don't plan to really lean on the engine. I would not use the cast rods because you can get inexpensive I-beam forged rods that will be a lot stronger, safer, handle the abuse, and is insurance for the engine.

You could keep the crank as the Pontiac cranks will handle big HP, so no issue there IF you keep it. Pistons will be a problem for the 389 as this generally means custom forged, like Ross, pistons. If you bore the cylinders .060" over, then much easier to select pistons because with .060" overbore you now have a 400CI bore. BUT, still an issue because the valve size and spacing changed with the 400CI and the valve reliefs are different than the 389, so you could have a valve-to-piston crown clearance problem if you use too high of a lift cam. BUT, once again, this issue can be solved with a custom forged piston, like Ross, with the correct valve reliefs OR dished pistons that will lower your engine compression _which is _what you want anyway.

Adding this all up, you may want the better forged rods, better forged pistons (dished or correct valve reliefs), and bring your power level back up to stock, or better. With new pistons/rods, you will have to get the engine balanced. (Get an aftermarket steel flywheel while you are at it to replace the cast iron flywheel - unless you are just going to baby the car and never ever do a burn-out, speed shift, or wind out the engine.

Butler, as well as a few other Pontiac specialty engine builders offer a complete rotating assembly - which in my opinion is your best bang for the buck once you start adding up individual parts. Go with the 4.25" stroker kit that will provide the lost HP and even more TQ. You can work with your machine shop to see what bore size you need. The less you can bore it over, the better because it leaves more meat in the cylinders for another overbore or two.

Check out the pricing here, Item Item #: BPI-4250-300-389, $2,099.00:



https://butlerperformance.com/i-24591340-butler-performance447-454ci-balanced-rotating-assembly-stroker-kit-for-389-block-4-250str.html?ref=category:1234862



You can see that is just the rotating assembly. The rebuild will continue to $go up from there. BUT, you can also do it cheaper using your crank/rods and custom forged pistons to lower compression.

So you have options based on your budget.


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## kkosche (Dec 13, 2021)

PontiacJim said:


> My suggestion. As pointed out by O52, the advertised and actual compressions are different. The 10.75 was for NHRA purposes when the Super Stock racers blueprinted their engines. They were allowed certain specs that they could play with, but had to still be pretty darn close to stock. So actual compression is generally lower at 10.0 - 10.25. The GTO will have "093" heads used for 1966 which are a "closed" chamber head that can get away with a little more compression than the 1968 and up "open" chamber heads.
> 
> First things, have the block/heads hot tanked and then magnafluxed for cracks. Then go from there.
> 
> ...


I really appreciate your guidance, expertise and time. Thank you.


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## pkentander (Dec 9, 2021)

I am restoring a 65 also in WA. I just finished the engine a few weeks ago. Expect long delays. Mine was in the machine shop for 6 months. Then when I ordered a rebuild kit moly rings had to be modified to fit as supplies are very limited. I lucked out and found heads that had just been rebuilt (another guy put on aluminium heads) and he sold them to me for $300. I had to drive 4 hours one way to get them but they were perfect. I purchased another 389 engine that I am keeping for a spare. Keep your eyes peeled on craigslist and FB marketplace. Stuff comes up more than you would think. I found a 4 speed that had been in a trunk for 30 years and just replaced the seals. It was perfect. Are you in Eastern WA or Western? We might collaborate. I live in Central WA right in the middle of the state. This has been so much fun.


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## kkosche (Dec 13, 2021)

Sounds like a great project. Getting anything these days seems a bit of a challenge.

The car Is currently is Woodinville. We plan to move to my shop near Lake Stevens, after the holidays.


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## kkosche (Dec 13, 2021)

pkentander said:


> I am restoring a 65 also in WA. I just finished the engine a few weeks ago. Expect long delays. Mine was in the machine shop for 6 months. Then when I ordered a rebuild kit moly rings had to be modified to fit as supplies are very limited. I lucked out and found heads that had just been rebuilt (another guy put on aluminium heads) and he sold them to me for $300. I had to drive 4 hours one way to get them but they were perfect. I purchased another 389 engine that I am keeping for a spare. Keep your eyes peeled on craigslist and FB marketplace. Stuff comes up more than you would think. I found a 4 speed that had been in a trunk for 30 years and just replaced the seals. It was perfect. Are you in Eastern WA or Western? We might collaborate. I live in Central WA right in the middle of the state. This has been so much fun.


Who did you end up having do the machine work? I saw something about Gipson Performance Engines is out in Spokane has done some 389's . . . not sure how many machine shops have a Torque Plate for poking new holes in the block. Looks like I missed the window for Butler Performance (orders in by Nov for the next Calendar Year) . . . and not sure I want to wait until some time in 2023 for a slot. . . I appreciate your help.


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## PontiacJim (Dec 29, 2012)

kkosche said:


> Who did you end up having do the machine work? I saw something about Gipson Performance Engines is out in Spokane has done some 389's . . . not sure how many machine shops have a Torque Plate for poking new holes in the block. Looks like I missed the window for Butler Performance (orders in by Nov for the next Calendar Year) . . . and not sure I want to wait until some time in 2023 for a slot. . . I appreciate your help.


What makes you feel you need a torque plate?


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## kkosche (Dec 13, 2021)

PontiacJim said:


> What makes you feel you need a torque plate?


Butler Performance


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## PontiacJim (Dec 29, 2012)

kkosche said:


> Butler Performance



Hmmmm, so no other reason? Not being a butt here, just inquiring. I see where some will make boring/honing a cylinder with a torque plate the best thing since sliced bread and anyone who doesn't do this will wind up with engine issues.

If a shop has a torque plate available, by all means use it. But if the shop does not have one, I would not discount the shop.

I understand the reason to use the plate, BUT, how do you counter the block twisting/movement that is encountered when the engine's torque pulls it over on the motor mount bolts? How do you counter the block twisting/movement that is encountered from the bellhousing when those tires are sending their grip through the driveshaft and trans gears? How do you counter the cylinder bore distortions when engine temps run the gambet from outside temperatures (prior to starting up the engine) to the engine temps encountered in stop/go 100 degree outside days? When exactly is the cylinder/engine at a constant temperature where cast iron is not expanding/contracting? Same goes for the pistons - they expand/contract which require a minimum/maximum piston-to-wall clearance. And then there are the piston rings and the ring gaps. 

Again, not busting balls, but I feel that the torque honing is fine for a race engine where a different set of variables are encountered. Most often, race engines encounter far more cylinder pressures than a street engine and they have aftermarket race blocks that may or may not have water jackets, have thicker cylinder walls or liners, have far more webbing & block support to counter distortion, may even have the water jackets filled with "hard block," use motor plates and not motor mounts, and maintain a better & consant temperature for far shorter periods of time.

If you do use the torque plate, find out what head bolts are used, ie stock or ARP because the torque used for each is different and using stock torque numbers when the plate was secured with ARP bolts will have an affect on cylinder/block distortion. I would also want to have the main caps installed and torqued while doing this.

Then, if you do the block, what about the heads? They too should be fitted with a torque plate when doing any valve work or port work to make sure the tolerances don't get skewed when the head is bolted down.

So my personal feeling is that I would not pass up a good machine shop just because they don't have a torque plate, nor would I limit my search for a machine shop with a torque plate. Sonic testing each cylinder and checking for core shift might be a better consideration to ensure the cylinder walls are thick enough to aid in preventing cylinder distortion.

Just my opinion, as usual.


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## kkosche (Dec 13, 2021)

PontiacJim said:


> Hmmmm, so no other reason? Not being a butt here, just inquiring. I see where some will make boring/honing a cylinder with a torque plate the best thing since sliced bread and anyone who doesn't do this will wind up with engine issues.
> 
> If a shop has a torque plate available, by all means use it. But if the shop does not have one, I would not discount the shop.
> 
> ...


i appreciate the view.

I figure Butler Performance has a bit of expertise in the area, and if they use it, so will I.

Not sure I would not use a shop that didn’t have one, as I could always just buy one for their use. . . . Then have it available for any other enthusiasts in my local who wants to have the benefit of it.


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## kkosche (Dec 13, 2021)

Thought I would conclude this thread . . . in the end, I went with Gipson Peformance Engines out of Spokane, WA. Took a while, but very happy. Generally stock rebuild, with the exception of a roller cam and electronic ignition. Got it back in, and fired it on Thursday. Starting a series of shake down runs, as the weather in WA allows. Rebuilt everything from Rad back, with very few exceptions. Putting tires on it tomorrow, exhaust on the 16th and then interior at end of the month, and finally a detail/paint specialist to see how far we can bring back the original paint. It has been a fun project, and enjoyable partnering on it with a life long friend on the build.


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## BearGFR (Aug 25, 2008)

kkosche said:


> Thank you all, for the advice.
> 
> Net / net: engine is coming out.
> 
> ...


(ooops - I see I'm late to the party again and you've already had your engine "done", but I'm leaving this here anyway in case it helps)

10.75:1 is indeed the "factory blueprint" spec, but no engines in production cars came off the line with that much compression. It's a game that most them OEMs played back in the day that allowed them to sell cars to the public that weren't quite as "touchy" to maintain (read: less work under warranty = cost savings) while at the same time let racers be competitive and legal in NHRA factory stock classes by re-machining their engines to "factory blueprint" specs. If you were to tear it down when new and measure all the volumes and clearances, then calculate actual compression ratio, you'd likely find it to be around 10.0:1. That's still too much (my opinion) for iron heads on today's lower octane fuel however.

The hardest part about freshening up a 389 might be finding pistons. I hear they're getting more difficult to find. Butler Performance has a relationship with Ross Racing Pistons so they're likely to be able to supply, even if you have to go to custom made ones. I have an Excel workbook here in the FAQ section that contains a handy compression ratio calculating tool. It's the only one I know of that also considers the small bit of clearance area that exists between the piston and cylinder wall above the top compression ring. 

I agree with others about trying to get it running as is. Especially if that's the "born with" engine in the car because it'd be a shame to have it digest itself beyond repair while trying to get it running. They're only original once.

Bear


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## geeteeohguy (Feb 2, 2008)

Ironic....When I moved I found a new set of Sealed Power .030 forged 389 pistons I bought back in 1980 or so. Nowadays, pretty much not usable due to the flat top construction unless they were dished, and I believe they are thick enough at the crown to be dished. I had forgotten all about them until I read this! Thanks, Bear!


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