# Early 1964 389 build input?



## bustac (Oct 21, 2013)

I'm putting together an early 389 and looking to get some input from others that have proven combos of internals. Plan is to run a rotating stroker assembly from one of the Pontiac guys. Possibly a roller valve train. Heads are 9773345

I don't know the history of the engine but I pulled a head and cylinders measured 4.04 as I recall with a small ridge that I can catch my finger nail on. I'm assuming it hasn't been bored before.

I'll be a running 64 tripower intake.

It's going into a 64 goat, 4spd, 3:23 not looking to race but a stout street cruiser.


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## BearGFR (Aug 25, 2008)

Sounds like it's going to be a nice piece. :thumbsup:

Since you're planning to use the original iron heads, the thing to be careful about is compression ratio.

Sources say those heads usually have 70 cc's of volume in the chambers (ALWAYS measure your heads! They can vary quite a bit for many reasons and even a couple of cc's makes a difference.)


Working from there, assuming a +0.030 389 with all the other critical measurements "factory usual", I land at a compression ratio of 9.958:1. My opinion: too much for today's fuel. It's likely to have detonation problems on pump gas. You'd be a lot safer with it running in the 9.3-9.5 range on 93 octane. Getting there would require running pistons with 12 cc's of dish in them, assuming the usual factory deck clearance of 0.020. If it were me, since you're going to need to have it bored anyway, I'd spend a little more and have the block zero-decked and then run pistons with 17 cc's of dish volume. That'd give you the same compression ratio (9.33:1) but with a much more favorable "quench area" - which will also help resist detonation.

Bear


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## bustac (Oct 21, 2013)

*389 build*

Yep, most of what I read was I'll need a set of custom dished pistons to bring the CR down.

Next up dismantle the engine and bring to the machine shop to have it checked out.

Any suggestions for head work I figured surface, triple angle valve job, valve guides. What about screw in studs and porting?


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## BearGFR (Aug 25, 2008)

Screw in studs - definitely a good idea. I'd recommend bypassing the Pontiac bottleneck studs through and instead using the 7/16's ones along with poly-locks instead of the original pieces. You gain both strength and the ability to positively adjust things.

Porting... eh, not sure I'd bother with (translation: spend the money on) it considering how you've said you plan to use the car. I'd probably out the money into something where I'd get more benefit from it - like brakes and suspension. A good gasket match ought to be good enough. If you're handy and want to take it on yourself, Jim Hand's book has a pretty decent description.

Bear

How much stroke are you planning on?


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## PontiacJim (Dec 29, 2012)

The heads are correct for the '64 big car 389CI engine, 250 HP 326CI, & 320 HP 421CI. Has 1.92" intake valves and 1.66" exhaust valves. Correct GTO heads were the 770716.

Compression is listed as 10.5. Bear is correct, too much comp. for your street intentions. As Bear stated, head modification is really based on what you are looking for. 

I like torque, and Bear can expand on this as well. So you build the Pontiac for torque and nothing does it better than cubic inches. You won't need a radical cam to achieve tire smoking results and yet have a very docile and drivable car. You can even aim for reasonable gas mileage with the tri-power if you drive it easy. You can get a complete stroker kit, balanced, which is the best bang for your buck as opposed to doing it piece meal. You also get all new parts and don't have to sweat it when you stand on the gas and wind it up to 6,000 RPM.

If you go more cubes via a stroker kit, then you may find the heads to be the limiting factor as they may hold the engine back because they don't flow as they may need. I would step up to the larger 2.11" intakes - which your machine shop can install with little problem. The 1.66" exhaust will be OK. I like stainless steel replacement valves, but there may be other opinions. Stock style seems fine versus high dollar race valves which in my opinion are not needed for the daily driver. Adding 7/16" screw-in rocker studs will require the stud pedestals to be machined flat, and then the holes tapped. You may want to do a simply port match on the intake side of the head as well as the tri-power. Fairly easy to do and look on U-tube for a video or two on this. You may want to also grind any flashing in the oil returns found on the push rod side to aid oil return and make sure none of it ever breaks loose and get into the engine. I use a die grinder and carbide cutter that you can usually get at most welding supply houses, tool supply, or of course the internet. Eastwood carries a "kit" you can buy if you care to spend the price and try it yourself. Machine shop will of course do this at a price.

For your street build, most seem to like the repro Ram Air III cast manifolds versus the pain in the butt headers. A good 2 1/2 " set of duals with the "X" crossover pipe and my choice of muffler is the Dynomax, but they do have a drone at about 2,000- 2,500 RPM that I like, but some don't care for. I like noise and the "drone" always turns heads to see what it is. 

BUT FIRST, choose a machine shop (that has experience in rebuilding Pontiacs, and not just Chevies or Fords) and get the block and heads magnafluxed for cracks before you buy anything. Once you know they are good, then you can plot your build.

Post more info on what you are looking for, or what you want to do with your car, and more opinions/help will be provided to direct you in what you may, or may not, want out of your engine. I also second Bear on purchasing a copy of Jim Hand's book. HOWEVER, it does not seem available at this time and copies on Amazon are starting at $139.00 and up (used) for an $18.00 book. ABSURD!! So until it goes into another printing, don't pay it.


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## geeteeohguy (Feb 2, 2008)

What these gents said, and I'll add this: I would run '68-up open chamber big valve heads. They can be had on the cheap, and will have bigger valves, screw in studs, and not need as much spark advance to make good power. Spending money on upgrading the heads you have isn't the best use of your funds. The only issue with the newer heads is that you can't run your '64 intake....you'll need a '65 and later unit.


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## bustac (Oct 21, 2013)

*64 389 rebuild*

I do already have a 64 tripower intake that I already cleaned up, painted and have 2 of the 3 carbs, still looking for a 3rd (rear carb.) 

Is it worth looking for the GTO correct heads, machinist seems to think he can make the heads I have better than the originals?


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## PontiacJim (Dec 29, 2012)

bustac said:


> I do already have a 64 tripower intake that I already cleaned up, painted and have 2 of the 3 carbs, still looking for a 3rd (rear carb.)
> 
> Is it worth looking for the GTO correct heads, machinist seems to think he can make the heads I have better than the originals?


First, they sell the base for the end carbs, so you can buy a standard 2 BBL carb and make your end carb.

No doubt your machinist can indeed make the heads better than original. Of course, the key here is cost. Geeteeohguy mentioned the '68 and up heads due to those things already found on some of the heads, like the screw in studs, push rod guide plates, & larger valves. (make sure the valves won't hit your block -read below)

The mid 1967 big car 061 head and all '68 and up heads were known as an "open chamber" combustion chamber where as the earlier '67 and previous year heads had what is called a "closed chamber" head or "bath tub" combustion chamber. Open chamber heads are the better of the two.

BUT, here are some differences to consider about the '64 engine.

1. The engine passes oil through the block to the heads through the rocker arm studs.
2. The valve chamfers are located differently in the block as the valves in the earlier head are closer to the cyl wall.
NOTE: You will not be able to fit the larger 2.11" valves of the '67 and up head into your 389CI head as I had thought and suggested - my bad. Looks like the largest size will be the 1.92" valves because they are closer to the cyl walls. Found a source that says all 389CI valves were 1.88" except the '64 GTO 389CI which was 1.92. The head number you gave listed the valves as 1.92, but check.
3. Because of the above, valve reliefs cut in the piston will have to match the head used.
4. The '64 and earlier heads used a 17 degree valve angle, in relation to the block deck, while the '67 and up used a 14 degree angle.

Good news is if you did the swap, using the '68 and later heads, you have to make sure you match all the parts together - pistons, heads, intake, etc.. You have to block off the oil supply holes in your 389CI block and use the conventional parts to use the oiling through the lifters/pushrods (but I would confirm this with your machinsit). You will also need to use the head gasket that matches the later heads and may have to chamfer your block to match that gasket.

BUT, the '64 heads would work just fine, in my opinion, for a good street engine. You can use your tri-power. You can convert the heads to the solid 7/16" rocker studs, and, this will block off the stud oiling. Ask your machinist if you need to plug the block passage as well. Then make sure the conventional lifters/pushrods from the later design will work - I am not an expert here, so I don't honestly know. I think you can also use the 67' and up push rod guide plates once you do this conversion. (The Super Duty 421 CI used a 7/16" stud having oiling through the stud and they were pinned to keep them from pulling out -but, can you find these if you wanted to keep the original oiling through the studs?) Get a good 3-angle valve job. Port matching the intake can't hurt.

I do know that some aftermarket piston makers state that their pistons won't work with the 17 degree heads that your '64 heads are, so make sure you check for this if you go with the '64 heads. Definitely need to use some form of a dished piston to get the compression down to about 9.0 to 1 for the street. Don't need to go too radical on a cam to make good torque/power.

So, I probably confused you more! HaHaha. But, a few more things to consider and talk with your machinist.


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## bustac (Oct 21, 2013)

*bottom end*

I'm guessing this engine didn't frequent jiffy lube?



















Got everything out down to a bare block, see what the machinist has to say.

Plans for now:
Clean and Mag
Bore
Align hone
Cam bearings
Freeze plugs


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## geeteeohguy (Feb 2, 2008)

There's a lot of water mixed in with that sludge....I hope there's no rust issues. Looks ok from what I can see, thouogh....


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## RunninLeMans (Apr 3, 2014)

I have a set of 9773345's, they indeed have 1.88" intake valves. Also the combustion chambers were 68 CC's +/-0.5 and the intake ports were 150 CC's. The heads I ended up using I did my own mild porting on using the same sources everyone's referenced. It's not that hard to clean 'em up and do the intake-match, I spent about 8 hours total on them, in shifts cuz it's nasty work. 

I love that you're sticking close to the vintage with the '64 389...


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## bustac (Oct 21, 2013)

I ended up with a rotating assembly from Butler Performance, Eagle Crank and Rods, Ross Pistons, Sealed Power Rings, bearings and I went with a Viton one piece rear main seal. Cam and lifters are from Lunati, it's a whole matched set they sell with timing chain and valve springs. Only thing I have left to get internally are rockers and pushrods.

I ended up having to bore .060 over. My machinist has the bottom end assembled. Only hitch so far was there is a slight clearance issue with the aftermarket crank you need smooth out a small piece of the block for the counter weight.


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## PontiacJim (Dec 29, 2012)

The '64 engine oils the rocker arms through the heads/rocker arm studs. Do some checking on this and the screw-in studs. I don't know enough about these earlier engines to give a recommendation. I know you can convert the engine over to the '65 and later oiling through the pushrods, but you have to close off the oil feed to the heads. Over in the restoration forum, "Grumpy's 1964 Lemans" uses a '64 326CI which he converted over to the later oiling system. His engine builder reversed the cam bearings to close off the cam oil feed to the heads. You may want to contact Grumpy on his Facebook page to get the details on how he had this done.

Your machinist may already know what to do, just saying, in case you were not aware of this.:bigSmile:


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## bustac (Oct 21, 2013)

*progress on the 389 rebuild*

Been working on this for a few months and machine work is completed!










Still need a couple odds and ends and the engine will be complete.


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## Rukee (Feb 8, 2007)

Looking good!!


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## bustac (Oct 21, 2013)

*Engine installed*

The engine is back in need a few things to finish up before I can fire it. Manifolds and gauges.


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