# engine for my 66...389 or 428



## beer guy (Oct 22, 2014)

Hey Gang
Well, I have just about had it with trying to find a decent 389 for my 66. They are just about impossible to find here in Ontario. BUT, I did track down a 428 today that has just been rebuilt (or so he says and I have no reason not to believe him). Thing is I know very little about 428's. I have done some research on the internet and found out some things like production dates, power and that it was an optional engine. Other than that...bugger all.
So, can anyone help me out by letting me know stamp codes for the block, what heads it came with and their codes, carburetor, common problems or issues and above all a range in what it should cost?
I sure hope someone can help.

Thanks


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## tonyskala (Feb 7, 2015)

*You are in luck*

1966 Pontiac 389

So I have physically laid eyes on this block. It is a GTO block cast code and is correct for a 1966. It does need a total rebuild. It is in Sacramento California.


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## oldskool (Apr 26, 2015)

I'd go with the 428 and a good Q-jet. But that's just me. If being closer to correct look for the year model, matters to you, then, obviously, a 389 would be better, for you. 

The 428's were not put into any F or A bodies. they only came in '67-'69 big cars, like Cats, Bonnies and GP's. You can find some 428 engine info at this site, by entering the info you have.

http://www.wallaceracing.com/enginesearch4.htm

Here's more. Don't know how much is correct. I think they were rated from 360hp up to 390hp. They were all high comp, rated at 10.5-10.75:1. Most used 400 heads with dish pistons. I've read that all had 4-barrel carbs--Q-jet I assume. Am not absolutely sure of any of this, of course. It's just what I've read.

http://www.pontiaczone.com/forum/showthread.php?t=21577

There are some guys on this forum who can tell you how much of the above info is incorrect.


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## PontiacJim (Dec 29, 2012)

It really boils down to what you want out of an engine. In stock form, the 428 is fine. You get more cubes, bigger stroke, and more torque. The 428 was a racers favorite as it had the same bore as the 400 CI with the longer 4" stroke. Most bored it over to produce 440CI. It would rev like a 400 and produce more power and torque when built for race. 

If you get a '68 or '69 engine, you get the benefit of the open chamber heads as opposed to the '67 closed chamber heads. This is a big plus on todays gas.

Some had 4-bolt mains, another plus.

You can certainly make the 428 appear as a 389 or 389 tripower on the outside if that is what you are after. Only a few would ever know the true difference and you would have the extra cubes to back it up. Again, depending on the year has bearing on this as the timing cover/water pump/brackets etc. are different, but all will fit the block if that is the route you want to go.

So give us an idea of your intentions on the engine/car combination and we may be better able to steer you in a direction you want to go.:thumbsup:


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## beer guy (Oct 22, 2014)

*more info*

Went to see the 428 today and outwardly it looks good. Guy selling it is a fanatic Pontiac guy and knows his shyte. Does this stuff for a hobby as he is retired.
Engine is 1969 with block code 9792968 and engine code XF. Checked it out on link for Wallace and it is rated for 370hp with 62 heads, 4bbl, auto. He sold it to me for a decent price and is going to finish building it to my specs...just wish I knew my specs?! 
Going with 62, 13 or 16 heads. Flat pistons. 
Not sure about cam but he recommends XE250H10 from Com(? think that is the name as hand writing is a bit difficult to read). Wants to put the intake and carb I have on current engine but it isn't going to work as I have 2bbl. 
So, I need to find out about this cam, what to do for exhaust (headers, manifold??), carb.
Any suggestions or advice would be most helpful.

I am looking for an engine that is super durable, street friendly with above normal power and torque. Also, not sure about rods or lifters???

Thanks everyone!


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## maktope (May 22, 2013)

I went with the number 64 heads on my 428. It was a good motor until I decided I wanted more. Just know when you go to order parts for it down the road some parts you can order for a 400, other parts you got to tell them you have a big car. And then again other parts like throttle cable I found you gotta make yourself. But I loved it.


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## beer guy (Oct 22, 2014)

*Good advice?*

So, as part of this engine build I need to decide on exhaust. A buddy of mine is strongly recommending ceramic headers with a full stainless system with 2.5" pipes.
Any advice?
He says the extra you pay now is going to come back as the ceramic and stainless will last longer than me!

Thanks again.


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## Goat Roper (Oct 28, 2014)

beer guy said:


> So, as part of this engine build I need to decide on exhaust. A buddy of mine is strongly recommending ceramic headers with a full stainless system with 2.5" pipes.
> Any advice?
> He says the extra you pay now is going to come back as the ceramic and stainless will last longer than me!
> 
> Thanks again.


This is quality factory reproduction stuff, give Eric a call and he will hook you up.

GTO Exhaust Systems - Gardner Exhaust Systems - Muscle Car Exhaust Sytems for GTO


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## PontiacJim (Dec 29, 2012)

beer guy said:


> Not sure about cam but he recommends XE250H10 from Com(? think that is the name as hand writing is a bit difficult to read). Wants to put the intake and carb I have on current engine but it isn't going to work as I have 2bbl.
> So, I need to find out about this cam, what to do for exhaust (headers, manifold??), carb.
> Any suggestions or advice would be most helpful.
> 
> ...



Well, you are already in trouble. The cam you provided, XE250H10 comes up as a Competition Cams Chevy small block cam XE250H-10, Camshaft Part#12-230-2 Dyno Sheet. YOU DON'T WANT A CHEVY GUY SELECTING PARTS FOR A PONTIAC, period.

For a "street friendly" engine, you want to drop your compression down to 9.0-9.5. This may mean dished pistons, not flat tops. You want to get the "squish" in the .040" - .045", and I'd go with .045" with forged pistons as I did on my 455. Several ways to do this, but this is important to control detonation.

The cam is all wrong for your engine. You DO NOT want a 110 Lobe Separation angle unless you plan on running under 9.0 compression. The 110LSA typically builds cylinder pressure and works great with lower compression engines for that reason. Put it in a higher compression engine, and you are asking for detonation problems unless you plan on running race gas.......but you stated "street friendly" so I am assuming pump gas.

Pontiac knew what they were doing when they made cams. A good street friendly cam would be the factory "068" cam which in a 428CI made 390HP. You don't need a lot of valve lift as Pontiac stock heads don't flow much beyond .400" lift, that's why they work so well at lower RPM's and have all their torque. Sure you can go more, but not too much on stock heads. 

GET a set of forged connecting rods to replace the stock cast rods. The price is slightly more than if you were to have your cast rods resized and fitted with better ARP bolts. The set is $288 at Butler. Butler Performance - Pontiac Connecting Rods

I suggest you might want to search the forums as engine cam choices, exhaust choices, engine builds, etc. have been covered many times. Do not have your engine rebuilt UNTIL you have some knowledge of what you may want, or don't want. You especially don't want to build it like a small block Chevy. :nonod:

Knowledge is Power. :thumbsup:


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## beer guy (Oct 22, 2014)

*Wow!*

Pontiac Jim thanks very much for the info. I am glad my engine guy has not started on the job yet. We obviously have some more to discuss. 
Where the heck did you learn so much!?


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## maktope (May 22, 2013)

As Jim said. My 428 had the 64 heads 68 cam. Originally ra 4 exhaust. Now where I changed things I had duel carb set up and switched to headers. I was putting out 380 horse at the wheels. And at the time used for my daily driver. It was a great motor. It's now in my garage as I look for a car for my wife. As soon as I finish mine of course.


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## oldskool (Apr 26, 2015)

Yeah, PJ gave some very good advice. Flat top pistons and 72cc heads, combined with an XE steep ramp cam, is a sure recipe for disaster ! 

Another way to reduce compression is to use flat pistons with later heads, like the plentiful and cheap 6x-8's. At 101cc and .005 deck height, with 3.8cc valve reliefs and .036 x 4.160 Cometic head gaskets, a .030 over 428 will have aprox 8.78 SCR. This should be super safe with pump gas.

Compression Ratio Calculator - Wallace Racing

Then if you wanna increase the SCR slightly, you can have some taken off the heads. 98cc heads will get the SCR up to about 8.99. Or you can cut the heads to 94cc either with the 6x-8's or uncut 6x-4's, and bump the SCR up to about 9.29. That's plenty for today's bad pump gas. 

At 8.78 SCR you could probably get by with a Lunati Voodoo 262 cam. They increase cylinder pressure for more of what's called dynamic compression. But, if you go with around 9:1 or slightly higher SCR, a cam with more advertised duration would probably be better. A Summit 2801 would be a good cam. It's sorta like an 068 factory cam, with a bit more lift. 

Another advantage to using the 6x heads is that they have hardened valve seats, for use with unleaded gas. The early heads do not. For lots of driving, many top engine builders say you need to have hardened seats installed in the older heads. With the 72cc heads you'll also need dish pistons. As mentioned, the #64 heads will work. But they were a 1 year only 455 head, which are not that easy to find, sometimes. And, they will push the SCR up to well over 9.5:1.

There are several ways to go about it. The main thing is to keep your compression below 9.5:1, and don't use a steep ramp cam if you have close to 9:1 or over. Detonation with pump gas is a common problem, and can kill an engine. 

AUTO TEC SMALL BLOCK PONTIAC - 400/428/455 FLAT TOP PISTONS ? Shanon's Engineering Inc.

Cometic Gaskets C5711-036, Cometic Pontiac Cylinder Head Gaskets | Cometic Gaskets

Racing Series 4340 Steel H-Beam Rods, Pontiac V8, 6.625" - Competition Products

https://www.lunatipower.com/Product.aspx?id=1775&gid=287

http://www.summitracing.com/parts/sum-k2801


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## PontiacJim (Dec 29, 2012)

beer guy said:


> Pontiac Jim thanks very much for the info. I am glad my engine guy has not started on the job yet. We obviously have some more to discuss.
> Where the heck did you learn so much!?



I'm just an old car nut. :thumbsup: Horsepower and speed has always been an interest and it doesn't matter if it is a Ford Model T 4-cyl all souped up or a Top Fuel dragster. I do a ton of reading of all kinds and have a small library of books from engine theory to horsepower add-ons. My oldest book is about 1910 and go up from there. Have a collection of about 400 magazines to include "the old ones" and of course my Pontiac reference library. I've owned a number of GTO's in my youth when they were cheap cars and had to improvise a lot because I never had the money to truly do anything more with them -so a learning curve of sorts as to what worked and what did not. Owned a few other Pontiacs as did my younger brother. Then I've owned many other older type cars and always wheeled & dealed in old car parts looking to make a few dollars to put into my ride at the time.

I am no expert and there are others more qualified than me who bring in their input as I hope I do. It's what makes the forums a good read and hopefully some good info that guides others......or makes them at least think about it. Not every question can be answered, but I think we try. I am also willing to learn from others and their experiences which aides me in my present car project. With the prices of car parts when it comes to rebuilding or modifying your ride, I hate to throw my money away or be disappointed in the parts, or combination there of, and wish I had done something differently. :banghead:

We all have our idea of what we want our car to be or do, from stock to tire shredder, and once you have your car defined as to what you envision it to be, then the easier it is to set into motion a plan to get you there. :yesnod:


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## beer guy (Oct 22, 2014)

*Finally some progress!*

Well, tomorrow marks some progress on my 66! The old engine (non original 350) is going and a fresh rebuilt 428 is going in. Also, finally found out more info on what the car has in it currently.
Front disc brakes were added.
Has a solid TH400 tranny
12 bolt rear differential with posi and 3.08 gearing.
Rad is screwed but is getting recored.
Frame rock solid
Some weak areas of brake lines
4 barrel carb (not sure which make)
Edelbrok intake

Should be driving her in about 10 days...knock on wood.

Can't tell you how excited I am. feels like Christmas when I was a kid!!!


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## Joe'sToy (Mar 9, 2012)

Beer Guy,

If the weather is warm and dry this weekend, we can meet up and go over what I did with my '65.

I have ceramic headers, Tri-power, a four speed and 3.08 gear in the rear. I'm putting her in winter storage next week, so won't be back out till next April.

You have my email, so drop me a line if you want.

Joe.


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