389 or 400

[stoneridge]

I have a 79' firebird that came with a stock 78' 400 engine in it. After bending some valves i pulled the motor and went looking for something else. I bought a 1964 389. Which stock engine would be a better base for building a moderate street buildup . Will the 389 be able to withstand a little higher rpm's.I want to take it to the local dragstrip but also drive it around town too! Generally i will only be adding bolt on parts.
Thanks for the help
Mark

[GTP Dad]

There is no doubt that the 389 was a good engine but it was not the performance engine that the 400 became later in life. The 389 tri-power from the 64/65 GTO was strong but the 400 ram air engines far outperformed the 389. You can build the 389 into a strong engine but you may have problems finding a lot of speed products for it. The 400 on the other hand was made for a lot more years and you should be able to find parts more easily! Just my 2 cents.

[PontAddict]

Try a 421! Could be wrong, but I think it's the same engine block as the 389! Found in Buick Wildcats, Pontiac Grand Pricks, Bonnevilles.. They are a beast. Same size block as the 389 from what I remember. Also the 389 was available with "HO" high octane performance. Not to slight the 400. I'd go with the 389 and bore the crap out of it or if you can fit it the 421.. Doing some research, I think you will find not too many dissatisfied peddle pushers (at least with me!). By the way.. what did you get the 64 389 out of? 65 Pont GP (first car), 64 Bonneville (my canoe get this.. with a 4 sp auto, awesome) 67 Catalina (my lost honey) all had 389's. Want them all back. Still have parts somewhere! I also interchanged a 2 BBL for the 4 BBL and didn't really get appreciative increase in gas mileage (8 gals per mile sittin' in the driveway or peddle to the metal) Tom

Originally Posted by stoneridge

I have a 79' firebird that came with a stock 78' 400 engine in it. After bending some valves i pulled the motor and went looking for something else. I bought a 1964 389. Which stock engine would be a better base for building a moderate street buildup . Will the 389 be able to withstand a little higher rpm's.I want to take it to the local dragstrip but also drive it around town too! Generally i will only be adding bolt on parts.
Thanks for the help
Mark

[stoneridge]

I dont know what it came out of but it was a 2bbl carb , not the tri power so probably a catalina or something. Is the 389 pretty much the same as the 400 for a rpm range? Thats what i didnt like about the 400!
I couldnt twist it too hard. I used to dirt race SBC's and we used to turn 7000 with pretty much stock internals. I turned 5000 in the 400 and i ended up with bent valves!

[1999montana]

Originally Posted by stoneridge

...I couldnt twist it too hard. I used to dirt race SBC's and we used to turn 7000 with pretty much stock internals. I turned 5000 in the 400 and i ended up with bent valves!...

If you're going to rev it in the mid 6 to 7 k range, you need something stout to handle the crank and bottom end. Four bolts mains for sure. A lot of stuff happens real fast at 7k, particularly with close valve to piston tolerances.

Even a GM will fly apart if coaxed to do so.

Bent valves; - sounds like the engine has hydraulic lifters. A solid, adjustable tappet and different cam might help.

My memory is short on the 389 or 400, but I think it made most of its Torque / HP in the lower end; - 3 to 4 k range. I don't think it was designed for extended high rev situations. Chevy, on the other hand was a totally different story though.

Look at your stock rear axle ratio; - that will tell you a lot about the engine's design performance. A ratio in the 2.70's to 3.25 range indicates an engine that generates most of its torque and HP at a lower RPM. If the ratio is in the 3.5 to 4.55 range for instance, the reverse is true. Is the trans (assuming standard) close ratio or wide?

In my case years ago, I had a stock Ford 302 with hipo heads, valve springs and hipo 289 / 271 horse hydraulic cam. It would rev 7400 for short periods although it was redlined at 6200. Didn't have four bolt mains you see! Would have blown apart for sure if pushed!

.

[MrPbody]

389 is parametrically identical to 400 except the bore size. Bore a 389 .060" and you HAVE a 400. Virtually ALL the "good" performance parts made for 400 will fit 389, including the later heads.
421 is a different casting, as it has a larger main bearing diameter, similar to 428 and 455. There are no Buicks in the '60s with Pontiac engines.
The '78 400 block is fine for a "mild" build. That is, under 600 horsepower. The later blocks are a bit thinner, and therefore flimsy compared to the '70-'75 block (considered the better one).
You can make plenty of real-world power with either. 4-bolt mains are not necessary under 6,500 RPM.
First thing to do is buy Jim Hand's book "How to Build Max-performance Pontiac V8s". This is a current study of the Injun engine. It will destroy some of the mythology surrounding the Pontiac. It will also show you where to make the right changes for both power and durability.
Lastly, the mounting holes on the side of the 389 will not line up with the mounts for the '89. You will need adapters made by India Adventures, Ames Performance or Performance Years. And it that 389 is a '64 block, check to certain the starter-mounting holes are drilled in the block. '64 was the "crossover" year, and some block/transmission combos still had the starter mounted to the transmission, rather than the block, like ALL '64 GTOs and '65-later V8s.

[MrPbody]

389 is parametrically identical to 400 except the bore size. Bore a 389 .060" and you HAVE a 400. Virtually ALL the "good" performance parts made for 400 will fit 389, including the later heads.
421 is a different casting, as it has a larger main bearing diameter, similar to 428 and 455. There are no Buicks in the '60s with Pontiac engines.
The '78 400 block is fine for a "mild" build. That is, under 600 horsepower. The later blocks are a bit thinner, and therefore flimsy compared to the '70-'75 block (considered the better one).
You can make plenty of real-world power with either. 4-bolt mains are not necessary under 6,500 RPM.
First thing to do is buy Jim Hand's book "How to Build Max-performance Pontiac V8s". This is a current study of the Injun engine. It will destroy some of the mythology surrounding the Pontiac. It will also show you where to make the right changes for both power and durability.
Lastly, the mounting holes on the side of the 389 will not line up with the mounts for the '79. You will need adapters made by India Adventures, Ames Performance or Performance Years. And it that 389 is a '64 block, check to certain the starter-mounting holes are drilled in the block. '64 was the "crossover" year, and some block/transmission combos still had the starter mounted to the transmission, rather than the block, like ALL '64 GTOs and '65-later V8s.

[69GTO]

MrPBody hit the nail on the head in regards to the four bolt main blocks, properly built you can take advantage of the torque that the old ponchos put out, the 400 in my own opinion would be my choice now if 389 may be the desired year with the forged steel crank that so many people desire I don't remember the years any more, maybe MrPBody might know but I know certain years were forged steel cranks and you might have one but Ponchos are not RPMers so dont fall into the myth that allot of small block Chevys and Fords fall into and try to get RPMs in excess of 5500 anything more than that is self destructive no reason that with the right cam, heads and gears that you should be able to have a machine that is respectable. If money is no option the Rock N Roll Engineering is something that you may consider a little costly but in a nut shell what they do is take a 455 crank and turn it down to 3.75 mains so it goes into a 400 Block which pisses allot of Mopar guys off now because now you have a 440 Pontiac the strength of the 400 block with the stroke of a 455. The block will have to be clearenced for the new crank (bigger counter weights). and of course proper head selection is needed to get the desired compression ratio that you want as well.
Sorry so long and good luck

[MrPbody]

No "production" 389s had forged cranks. The 425A (389 SD) engines had a forging. VERY rare... Most were "ArmaSteel". That is, WWII armor, recycled into cast steel. Good cranks. With the 3" mains (389/400), under 750 HP, a forging is not needed. We've done some 455s with as much as 900 horsepower with the nodular iron crank. The block becomes the weak link over 650.
You will need good forged rods. We use Eagle, almost exclusively. Best for the money.
Word to the wise. Go to some of the Pontiac-specific sites (performanceyears.com, boyleworks.com (muscle cars) and classicalpontiac.com) and ask their opinion of Rock and Roll "Engineering" . Let the buyer beware.
A 440 Pontiac is a .060" over 428. It has a 4" stroke. IMO, the MOST effective race combination from factory parts.
Edelbrock and Kaufmann Racing make excellent heads for the Injun. The E-heads require a bit more exhaust system (round ports versus "D" ports). The KRE heads seem to be the better for a streeter at reasonable levels of tune. The E-head can be ported to flow more in the long run.
For racers, there's a new head coming (still in development, but well on the way) called "Tiger", sold by allpontiacs.com. Once they get their valve train issues resolved, it will change the face of GM racing, bringing Pontiac back to its rightful place at the table, smack in between SBC and BBC.
KRE also has introduced a "high port" version of a round port head. It is in the performance range with the Edelbrock, and responds to modifications very well.
A new intake is also out now, called "Tomahawk". It's a large, open-plenum that will "fit" under a T/A shaker scoop. Initial reports place it on a par with Torker (1) for power production.
The most important investment you can make for your Pontiac today, is buying Jim Hand's book "How to Build Max-performance Pontiac V8s", by SA Designs. It is a CURRENT study of the Injun engine. It dispels some myths and tells you real world changes to make to make it tougher and faster. It's target audience is the street engine crowd, not the all-out racer.

[69GTO]

Thank you for the correction MrPbody I got the stroke mixed up with the main size I would rather be corrected than giving out false information on the block dimensions again thank you and stoneridge please accept my apoligies on the information maybe these sights will help you
http://www.pontiacstreetperformance....8displace.html
http://www.pontiacstreetperformance....traingeom.html
http://www.pontiacstreetperformance....ockerArms.html

[MrPbody]

69GTO,
Not a problem. I see you like Bill Boyle's site. Me too! Best one out there!

Jim

[69GTO]

Oh yah used it many a time for head ID and Figuring copression ratios the site is very informative