I have just spent the past hour reading past posts regarding the proper designation of the Pontiac 400 engine.
My main question originally was whether or not it was considered a small block or big block engine. Come to find out, I will be drawn and quartered if I call it that around Pontiac buffs! From what I read the Pontiac blocks are all the same dimensions from 326 to 455 but the internals are different, ok, cool, I can understand that. However I do have the following questions that have now arisen:
1) I thought that a 350 was a 350, no matter what car it originally came in. Are 350 Pontiac’s different from 350 Chevy’s?
2) If they are different, what is difference and how do you know if you have a Pontiac or Chevy engine?
3) Is a 400 block from 1968 the same as one from 1973? Does this goes for other components too?
4) I hear a lot of talk about different heads that came on 400 cars and ratios, reliability, etc… What is the difference, which are the best, worst, where is this information. I have 6X, #8 1975 heads on a 73 block. What does all this mean? Where can I learn about the different combinations and qualities of these parts?
5) How can you tell what block you have (code locations and where to reference them, web site)?
6) Aftermarket manufactures always reference Chevy small block, big block, etc... never Pontiac engine sizes. In this arena, for ordering purposes is the 400 considered a Chevy small block (sorry for that, I have to know)?
7) I want to replace my waterpump with a high volume one, but the manufacture is referring to them as small or big block Chevy short or long, etc... What’s the difference and which applies to this car?
I know that these are a lot of questions that may be common knowledge to the seasoned Pontiac buff but I am new to these cars and need to know so I can hang with you guys and gals
A quick answer to all your questions is that Pontiac engines are as different from Chevy's as Ford's are to Chevy's. Very few parts are interchangable (maybe carbs, distributor caps, a couple of thing like that). An easy way to tell the difference is the Pontiac engine has an aluminum timing cover/water pump assembly with the fuel pump bolted to in on the right side (looking at the engine). The Chevy has a stamped steel timing cover with a water pump that sticks out away from the motor and the fuel pump is bolted to the left side (looking at the motor) of the block.
1) 350 Pontiacs ARE VERY different from 350 Chevys. As you found out, all Ponitac blocks are the same external dimensions.
2) You have a Pontiac engine if there is an "air space" under the intake manifold. That's the fastest way for a novice to tell.
3) A 400 block from 1968 is the same as one from 1973 except the locations of motor mount bolt holes. This is a long discussion. Internals are all the same. The water pump and timing cover can be different.
5) Two letter code stamped on the front of the passsenger side cylinder bank, along with the four-character date code next to the distributor hole define the size and factory rating of the motor. The date code is a letter followed by three numbers. The last number corresponds to the year, i.e 9 is 1969 or 1979.
6) Aftermarket manufactures don't have a whole lot of Ponitac stuff unless you kow where to look for it. Summit, Jegs and P.A.W. carry a lot of aftermarket Pontiac goodies.
7) Replace your waterpump with a high volume "Flow Cooler." You will have to count the bolt holes in it and make sure the one you buy has 8 or 11. 1968 has 8, 1969 and later have 11. There's a rare chance you'd need a "short" 11-bolt version from 1969. That's also along discussion. Yours SOUNDS like you need the standard 11-bolt 1969 and later IF YOU HAVE AN 11-BOLT. If you have an 8-bolt, you need a 1968.
The rest comes with 25 years of playing around with these beasts.
There are several good Pontiac engine info books out there. Jim Hand's book just came out last year - very good. Find any issue of High Performance Pontiac or Pontiac Enthusiast magazines and you will find not only most of the answers to your questions, but lots of good Pontiac engine only suppliers and places to order the books mentioned above.
...and the Pontiac distributor turns counterclockwise while Chevy's turn clockwise.
You'll also notice that your engine is crooked in the engine compartment. That's because the Pontiac engine is wider than the Chevy and the Firebird chassis was designed by Chevy (the Camaro). The engine is cocked so it clears the steering box and linkage.
68Blkbrd, the quickest , (but not always reliable) way is to check the color! baby blue or metallic blue are Pontiacs, Chevys are orange... its reliable if not re-painted...
my 400 pontiac came bright yellow (obviously re-painted! ) but the location on the block as PMI states in his 5): " Two letter code stamped on the front of the passsenger side cylinder bank, along with the four-character date code next to the distributor hole define the size and factory rating of the motor. The date code is a letter followed by three numbers. The last number corresponds to the year, i.e 9 is 1969 or 1979" is a good way to tell...
And just think I was asking those same questions in April of 2003...but it took me a year to find FGF. Prepare to be immersed in a total learning environment, powered by a lot of good natured people!
Vikki 1969 Goldenrod Yellow / black 400 convertible numbers matching
I am addicted to this site, I am on it all day at work and check it when I get the opportunity. Everyone here is really great including yourself. I want to learn everything I can about my baby that I can.
Anything that you all have to offer is greatly appreciated. This is an in-valuable resource. Thanks
I know the feeling! If I'm not on the road, I have FGF open. So I'm drifting in and out about 18 hours a day.
If you have any specific questions that you haven't found the answer to, just ask.
Is that true that the engine is supposed to be cocked? I was going to replace my engine and trans mounts to see if that would straighten it out! It drives me nuts to see the car from underneath.
In a catalog, look for listings for "Pontiac 326-455". Don't assume that anything listed there will be suitable for your particular engine. An aggressive cam selected for a 350 will be mild on a 455, and a street performance cam for a 455 will be far too much for a 326, so there is much more to take into account than if it "fits".
Vikki 1969 Goldenrod Yellow / black 400 convertible numbers matching
You can also search this Tech Help site. Alot of things have been covered over the years.
Vikki, the motor is supposed to be cocked. Look at the fan shroud - the bulge for the fan is off center. I thought there was something major wrong with my car when I first got it an noticed the engine was crooked. I found out here they're all that way. The OHC's might not be.
My 'bird has a 400. I never even noticed until I had the exhaust system installed last spring. Once I saw the car from underneath it just didn't look right! It's good to know it's not something to fix.
It seems that there would be additional stresses on the front universal joint due to the geometry. But mine are still intact, plastic and all.
Vikki 1969 Goldenrod Yellow / black 400 convertible numbers matching
I agree, Vikki. I never knew they were offset either. Mines still a rolling chassis and the only other one Ive ever checked closely was my uncles 68, which has an OHC-6. But that does seem like itd cause unwanted stress.
its about 1" offfset to the pass side...you`ll see if you check center vs the nose/beak....it was done to get clearance for brak booster , I hear... Imagine how hard it is for the guys down under when converting to right hand steering!
I've seen some red ones, too! I don't get it. But, it looks better than that "original" aqua color Classic Ind. sells. I much prefer the mettalic bue/green. Next time...
I'm a hobbyist. Not a professional. Don't be hatin'!
Another quick identifier of a Pontiac engines is Plug location in relation to the exhaust manifolds. The plugs on a Pontiac are ABOVE the exhaust manifold where if headers were installed you would not have any problem getting to plugs, Chevy plugs are below where the exhaust manifolt and head meets.....if headers are installed the plugs are behind the headers instead of above them.....harder to get to....
Also the distributor can be removed without taking the intake off (it's outside the manifold,unlike chevy)
David
http://FirstGenFirebird.org/show/closeup.mv?CarID=571 If i don't get this car back on the road soon i'm gonna go postal! On a quest for FGF knowledge 1968 Pontiac Firebird Convertible 1969 Oldsmobile Cutlass "S" Convertible *Sold*
I see mention of different mounts for a 73 pontiac 400 vs a 68. I have a pontiac 400 out of a 73 catalina that I was wanting to put into my 68 convertible that orig had a 350. My question is that will this work and what problems might I run into.
I just recently put a '73 400 in my '69 that originally had a 350. I had no problems.
The blocks are exactly the same physical size, so there are no "fitment" issues.
The only thing you need to check is your motor mounts. The best way to check this is to measure the distance between the bolts on your existing motor mounts on your 350 block, and then the distance from the front of the block to the first motor mount bolt. Compare that to your new block to make sure it is a bolt-in fit.
Most mid-70's blocks (like the 73) were made to fit both the older 60's mounting locations, and the newer 70's mounting locations. You should be ok, but please double check.
)
