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anybody up on the old Pontiacs? I've got a 336 with 3 2's and I want to go with more cubic inch while keeping the same front mount, bell housing and so on. Can I get 455? I've been rounding up parts... 389 block, 455 crank, 66 3x2 intake manifold, early 70's open chamber heads. I know the water flows differently on different years and cast iron front covers only fit certain years. Is there a combo that works? Anybody try this?

Thanks,
Greg

Do a search for bigbadswingdaddy and check out his posts on the subject. (This really should be in the HiPo shop forum)

You are probably going to have difficulty with the engine mounts for a 455 in a 1958 chassis.

Since you are interested in Pontiac power, there is a really good book available. 1955-1979 PONTIAC MUSCLE CAR PERFORMANCE by Pete McCarthy. Another is Pontiac V-8 Engines by Jim Hand.

Jon.

the 336 Pontiac is the stock motor. With the same bell housing and the right timing cover it should mount up the same.

You might try www.pontiacsafari.com/L1Garage/EngineID
It talks about the differences on the Pontiac engines and the change in water flow through the engines.....

John

Here is a quick early pontiac lesson.

1955-1960 pontiacs have the same rear bellhousing to engine mounts. This changed in 1961.

1960 pontiacs are not reverse cooled like 1955-1959 pontiacs. In order to have a perfect drop in replacement, 1955-1959 gmc or pontiac engine needs to be sourced.

The 1958 gmc 336 is based off the 1958 pontiac 370. The main bearings are smaller than 3 inches, and it has a shorter stroke than a 1959 336.

Find out for sure which motor you have. There are many more performance mods that can be done with a 1959.

The 455 has 3.25 inch main bearings and a 4.21 stroke. The 455 crank is not really compatible with a 389 crank due to the oversize main bearings.

Stroker cranks are available for the 1959 to 1979 pontiac 389-400 motors. A 1/2 inch stroked crank with a 0.030 over bore piston hole will make 447 inches. I believe a 0.060 overbore will make 453 inches but it has been a while since i did the math.

If stroking a 1958 pontiac block, the engine would have to be line bored for the larger 3 inch main bearings. This would be a good time to install 4 bolt caps. The machine work is not cheap.

I'm not sure about which tripower manifolds will bolt up to the engine. I know 1957-1959 manifolds will bolt up. 1957 and 1958 pontiacs used 3 small rochester 2 g carbs. 1959 to 1965 pontiacs had 1 small 2g in the middle and 2 large 2 g carbs on the ends. 1966 ppntiacs had 3 large 2 g carbs. Sometime after 1959, but before 1964 the intake manifold match up to the heads changed.

1959 pontiacs will be the easiest bolt in swap with an increase in displacement.
The timing cover will interchange between 1955-1959 pontiacs and gmc v8 motors. I used the 1958 gmc timing housing on my 1959 pontiac 389 because my truck had the rare factory power steering that bolted to the timing cover. The power steering pumps were relocated on 1959 pontiacs. Oil pans interchange between 1955-1958 pontiac and gmc v8 motors, but 1959-1979 pontiac v8 pans will not interchange with the 1955-1958 motors.

Butler performance sourced all the rotating parts for my 1959 pontiac 389 which was bored .030 and stroked to make 447 inches. I used a 1957 pontiac tripower that i had got years earlier with some other gmc parts. The stroker kit came as a ballanced kit with new rods, ross racing pistons and the stroker crank. I used a forged crank, but cast cranks are also available and cheaper. The block does have to be clearenced for the stroker crank.

My 1958 gmc flywheel had to be bored out to fit on the 1959-1979 stroker crank.

Oh yeah, the first time i opened up the trip deuces, i ripped both spring perches off the rear axle, actually tearing the the axle tubes apart. This forced me to source a stronger rear axle with posi-traction.

A few years ago, Cletis drove my truck in pleasanton california. It was loaded with about 1400 lbs of stuff in the back including a gmc 302 inline 6 on a run in stand. Cletis raced some rice rocket downtown from stoplight to stoplight. There was no problem pulling away with a 1400 lb load in the back.

The manifold to head interchange WHEN USING STOCK MANIFOLDS:

(1) 1955~1960
(2) 1961~1964
(3) 1965 - up

When using aftermarket manifolds, SOME will fit 1955~1964 by changing a couple of plugs.

Jon.

Thanks. That's a lot of good information. I'm thinking I can buy a crank with 389 size mains and the stroke of a 455. Bore the 389 .080 and use a stock 455 piston. Another issue is compression. It's going to be sky high with almost all of the Pontiac heads.
I found a pair of 114cc heads, 1973 I think. Which should put the compression at about 9.5

Let me know what you think might not work with this recipe...could save me some time and money

Thanks,
Greg

I'm skeptical of an .080" overbore.

yeah most engines only go .060 John

The 1959 389 motors are known to have thick walls. They can be punched beyond 0.100 with block filler.

A 455 has a stroke of 4.21 inches
Aftermarket stroker cranks give you 4.25 inches of stroke, or about 0.040 more. You can't exactly just choose a piston, and expect it to work.

Lets go back to the beginning.

What year pontiac block will you be running?
Do you still want it to bolt in like the stock 336?

Well...most blocks will go way more than .060 It's just not recommend to go over .060 Why would you? You just get another block, especially in the SB chevy world.

In my case I need to use a '59 389 block and I've got to get the bore to a STD 455 piston size which is 4.150 With the 389 bore of 4.0625 it actually works out to .090 over. I think (hope) there will be plenty of cylinder wall integrity. I don't know what the actually cylinder wall thickness is but I'll see if I can find out. It may be the weak link in this whole project but I think it will be fine.

If your OK with .060 over. Think of it this way, I'm only going to go another .015 cut to get .090 If you look at a .015 feeler gauge, it's not much.

Thanks for your comments - keep 'em comin'

Greg

1959

yes- bolt right in

OK!

Someone with more knowledge than me might know about Pontiac Head interchange. I believe if you use any heads other than 1955-1959, you would have to re-design the cooling system of the motor. That might require using a 1960 front timing housing. 1960 pontiac motors were side mounted in the front.
1959 motors have the side mounts cast into the block, but can use the bottom timing cover mount.

My 1959 pontiac motor has the stock 1959 heads with hardened seats for the exhaust.

I have mine built to run on 87 octane pump gas. I have a very mild cam. My engine idle is set at 500 rpm, and the truck will pull hard to 5000 rpm. After 5000, the valves seem to float a bit. My motor really takes off when you get into the secondaries above 2100 rpm.

yeah the 3 inch mains on the 389 block got me. I can't use the 455 crank. I think it's EAGLE that makes a 4.21 stoke with 3 inch mains crank. I think it is a 1960 cast iron front cover I was hoping to use.

bigbadswingdaddy what is the compression ratio on your motor? It must be pretty low. ...and how did you get it so low with 68cc? heads?

About 9:1 or so.

I ordered everything from Butler Performance.

http://www.jbp-pontiac.com/

I had my machine shop cc the heads and gave that number to Butler. Ross racing pistons came out with the correct compression ratio. I think there may have been a slight dome on them.

My cam is colder than a rv spec cam. I may get a hotter cam in the future. I had several phone conversations with Butler performance. My engine build exceeded all my expectations.

I believe it is also possible to have a 455 crank ground down from 3.25 to 3 inches. The trick is in having it radiased correctly. Lots of info on the Wallace Racing site. Ad don't forget this link

http://www.pontiacpower.com/

You might look into sonic testing the block for that large overbore.

If you want a 455 crank for a 389, just buy a aftermarket crank, don't bother grinding one down. Once you grind past .030" you start to loose the hardness of the surface. I will forward this post over to my dad and uncle, they both raced '58 and '59 Pontiac's.

I also don't believe you can swap '65 or later heads to the early blocks. You will run into pushrod length problems and cooling issues.

Joe Hand

Here are a couple of pictures of my mock up.

I had not thought about push rods but they can be had/made in any length- no big deal

as far as the cooling...I'm going to run the water thru the block first ( 1960 front cover and water pump ) and then thru the heads in to the manifold/ thermostat housing. Like "normal" If I have any over heating issues I can exit the water out of the back of the heads into a spacer under the T housing



http://sdrv.ms/177vqvf

It is so EASY to drop a 455 engine/trans into a 55-59 and one doesn't have to worry about any head, crank, intake, or other fitment problems. Got all the motor and trans mounts along with the frame perches from Chassis Engineering and I'd bet it was less expensive than boring,stroking, machining, etc. IIRC CE offers the mounts in either bolt in or weld in application. If the goal is to bolt a bigger cube engine onto the factory mounts then disregard the above.

why would I do it the easy way? haha No, the 455 block won't work. I've already spent a lot of time and money to get a New Procces 5 speed Overdrive to fit the stock bell housing, clutch, mounts etc. The 455 block has a different bolt pattern

Goob, i didn't know you were running a 5 speed. I have the nv4500 in mine. If you ever come out to San Francisco, look me up. I'll let you drive my truck, and bbq some steaks.

John

How did you get the block so clean? That looks very cool, and it appears you don't need any help ! Round port heads and tri-power? Thats going to take a bit of tuning to work out, but it should be a real runner when finished.

Joe

I bead blasted everything. got to make it clean!

If you want custom pistons contact venolia, or Ross. Once you step into the custom price category, (which isn't as completely terrifying as you might imagine) The fellas statement was "we make it to the customers specifications" you can get any compression you desire, any compression height, ring/ring groove sizes, wrist pin size/retaining method. They would even make pistons that were .005" over, (.015,.025 etc) Meaning that you could get slightly smaller 455 pistons. Hence the term "custom" pistons. That way you won't have to worry about possibly overboring your engine. As it sounds like you have and will be spending plenty on this engine. Just a thought.

Not having messed around with Pontiac's much. I thought I could use all stock parts if I found the right years and combinations.
For pistons I'm going to use stock 455 hypereutectic flat tops #L2359NF as you can see in the pictures I posted. It looks like the crank is the only custom piece because of the main bearing size. It was just under 800 bucks. Haven't got far enough along yet, but it's been suggested the push rod length might be an issue too.

Push rod length will be determined by which head and the valve length. When the heads switched to open chamber, the pushrods got longer. Just be sure to mockup the heads and valve train to check for proper rocker arm to valve tip contact. Also be sure the rocker arm ball is seated on the 7/16" diameter part of the rocker stud.
Adding big block Chevrolet 7/16" rocker studs is wise move. You gain strength and more adjustment room for odd combinations of pushrod and valve length. If you use a poly-lock rocker arm nuts, you most likely will have to shorten each stud some. I setup a fixture in my cut off saw when I shorten them.

Those piston you chose are good replacement pistons. They are how ever brittle and do not like to detonate or take much abuse. When they break, they explode into lots of little bits. A forged piston is the best choice, cast would be my next choice.

Have you called Butler Performance yet? I would bet they can make up a kit for you cheaper then then you can piece it together. I have installed a few of there kits with great success. They come fully ready to install. The balance was perfect, in fact it was the smoothest engine I have ever built, and the machine work was perfect. Every bearing surface was identical in size and spot on.

Joe

Hey Joe H, is your dad the famous Jim Hand of Pontiac Performance fame? And what does he think of all this?

Yes he is, I have sent the post over to him and his brother, but haven't heard much from him. He doesn't do much work anymore, he follows along on the PY board but does get involved. We never messed with the smaller engines, 455s were all we ever built for racing. I have built a bunch of Pontiac's from 326 on up, nothing this old unless you count a '54 straight eight.

Tom Wilhite will know what to do for your engine, he does a lot work with the older stuff.
http://www.blaggbodyshopinc.com/1796788.html

Joe

Thanks Joe. Hopefully they chime in. Guess I should have asked a few more questions before I got started on this project.

Remember, I'm not building a race motor but a truck motor. I just wanted the most cubes I could get and have it look just like an original 336 on the outside. I think for 9 1/2 to 1 compression, those Speed Pro pistons are fine. Especially since 99% of the time the truck will be between 5500 and 8500 feet elevation ( much less cylinder pressure ) As far as RPM's, it will never see more than 4500 and spend most of it's life between 2200 and 3200 RPM. Haven't checked it with a GPS yet but I think 3200 RPM is about 75MPH

Thanks for the input guys. Keep it coming. Hopefully I'm not painting myself into a corner.

Greg

The heads are nice but not really the best for application. The do not flow air as you think they would. A stock set of 6X-4's would be a better choice, they have better designed runners to keep air flow at a high speed, which as you know, fills the cylinders better and gives a much better throttle feel.

Depending on your casting number, the round port heads have 71cc chambers or 111cc chambers. 71cc on a 455 will give about 10.75 t0 1 compression where the 111's put it in the low 8 to 1 range. Most 6X-4 are 94 to 96cc which puts you in the low 9 to 1 ratio. Even 4x heads can be made to work, but they came in a few cc ranges also. Look for heads off a late 350 for the smallest cc's or the high output late 400's. 455's never had any compression other then then 1970 #64 heads, they were 87 cc's and worked very well.

Don't lower the pistons in the bore to adjust compression, that really messes up the quench area (power loss). Adding a dome to raise compression is OK, or opening up the chamber some. You can only gain a few cc's in the chamber area and still have it work right. Milling the head surface will raise compression, but again only a few cc's.

Joe

I already have the heads I'm going to use. The heads I have are #197. I wasn't after the big ports and valves but I was after the 111cc combustion chambers ( mine are now 114cc ) My research says these heads are off of a 1971 Ram Air IV 455

http://www.firebirdnest.com/index.php/15-2ndgen/transam/4-1971transam

This motor, with these heads was 8.4 to 1 I think the stock piston was a 34cc dish. My pistons, flat tops with four valve reliefs should give me around 9 or 9 1/2 to 1. I haven't done the math or checked the piston/deck yet. I don't think compression ratio will be a problem. But, something else...yeah maybe

Which tripower manifold are you going to attempt to run?

With all due respect, at your altitude, and with your compression, a 455 and those heads; I would NOT want to be the guy that tried to tune it!!!

Jon.

Your compression is still only around 8 to 1 or 8.25 to 1 at the most.

.http://www.wallaceracing.com/cratio0001.htm

I been around these for years and know you can not pick up compression so easily. Swapping pistons or gasket thickness will or get you a cc or two, and a simple valve job can loose you just as much.
I just restored a '71 HO engine last fall for a 100% stock, numbers matching Trans Am, and I can tell you for a fact, it did not have dished pistons. Pontiac used four valve relief flat tops.

As Jon pointed out, tuning a tri-power is tough, even tougher on a 455. Unless yours uses the larger center carb, I wouldn't even attempt it. Dad tried for a couple of years to get one working and never could, and tuning is what he loved to do. The Quadra-jet will run circles around the tri-power, thats why GM went to them.

Joe

Just a comment:

Tuning ANY single carburetor to run WELL at both 5500 and 8500 feet is going to be exceptionally difficult, if possible at all.

As a general rule (remember that "general rules" were made to be broken by us privates ) single carburetor calibration would be along the lines of:

Sea level to 4000 feet - standard calibration
4001 to 6000 feet - 1 size lean calibration
6001 to 7000 feet - 2 sizes lean calibration
7001 and up - 3 sizes lean

This gets even more complex when one adds an unknown quantity of ethanol to the fuel.

(Opinion, others may differ) The easiest way to approach this issue would be either:

(A) A single Carter AFB 750 CFM carburetor part number 4760s, modified with Pontiac profile rods, jets, springs and auxiliary air valve.

OR if you like multiple carburetors:

(B) Two Carter AFB 625 CFM carburetors part number 4759s, modified with Pontiac profile rods, jets, springs, and auxiliary air valves.

The reason for using the Carter AFB's is simple. One can dial in the carburetor(s) at the altitude where the truck lives, and then acquire custom rods to change as one drives to different altitudes. The rods may be changed without removing the carburetor or even removing the top. To prove a point, I once changed a pair of rods on one of the AFB's on my shop truck with the engine running. I don't recommend this practice, and only did it to prove how easy it was to change the rods.

As Joe mentioned, going to be virtually impossible to dial in a tripower on a 455 unless you have the 1966 manifold with the large center. Even so, the easiest way (and the least expensive way) to tune for multiple altitudes would be to acquire two or three center carbs, dial in each for a different altitude, then swap the carbs as needed.

Jon.

OK. Thanks for the input. You guys know more than I do which is why I'm on here asking questions and discussing issues.

I'm using a 1966 tri power which takes three 500cfm carbs. I know a single four barrel is way more efficient, easier to deal with and it's also more common than a Camaro. I just want something a little more impressive under the hood.

Lets just consider I'm going to run a single 500cfm 2bbl. I can set the linkage up so the outside carbs open at 75% throttle or, in other words -hardly ever -just for show.

8.25 to 1 would be a little low but a lot easier to deal with than too high considering a big heavy truck and pump gas.

This foolish exersise is just an attempt to keep this GMC all GMC, which means keep the motor ALL factory Pontiac parts and get more cubic inches.

The proof will be in the pudding.

One other comment:

Ironhead recognized that Joe is the son of Jim Hand. Joe is too modest to promote his Dad's book on modifying Pontiac engines, so I will promote it for him, required reading for anyone who enjoys Pontiac power.

There is an unsubstantiated rumor, that before Noah unloaded the animals from the Ark, Jim drove an old Pontiac down the gangplank . He has been making power with Pontiac for a long time!

Pete McCarthy also has an excellent book on Pontiac modification.

Jon.

"I been around these for years and know you can not pick up compression so easily. Swapping pistons or gasket thickness will or get you a cc or two, and a simple valve job can loose you just as much."

That would be good news for me. I think.

I'm using the biggest combustion chamber Pontiac has...your saying that the compression ratio will be too low. Right? and it would be difficult to get it up into the 9-9 1/2 range?

With 111 cc heads, you will not get close to 9:1, I doubt you can even get 8.5:1 using the thinnest head gaskets and true flat tops.

These are the only decent bolt on Pontiac heads that work well on a 455,

#64 1970 455 87cc,
#96 1971 400 96cc,
#7K3 1972 400 96cc,
#6X-4 1977-79 400 84-86cc,

The 1971 HO wasn't much of a engine. It had a terrible cam in it, the compression was to low, and the exhaust ports were way to big. Other then the heads, the engine was just a stock 455, in fact, every 455 made other then the super duty, used the same crankshaft, rods, and block. The last castings in '76 were weaker ( lighter ), but pretty much the same engine. Pontiac varied the compression with heads, from 10:1 down to 7.6:1.

Call Jim Butler, http://butlerperformance.com , and ask about a dome piston. You will need to buy pistons anyway, so why not spend a little more and get the compression where you want it. Explain the engine combination, altitude, and fuel availability, and see what they suggest.

If you go with a 389 or 400 cubic inch engine, you can easily get 9.5 to 9.75 :1 compression and still be with in the limits of the Tri-power. You will be amazed how well the combination will run. Dad's 1965 Catalina wagon had a 330 hp 389 tri-power engine which he won stock eliminator with 1965, and still drove it to work everyday. Hauling seven of us little snot's, it could get 14 mpg. The big cars had vacuum controlled outer carbs and the small center carb, GTO's got the mechanical linkage.

Any 72cc head from any 4 barrel Pontiac will work pretty good, they all flow about 210 cfm in stock form, even your round ports. Just look for any head with screw in rocker studs, they all had the 2.11" intake and 1.77" exhaust valves. Some heads used smaller exhaust valves and press in studs, but can be machined for performance applications. The smaller engine will save on buying a crank, as most guys throw away stock cranks and replace them with the stroker kits.
The older closed chamber heads with the 1.92" int and 1.66 exh valves had 68cc chambers and work decent ( pre 1967 ). In your application where rpm is not a factor, these old heads will work just fine and still give decent performance. The '65 - '66 GTO's ran really good with 389's and the same heads were used on the big 421 tri-power Grand Prix's. At the drag strip, dad's 389 wagon could beat the 421 cars due to wheel spin. The wagon wold hook and go, the 421s spun the tires and couldn't make up the time by the end of the track. The 389 was a real runner.

Joe