64 Pontiac Engine Swap

I have a 1964 Lemans convertible with the original stock 215/6cyl with a Muncie 4-speed. I've been collecting parts to make the swap from the worn out and wheezy 215/6cyl to a more fun 389. The engine is a stock unit from a 64 Cat. Everything so far is from 1964 so it should be easier to narrow down the belts and pieces without too much of a mix and match issue. I'm not looking for a concourse solution, this will be a reliable driver that will probably never be finished.

I have the frame mounts, the engine mounts, the battery tray, the wiring harness and a few other misc items. The front springs were already replaced with the V8 units years ago. Still have to hunt down the carb and a radiator/mount for it.

I have a few questions for the great collective mind of the pontiac pros.
1. Since the 6cyl is based on the GM/Chevy 230(?), is the bell housing a Chevy pattern or a Pontiac BOP pattern.
2. If its a Pontiac BOP pattern will it bolt to the 389 block?
3. Can I reuse the old 6cyl flywheel on the 389? And if so, will I have any starter issues.
4. I have heard references to adjusting the shape of the Z-bar to accommodate the exhaust. Is this true? Can I modify my existing or will I have to find a replacement.
5. Anything else I might not be aware of on this swap?

The clutch went out on me and moved my time table up. I was really planning on this being the winter project ...in a couple of years. Oh well, rebuilding the steering can wait I guess.

Thanks in advance.
Jim

 

The 6 cylinder had the Chevy pattern. The 2 -speed automatics were multi-pattern .
You probably have a Chevy bellhousing. You need a GTO type bell.
Most 64 389's had the starter holes in the block. You will need them, one way or the other, to bolt up a GTO/Tempest type starter.
The flexplate has to come from a V8 Pontiac.
The exhaust should clear the clutch eq. shaft unless you are using headers.

Hope you have a bigger radiator.

 

Although Pontiac adopted what later came to be know as the B O P C corporate bell housing pattern in 1961, if you do not have a block set up for the block mounted starter you will need a bell with that pattern with provisions to mount the starter. As bell housings for a block with starter mount provisions are generally far more plentiful, not having one of these will probably complicate the search.

If you do indeed have one of the engines made in 64 with block mounted starter provisions (GP and GTO most likely, but possible in the other lines, too), just about any of the aluminum bells common to most (if not all 64s) and all 65 up Pontiacs up to the end of standard (326 350 389 400 421 428 455) Pontiac V8 production (around 1978 or so) made to work with a block mounted starter should work for you. I had a big car and it used a bolt on plate to put the ball mount in the right place for the clutch linkage cross shaft. You might have to modify and/or build what you need depending on the bell you find. The shaft itself might also need it's length "adjusted" for the V8.

Possible, but not likely the six will have a heavy enough clutch (or a 10.5 or 11 inch for that matter) suitable to transfer to a torque monster like a Pontiac V8.

Food for thought; my neighbor's OHC Sprint (produced 66 to 69) motor appears to have a bell the same as the V8. Probably harder to find than an actual V8 bell, though.

All REAL Pontiac V8s with a block mounted starter use a neutral balance flywheel with the same ring gear regardless of PP/disc (10.5 or 11) size and take the same starter. Totally incompatible (ANY Pontiac V8 for that matter) with the one for the Chevy based six cylinder.

Using the correct manifolds for the Tempest/Lemans/GTO chassis will allow "off the shelf" head pipes made to clear things like clutch linkage.

Is the transmission is really a Muncie, or is it the much weaker sister Saginaw? If the torque of a healthy Pontiac V8 can make short work of a Muncie, think what it will do to a Saginaw (or early BW T10 for that matter).

Remember too, production 61 to 64 Pontiac used heads compatible only with production intake manifolds from 61 to 64. 65 and later heads and manifolds all interchange with each other regardless of year if you take into consideration possible port mismatch. This includes the 67 and later heads with 2.11 intakes and all heads up to and including RA IV, if you remember to flycut the pistons in 66 down engines for valve clearance of the later heads.

Any exuberant use of the torque produced by a Pontiac V8 will SEVERELY shorten the service life of the rear axle, especially one originally behind an anemic six.
Case in point: After replacing two stock 10 bolt rear ends (both 3.55 ratio with limited slip) in my GTO in three weeks, I put a 65 Chev 12 bolt posi in (3.55 ratio also). A short time later I got to watch a 12 X 15 Ansen Sprint with N50 15 Mickey Thompson tire attached and axle flange still bolted on, rolling past my drivers door across an intersection. As it turned out to be mine, my embarrassment severely curbed my enthusiasm for abrupt clutch engagements from a standing start for a while (a short while, almost as short as the time needed to find another axle shaft and stuff it in, you know how it is to be young and dumb).

 

You guys are fantastic. I can't believe the amount of info in such a short time.

I guess its time to chuck the 215 and make the swap. The 389 is gonna be pretty stock and tame for a while while I work out all the bugs in the chassis so I can eventually step up to something a little more fun. Hopefully no parts falling off this soon.

 

In other words, except for the frame/motor mounts, I'm already set up for a small block Chevy? As much as I'd like the keep it all original Pontiac, it would be easier to go the SBC route, at least temporarily. The 389 still needs to be rebuilt and I actually have a running sbc...er, I mean a "corporate" engine waiting for a home. Either way, I'd rather not put any more $$ into the 6.