Customs Engine Vote 1948 Pontiac Streamliner

I'm thinking that you have three choices: Pontiac, Pontiac or Pontiac.

Did I mention that I am biased toward Pontiac engines?

 

Myself I like to keep everything by the same maker. Pontiac deserves Pontiac. I would go with a Pontiac 400. More common, more aftermarket parts and cheaper than that straight 8. In reality though it is your car and your wallet. Do what you want and can afford. Just check around for like drivetrain configuration and get some goods and bads from those in the know. Then base it off your use as well. Dependability always plays a part. Frequent break downs tend to leave a bad taste in your mouth for that vehicle.

 

A quandary for me as not my car, a Poncho in a Poncho. A 389 or 421?

 

If the original engine is rebuildable it may not cost a small fortune. I don't know about Pontiac but other brands of flathead engine are simple and straight forward to work on and if you can find NOS parts reasonable on Ebay or get common parts like rings, bearings and gaskets from NAPA it shouldn't cost much more than a Chevy V8. Provided you do most of the work yourself.

The big expense is labor because the engine shops are not used to these motors and it takes them extra time to look up specs and figure things out, and to cut gaskets or find small parts. If you do the work you can save all that. Of course you will need to farm out machine work but if you are lucky and the bores and crank don't need trueing there will only be grinding the valves.

 

A Pontiac 350 would be easy to find and cheap, good runners are sometimes even given away because the owners are swapping in one of their bigger-cube brethren. The Pontiac V8 is unique in the sense that there is no big or small-block, all the different displacements use the same size block (same external dimensions), so a 389, 421, 428 or 455 will bolt right in place of a 350 or 326. Even uses the same intake and exhaust manifolds. (I'm not including the later short-deck 265 and 301 econo-engines here in this comparo)

You'd be surprised to see just how well even a lowly Pontiac 350 would tug your barge along. The 350 shares the same 3.75" stroke with the 389 and 400 as well as the often overlooked 326. Starts making nice torque a few hundred RPM sooner than a comparable Chevy 350 that has a 3.48" stroke.

The Poncho V8 is a damn nice engine, I'm kind of surprised that more rodders aren't using them.

 

I scarfed this photo off the HAMB ...coverage of an event in Texas somewhere..not my car.

 

Get a Caddy 472 or a 500 if you can find one at your local Pick a Part. Get the TH400 too. Cheap and lots of power. BBC is better but more dough. Pontiac 455 to keep it in the family but even more dough. Forget the straight eight, costs too much to fix.

 

bggreen30! I'm probably more qualified to advise you as to what engine to go with than anyone here. My first Pontiac was a '46 Torpedo sedan identical to yours, but a three speed. My second Pontiac was a '55 Catalina hardtop with a 389 Tri-Power and modified 4 speed Hydro. Even back then I was tired of seeing SBC 's in every street rod. My '41 coupe (my avatar) has the straight 8 from my '46 with a Muncie 4 speed and a '53 3:63 gears. I've been driving it for 45 years--the basic Pontiac engine is dependable as a rock! The only old engines that aren't dependable are when their systems are in poor condition or the mechanic was negligent . Pontiac Straight 8 speed parts are few and very rare ($$$) Mine is bored .125 ,has a Crane cam and .080 milled head, but I made the dual bank headers, 2 duce intake, and adapted a Pontiac HEI and full-flow oil filter. It runs a LOT better than stock --I can cruise at 70+ all day. It can go from 50 to 70 in 6 seconds--but its no V8. Stock it was 110 hp -- even with all the mods, I'd be lucky if it puts out 1 40 hp now. What I'm trying to tell you is, if your a mechanic and fabricator and you want a good running car thats different, build a new Straight 8 with a manual trans (T-5?) If you want plenty of reserve power, tire burning acceleration, A/C, and off the shelf speed parts : Drop in a Pontiac V8. The money you spend will work out about the same.

 

I agree with Draggin GTO , you could find any Pontiac V8 1964 and newer with an auto trans for next to nothing, and still keep your Poncho all Poncho!!!!!!!!!!

 

With the history of GMC and Pontiac a 302 jimmy would be cool but not cheap and the inline would be easyer to swap.

 

This is ancient history, but back in the '50's there were two brothers in our car club with these Ponchos and they went with the then-popular Olds Rockets for power. Pretty darn cool for the day.

 

Any PONTIAC 389-455

 

...yeah...no real choice to be made.
1. 455 Poncho
2. any other Poncho..370-389-421-428
3. 455 Buick
4. 455 Olds
5. 472-500 Cad
The Cad will be the easiest/cheapest to get, the others about equal.

And having a big-inch torque monster does not mean it should be a gas-guzzler. A lot depends on how you drive it, but it sure is fun to have mega torque available. If you think that a smaller engine is what you need then use a 326-350 ...350 Pontiac.

 

A Pontiac needs a Pontiac motor. Chevy motors belong in Chevys........

 

I have a factory rear wiper for your Pontiac, if you are interested

 

I have to agree with a Pontiac 350 or 400. With a new timing chain and gears they are pretty damned reliable and hell for easy to work on.
I've been around several OHC Pontiac sixes and Sprint sixes and while they have a great cool factor they almost always overheat on #5 cylinder before all is said and done. Parts may be harder to get now than for the flathead that is in the car also.

My 48 actually has a 74 250 "Pontiac" six in it out of a 74 Ventura. That would be an option that would probably drop right in and have more than enough room but might be a bit under powered.

 

Or just something like this, take motor and trans, maybe rear and make it drive. be quick to do and be fun.
http://sandiego.craigslist.org/nsd/cto/5026473425.html

 

I realize this is the HAMB and everyone thinks there is no such thing as too much motor, but I'll second the vote for a Pontiac 350. They really are cheap or free if you find one. There are a couple running 350 Pontiac cars on my local craigslist right now for under $1,000. You buy the car, park it next to yours, transfer everything you need, then scrap the rest. Your old motor + the donor body = a few hundred bucks scrap.
You're not trying to go racing or win shows so you sure as heck don't need a 455, 421, or nailhead Buick!
A 350 will pull that car down the road just fine.

 

I know this is not a popular opinion but guys that DRIVE their cars, usually build them on the mild side. If you want a Pontiac V8 you would probably be best off with something in the 326 - 400 cu in range in stock or near stock condition.

Yeah you got to have a 600HP motor, bullshit. Go that route and you also need new suspension, brakes, drive train, heavy duty everything and if you really use the power will most likely twist the chassis and body to oblivion.

And the big motors are not much fun for everyday driving and especially not when it comes to filling the gas tank.

There is a reason the older guys usually have the milder motors, more fun for less $$$ bucks and not wrecking parts all the time.

So my vote would be for a Pontiac V8 (or Chev if you prefer, it's all in the GM family) in stock or near stock tune, with automatic, stock suspension rebuilt and possibly disc brakes, radial tires, and tube shock absorbers.

PS you Pontiac die hards should know, Pontiac built cars with Chev engines and not just in Canada.

 

i think the ohc sprint 6 would be too underpowered. and what's wrong with the hydromatic that's in it? wouldn't that mate up to a 389 or a lot of caddy engines? as i recall, chevy and gmc put them behind sbcs back in the '50s. however you decide, that's a beautiful car!

 

The 326 would actually make more zot than the old straight 8 and should pull the old heap around just fine. Probably not going to with the winter nationals with it but it should get you to and from just fine. The down side is that how often do you actually see a 326 for sale anywhere?

350s and 400s should be plentiful I would think. And have the added caveat of being backed by a 4 gear or a T400.

WOW I just thought of it a 235 would make it traditional.

 

Let the car tell you what to put in it.
The patina on that car is killer right now.
The car looks like one from the late 50's that
a teen got from his schoolteacher spinster aunt.
Find the straight 8 that somebody is pulling out
of any Pontiac from 46 to 54. they tend to be runner drivers already.
Ring it valve it and put it in. Then drive while you look for speed parts.
I know there were some.
Just my $.02

 

The HAMB makes it sound so easy.............just bolt in a "......". Only the factory engine is bolt in. The rest will take a good bit of fabrication. A newer engine isn't going to just bolt up to the old transmission. (did someone make an adaptor? I don't know but if they did, good luck finding one).

That's not a reason to not do it though. I was never a big fan of the flat 6's. To answer an earlier question, no I would not spend good money rebuilding the old engine as good running pulled ones are cheap. (yeah, you'll have to do a little looking). You could likely find a running beater for less than a rebuild.

There are a lot of cool engine swaps that don't require a brand for brand swap. Such as a Cadillac in a model A but it doesn't make sense to put a SBC in something like this when a similar Pontiac will work as well and probably cost less. (as long as you are going to go mostly stock)

Or a mid late 50's Pontiac V8. It will be as close to bolt in as you'll find. I've seen running rusty 4 doors for less than $1000.

 

What about an early 389?

 

That's an odd duck, and I love it! I'd stick with the straight 8, and make the most of it.
That's what I did with my 4 door Fleetline 216. No regrrets! ($$$)

Split the pipes, mill the head, grind the cam, and Pertronix conversion in the distributor.
Swap the rear gears, and ease on down the roadf!

I just love this set-up (from a HAMB'er)!

 

Just today saw a '62 389 advertised, a complete running engine equipped with the Slim-Jim auto trans for $200. You can even see it run in the car before pulling it.

These Pontiac V8s are a torque and horsepower bargain, because almost nobody in the hot rod world really knows what a great, reliable and easy to work on engine they truly are.

 

Many years ago when I had a 47 Pontiac and a 53 Olds that was hit in the rear I got looking the two over and I think the 303 and hydro would have came close to bolting in,the rear mounts looked identicle but the front mount would have needed to be extended. Never got around to doing the swap as the 47 got sold and I traded the 303 for a dirt bike but if it was mine it would get a 350 to 400 pontiac unless a 472 or 500 caddy came along cheap.

 

Bumping this up, with some more eye candy.
How about this Edmunds head? (You should be so lucky!)
I repeat, though; old hop-up tricks, and a 5-3 split on the exhaust will let the neighbors know it's you, when you drive by!

 

Got a 454/400 combo in my wifes 48 streamliner more door.