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fantastic stuff, Richard, muchos gracias,
good info, looks v. accurate, loads of juicy looking references, too... would you believe it, it's now 4.23am over here, and I'd sworn I'd turn in early tonight - my eyes won't focus properly on the page, dammit!
So I'm gonna digest it properly later in the day - if I try any longer, I'll press another wrong key and delete myself...
catch you all soonest,
'a million thanks, good luck, good luck',
Len
Len,Quote:
Originally Posted by freewheelX1
Welcome to the fun - that GMT time vs various US times will get you !!:eek:
Just for the heck of it, I dragged out my 1950 Motors Manual and looked up a '48 Pontiac. My recollection of a long time ago is that these engines were a bit "tender" in the bottom end - they have 5 main bearings, and all are of a different diameter from 2.375 in the front to 2.4975 in the rear. For a 249 cu. in displacement engine that should be OK but a long crank may have a tendency to whip.
With that being said, an awful lot of these get treated to small block Chevy's - hope you consider something along that line and build a street rod out of it.
Again, welcome, and we'll hope to keep hearing from you.
Richard, thanks a mill for this reference, what an impressive piece of detection. Sorry I was too wiped to do anything with it last night, but I've crawled all over it today. It's taking up to five minutes to download one page on this steam-driven dial-up I'm on, and I hope to finally get broadband connected this week, halley-lujahhh:3dSMILE:Quote:
Originally Posted by techinspector1
Even so, i couldn't wait, and I've got hours of reading downloaded from it, terrific.
...and, yeah, it does put turbos back on the menu, doesn't it. I'll have to go talk to some people over here over the next couple of weeks, to see if they can swing it with the insurers - you never know.:HMMM: :HMMM: :HMMM:
I knew I'd come to the right place as soon as I found the site; great to find enthusiasm matched by ability, driven by imagination:)
I'm keeping it brief tonight, 'cos I've got some serious 'kicking my butt into gear'
ahead of me, and the club's given me lots of the inspiration I've been looking for. 'Got to go out and hunt me down a workshop if i want to get anything done, so, finger out, got to get the grim stuff out of the way - place finished up and on the market, etc, etc, sure we've all been there... like putting of doing your homework when you were a kid, the feeling doesn't change, does it?
thanks for the lift, guys, speak soonly,
good luck, good luck
len
Dave, I've just lost the detailed reply I was ready to post. Here's a nutshell - must get some work done/sleep tonight! ...Thanks for the warm welcome, and thanks for the pics of your fantastic Model A, which I've printed out to mount over my mantelplace, and inspire me and remind me why I've got to get the bread and butter work done...Quote:
Originally Posted by Irelands child
Those headers - sex on a stick:cool:
Yeah, tapering crank bearings, probably gonna benefit from line-boring at some point, I can imagine that crank whipping like a jump-rope.
You're right, small-block makes sense on so many levels, though Richard's research has me thinking about propane-powered turbo/s as a possibility. I have to talk to some propane people over here in some depth.
If you guys can bear with me taking my time, it's reeally good to dig through the options with people who know what they're talking about
I'll get the hang of the time difference, hoping to get broadband in this week, going to make life sooo much easier.
Greetings to wifes65 and Mustang777; anglia pops, oh, the joy, the joy!:3dSMILE:
thanks again, back soonly, len**)
Usually Tech1 is super correct, but as I recall a turbo will put more stress on the crankshaft bearings and if that part is tender a turbo may agravate the weakness. Still several options appear feasible:
1. install a modern sound system in the car and just enjoy the resto-environment.
2. Convert to LPG without the turbo and just gve it a tune up.
3. Make some measurements on the inner fender panels and compare to the width of a Chevrolet small block.
4. Check into some shop that installs Pontiac OHC sixes into Jag roadsters and look into installing a newer Pontiac six.
5. Check into a GMC 292 OHV six as to whether you can find one and contemplate a swap for such an inline engine.
Just some ideas.
Don Shillady
Retired Scientist/teen rodder
Don, this will explain my thinking....here's what Len said up front.....
"i bought the poncho thinking i'd warm her over using the tech of the time; y'know, back in the day, with guys doing so much of their own work - as i understood it - and with the engine being in such a soft state of tune to start with, i was thinking i could make up some decent manifolds, match in more sophicated carbs, maybe a pair of beefy webers, flow the head, fit a slightly lumpier cam, find or turn down some light-weight pistons and retro-fit a decent spark system"
I'm convinced that it would be far easier and less costly to adapt a propane mixer and small turbo onto the motor and make the same power as he is talking about making in that statement. You could limit the boost to 4-5 lbs and drive it forever. And the turbo and mixer are easy to come by. Try finding a blank to turn a '48 Pontiac camshaft!!!
freewheel , I wouldn't consider that straight 8 a problem, former My father in law has one in a roadmaster that runs like a scalded dog , it produces a boatload of torque at lower rpm , and he has wound the stock motor up to 5 grand at times without any problems ( he blueprinted the block and balanced/bluprinted the rotating assy's) he has a Wcfb Carter 4 bbl on it too . its nice to cruise along in the big sled and punch it and have it accelerate smoothly and strongly . if I see him I'll see what he has to say about the turbo ( hes a mechanical engineer at Case international harvester ) but knowing him he probably will lean towards a engine driven supercharger **)
oh tech if you know the right people you can find parts for these things , more than likely they will take his cam and recut it with a smaller base circle .
as for my pick up motor its dyno pages said 517fhp @5000 and 603ftlbs @3500 this truck( 6800 pounds) is used for towing a trailer with 4:10 gears it doesn't act like they are there and my milage is in the high teens on the highway but very low in the city ( leadfoot )
Among several suggestions above, I agree with Tech1 that the turbocharger would be more gentle than any type of roots blower and I would think that if you take the engine apart for a rering/rebuild it should be possible to find someone to grind a new profile on the cam. If it were my car I would be tempted to just get it into good shape and maybe split the exhaust manifold for dual pipes and then just enjoy cruising in nostalgia.
Don Shillady
Retired Scientist/teen rodder
You could regrind the stock cam, but the point is that you wouldn't have to with a turbo. The torque grunt would come in at the same point of the rpm scale to haul that heavy boat, except there would be more of it. I suspect it would be a lot of fun to drive.
Tech1, probably so since usually the cams of those days really emphasized low rpm performance. I too have a "Motor's AUTO REPAIR Manual", copyright 1951, which covers most American cars from 1935-1951. Our new friend has not told us yet how many spark plugs are in the head of his Pontiac. There were two engines in 1948, a 239.2 cu. in. six cyl and a 248.9 cu. in. eight cyl. No torque values are given but the six was rated at 93 H.P. @ 3400 rpm and the eight was rated at 107 H.P. at 3700 rpm. Probably the H.P. peak was past the torque peak but we can use the formula:
H.P. = Torque x (rpm/5252)
to calculate the torque. For the six that would be about 144 ft. lb. at 3400 rpm and for the eight it would be about 152 ft. lb. at 3700. Since it is relatively easy to get 300 ft. lb. of torque from a SBC 350 that is a good reason to consider that option. By contrast the stock '48 Ford flathead put out about 175 ft. lb. of torque around 1900 rpm from a 239 cu. in. engine, although that fell off to about 140 ft. lb. around 3500 rpm. I don't see any mention of the rear end ratio in the Motor's Manual. I can only recall two Pontiacs from back at that time. One was the "sedan on a Woody frame" my buddy built and another was a '48 convertible. As I recall the convertible could hold up to six cheerleaders with the top down and the owner really flogged the engine, but I doubt if it could keep up with the many '41 Ford 59A flatheads of that era because the luxurious body was on the heavy side! Well, again If I had that car I would just wash and wax it and add dual pipes with chrome tips and a CD player and just enjoy cruising.
Don Shillady
RetiredScientist/teen rodder
:D :D :D :D
Thanks for the math Don.
Don if my memory serves me correctly ( it kind of been on the fritz the last few weeks ) it comes with a split manifold stock , and if you have ridden in one of these the torque is something thats unbelivable , it pulls hard but smooth kind of like a diesel with an auto , the exaust note is a little strange also . with the equal firing order on the crank throws it might be a good canidate for a turbo ,
Well I guess it is up to our new friend from the UK to send a picture or give more details about the engine. The only picture of the engine in the "Moter's Manual" shows a very primitive single carb on the middle of a long intake manifold that stretches across the side of the block with a similar long exhaust manifold with a center exit and bolted to the bottom of the intake manifold. Perhaps it was the combination of a world-wide Depression followed by WWII but it is amazing looking at the engines of the time from 1935-1951 how little they changed and how primitive the side valve engines were as well as how many companies stayed with that design. The OHV Chevie six looks downright modern compared to the many flathead engines and the only hint of present design shows up in the 1949 Cadillac 331 OHV V8 and that was rated at only 160 HP @3800 rpm. For the sake of homespun history the term "Fordillac" preceded "It's a Hemi" for automotive awe in the early 1950s. Looking at the Motor's picture of the Pontiac 8-cyl, it might not be hard to fabricate a header or split headers that would surely flow better than the stock manifold. That would be a way to improve performance without a turbo. But even with a turbo some plumbing would be necessary to adapt the exhaust flow to the turbo. Just for fun, and recalling pictures of Smokey Yunick leaning over a Hudson six, perhaps the ultimate six of that era was the 308 cu. in. side valve Hudson Hornet rated at 145 H.P. @3800 rpm (equals about 200 ft. lbs. at 3800 rpm). If the Pontiac is to be rebuilt for performance perhaps the lost art of relieving the top of the block might help, although I suspect that is very difficult to keep all the cylinders equal. Maybe with modern milling equipment that could be done in a reproducible way across all the cylinders but that sounds expensive.
Don Shillady
Retired Scientist/teen rodder
hello again guys, and thanks for all the solid feedback,
a quick few notes here before my connection crashes again...
I'm trying to get owner's manual so don't have to ask dumb questions here, still trying to get a definitive id on the engine through some other websites, though, responding to Don first; she's a flathead straight-eight, with the carb/intake/exhaust setup exactly as you describe in your posting, Don.
On the top of the head, right-hand side looking fromthe front of the car, half-way along is stamped 512121 GM2
similarly viewed, above the water pump is stamped J 138 (but smaller)
Where the numbers on the block should be for this engine i can't find anything, but what might be the screw-heads that held a metal tag to the block perhaps.
The bulk-head tag I've used to id the car as being built in '48, at the South Gate plant, having a streamliner deluxe body, production number 10412.
The plugs fitted are AC 40's, where the specs I found on the secondchancegarage website (nice site, by the way) say they should be 45's, so it seems possible I've got another 8; maybe right plugs, wrong engine, or maybe the mechanic wanted a harder/softer plug from standard, won't know 'til I've a definitive on the engine year/model.
the seller told me it's a hydramatic box, and that seems right, though he said it's a four-speed; well, i haven't had her out on the road to find out yet!
the hp ratings I've found so far agree with yourfindings, Don, and the max torque figure quoted is 190lbs.ft @ 2000rpm
if it's the stock engine, it'll be the 248.9, won't it?
Tech1, I'm still thinking about the turbo possibilities; though a small-block v8 is a really attractive option, the car's clean all over as far as I've found so far, and if I can hold off chopping engine mounts, steering/sus about just yet,
i still love the novelty value of the straight-eight engine. You guys will no doubt know the Bonneville specials of '54; with three side-draught carbs and other internal mods -hotter cam, light-weight pistons, flowed head, etc., I think they raised the hp of those concepter over 250.
I think that i'm going to have to do this project in stages, finding out what i
can get from her as I go along.
Stimpy, thanks for the encouraging noises, love to hear more about your out'laws;) roadmaster when you can.
guys, i'm still open to all the possibilities, 'specially Don's one of filling her upwith cheerleaders!:3dSMILE: thanks for the constructive input and options,
Len
freewheelx1, I could post the picture from the Motor's Manual but it would seem that you have the 249 straight eight engine. The manual says the stock compression ratio is 6.5:1 which is pretty low. Actually 190 ft. lb. of torque @ 2000 rpm is not too bad considering the Ford flathead V8 was only about 175 ft. lb. at 1900 rpm (3 3/4"stroke, not the later Merc 4" stroke). Other folks with the early Chevie six engine note the loss of a carb heater if you use headers. You can continue to research the turbo angle and I am sure Tech1 will help a lot with the details. Still with a low CR the Motor's Manual says the main bearings are the more modern insert type and hence a bit stronger than the old poured babbit bearings, so it might be possible to do a "poor boy hopup" the way a financially limited high school kid would have done in the '50s. That would be to increase the compression ratio by shaving (resurfacing, milling) the head and adding a fabricated set of headers for that neat look of two pipes out the rear. I do not know how much you can safely shave from the head but it might be in the range of 0.050" but probably not more than 0.100". On the flathead Ford V8 the heads could be shaved about 0.070" but the combustion chambers could be entirely different on the Pontiac 8 cyl. When shaving a flathead, too much is too much and two problems may emerge. Without "relieving the block" around the valves the flatter combustion chamber may actually restrict the flow of fuel-air mixture and of course you don't want the pistons hitting the underside of the head! Check with a machine shop about the limit for your head if you decide to do this but I am GUESSING that 0.050" would work. I recall a wild guy who was a driver of a GMC van employed by Howard Johnson Restaurants to taxi employees and he wanted more performance from his work machine. Between the morning pickup and the afternoon take-home he visited a local machine shop and in a matter of three hours they took off the head, milled it 0.100" and replaced it in time for him to take the waitresses home; all without the knowledge of the van owner! 0.100" is a lot to "shave" but the shape of the pockets in the GMC OHV head are different from a flathead. From a restorer point of view a shaved head might give 5 to 10 more H.P. and even a slightly better mpg value and would not show at all on the outside. Headers and dual pipes would cross the line from restorer to rodder but might add another 5 H.P. Have fun.
Don Shillady
Retired Scientist/teen rodder