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1948 Pontiac Streamliner 8


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That doesn't look bad at all. Is it brass or steel? I believe it is supposed to squirt at the underside of the exhaust valve seats, so maybe that is a clue to the orientation.

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Posted (edited)

@Bloo, it’s brass and the tube itself is in fantastic shape- you’re right, only one way it can go in. There was quite a bit of crud in it. Also the head was blocked off around the back where the temp sending unit goes in. Petcock on the block didn’t flow either. Quite a bit of crud in the block. Buttoning it all back up now. 

Edited by cevensky (see edit history)
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Ok. So after I spent a couple hours flushing the block really well and slapping it all back together, I started it up. It took too much to start, so I went to look in the engine bay. There was water around the plugs from the work I did and it showed bubbles around 5/8 plugs. Tightened them down and bam, quick starts and smooth running. I took the same circuit I did the other day, with considerable improvement on the temp gauge. Holds at 180 till a long light is hit, then it’s hard to get back below 190. I’m gonna call it a day with some antifreeze and setting the timing with a light, the heat here is just unreasonable.

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Posted (edited)

Made the trip this morning to a wedding venue south of town about 25 minutes. Temp held about 190°-200° the last half of the trip and my top speed is still 53 no matter how I push it. Gonna rebuild vacuum advance next, but probably needs a little more than that in terms of the transmission.

Got kinda hot maneuvering in the parking lot after the drive, but overall I’m proud of how it handled and the drive was scenic and nice.

Got the passenger rear fender repaired, put some temporary “chrome” trim on, and got new gravel guards too. I re-covered the seats, put a headliner of sorts in too. 

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Edited by cevensky (see edit history)
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Mine pops and burbles on over-run because the manifold to downpipe gasket is poor. It draws air in there and burns off. Also got one exhaust port that doesn't seal well (under moderate acceleration when cold it chatters).

You can take up a fair bit of warp in the exhaust/intake manifold with silicone window sealant, the clear stuff. It's actually rated for higher temperatures than the manifold gets...

 

Re vacuum leak, you got a dual fuel/vac pump? Diaphragm on mine had perished with age and it was drawing in a significant leak from the crank case which is inaudible. Easy way to test, undo the vacuum pipe, plug the vacuum port on the manifold (either a proper fitting from the hardware store, or a bolt or something) and then take it for a drive and see if it's better. If you cannot set the idle mixture easily and get it to idle smoothly then yes, vacuum leak. Mine will idle down to about 150-175 RPM now.

 

Mine takes about 2 miles from cold to get up to 180 in this weather (90+). In winter it was holding 170 on the gauge, the block read about 175 with the heater valve open.

Summer it'll hold 170-185 at 55-60 mph, fairly steadily.

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It'll idle all day long and hold 170-180. The fan moves far too much air, which is pretty normal for this era of vehicle.

 

You should have a bit more "get up and go" than that though. At that speed I'm doing 2600 RPM so just waning off the top of the torque curve but it'll accelerate modestly well if I squeeze the throttle open. Cruise on the flat is under 1/4 throttle at that speed. It'll hold about 12-14 inches of mercury vacuum at 60, at 35 it'll easily hold 19-21"Hg.

 

Got a timing light? Running 87 non ethanol gas mine is happiest with about 15-17° advance. 

 

Phil

Edited by PhilAndrews (see edit history)
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Posted (edited)

@PhilAndrewsthanks for the info, that's exactly the kind of stuff I need to know. After I got them surfaced, I used the Motorcraft TA31 silicone, which came highly recommended, on either side of the gaskets. It appears to be holding nicely. Plugging at the manifold is on my to-do list, but my fuel pump is also newly rebuilt, so hopefully that isn't the issue. 

 

My winter temps (and early spring) are similar to yours, as well as a similarly quick heat up in our current weather. I believe you on the fan and can't see a benefit to a six blade, but my idle temps just don't seem to be the ticket. One thing I did not do, which I should've, is check how accurate the temp sending unit and gauge are at higher temps. Other thoughts are that the engine still has not had many miles since the total overhaul and an oil change is certainly due soon.

 

As far as my speed, I am going to make sure I don't have a fuel restriction (carburetor blockage, float set too high, linkage bent, etc.). I do have a timing light, which I will break out in addition to probably just replacing/rebuilding the vacuum advance. 

Then I may try my hand at adjusting the bands on the hydramatic... I have a manual but if anyone has tools to loan or tips to share, please do!

Edited by cevensky (see edit history)
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I would be concerned that you're pushing the engine hard needlessly- if the ignition timing is way off you'll get high running temperatures, poor power/torque, bad fuel economy and erratic idle.

Get a vacuum gauge. They're fairly cheap. Hook it up and see what you get at idle, driving, deceleration etc.

It's actually a modestly good diagnostic tool.

Then check your dynamic timing with a light. For baseline, set it on the middle of the three marks.

 

Once you've fixed that, yes. Check you have good fuel delivery, mine likes to boil the fuel on a hot day when it's been sat after a run. Modern gasoline is terrible.

 

Phil

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@PhilAndrewsI set my timing with a light, a little advanced, but have wiggled around since then to see if it helped performance at all. The idle is good and acceleration is typically very smooth and even. The power and torque leave something to be desired and fuel economy isn't the best (but not yet calculated). I'm in the market for a vacuum gauge for sure!

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Re the gearbox, I set the bands on mine with it off the car, per spec in the rebuild manual.

 

Setting the rear band is easy, that's just a measurement from A to B points but the front band I made a tool from a bolt and a brass fitting- knowing the TPI of the bolt meant turning it a specific number of times to get the desired preload. You can do that by dropping both pans but it is a two person operation with the thing installed (one underneath measuring, the other up top adjusting the band bolts).

 

Never tried the "in the car" setup, which requires a tachometer to be fitted and you watch the RPM to see when the band begins to bite as it's adjusted.

 

You're still running the original 6V system, yes?

 

Phil

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Transmission feels like the revs almost always go too high for how fast I’m going and the shifting usually has to be achieved by taking my foot off the gas. Then there’s the fact that it doesn’t downshift whatsoever.

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2 hours ago, cevensky said:

Transmission feels like the revs almost always go too high for how fast I’m going and the shifting usually has to be achieved by taking my foot off the gas. Then there’s the fact that it doesn’t downshift whatsoever.

Might just be junk in the valve block and badly adjusted throttle modulator linkage. If the rods aren't set right the geometry goes all to pot and you'll not get full range or the arm moves too far for a given throttle pedal movement.

 

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That's a GPS 51 mph. Oil pressure holds about 30-35psi (30W and it needs a change). Temperature stable just under 180 on the gauge.

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(So sue me, they are useful gauges because I drive it regularly and like to keep an eye on things). That's 2200 RPM, on the flat holding a steady 15" Hg.

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Home, and idled for about 5 minutes. Oil pressure hot 15-20psi. Temperature gauge crept up a hair.

Ambient 88F, 76%rH. Round trip 19 miles.

 

The eight really does sound like you're wringing its' neck, compared to, say a V8. 

But, at light throttle mine changes 1-2 at a walking pace, 2-3 at a jog, 3-4 at about 14-15 mph.

Accelerating with regular traffic it'll change 1-2 about 6 mph, 2-3 about 15, 3-4 about 30, which is higher RPM than 55 in 4th.

It will kick 4-3 as soon as it's in 4th.

 

I think what takes the most getting used to is the first harmonic you get from the exhaust. 2000 RPM sounds like a 4-banger running at 4000- it does sound uncomfortably high revving when in fact it's not.

 

Phil

Edited by PhilAndrews (see edit history)
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Thanks @PhilAndrews, this is a wealth of information and I greatly appreciate it. I think you’re onto something with the rods being set incorrectly. I was careful to keep them in the same place through taking the linkage off and taking the engine and transmission out. 
Here’s a little peek at how the interior looks. Not professional, not great, but serviceable. I also wanted a trial run of putting headliner material up and tacking and all that. 

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Posted (edited)

Well, braintrust… don’t quite understand this one. A month ago I was doing 50+ miles in a day on the highway. Could scoot around town for errands pretty good. One day a couple weeks ago I went out to go for an errand, no easy start. Had to adjust the choke and get a bunch of gas in. I left it and took a look later. Manifold stud nuts needed tightening for sure. They shake loose quite a bit after new gaskets. Still kinda crummy, I did new plugs cause I figured it was running a bad mixture as the manifold leaked.

Still running like a kitchen sink dispos-all without constant manual choke adjustment. It can high-idle well, but after a block from home with jerking and stumbling, I turned ship quickly. It’s never really gotten that low idle. Hmm. So. I checked points, they were fine. 

Now. I have a board exam in a week, but after, the manifolds are coming off again. May go back on with no gaskets? Going to check behind valve covers. Compression test (hopefully a still-new engine will pass…). May swap points for pertronix eventually. Removing the metal wire loom from spark wires. Checking spark wires/cutting ends and redoing contacts. Should I pull the head?

I had read through some manuals and originally wanted to spend this time adjusting the throttle/transmission linkage.

Sad and confused, but not discouraged. She’s taking me on rollercoaster but so goes life with old cars.

Edited by cevensky (see edit history)
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And this is a thread I found from 2017. It prompted my weariness with the metal loom... he was having the exact same symptoms I was (prior to this). My plug wires are new (coil isn't) but that doesn't mean something hasn't happened or there isn't something funny with the loom.

@PhilAndrews, you do not run manifold gaskets, or is that something I made up?

 

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On 6/15/2021 at 5:17 PM, cevensky said:

Transmission feels like the revs almost always go too high for how fast I’m going and the shifting usually has to be achieved by taking my foot off the gas. Then there’s the fact that it doesn’t downshift whatsoever.

sounds like there's too much throttle pressure, do you have the Pontiac Hydra-Matic shop manual that covers your Pontiac ?

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@pontiac1953, I agree. I don't have that, but I have gotten some insight from the on the car adjustment manual and the car's general manual. One issue I'll run into is that I haven't been able to figure a tachometer for this 6v system... what do you use?

And of course, I need to get it to run well before I can go adjusting a throttle... so, first things first.

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2 hours ago, cevensky said:

And this is a thread I found from 2017. It prompted my weariness with the metal loom... he was having the exact same symptoms I was (prior to this). My plug wires are new (coil isn't) but that doesn't mean something hasn't happened or there isn't something funny with the loom.

@PhilAndrews, you do not run manifold gaskets, or is that something I made up?

 

Nope, your imagination! I had issues with my manifolds being bowed in the center, which I attacked with a belt sander. I run two gaskets in the middle and one on the outers. That so far has worked (sadly).

 

Sure you don't have a bad vacuum leak?

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@PhilAndrewsah ok, I knew it was something. Don’t be sad if it works!

Im not sure I don’t have a bad vacuum leak, but historically when I have, the idle air screws don’t do jack… right now they certainly do affect the idle (albeit high idle). Next Sunday I’ll be disconnecting the manifold to pump vacuum line and plugging and also plugging the wiper vacuum line at the carb.

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