1936 Packard Super Eight Vapor Lock or?

[Guest 36roadsterdave]

Hello,

Looking for some insight to identify my engine issue. '36 Super Eight, runs fine at any speed to 50 MPH. Now, we go to 60-65 MPH for 2 -3 miles and the engine shuts down, Temperature gauge buries needle. So now we open the engine compartment to cool things down for 15 minutes, engine starts, temp down to 180-90 and things are fine (did not go over 40 MPH). New water pump, using Evans coolant. Could this be vapor lock? Many thanks in advance for anyones thoughts.

[nickelroadster]

Notice the discussion on Evans in the regular forum, The Evans may not be up to the job with your car. I would still check all the other parameters such as timing, crud in the cooling system etc. Vapor lock it aint. Vapor lock is not going to cause the car to run hot.

Edited June 2, 2013 by nickelroadster
addition (see edit history)

[Guest 36roadsterdave]

Many thanks.. A moment before the engine stopped (at 60-65 MPH) I looked at the temp gauge, it it was reading about 195. It was only after the engine stopped, did the gauge bury itself. If not vapor lock, maybe this is an electrical issue??

[TexasJohn55]

Coil breakdown or sucking air into fuel stream? Hook up a timing light and drive it while watching strobe. Hook up a temporary clear fuel filter with long rubber hoses and hang it where you can watch it. That's all I got. TexasJohn

I think the suggestion about temperature was that the high temperatures might relate to inducing vapor lock, not that vapor lock caused high temperature.

Edited June 3, 2013 by TexasJohn55 (see edit history)

[Guest 36roadsterdave]

Many thanks... Will look at / test the coil. Great suggestions...

[Owen_Dyneto]

The temperature gauge continuing to rise after engine shut-down is entirely normal, you have a huge heat sink and w/o water circulation the temperature continues to rise for a while from latent heat. You mentioned a new water pump - did you check the clearance gap between the impellor and the housing? Very important!!, the larger the gap, the less the efficiency of the pump. One last thing based on my 34 Eight, it normally runs at a higher temperature (but never as hot as yours) at higher speeds, dropping back 10 mph will drop the temperature 10 degrees, more or less.

[bobcanuck]

Many thanks... Will look at / test the coil. Great suggestions...

Might it also be possible that, above a certain speed, the fins on the radiator are being blown closed?

[TexRiv_63]

What is the rear axle ratio in your car? If it's anything above 4.00 to 1 going 60 to 65 is revving the engine very high, could definitely overheat and cause vapor lock.

[Guest 36roadsterdave]

Many thanks for the advice. Gap of the water pump impeller/housing should be good. Checked the coil, coil is 14K ohms from the coil wire to the positive lead. Also, I will look into the rear differential ratio. That will certainly make a difference (car revs quite high, so the ratio may be jus that or close).

Have another question on the Super Eight engine not related to overheating. How does the timing chain receive lube?

Thans for all the interest to assist!

[Owen_Dyneto]

Unless the buyer specified something different, the rear axle ratio on your Packard is probably a 4.41/1; others available were 4.69, 5.07, or 4.06. The 4.06 was normally fitted to only the lightest cars, coupes and convertible coupes.

[Guest 36roadsterdave]

Many thanks.. My car is a Coupe/Convertible Dietrich bodied Super Eight, perhaps it may be the 4.06/1. With that said, the ratio may be too great to run at 60 +MPH

[Guest 36roadsterdave]

Thanks for the thought, not sure if that is occurring, fins are open when stopped after running and I checked the "tension" on the fins to see if they are loose in anyway, seem OK...

[Guest 36roadsterdave]

Just check with my manual, looks like my car has the 4.41/1 differential. And, new the Super 8 engine was rated at 3,200 RPM, now that is probably not near that today, so lets say, take off about 10%, and you are around 2,800 RPM. With that in mind the car is only capable of 56 MPH max (10 MPH at 494 RPM). Guess I may have been pushing things a bit..

Thanks for everyones help and thoughts:)

[Friartuck]

I think this is being over thought and that the heat and ratios are red herrings to the fundamental problem. Thus, isn't this a simple case of a fuel delivery problem as roadsterdave first suggested in the OP? At the higher engine RPM is it possible the fuel pump is not delivering the capacity leading to the engine shutdown?? A small rip in the diaphram?? While vapor lock is possible, would think that that would occur even at 40MPH--therefore dismissing it. Suggest a pressure and capacity test before exploring other avenues.

Edited June 4, 2013 by Friartuck (see edit history)

[TexasJohn55]

You may be correct, maybe he should tee into the fuel line with a pressure guage at that clear fuel filter and drive it again.

[Grimy]

I'm a Pierce guy, so I've withheld comment while waiting for you Packard guys to chime in. (But I have many friends with Packards, and I've driven them!) I can tell you that my 1934 Pierce-Arrow 8, with the identical bore and stroke (3.5 x 5) and thus displacement (385 cid), and with 4.23 gears and 700 x 17 tires (Bedford Cord, which are a bit larger than original equipment) is turning about 3,000 rpm at 60 mph--against the maximum horsepower rpm of 3,400. For the sake of my babbitt bearings (have yours been converted to inserts?), I cruise at no more than 55-58 mph although I will run it up a bit higher to pass or to get a run at a grade. I've done a couple of 1,500-mile round trips and haven't been run over yet. TexRiv_63, thanks for raising this issue, but let me explain further.

Before Packard offered overdrive (at the end of the decade), they were not high-speed cruisers. Perhaps your car has been converted to high speed diff gears from Phil Bray or someone else, in which case it's not really a problem. If you have factory diff gears and especially if you have unconverted babbitt bearings, you are risking serious and **very** costly bearing damage by cruising at 65 mph. Further, cars from the 1920s and 1930s were designed for hill-and-dale driving rather than constant cruising speed on an Interstate. That doesn't mean they can't do it--I drove my 1936 Pierce 8 from the SF Bay Area to Cleveland, solo, on I-80 in three days' driving time--but that car has factory overdrive which changes the differential ratio of 4.58 to an effective final drive ratio of 3.22 in OD, requiring only 2700 rpm at 70 mph (I cruised at 65).

Please look at the McCullough Formula for calculating rpm at various speeds in this regional CCCA publication: http://www.metroccca.org/tech_articles/tech_08_fall.pdf

I find that overheating in my 1920s and 1930s cars can usually be prevented by backing off on the engine load on a hot day, including at lower speeds as when climbing a long grade. Just don't pour the coals to it as much! With the narrow frontal aspects of these cars, there's a problem getting enough air **in** (and heat **out**) of the engine compartment. The more fuel you throw into the engine, the more heat the engine will produce. At some point the engine compartment temperatures become seriously elevated. PERHAPS that's just enough extra heat at 60-65 to cause vapor lock symptoms. That extra heat can also hasten or provoke coil breakdown and other ailments.

I urge you to determine your actual differential ratio (jack up a rear wheel, put the trans in top gear, and count the revolutions of the driveshaft to one full revolution of the off-ground wheel) and then use the Formula to determine your rpm. I strongly recommend your keep your cruising rpm below 3,000.

Please let us know the results of your tests.

Edited June 4, 2013 by Grimy
improve expression of a thought (see edit history)

[Owen_Dyneto]

Grimy, just a comment, roadsterdave's Packard should have insert bearings - the last year for babbitt bearings on Packards was 1934. But your comments agree with my experiences with my 34 Packard with 4.69 gears and 7:00x17 tires - I rarely exceed 50 mph for sustained driving. We do tend to forget that in the era of these cars, less than 50% of the nation's roads were paved and capable of sustained 65-70 mph and the cars were geared correspondingly.

[Guest 36roadsterdave]

Good morning, many thanks for the insight! I plan to look at the gearing ratio this morning and will respond on the correct ratio. Many thanks for the link to the "McCullough Formula" This is a great reference tool!

FYI, I am running an electric fuel pump, through my rebuilt mechanical. (if needed , I can install a temporary fuel pressure gauge). The metal fuel line from the mechanical pump is close to the engine block. There is a small bit of insulation in one area on the metal line, but certainly not enough.. All said, the car was restored to be period correct, but since I am not showing it, I have some flexible heat ribbon that I plan to wrap around the metal line close by the engine..

But many thanks for all of your help!

[Guest 36roadsterdave]

Again thanks for all the input on my issue. I discovered the differential ratio is 4.41:1 . (also I discovered it is stamped on the diff. cast casing).

And with all calculations, 50 MPH should be the limit and all should be fine. Many thanks again!

[Grimy]

36roadsterdave, despite the ratio stamped on the diff housing, I respectfully suggest that you verify the ratio as described in #16 for your own peace of mind, if no other reason.

Insulating the fuel line from pump to carb: Sounds like your "heat ribbon" is a product like "Cool Tape," available at performance stores. The stuff works but it looks very non-period. Here's what I do: I remove the fuel line, wrap it with Cool Tape in a spiral wind with 50% overlap, leaving about an inch at each end uncovered to allow for fittings' movement. Then I slip asphalted corrugated loom material (available at better electronics stores, NOT at Radio Shack) to hide the Cool Tape and provide a period look.

Owen_Dyneto, thanks for setting me straight on insert bearings in the late 384/385. I know the 12s in 1937 still used babbitt, and guessed (wrongly) that Packard allowed the 384/385 to expire in '36 without converting.

[Owen_Dyneto]

Actually, the Twelves went to insert rod bearings in very late 1934. The reason some folks find babbitted rods in later engines is that finding new insert bearings has been long-standing problem and some later engines when restored years ago were switched back to earlier rods so they could be babbitted, given the unavailability of new insert bearings.

[Guest 36roadsterdave]

Many thanks for the input! Yes, I did also check the ratio with rotating the rear wheel/driveshaft count. It confirmed the stamping. Grimy, I like very much your design to hide the heat tape. Will do this! Thank you!