VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 Tune up Info.

I read the tune up books and specs, but I was wondering, for long highway trips;

Spark plug gap ?

Timing set at ?

What kind of milage should I expect on the highway ?**

I was also wondering, if there's any thing special I should pay attention to, tune up or preparation wise for a long trip ?

Engine is a stock 216, stock carb, .30 over bore, balanced, split exh. manf. w/11,000 miles since complete overhaul. 3 speed w/Stock rear end gears.

Car: Special Deluxe Coupe, Stock.

Thanks
Michael41

** Be sure to figure in that I'm not as skinny as I was at one time.

Michael41,
I just completed a 205 mile trip in a 1940 2Dr town sedan Special Deluxe, 216 all stock, cruised at 53-55 and got right at 20 mpg. Tuned per the manual. Picture in profile.

Set timing up to 10 degrees advanced.Follow manual instructions.Set octane selector at base of distributor to the center mark or zero.Set timing (with light) to the specified pointer on the flywheel ball.The turn octane selector as far towards advance (A) as you can with out causing the engine to ping at full throttle.(as per shop and owners manual).With todays high octane regular (85 in Colorado) (87 in the low lands) I doubt if the engine will ever ping.If being advanced that far causes the engine to turn over slow when hot or run a little "bucky" on the road retard the timing a little ON THE OCTANE SELECTOR....That was the purpose of the octane selector, it allowed the owner to set the timing as advanced as possible according to the octane of the gas he was using.In 1941 premeium was about 80 octane (by todays rating method) and regular about 75.Unlike today the octane could vary from brand to brand and location to location.The octane was not shown on the pump and you were at the station owners mercy.The octane selector allows you to play with the timing with out losing the correct setting.
In 1951 I drove my 1941 coupe to Colorado, to the farthest sowth west area,back up thru the Black Hills...3900 miles in 9 days,, at between 60 and 65 MPH and averaged 18 MPG.That includes going up Pikes Peak and Mount Evans and the Million Dollar highway north of Durango.In the 50 MPH range you should average around 20MPG.
One warning , a tip from a local that was given me on this site.Most of the 85 octane gas in Colorado contains a high amount of Ethanol and will cause vapor lock problems when climbing to higher elevations.The content is listed on the pump...go to their mid grade if the Ethanol is listed for the low grade on the pump.
Other than that a lower octane gas can be used at higher elevations due to the reduced oxygen content of the air....Also your car will have a very noticable power loss.
Back in the olden days some flat head cars offered a high compression cylinder head option for high altitudes to increase the diminshed power...Also some makes offered a lower rear axle ratio for mountains....like Pontiac and Olds offered a 4.55 ratio in place of their normal 4.1 and 4.3.(a 4.78 in the earlier-mid '30's) and every one thinks a 4.11 is bad.

Gene: Just drove 200 miles from VA to PA this past weekend in my 39 Mstr Dlx (after fixing the brakes!) with a stock 216, 3spd, and rear. Drove between 50 and 60 mph with the occasional traffic light on Rt 301 in MD. Avergaed about 14.5 mpg using regular. Normal for the stock Mstr Dix stock rear? Car did seem a bit "rough" at the higher speeds (bit of a vibration).

We drove our 53 2door sedan on the SST9 in Beaumont from Wed thru Saturday afternoon for 347 passport miles plus all the around town miles for a grand total of 425 total miles, usually at speeds of 40-50 and to 60 on the freeways and catching up to the four and early sixes that went out first. We had backseat passangers two days of touring, The standard shift 235 (replacement 53 to 55 truck engine mechanical lifters) with full pressure and inserted rods short block with a stock 235 head tuned as per the book got a solid 20 mph. It usually will get 17 to 19 when we drive it normal speeds of 55 to 65 on the 215-75-15 steel belted radials.

Ralph,The 1939 gave poorer gas mialge than a 1941 for sure.Over the years I experimented with several different carburetors on my '39 as well as other things.Milage usually ran around 16 MPG at 60 MPH at the best.In the 65 MPH range I would get 15 on a long trip.Less if I had a head wind.The greatest improvement came when I installed the 3.73 rear end.Average came up to 17 MPG at 65 to 70 and 18 below 60....not to mention the reduced engine noise.
If you are have a drumming vibration at higher speeds (very common) your drive shaft bushings are lose and its time to install a one piece Oakie bushing -- available from the Filling Station + a new U joint.
Years back several of use would travel together on long trips.Most of us had 1937-40 cars with the 4.11-4.22 rear ends and all would et about the same milage as my '39.The 1941-48 cars would average aabout 2 MPG better , inspite of them still having a 4.11 ratio.There were several carbretor and cyl. head improvements made in 1941 that increased gas milage.My '34 actually gives better milage than the '39.Years back my wife drove my '57 V8 to a meet and I drove the '34.At 55 MPH both cars got the same milage , 18 MPG.

Anyone using a lead additive for highway driving?
Mike

I don't and wouldn't if there was one.I'm glad there is no lead in the gas and additives that say they contain lead really don't.I do add MMO for certain conditions but add nothing for normal use.

Another thought...the "high altitude" cars ran a leaner mixture years ago.Usually a one or two step lean jet.Seeing the engine recieved less oxygen it could also get by on less gas.Not worth the effort changing the jet just for a visit.
Modern cars do this all thru the computer so they are running at 100 percent efficiency at all times.

I run a one step lean jet in the Rochester B and haven't seen any bad effects, just better gas milage. The sparkplugs show the right color for a correct mixture (hard to tell with unleaded gas). I don't use the original automatic choke, but use a truck carb body with the manual choke. I have found that most of the flooding and poor starting was caused by the automatic chokes, but I am biased against them anyway.

"I run a one step lean jet in the Rochester B" Have you found a source for jets, or are you soldering them shut and drilling them to a smaller size?

The 235 came with anything from a 56 thru a 59 jet-depending on application.I believe that the 1959 small truck unit had a real lean #56...will look later.Would be ideal for the Denver area.

I have found in the parts manual for 1953 -54 235 engines jets of Standard (#58) one step lean (#57) and one step rich (#59) I also have several model B, BC carbs with jets from #55 thru # 66 those above #59 in carbs for the 261 truck engines. I have a collection of jets that fit Rochester from #47 thru #59 that I picked up at swap meets and on ebay. Maybe Gene with his extensive parts manuals will know which carbs the smaller jets were produced for.

Thanks everyone. Much appreciated.
Michael41

Are the jet #'s the same as drill #'s? In other words, is a #56 jet hole the same size as a #56 drill?

Yes - and the 56 refers to .056" of an inch.

A number 56 drill is .046" in diameter so number drill size and jet opening diameter are not the same thing. As Gene stated, the 56 jet has an .056" diameter opening.

I just learned something - and I sold numbered drill bits in my tool selling days....although it was not a big seller....may be I knew it and just forgot :o

Yes Gene, the number drills reflect the wire gauge system, the larger the number the smaller the diameter of the wire or drill. I never have known why we needed four systems for sizeing twist drill bits A-Z, numbers and by inches and fractions of an inch and metric. there are probably even more.....If you buy a 115 bit set you will have plenty!

Maybe a retired GM Engineer like Oldie will elaborate.

Nope! Somethings in life are not explainable.