The Stovebolt Site Forums The Shop Area Engine Shop 1954 235 tune-up advice needed

I finally got around to adjusting the valves, timing, and the fuel mixture on my newly rebuilt 1954 235 (~1000 mi since rebuild). I really was reluctant to mess with anything as it ran so well. I drove the truck for about an hour and came home and quickly set the valves. Most valve gaps were okay with only a few having too wide of a gap. I adjusted the valves 0.008 intake and 0.020 exhaust.

Below is an image of the plugs.

[img]http://www.surfacezero.com/g503/data/3176/medium/IMG_7966.JPG[/img]Cylinder one is on right and six on left. I don't have much experience with old engines, does the coloration look okay? All were gapped to 0.035.

I sourced a vintage vacuum gauge to set the timing and fuel mixture. Before disturbing the timing, I checked the marks with a timing light and it had been set to 5BTDC. With the vacuum guage installed, I got a maximum reading of 20.5 inches of Hg after correcting for elevation. When checking with the timing light, the flywheel markings are much more advanced (most likely somewhere 10BTDC based on the estimated distance from UIC and the bb at 5BTDC). Is it okay to run a 235 with timing advanced this much? Is the final test for timing based on trial and error with pinging being the indicator of too much advance?

[img]http://www.surfacezero.com/g503/data/3176/medium/IMG_7963.JPG[/img]My "new" $11 USA made vacuum gauge. Never set timing or fuel mixture with a vacuum guage before...kind of neat.

Any critiques,recommendations or advice are welcome. I also want to thank the collective knowledge base on stovebolt for providing so much useful information.

Paul

Plugs look good, no need to do much else. As long as the truck starts and runs fine, the actual time setting doesn't really matter. Being advanced is good, fuel mileage will be better this way. Todays fuels are better then those of fifty years ago even with the corn added, so timing settings don't really apply anymore.

Drive it awhile and see what the fuel mileage does and how it acts when the weather gets hots, you may find it's just right, or needs a little tweaks.

Joe

Paul,

Good job - good/clear description.

I set my valves at .006/intake and .016/exhaust (for normal driving).

I do not know if 10 BTDC is too far advanced. I simply use the vacuum setting technique and go with the setting.

The "pinging" technique is as good, or maybe better, technique.

Using the vacuum gauge for carburetor and timing settings makes tune-ups a piece-of-cake.

The only other setting to check is the points gap.

Congratulations,

"Reading" plugs with modern fuel...is hard. A bit of discoloration is all you will see, most of the time. Some "old" rules still apply. Wet? Black? Too rich. White and dusty...has any one seen this in the last few years? Too lean. The Vacuum gauge works well. The "Ping" test and adjustment works too. These are not fussy motors. We complain, and obsess over all the stuff any way. It makes us happy.

Can someone point me in the right direction as to how to use a vacuum gauge to adjust fuel mixture and timing? is there a tutorial somewhere?

I have reason to believe that my 216 may be running a rich.

Justin, Most carbs are set with the mixture screw at 1 1/2 turns out from a soft close. Don't twist it tight, just seat it in the housing and back it out 1 1/2 turns. The vacuum gauge won't show much when setting the mixture, you can get just as close by ear and feel. The engine should smooth out when you are close.

The vacuum gauge really helps when setting timing, but once its set, you might need to tweak the mixture again along with the idle speed. I usually set all three at the same time and fine tune them till it feels right.

High vacuum, good idle speed, starts right up, and doesn't burn your eye's, thats a good tune up!

The vacuum gauge is quite useful and easy in setting carburetor mixture ("Idling Adjustment", as described in the 1954 Truck Shop Manual).

Good description at Maybellene's link:

"Carb Adjustments

To adjust the carb, start by leaning out one of the mixture screws (turn in) until the gauge as well as the engine begins to shudder. Next bring the screw back towards rich (turn out), while watching the gauge. Stop adjusting when the gauge reaches it's highest reading. Then do the same process for the other mixture screw. After each adjustment is made, reset your idle speed.

Small adjustments are best, and in fact "optimum" carb settings on the vacuum gauge (highest reading) is usually richer than it needs to be. In other words, once the highest reading is reached, back-off (or lean) the adjustment approximately 1/4 turn in. You may have to repeat the process a few times to get optimum results, but it's worth the time and effort. "


my simple-minded vacuum-gauge tuning techniques

I will try this "modification" of the vacuum-gauge timing-technique: "Then retard the timing until the vacuum gauge reading drops slightly, approximately one half to one inch."

I get good gas mileage and good performance.

Tim, do you have to disconnect and plug the vacuum advance on the distributor when setting the timing with a vacuum gauge? I've never used this timing technique but am looking forward to trying it.

Thanks,

Matt

I have a 53 235 with hydraulic lifters. I cannot make it ping under load no matter where I set the timing. Is pinging masked by the action of the hydraulic lifters?
Carl

Thanks for the supportive comments and input. I took the truck for a drive timed as stated (approximately 10BTDC) and it ran great, no pinging that I could hear. Lots more power than before. I did notice that the truck was a little more difficult to start when hot though (it was siting on a steep hill facing downward...perhaps that was a factor?). I suppose this is an opportunity for additional "tinkering"...darn I will have to drive the truck more. Oh, I forgot to mention in my original description, I did check to see that the points were set to 0.016. How long to points last, and how does one know when they are no longer serviceable? Can/should points be filed during maintenance inspections?

Oh and you guys looking to time an engine with a vacuum guage...it is fun and inexpensive gauges can be found on ebay.

Thanks again,

Paul

What wears most on the points is the rubbing block. As it wears the point gap changes. Another wear spot is the contact surfaces. They will deteriorate over time which also changes the gap. Regular engine operation is good to keep the point contacts from corroding which can get to the point where they don't conduct.
I have a point burnishing tool but only use it when the points don't conduct. If I do feel the need to clean a working set of contacts I'll drag a piece of stout paper through the closed contacts a couple times. The spring tension is enough force to clean them up. If theres a ridge or dish worn in the contacts replace them. The burnishing tool can clean them up enough to get you home.
Spring tension can also wear but that takes along time.

I've got some point/condenser engines that haven't had their points changed in over 5 years. I check the gap at every oil change and adjust as necessary but as long as they hold their gap fairly well and the dwell is within spec I'll run 'em until they start giving trouble, i.e. need constant adjustment, intermittent ignition problems, worn contact surfaces, etc.

Plugs are another story as they live in a very hostile environment and get checked more often and either cleaned/changed as necessary.

I like the vacuum method for setting the carbs and also use it for timing but I'm getting to where I like setting the timing via max advance at 3K rpm. If you have an adjustable timing light, set TDC to 35 degrees advanced with vacuum disconnected and plugged. With the vacuum connected it may read near 40 degrees at 3K rpm.
With this method you will more likely read a lot higher idle advance which is fine. But if the engine pings under load going up hill you may need to back it off a little.

Oddly, my stock 49 216's timing is just about spot on the BB when I use both the vacuum or max rpm method. My 54 235 is another story.....

Anyways, with these old engines that are either modified or bored or with different carb(s), exhausts etc, just another option/opinion to give them the coon tune

Dave

Matt,

No

Thanks guys.

From the consensus it sounds as though that setting timing with todays higher octane fuel is not as "cookbook" as adjusting to the manual specifications. So it looks like I will hunt for a advanced timing position that is a happy median between highest stable vacuum, presence of pinging, and difficulty in starting. I thought I read somewhere on here that too much advance timing can be harmful to the valves...is this true?

Dave, my gut reaction was to pull a piece of xerox paper through the points to knock the oxidation off of the contact portion similar as with voltage regulator points. Somewhere in my gray matter I recall that copy paper is equivalent to approximately 1000 grit sandpaper. The presence of contact point files sort of had me second guessing. Thanks for the intel.

Paul

Not to hijack this but 52Carl did ask if hydraulic lifters would make a difference with PINGing. My pointy head says(opinion) no. But then I don't know much about the 54 235. Is this the last of the babbitt rod engines? What is the compression on one of these? Still, I would think if the ignition is advanced, the engine will PING. Old school ideas on points(what I was taught for emergency fixing): A book of matches, the cover will gap the points, the strike strip will clean the contacts, and if you have the cellophane wrapper(from those evil cigarette packs) with a rubber band you can set just when the points open. Copy paper will burnish the contacts, so will the cover from the matches. And last but not least, point files work and don't leave any grit behind.

All 235s from 1954 onwards were high pressure engines, with insert rod bearings.

The 1953 235 with Powerglide transmission (car only) was the only (and the first) 235 with insert rod bearings (and higher pressure engine lubrication).