EmTee Posted October 5, 2021 Share Posted October 5, 2021 I am trying to check the ignition timing on my recently acquired 1938 Century. I removed the cover from the timing hole at the back of the block and see the flywheel and ring gear. Before using my strobe, I wanted to clean and chalk the flywheel mark that aligns with the mark above the timing hole. So, I bumped the engine until the distributor rotor was pointing toward the #1 wire on the cap and looked into the timing hole expecting to see a TDC, or other marks (the shop manual mentions "ADV"). Instead, I saw nothing... Well, the figure in the shop manual shows a black hole, so I guess that's exactly what I saw until I pointed my droplight at the opening. I see the ring gear and flywheel, but even after moving the crankshaft back and forth around that point I still see no marks on the flywheel... What am I missing? Bonus question: The shop manual states the valve lash should be 0.015", but doesn't say whether that's hot or cold. I'm assuming it's measured when cold... Link to comment Share on other sites More sharing options...
Matt Harwood Posted October 5, 2021 Share Posted October 5, 2021 Here's a truly dreadful video I shot of me adjusting the timing on my '41. You can sort-of see the mark on the flywheel although I never got a very good camera angle on it. Sorry. It's there, but it doesn't look like any other mark you'd expect. And fortunately for me, someone marked it in white like you're trying to do. It's not terribly visible but if you get close to it, you should be able to spot something. Valve lash is set hot. Take it for a 30 minute drive, pull the valve cover, and start adjusting--quickly. That said, if it's quiet, my advice is to leave it alone. Mine were quiet and I decided I had to adjust them and it has never been the same since. If it ain't broke... Great car you've got, enjoy! 3 Link to comment Share on other sites More sharing options...
EmTee Posted October 5, 2021 Author Share Posted October 5, 2021 Thanks Matt - I'm going to hook up my light to a 12V battery and give it a shot tomorrow! Link to comment Share on other sites More sharing options...
Fireball8man Posted October 5, 2021 Share Posted October 5, 2021 Emtree: We also had a hard time 'seeing' the mark on the flywheel on my 1938 Buick Special. We removed the flywheel cover on the bottom and moved it by hand and marked it with a yellow colored chalk which is easier to see and locate especially when using a timing light. We used a 6-volt timing light, but we closed the garage door and turned off the garage lights to see the timming light better. This operation usually takes two (2) people in lieu of getting up and back under the vehicle multiple times. We did this after installing a new head gasket and torquing down the head. Lawrence 2 Link to comment Share on other sites More sharing options...
Ben Bruce aka First Born Posted October 5, 2021 Share Posted October 5, 2021 What Lawrence said. Except I use paint . There are two marks. One TDC, the other 4-6 degrees btdc. I was always going to try fluorescent paint . Have yet to do so. Ben 2 1 Link to comment Share on other sites More sharing options...
Gary W Posted October 5, 2021 Share Posted October 5, 2021 8 hours ago, EmTee said: Bonus question: The shop manual states the valve lash should be 0.015", but doesn't say whether that's hot or cold. I'm assuming it's measured when cold... The '37 is adjusted to .015 Hot. 1 Link to comment Share on other sites More sharing options...
Gary W Posted October 5, 2021 Share Posted October 5, 2021 9 hours ago, EmTee said: Instead, I saw nothing... Well, the figure in the shop manual shows a black hole, so I guess that's exactly what I saw until I pointed my droplight at the opening. I see the ring gear and flywheel, but even after moving the crankshaft back and forth around that point I still see no marks on the flywheel... I don't know if the '38 flywheel is like the '37, but the flywheel can be mounted in six positions, only one of which is correct. When I refurbished my 248, I made sure to attach the flywheel with the markings showing through the window when the crankshaft was at top dead center. When #1 was fully up. Easy when the motor is all apart. If you can, turn the motor so #1 is up top. Maybe use an awl to scratch a line on the flywheel through the window. then remove the flywheel cover as suggested above, rotate the engine and you'll have a mark there to paint white. Enjoy that beautiful automobile!! Truly a roadworthy car and a pleasure to drive! 1 Link to comment Share on other sites More sharing options...
MCHinson Posted October 5, 2021 Share Posted October 5, 2021 It took me a while to find the photo, but here is what you should find. My white paint mark should still be there to help you locate it. 3 1 Link to comment Share on other sites More sharing options...
EmTee Posted October 5, 2021 Author Share Posted October 5, 2021 Matt (Hinson) - thanks for the picture; I'll try to get a closer look at it today. Lawrence - Duh -- I should have thought of removing the lower flywheel cover! That'll allow me to verify Matt's mark is still visible, or re-mark it if it's not. Thanks again to all who responded; this Buick forum community is really outstanding! 1 Link to comment Share on other sites More sharing options...
DonMicheletti Posted October 5, 2021 Share Posted October 5, 2021 My '38 Roadmasters flywheel was on wrong and the timing marks were way off. I ended up just timing it by ear until I did a clutch job and fixed that issue then. When I was young we didnt have any of that "fancy" timing light stuff - we timed by ear. It actually works very well if you know what you are doing. Time By ear: After running, advance the distributor until the engine pings under load, then retard until it doesnt. Or, advance until it pings under load and then retard until it doesnt. 1 1 Link to comment Share on other sites More sharing options...
EmTee Posted October 6, 2021 Author Share Posted October 6, 2021 I dropped the clutch inspection cover today and found the markings. I cleaned them and added some white paint to highlight the "UDC" and 6* "ADV" marks. The markings are as shown in the photo above and were in the window as they should be -- I just didn't see them because I didn't know what I was looking for and the engraving is very light. 4 1 Link to comment Share on other sites More sharing options...
EmTee Posted October 7, 2021 Author Share Posted October 7, 2021 (edited) I hooked up my timing light yesterday and checked the ignition timing. I connected the light to my 12V boat battery (since it's now in winter storage) and loosened the distributor hold-down bolts enough to just allow me to rotate the distributor by hand. With the engine running I set the idle to 400 RPM as called for in the shop manual. I didn't see the timing mark in the window, so I slowly turned the distributor CCW and the mark came into view and I was able to align it with the one above the window. Note that when I began, the distributor was turned almost as far CW (advanced) as the adjuster slots would allow. In fact, before I started I was wondering whether the distributor might be installed one tooth 'off'. Once I aligned the marks (6* ADV) the distributor was about in the middle of the adjustment slot and the Octane Selector was slightly off center to the 'Low' side. I loosened the pointer set screw and set the Octane Selector to the center of its scale. What a difference! Whereas the engine previously labored to start, to the point where I sometimes had to walk away for a few minutes before trying again, now it lights-off right away. With the timing set I checked the dwell, which is 29*. The book calls for 31*, but does say up to 2* less is allowable for new breaker points that haven't 'run-in' yet. So, I'm calling that good. I raised the idle to 600, which seemed to be high enough that I'm not likely to stall when starting off but not too high. The other thing I had done the day before was check the valve lash with the engine OFF and COLD. With the spark plugs removed, I rolled the motor through the firing order checking the intake and exhaust valve lash at each cylinder with the piston at TDC on its power stroke. Recall that the specified lash is 0.015" (Hot). (Which I discovered is actually embossed on the spark plug cover.) Measurements were as follows: 1E=0.011, 1I=0.013, 6E=0.008, 6I=0.0.14, 2E=0.007, 2I=0.000, 5E=0.014, 5I=0.011, 8E=XXX, 8I=XXX, 3E=0.012, 3I=0.012, 7E=0.008, 7I=0.009, 4E=0.006, 4I=0.004. (I screwed up measurement of cylinder #8.) After measuring, I reset each valve to 0.019" (as this was cold, with engine not running) and verified by ensuring a 0.20" gauge would not fit. When I started the engine to set the timing, the valves were definitely louder than before (as they were practically silent before), but really not bad. Based on the cold measurements I observed I'm really inclined to run it this way for awhile before re-checking the hot lash. I really think that there were valves not completely closing when the engine was at temperature which exacerbated the hot start situation. Between the advanced timing and tight valves it really didn't want to light-off when hot. So, good progress yesterday and I hope to get a few miles on it over the next few days to see how it behaves... Edited October 7, 2021 by EmTee (see edit history) 3 1 Link to comment Share on other sites More sharing options...
JeffH Posted October 7, 2021 Share Posted October 7, 2021 Feel free to chime in and correct me if I am wrong. But, I do believe dwell should be set before timing, as dwell will affect timing - much more than you may think. Also, my '38 248 valves are set HOT, with the engine running. Yes, it is a challenge. There is a tool designed for this purpose that combines the wrench and screwdriver in one tool. Jeff Link to comment Share on other sites More sharing options...
EmTee Posted October 8, 2021 Author Share Posted October 8, 2021 (edited) Jeff, You're correct - dwell is set first. What I didn't say above is that when I removed the plugs I gapped them all to 0.025" (per the book). Next, with the plugs removed, I connected my dwell meter and set the points (they read 30* at cranking speed). Then I measured and reset the cold valve lash. The ignition timing was set last (well, actually idle speed was last). I went for a short ride today (5 ~6 miles) and it feels pretty good. I must have started it a dozen times today in various states (cold, hot, warm) and it seems to need only a couple of crankshaft turns to light-off. I'm really happy about that. Even stone cold this morning with no choke (currently disabled) all I did was pump the accelerator twice and hit the starter. It woke up right away and with no choke I did have to feather the accelerator while I set the throttle for a fast idle. About a minute or so later I pushed the throttle all the way in and she settled right down to the 600 RPM idle I set yesterday. I think it's time to start making some short rides to continue finding and fixing any remaining bugs. Edited October 8, 2021 by EmTee (see edit history) 2 Link to comment Share on other sites More sharing options...
Rock10 Posted October 8, 2021 Share Posted October 8, 2021 (edited) Do you know where to buy one or can you post a pic? The all in one wrench Edited October 8, 2021 by Rock10 (see edit history) Link to comment Share on other sites More sharing options...
EmTee Posted October 8, 2021 Author Share Posted October 8, 2021 I don't have one; I just used a 9/16" box-end wrench and screwdriver. I'll bet you can get one on Amazon, or NAPA. I 'cheated' in a sense, as I set the lash with the engine off and cold. I plan to drive it as-is for awhile before I attempt to measure the hot lash (engine running). What I do after that depends upon the hot measurement results (i.e., how close I am to 0.15"). If, for example, they're all consistently .001~.002 loose I may just perform another cold adjustment using .0018"/.0019" as the GO/NO-GO criteria because I believe I can get much more consistent gaps this way as opposed to wrestling with hot, moving rocker arms... 1 1 Link to comment Share on other sites More sharing options...
Gary W Posted October 8, 2021 Share Posted October 8, 2021 6 hours ago, Rock10 said: Do you know where to buy one or can you post a pic? The all in one wrench they pop up on eBay frequently. 1 1 Link to comment Share on other sites More sharing options...
Rock10 Posted October 8, 2021 Share Posted October 8, 2021 4 hours ago, Gary W said: they pop up on eBay frequently. Thank you Link to comment Share on other sites More sharing options...
JeffH Posted October 8, 2021 Share Posted October 8, 2021 Yep, that's it! Still a challenge, even with this tool. It helps though, because there is one less thing to keep track of. I believe I found mine on this forum. Jeff 2 Link to comment Share on other sites More sharing options...
Matt Harwood Posted October 8, 2021 Share Posted October 8, 2021 I have one and it's yours if you want it, just give me your address and I'll send it to you after I get back from Hershey. I didn't find it useful, especially not on a running engine. I stuck with the screwdriver and wrench technique. 1 Link to comment Share on other sites More sharing options...
Rock10 Posted October 8, 2021 Share Posted October 8, 2021 2 hours ago, Matt Harwood said: I have one and it's yours if you want it, just give me your address and I'll send it to you after I get back from Hershey. I didn't find it useful, especially not on a running engine. I stuck with the screwdriver and wrench technique. Sent message. Thanks Link to comment Share on other sites More sharing options...
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