Im losing a battle with a sbc 350 from a 70 caprice. Engine is stock as far as i know. Eddy 1406 on a offenhauser 360 manifold. How much initial and total timing can i run ? Spec calls for 4btc but that was probably a smog setup. I had total at 36 and initial landed at 12. When i hook vacuum advance back up to manifold, the idle slows down, and it flops like a fish outta water. Vacuum advance pulls 15. Once you get beyond about 1100 rpm it runs really nice. Worked idle mix screws with no luck. Slightly better if i wind them out about 3 turns. Plugs are white with a little brown coloring. If i set timing back to 4 to 6 degrees it idles great but runs very lazy. I do get slightly over 20 inches of vacuum idling with a steady needle. I guess my question is, is there a limit on a stock engine ? Is 12* too much ? Also does anyone have problems with eddy accelerator pumps not squirting after about a month ?
most smog motors had vacuum advance connected to ported vacuum source on the carb, not manifold vacuum...the first thing I would try is to make that simple change.
I had it on ported and it does idle better it just tends to run hot in traffic. Would 14* hut it if it doesnt ping and starts ok ? Im trying to get better than 10 mpg thats why i want to advance timing
If it doesn't ping, and starts ok, and runs ok, and is peppy, then it's probably close enough. Fall is in the air, eh? It'll cool off soon.
I’ll try bumping it up a little more and go back to port vacuum all i can do is try. I like fall but hate winter. Hey i wonder if theres a message board for all the snowblowers that wont start on the first snowfall !!
There's no set standard for what an engine want's for timing, factory numbers from 40 years ago are irrelevant today, but will give you a starting point. If you want to get it as close to perfect as you can get, it will take a lot of testing. Get yourself a mildly inexpensive wideband air fuel meter and start tuning. Play with the jets, metering rods, step up springs, distributor springs, initial timing, etc... until you find the sweet spot your engine likes. My father told me a "back in the day" story of having someone lay on the fender of an old jalopy and hang on for dear life while adjusting the distributor while the driver held his foot to the floor and tried to achive top speed to find the high end sweet spot in the timing. I think society would frown on that today though.
I had similar problems with the '78 350 in my '53 Chevy. First it ran great but pinged like crazy. Short version: replace vacuum advance can with an adjustable one. Set timing at idle using a VACUUM gauge. Don't know what it's set at, don't care. Vacuum advance on manifold vacuum. Adjusted until no ping with 87 octane. No problems since then. I found instructions to set timing with a vacuum gauge here on the HAMB but a quick Google search will show it. If I remember correctly you turn the distributor until you get the maximum vacuum and then pull back 2-4 inches of vacuum.
Why not try a different tact? Set the timing with a vacuum gauge for highest steady vacuum reading. That's where it's going to run the best. Then check the other numbers just to see what you got. You can also set it by ear, advance it at idle listening to it very carefully, you'll hear the changes in the way it's running and the changes in rpm. Advance it until it starts to run rough and loses RPM, then back it off to where it runs well again. Check it for hard starting and for pinging under load. If all is well, run it. If it runs right, it is right.
I have found that our brains, as hot rodders, don't function the way the rest of society would expect.
I don't believe I've set engine timing with a timing light in 40 years. I'm not sure there is even a timing light around here. Wondering, you said you set your timing total at 36 degrees, but when you connected your vacuum advance, it didn't run right. Back when I was a young guy with a timing light, timing total meant the vacuum advance was also connected. If you didn't have the vacuum advance hose connected, you didn't get the total timing, you added 10-12 more degrees when you added the vacuum advance. And at what rpm did you set your "total" timing at 36 degrees? Gene
nowadays we talk about total timing with the vacuum hose DISCONNECTED....because we aim for a specific number of degrees advance, at WOT at high RPM. Because that's what makes the most HP. If you never run your engine at WOT then I suppose it doesn't matter. But I figure, that running at WOT is what hot rods are all about.
"Total timing" is a misleading term because it doesn't include vacuum advance. The reason for that, it is a drag racing term which doesn't include a vacuum advance because it doesn't need it. Using a mechanic's vacuum gauge can be a good way to find what a stock or mild performance engine likes at idle, but it may prove to be otherwise too far advanced in terms of total centrifugal timing. Back off just slightly, about 1/2", from the highest steady reading achieved should he OK for pump gas. Some people object to the vacuum gauge method, screech like wounded Eagles, but it's not really a bad way to go to get in the ballpark, which is what most people seem to do anyway.
I'm not always the sharpest knife in the drawer when it comes to setting up a distributor correctly. But I do have people in my life that will come over and work for a free lunch.. and they like to see someone spend sick $$ on car stuff... I have a small body HEI with external coil on my 355. Dart intake, dual plane with a Holley 700, full manual carb. We discussed having all the timing in by 2500 RPMs, close to what I did with the stock cars. So my total is 38* and it runs strong. The initial is 12* and I don't use the vacuum advance. I have it capped off.
Your right ! I tried setting timing with a vacuum gauge and it was advanced a lot ! So I’m just backing off a couple degrees at a time till it feels right.
36* is all it will do. That happens at about 2900 rpm. At idle its 12*. With vacuum at idle its about 26*.
I would think with your setup and oem cam there is only so much timing that cam will allow you to run. My dad set timing and carbs with a vacuum gauge and a glass of water sitting on the core support. Used to tell me "watch the ripples in the water, when they smooth out the most with the highest vacuum stop". I know he owned a timing light, just never seen him use it.
Well i adjusted timing yesterday, took it for a ride and it ran really good. Till i got a couple red lites and it started getting hot. Got home and realized i didnt reconnect the vacuum. Got vacuum on port side now cos it wont idle on manifold. Hopefully it wont boil over
Yeah not sure with stock set up if im trying to make it do something it doesnt like. Kinda like my mom telling me you like liver and onions and your gonna eat it !! So the best idle is at 4* but it cant get out of its own way.
I thought we went through this already, and you had a bum condenser, replaced it, and everything was all copacetic?
Yeah i did have a bad condenser,you helped me out with that. i cant seem to hit a sweet spot and and keep it that way. Went to a cruise today, by time i got there about 45 minutes it was running like crap again ! Well with several heads under the hood we found the distributor lock down bolt was too long and was bottomed out just enough to let distributor turn. Set timing by ear Added a couple washers now its not moving. Hopefully end of problem.
I've had problems with cheap ass chrome ones that slipped also. Back to GM painted factory ones....no problems
yeah, I always use a 1970s factory Chevy clamp, and the special bolt they had with them (it's an odd length, and has a built in washer flange) I guess it's getting hard to find this stuff, if you didn't sock them away 10-20 years ago
Well thats what it is, cheap chrome that u really dont see anyhow. Squirrel is right, need some early 70’s parts.
The Jalopy Journal
