Ive' just fired up a SBC 327 got it timed somewhat. Got it idling at 750 rpm. Here is the problem... If I set the timing at 8 deg btdc then it is a little hard to turn over. Once it's been running and I turn it off it wants to diesel quite a bit. I set the timing at 4 deg btdc and it starts a little easier but still diesels a little when I turn it off. The timing gears are set at 0 deg, The new vibration dampener is lined up at 0 deg as well. I'm about ready to ditch the timing light and set the timing by ear. Any thoughts on the matter?
Is it the correct timing chain cover for that balancer? You need to set the No1 piston at TDC [with a piston stop] then check the marks.
Not a expert by any means but it sounds like your spark plugs wires are not in the right order,or your distributor is 180 out
It's the correct cover. I didn't rotate the crank after installing the timing gears and chain. When I put the vibration dampener on it lined up correctly with the pointer on the cover. Since all of that was correct I didn't see the need to verify that #1 cyl was at tdc with a piston stop. It's just me and the cat in the shop so someone didn't mess with anything when I wasn't looking.
Toss the light then. Maybe turn the idle down a little. Really who gives a **** where the timing is at idle anyway? Set the total timing 36ish * all in at 2500. But you’re gonna need the light. If it starts fine after that you’ll be fine, if not the distributor needs recurved. If you’re certain of your timing marks being correct then question the light. Oh and I’ve never seen a car start let alone run with the distributor 180* out.
OK its the correct cover, but you stated a "New" vibration dampener .[did you install it with the Heads off to confirm actual TDC?] Most replacement balancers are for a 350 sbc which has the "0 deg" mark in a different position on the timing cover compared to a 283/327. If you still have the old balancer, hold it against the new one [lining up the keyway] and see if there is a difference. Also be careful if using a cheap "advance" [or dial back] timing light
Put the inductive pickup on cylinder #6. It should read the same as # 1. If not, you need to dig deeper. Are you using a dial back light? Do you have a multiple spark ignition?
The timing light is a craftsman non adjustable that I've had for 40 years. I am very confident that the #1 piston was at tdc when I installed the vibration dampener. The plug wire firing order was checked numerous times to make sure it was correct. The distributor is a MSD with MSD ignition box and a Blaster coil. The cam is a 268H from Comp Cams. New large port Aluminum heads. New hydraulic lifters, pushrods, roller rockers and valve springs. It has a tunnel ram intake with an single Edelbrock 4V carb. This a fresh rebuild. I have done all the ***embly.
Do both the timing cover and dampener have a matching style of timing marks? Chevrolet moved the timing marks in about 1968. Obviously, if a timing cover with the early mark location is used with a later marked dampener, (or vice versa), problems result.
It's an after-market timing cover. The 6.75" dampener is from summit racing. The timing marks on the cover are the bolt-on style. Summit indicated that the dampener and bolt-on timing marks are correct for my application. I have been ruminating on some of the comments and I now think it may be time to verify #1 tdc using a piston stop.
Use a vacuum gauge. Set the timing to achieve the highest vacuum at idle and then back it off to drop about 1 inch of vacuum. That should get you very close. Then check to see what your timing light says. If it shows zero of after TDC then it points to your timing marks being off.
An engine will not " run on" without fuel . Too much throttle opening at idle brought on by timing problems.
Usually began w/6° then tweaked by ear, depending upon fuel. Light compressed clamp allowed turn of Dist.
Even when using the correct indicator and dampener, when using the piston stop method, I have seen up to 4 degrees of error at the indicator. The only way to accurately check TDC is the piston stop method. I have seen people try to do it with a dial indicator (heads off). This doesn't work either. There is too much dwell at the top to be accurate. Accurate TDC indication is the basis for all tuning. I would bet this is generally one of the most commonly, overlooked and problem causing areas when trying to put a tune on an engine. It is a really easy thing to do. Probably can do it in 20 minutes or less. Then you know, not "pretty sure". I buy adjustable indicators for all my SBC's.
Here's the really silly part , its not really important to have a specific number . through experimentation you'll find where the engine runs best , whether the indicator is pointing at 4 or 40 , its simply a point of reference denoting where the engine runs best , once set , unless you have to replace ignition parts ,or somehow otherwise disturb the "that's where it runs best" setting , there's no need to change that setting .
Kinda kills me when guys FUSS over timing numbers they get without verification of the marks they are reading. If the marks are off the light is just telling you stories.
I'm also thinking you will find the 8 deg btdc ignition timing is in actuality a good bit more advanced in the pistons' opinion. Some "timing tape" installed aligned with a verified TDC , along with a tach, will allow plotting out the timing curve with your trust Craftsman timing light. Once the damper timing mark is verified a narrow paint stripe across hub and outer ring will provide a visual warning when in a few years the damper starts to go senile. Just for fun, what is the manifold vacuum when cranking, and does the MSD distributor offer vac advance? If so is it plumbed ported, or direct to manifold vacuum? What ignition curve does the paper work say is allegedly installed? Can it be started with foot off the gas, or does it require some pumping and feathering ?
That's just the conclusion I came to after reading all the comments/ advice. I had to push my stubbornness aside to get there.
The MSD distributor has no vacuum advance. I give the throttle a couple of pumps before starting. Sometimes I crack the throttle when it's cranking over. Once it's started I goose it once or twice to make sure the high idle is positioned properly. It idles really good without any throttle input after that.
Jawsman, people are going to read this and say that I am crazy, but the only time I use my timing light is after I have modified the advance curve for increased timing, to see how many total degrees I have at 3500 rpm. I'm old school, and I set timing by ear, still use vacuum advance, non-HEI. I start it up, bring it up to 3000 rpm with no vacuum advance hooked up and continue advancing the distributor until it starts to run rough. I then back it off slightly, let it idle down, adjust the needle valves and set the idle to desired level. Fires right up without touching the gas, never run-on. Just my method.
sounds good. It's certainly worth trying. I hope my results mimic yours. I'm still curious about the accuracy of my timing marks. Thanks for your contribution.
You are absolutely correct in that the specific number on the indicator is not important. I adjusted timing by ear a lot as a kid 'cause I couldn't afford a timing light and they ran alright. But why not start from a meaningful reference point and use a light to adjust by a degree or two, instead of just grabbing the distributor and giving it a twist. Then any information you might read on the internet will be meaningful.
Yeah and then there’s the really important stuff. The total timing. You see IF IF IF the engine, its internals and all the scary alien technology within the centrifugal advance mechanisms of the distributor are only exactly as the factory engineers meant them to be will the FSM timing numbers at idle speeds be relevant.
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