![]() Perhaps a comprehensive set of pictures would help. It appears as though your timing mark is accurate, so unless another source of error can be found (timing light on wrong cylinder, wrong timing scale somehow installed, etc.), I have no good explanation. The numbers you are giving for ignition timing do not make sense under the conditions you describe. If your balancer mark is not almost exactly, within 1-2 mark widths, at zero degrees, then you need to replace, alter, or adjust parts to correct that." Compression stroke or exhaust, makes no difference. ![]() That is true TDC within a degree or three, depending on your skills. One person holds and gently guides the wire or rod while another turns the crank back and forth until that wire is pushed out as far as possible. "To check your mark very accurately, within a degree or two, insert a copper wire or coat hanger or the like until it touches the #1 or #6 piston, whichever is handier. At that point, the balancer line should be at the tab's Zero. to determine within a degree or two when the #1 piston is at top dead center. ![]() as soon as it's running, LOTS of advance for good- no GREAT performance and throttle response. I ended up with the timing too advance to start ok, unless I hooked VA to manifold vacuum. advance, and total advance, specs are listed. Google search for vacuum canister specs, or request my PN database where PN's and vacuum vs. Same with the mechanical advance, I measured and tried various weights and springs until I got the required amount of MA.Ĭan't increase it much either, maybe a degree or two as the vacuum canister is hitting the firewall.ĮASY REMEDY by removing the spark shooter and reinserting it ONE TOOTH off in the favorable direction.Ĭheck the ROP thread where I wrote all about that. Then I had pinging, so the vacuum canister was replaced with an adjustable one which was set to ~11 degrees allowed, which I calculated from the engine's happy static and allowable maximum. You NEED enough advance to make YOUR combo happy. I suspect the super low vacuum- it dropped off to under 8 at idle- allowed the power piston in the carb to enrich the mixture which just made things worse and worse. Retarded to std issue specs I was used to, like 10'BTDC, it was a sloth pig that overheated on a 2 mile test run. If I try to dial the initial back to 12/14degrees the engine starts to want to die.ĮXACTLY. My experience with putting non-computerized HEI into a high compression 403 was that it needed a lot of fiddling and unconventional work to be happy. All I can think of is a cam, so the initial needs to be higher. Maybe my curve is off, maybe the weights in the dizzy need replacement of adjusting or replacing, but if normal is 16ish (with hei) initial, and 36 all in, that's 20* advance, just way high initial. Does that make sense? Just for the sake of checking the timing light, I'll stop at the 12 mark again tonight, and then add 12 more to the light and see if it drops me to zero on the timing tab, I'm sure it will, seems I have something else going on here. Same as going back to the 0 on the tab really. 1 fractions, so in the essence of time(and it was getting dark), I stopped at 12, and did the math. That's essentially what I did, except I brought it to the 12* mark on the timing tab because the timing light is digital and it moves in. With the engine rev'd to 3500 and the vacuum advance disconnected, you adjust your distributor so that the mark on the balancer reads "0" on the timing tab.Yes the timing light is on the number 1 cylinder. It was getting dark and I was getting tired so I didn't try to dial it back to find it, but I thought that was weird.ĭo you have the timing light connected to the number 1 spark plug(drivers side front plug)? To use your light set the dial or what ever needs to be set to 36. How much would I pump into it to check.Īlso, if I connect the distributor to the manifold port of the carb(for non emission controlled engines per edelbrock book), the timing mark jumps way out. The instructions for the timing light say to have a vacuum pump to add vacuum to the port per OEM spec. Can't increase it much either, maybe a degree or two as the vacuum canister is hitting the firewall. If I try to dial the initial back to 12/14degrees the engine starts to want to die. Motor is a 72 350, HEI ignitiion out of what appears to be a newer 76 vintage car.Īround 3800 rpms(timing light calculated), I have to add 43* to make the damper mark hit the 12* mark on the tab, or 55* timing all in.įor reference, I checked the rpm's in drive and park at idle and I got 560 and 800 respectively. I have to dial it back 27* to get it to the 12* mark on the timing tab. So I bought a new Craftsman Timing Light with Tach/Advance built in.Ĭhecked the initial timing tonight with the vacuum advance unplugged, base timing is approx 39*.
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