![]() Be careful that the cables do not end up on the manifold or in the fan. The lamp is of good quality and lasts longer than most competing products. See also the video Adjusting the timing spark. You do this by equating the dash with the engine running. ![]() Set the engine speed to the rpm specified by the manufacturer, usually around 1500 rpm. This allows the ignition timing to advance properly. Start the engine and allow it to reach full operating temperature. You can then adjust the ignition time very precisely. The timing pointer is on the timing cover with a scale of degrees.In many cars, 8 degrees before top dead center, without vacuum advance, is specified by the manufacturer. You can get the most out of your workshop manual for the ignition timing.This reflects well when the lamp flashes. The most convenient is to mark the desired ignition point with a white line (white-out fluid).Place the current clamp around the spark plug cable of cylinder 1.You can then adjust the ignition to 8 degrees for bdp with the bdp mark. If you only have bdp and want to adjust 8 degrees for bdp, you can make the flash happen 8 degrees later. This also allows you to accurately read a time. ![]() You can read the speed in the display and you can set the moment of flashing to take place later or earlier. This is the more luxurious flash lamp with display and conjugation function. The xenon flash lamp gives a lot of light and due to the narrow design with articulated arm you can also reach hard to reach places. I’m surprised by these symptoms because since it was backfiring through the carb I was expecting the timing to have been too far advanced.We have been using this no-nonsense timing light in the workshop for more than 10 years. the backfire is gone, the truck runs better, but still the truck is difficult to start when at temp. They adjusted it to 10 degrees of advance. They put a timing light on it and showed me it was running at 2 degrees of advance. I understand that the 350 should have about 34° TOTAL timing. Im using an aftermarket distributor with vacuum advance and the tech data states that it 'has 24° (crankshaft degrees) of mechanical advance (between 3,000 and 3,200 RPM). When I got the truck back, I was disappointed that the engine still idles low (and poorly) particularly in drive, still was difficult to start when warm, and would occasionally backfire through the carb. I have regular street cam in this 350 SB. I paid a local shop to install them, including new roller tip rockers and pushrods. I bought brand new 64cc aluminum heads to up the compression. After going through many processes, including timing, I determined that the heads, which are a mid-70’s 76cc low compression smog type of head originally for a 350 sbc, were a contributing factor. It would also be hard to start (difficult to crank) when up to temperature. It has a big, lopey cam, but had starting and idling issues, especially when cold. I have a Chevy 327 of unknown origin in my truck. If the timing chain has too much slack in it, you will need to replace it and at least the cam gear before you will be able to set the ignition timing correctly. Old GMs have a sticker near the rad which should tell you the timing spec at the correct idle speed. If you have a timing light, warm up the engine to normal operating temperature, disconnect and plug the vacuum line to the distributor, and set the timing according to the timing marks on the chain cover and balancer. High mileage small block Chevys are notorious for this and the fact they used Teflon coated cam gear teeth that would break off over time and make the condition even worse. Also, in your case, it sounds like you might have a stretched timing chain. If you are not using a timing light, I would recommend that you do so. An overly advanced condition will cause backfire through the carb and overly retarded will cause backfire through the exhaust. Usually, hard starting occurs when the ignition timing is too advanced, not retarded.
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