If the heat riser valve is still in the exhaust system, check to see if it's stuck closed.
If 8 degrees advance at idle gives you too much advance at higher RPMs then you might check to see if you can get a different set of centrifugal advance weights for the distributor.
Is it safe to assume that the radiator is clean and all of the seals are in place around it and on top of the radiator and also the fan is working properly?
1973 L-82 4 spd
thanks, I'll check out the weights in the distributor. The aluminum radiator and duel electric fans are pretty new and fans are functioning properly. I have ceramic coated headers on it with no exhaust valve. Thanks for advise.
Are you using ported vacuum or manifold vacuum for your advance? I'm using manifold vacuum with an MSD distributor and I'm running about 16 degrees btdc.
I also blocked off the exhaust crossover at the intake manifold gaskets.
Here's a couple of good threads on timing, vacuum, and carb adjustments. Both have excellent info from super knowledgeable folks.
Joel Adams
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Another potential timing problem is having too light of a spring on the distributor centrifugal advance weights. What can happen if it's too light is that it will start advancing at idle speeds which makes it very difficult to both set the idle and the timing.
1973 L-82 4 spd
Good afternoon,If the picture in this query is the 383 you are having issues with,let me make some suggestions.
I have built several 383 engine here in FL. (VETTER BOB in this forum) and in CA. and the first thing to address and that is you will have to go with a mechanical fan,preferably a 7 blade which they are hard to come by,but can do with a 6 blade.It can be installed with your present pulley with adapter, I had the same pulley on my '80 Vette..After you install the mechanical fan,then we can work on my next suggestion.
Connect a vacuum gauge to the vacuum port in the intake manifold behind the carb or the non metered port on carb,however the intake manifold port is more accurate..Depending the gross lift of your cam the vacuum will be about 9-12 inches optimum of mercury again depending on cam lift.Get the starting vac.. and record the inches and advance the distributor to increase the vacuum if it will,if not set at between 9 -12 inches at the highest you can go without advancing to far and if it does increase vacuum then it will increase idle speed, reduce idle speed as vac. increases to set at 850-950 rpm.If you are advanced to much you will have resistance( bucking and "rumping)) in spinning engine..If all goes well you can install your timing light to get actual timing by gun..
Good luck and success.. nosal Sal C
Sal C
Thanks everyone for the suggestions. I am now able to get 35 degrees at 2500 rpm and 10 degrees advance at idle. A short test drive seemed to produce good results. My starter crapped out and I'm awaiting a new mini high torque 14:1 starter to give it a longer trial but I think I'm ok.
Was it the distributor advance springs?
Look into a advance timing light vs the digital one. The instructions are simple & you will get the timing set perfectly especially on a modified engine. Use some water wetter & use a 25% antifreeze 75% distled water setup. If it still heats up you have other problems.