alextucker
Well-Known Member
what should my timing be on my 67 383 4 barrel? Just at the Dyno now
34 to 36 btdc all in.what should my timing be on my 67 383 4 barrel? Just at the Dyno now
All stock I think, I presume thats 270-280bhp at the flywheel? Mines not so bad thenwhat pistons were put in it; 8:1? a stock 383 4bbl (10:1 pistons) would only do 270-280hp.
I plan to rebuild the carb next month so I'll get it all re-tuned and timed up again ... after I struggle to get the carb set up ... so when I go back I should probably look to see how it runs with 34 to 36 BTDC at idle, is that what you reckon? That seems to be the magic bracket.Just an FYI "back in the day" on my street low compression 383 I worked with the local Mopar carb & ignition guru on my distributor. We brazed up the stock mechanical advance slots and used lighter springs. No vacum advance. Set total at 35* - 36* with static about 10* in order to get the 35* total. But, my iron head race motors with 12 to 13 to one compression ran 38* total never looked at the idle number. New aluminum head motor is at 35* total & it's all in by 1500 rpm, but that's a race style motor.
your 34-36 should be all in timing (depending on the engine, around 3000 rpm) I use manifold vacuum on the vacuum advance with an initial timing of 18 and with the vacuum plugged in, I have 30 at idle and 36 all in. Every engine is different, but if you use a vacuum gauge and tune it until you get the highest possible manifold vaccum, that should be close on the initial. Unless you are planning to run high octane race fuel, 36 at idle is going to give you too much advance all in. Around 36 all in is where you want to be to prevent detonation.I plan to rebuild the carb next month so I'll get it all re-tuned and timed up again ... after I struggle to get the carb set up ... so when I go back I should probably look to see how it runs with 34 to 36 BTDC at idle, is that what you reckon? That seems to be the magic bracket.
What did you think of my Dyno results?
Excellent thanks for clarifying, at least I have a good starting point nowyour 34-36 should be all in timing (depending on the engine, around 3000 rpm) I use manifold vacuum on the vacuum advance with an initial timing of 18 and with the vacuum plugged in, I have 30 at idle and 36 all in. Every engine is different, but if you use a vacuum gauge and tune it until you get the highest possible manifold vaccum, that should be close on the initial. Unless you are planning to run high octane race fuel, 36 at idle is going to give you too much advance all in. Around 36 all in is where you want to be to prevent detonation.
Yep thats what I went off ands it running well even with my electronic dist insertService Manual says 12.5 BTC. Just sayin', that's what it says.
But there are so many variables that can affect the correct setting for your car. Convert to electron Ign or Clean Air Pkg for that matter, if it has that.
No for your application you don't want full advance at idle, for what you've got 34 ish at 2500-3000 seems more like it. My all in at idle setup is for BIG camshaft, high compression race style motor. Also the service manual advance numbers are a bit confusing. They are listing the mechanical advance inn the distributor separate from the vacuum advance number. I just set the total using a timing tape & timing light.I plan to rebuild the carb next month so I'll get it all re-tuned and timed up again ... after I struggle to get the carb set up ... so when I go back I should probably look to see how it runs with 34 to 36 BTDC at idle, is that what you reckon? That seems to be the magic bracket.
What did you think of my Dyno results?