355 sbc timing help
hey i have an 83 camaro with a 355 sbc and was wondering what i should set my timing to and how do i know if i need differant springs for my distibutor its a 350 bored 30 over with summit racing flattop pistons vortec heads summit intake manifold header back exuast 600cfm holley carb w vac sec with a one inch spacer and im using a summit 1104 cam which is 224/224 duration at .05 and .465/.465 lift and a 114lsa any helpwould be greatfull thank you
Assuming you have it running......this is what I would do. Get a timing tape and a set of light weight springs for Summit or maybe your local auto parts store. Attach the tape to the harmonic balancer as per instructions, with the TDC on the tape to match the TDC markings on the balancer. Install the light springs in the distrib. Using your timing light, with the vacuum advance plugged, bring the RPM up to about2000-2500rpm. Turn the distrib until the pointer is on 32 degrees on the tape. Tighten the distrib down and plug in the vac. advance. Go for a test drive. If no spark knock move the distrib. up until its 34/36 at same RPM. Try that. See if it cranks over ez or does it drag. Play with it until it feels like you like it and does not spark knock(rattle) under load. Re adjust carb after timing is right. I would guess about 10/12 degrees initial advance with full advance of 34/36 @2500RPM. Yours maybe a little more or less.
With what you have I would suggest a timing curve as follows:
idle base timing 16 to 24deg
max mechanical advance 34 to 36deg
advance rate: smooth curve starting from off idle, maxing out at 3000-3200 rpm
vacuum advance: 10-15deg (max limit) at hiway cruise
The vac advance rate, in/out (vacuum diaphram spring tension) has to be found by drive testing trial and error. (every vehicle is different)
Find out what the motor likes best for base idle timing (16 to 24deg) idling while
"in gear" (auto trans) 750+/- rpm and start from there.
3000 stall converter and 3.73-4.10 gears is not too much if you like "take no prisoners" light to light acceleration.
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