Opinions on 327 timing setup

[Fuzz1957]

With the timing set at 10 dgs with the vacuum advance plugged once you reconnect the vacuum pot hooked to manifold vacuum you should see the timing jump to 18 or 20 dgs. This should give you a nice clean idle. The small block 327s I worked on seemed to like 34 dgs. total all in by 2400/2600 rpm. Advanced timing at idle allows you to get a really good air fuel mixture adjustment which in turn allows you to back off the curb idle adjustment which gets the throttle blades out of the transfer slots of the carb leaning out the mix making for snappy throttle response. It's all good. Best way to set air fuel bleeds is with a vacuum gauge. I used to be the go to guy around here for tuning. Lots of free breakfasts from my buddies. Small block Chevy's especially responded to a good tune up because the engine was so well designed.

Called Pertronix yesterday and talked to technician. He told me to put on one lighter spring and that should get me “all in” by 3000 rpm. Also asked him how many crank degrees the vacuum advance can added. He said 16 degrees. So if I have 12* initial and 16* vacuum advance hooked up = 28* at idle. Haven’t done anything yet changing spring. Did check voltage at positive side of coil with key on = 11.95 or basically 12 volts as it should be.

Fuzz

MAGA

 

[Fuzz1957]

Worked on 327 today. Hot and humid in garage with flies attacking.

Started with this:
Pertronix two silver springs.
10* - 12* at idle of 1000 rpm with vacuum can plugged.
36* “all in” at 4000 rpm.
Voltage at coil with engine running - 14.85 to 14.90

Changed to this:
Pertronix - removed one silver spring and replaced with a copper spring.
10* at idle of 900 rpm with vacuum can plugged.
36* - 38* “all in” at 3200 rpm.
Vacuum can hooked up as normal to full vacuum port of Edelbrock carb - idle raised to 1100 rpm and timing at 26*.
Reset carb to 1.5 turns open (started with each side closed) and full manifold port of carb “teed” to vacuum can and vacuum gauge. The 1.5 turns open of the idle/gas screws on carb gave me 14 - 15 hg inches.
Engine idled good. Took ‘57 out for a drive and to me, performed the best it ever has. It seems I can still feel the engine “respond” in the later stages of first and second gear. Might be just me. Seems that way though. So, installing the one copper spring did do its job of bringing engine “all in” at lower (800) rpm’s. Tech. at Pertronix told me putting in the copper spring would get me “all in” between 2500 - 3000 rpm. Not so.
If I install other copper spring and it gets me “all in” by dropping down another 800 rpm’s - that would put me at 2400 rpm. Would that be correct? Would 2400 be too early? I like how it’s running. Should I just leave it as it is now? What’s your opinion? Thanks everyone for your input. Has helped a lot.

Fuzz

MAGA

 

[Don Jacks]

No,with that cam[it's apparently fairly mild],it's not uncommon to have the advance all in by 24,2500 rpm.If it doesn't like that setting you can always go back to your current settings easily. I'd suspect that it's somewhere in the 224-230@.050 range so it'll be a little "soggy"below 3,000 in a 327 with that short stroke.

 

[Don Jacks]

Once you get the timing dialed in,a carb change to the new AVS2 650 will likely sort the rest of that low rpm sogginess out of it.The reason being the small primary[think spread bore design] and the annular discharge primary nozzles.

 

[Fuzz1957]

Once you get the timing dialed in,a carb change to the new AVS2 650 will likely sort the rest of that low rpm sogginess out of it.The reason being the small primary[think spread bore design] and the annular discharge primary nozzles.

Don, Thanks for your help. Most of your last sentence is “Chinese” to me as I’m an old guy learning new stuff. As to a new carb - probably not going to happen. Spent around $300 for this one and finances say “no” to a new replacement. (I could say I’m saving for a cement garage floor). Maybe further down the road. Just looking for better performance and drivability than the dog it seemed to be and I knew could be better. (Had a 300 HP 4 speed ‘64 Impala in high school that ran well). Also just spent over 2k on new Autogear transmission with 2:98 first gear. That’s helped too. Will put in other copper spring and report back. Thanks everyone again.

Fuzz

MAGA

 

[boxerdog]

I have had combinations that didn't like "too light" springs also, especially with some cams. It seems like there was fluctuation right around the idle speed which in turn affected vacuum and on and on...I always thought that bringing it in sooner was always better, but that may not be true, especially if you have vacuum advance. But I don't think 2400 is too early. It's interesting that the Pertronix tech was off a bit, too. You have the right idea, the road test won't lie.