Combo is a carb 383 SBC with MSD 6AL box and MSD Pro-billet Distributor 8361 Vac. Advance.

Problem is: I have set pointer mark using Piston stop on my Jeg's adjustable timing pointer. When I mark TDC on balancer, unplug vac advance, plug carb port, and shoot the timing light I'm off by a lot. To describe I had to adjust my Snap-On Light to 38*-39* just to get my 0* mark to line up with my pointer! I have also tried marking the balancer at 14* and shooting it with intial baseline timing selected on the gun, but it's still off by more than 20+*. If I try to adjust the distributor the car bogs and about dies, so I'm pretty sure I'm in the sweet spot right now, but want to confirm before I run the motor to much. Barry Grant says 14* to 16* base timing for the camshaft, so I'm looking just to confirm I'm at 14* for now. I have called Jeg's Tech Support which told me I'm showing 38* because that's how much I'm running at baseline. When I told him there would be no way a motor would run at that he just stated well if that's what the light shows that's what it is. A lot of help there, then he said make sure I used the right balancer.... Just to assure myself that shop didn't mess up I removed my pulley and balancer bolt and yes the TDC to keyway is the same as my old stock balancer. Sugguestions?


Detailed specs:
4 bolt main block with ARP studs (late 70s truck)
4340 Forged Eagle 400 Crank internally balanced & reground to 350 mains
4340 Ultra LW Race I beams
TRW forged floater flat top pistons
210CC Race Ready AFR heads (76cc)
1.6 pro mag rockers with stud girdles
Solid roller cam (XE280R Advertised Duration 280/286, Lift .570/.576)
Comp Cams Solid Roller lifters with rev kit
TRW (Speed-Pro) ring gapped at .022/.024
Victor JR hand ported intake with 2" 4 hole spacer
750 DP Speed Demon Carb
Using billet Jeg's timing pointer mounted on a 3 piece CompCams Aluminum timing chain cover.
Pete Jackson Gear Drive installed
Complete MSD System (Distributor, Blaster 2 coil, 6AL box)
Distributor has the blue bushing stop removed (21* advance stop) and the black stop installed (18* advance stop)
283-350 SBC V8 7" Internal Steel Harmonic Race PowerBond Balancer (shop provided it)

 

Two quick questions:

1) Did you check TDC with this specific balancer setup? Different balancers have different marks.

2) Have you tried using a non-adjustable timing light?

 

1.) I removed balancer bolt and checked the Aftermarket 7" balancer to my OEM one on my 350 (which is on an engine stand) and it matches. I also removed #1 plug and put my finger in the hole and manually turned the motor over with a 1/2" drive ratchet with a 24" crescent wrench on the end. It builds compression all the up to TDC, where I released my finger. I then put my finger back on the hole and I can feel vacuum after TDC. So I'm confident my mark is correct to at least a few degrees.

2.) No, I have not used a non-adjustable light yet. I'm thinking thats the problem though, because I read on MSD forum that they recommend only using non-dial back lights, because the dial back ones have a highly sensitive sensor that can pick up on multiple spark output.

 

Update: Bought $40 inductive only timing light from AutoZone. Lady behind counter acted put off when she tried to sell me the digital one and I told her I just want the cheapest one because if I wanted to use a good one I would just use my Snap-On Light.

Anyway ran timing again. The cheap one also picked it up at very very high reading also. Started adjusting it down. I probably got it to around 20* or so, but then idle got really lumpy and started popping back through the exhaust. So next on my list is reset transfer slots again on the carb, check fuel pressure, and float level. To get it to idle a little better. Then revisit the timing again. Definitely getting closer though.

 

Timing is now set. I put it right at 18* at idle with the vac. advance unplugged. That's basically ~16* base and another ~3* from my centrifugal advance. Since I have the 18* advance stop in now I should only see another 15* centrifugal advance giving me the total of ~33 to 34* right at 3500 RPMs. Carb ran much much better once I reset base plate slots and readjusted idle mixture screws back to 1 1/2 from fully closed. I have it fairly right now. Motor got another good heat cycle on it so I'm waiting for that to cool down. Then I'll check my float height and play with the idle mixture screws a little more.

Also found out why the car was so hard to start:

1) WAY to much timing before!
2) Think all that added stress on the starter made the bolts loosen up cause it was pretty loose and grinding so I had to crawl under there and tighten them again.

Now going to research into my next problem of my stupid speedometer (OEM) no longer working!

 

If your centrifugal advance is coming in at idle, you will forever have a hunting idle. It may not bother you now, but it will come back to haunt you later.
What's the idle speed? I'd try using a slightly stiffer spring combo so it absolutely isn't coming on at idle.

Funny how it wouldn't run with less than ~20* before, but now it runs ok with 18* right? But yea, 18* at idle, with that cam seems about right, maybe even more. Just make sure you can get it to idle with the base plate slots just right - so you don't have an off idle stumble.

Other then that, I think you're really close. That combo should run crazy well!