OK Let me start by telling you what I have. I have a zz430 replica (350 zz4 sbc short block, gm fast burn heads, air gap manifold, holley 4150hp 750 double pumper, gm hot cam 218/228 .525/.525 lift 1.6 rockers, th 350 trans with 2800 stall converter, 4.11 posi, 28" mt et streets) in a 68 camaro. It has a bad off idle bog...almost stalls. It runs very rich! The carb had 70's up front and 83's in rear, 27 and 35 squirters, all other adjustment are good. When I set total timing at 36, it had no power and very bad bog. To get the car to run clos to good, I hav total timing set at 50 degrees. I am not sure what is wrong. Should I pull apart the front and check the timing between cam and crank? Also, If I am taking apart the front, would anyone recomend a different cam. I would like something more tougher sounding with more power and with using these heads. I read before about a gm cam part #12370847 234@.539 intake and 242@558 exhaust with 1.5 rockers. I appreciate any input on my bog problem and any suggestions on the cam. This car is a sunday street rod. Thanks

I been playing around with it and came up with something. I set cyl 1 at TDC, harmonic balence dead on, and the distibutor seemed off by a tooth. By me haveing the engine at 50 total was I just compensating and not really 50 degrees. I removed the dist and set it right (I think), I can not get adjustment out of it because the square part of the HEI cap hits the firewall. ???

By me haveing the engine at 50 total was I just compensating and not really 50 degrees. I removed the dist and set it right (I think), I can not get adjustment out of it because the square part of the HEI cap hits the firewall. ???

50 degrees is 50 degrees, period. There is no such thing as "off a tooth" unless the distributor body is positioned in such a way that you cannot rotate it enough to set the timing (the situation you have now)

To phrase this another way... regardless of where the rotor points when you drop the distributor, there will be a point when rotating the distributor where the timing is correct (assuming you have clearance to spin the distributor without fouling the wires or putting the vacuum can into the firewall.)

You need to separately and independantly adjust the initial and total timing.

Initial (at idle with vacuum advance hose disconnected) needs to be around 18.

Total Reved until it advances no more, vacuum still disconnected) needs to be no more than 32 degrees with the fastburn heads.

You will need to "mess with" the advance weights and springs under the rotor to get the total right.

THEN and only then hook the vacuum advance back up to full manifold vacuum.

What distributor are you using?

Here is an excellent thread on timing from the chevelle board: http://www.chevelles.com/forums/showthread.php?t=189195

Jim is right on the money. That engine needs no more than 32-34* total timing. To set it somewhere else is only adding to your problem.

A Holley 650 DP would be a more appropriately sized carb for your engine, but you should be able to tune the 750 you already have to work.

How did you set the idle mixture screws? That's where I would go before you change anything else. (after you set that timing to 32-34*)

I been playing around with it and came up with something. I set cyl 1 at TDC, harmonic balence dead on, and the distibutor seemed off by a tooth. By me haveing the engine at 50 total was I just compensating and not really 50 degrees. I removed the dist and set it right (I think), I can not get adjustment out of it because the square part of the HEI cap hits the firewall. ???

Set the distributor in so that you have adjustment room for the canister and then move the plug wires to where they need to be with the rotor at #1.

Have you verified that the harmonic balancer hasnet "spun"? (outer ring rotating on the inner ring)

Do you have the correct timing pointer for your balancer?

Chris:cool: