Hey Guys, trying to get the timing ironed out on my 1969 350. Swapped out the 750 cfm with. 600 cfm yesterday. After some minor tuning took it for a spin...ran just okay, certainly didnt wake the engine up as i hoped it would. Had lots of pinging under acceleration and had a real tough time restarting, cranked real slow. I tried retiming it this morning to 8 and 10 btdc and car will not crank fast enough to fire. Car has new battery, edelbrock performer rpm, edelbrock 1405 600cfm carb, HEI ignition and headers. Any thoughts on timing setting? Motor was originally a 1969 350 2 bbl, (250 h.p.) Thanks.

 

I would drop your timing to 7* btdc. If its still pinging, it may be getting to much vacuum advance. You may possibly have to step up a grade in gas.

 

I tried it at 8 and it wouldnt even think about starting, set it at about 15 and the pinging is cleared up and runs much better on the low end. Did fill it with 91 octane yesterday....something odd here....

 

Do you have the vacuum advance disconnected when you check it? Pull the #1 spark plug and bump the engine till its at top dead center and see if your mark on the balancer is at 0 and your rotor is pointing to #1 on the cap.

 

Yup vacumn advance to distributor is unplugged. I will check tdc in #1 hole tmrw.

 

Is it possible that harmonic balancer has shifted, making timing marks off? Your check at TDC will tell. It happens rarely, but I have seen it.

 

HEIs are different than points your ponits dist was proably 8°BTDC the HEI will be closer to 20 ° BTDC. you may need to limit vac advance also. and check your mech advance mechansim works freely....should get at least 15° mech advance, check that by leaving the vac advance unplugged and running the engine up to ~3k or 4k rpms w engine revving check timing it should be 35° BTDC w intial set at 20°BTDC

 

That would explain a lot. I will give it a shot at 20 degrees tomorrow. Thanks for the info.

 

Another quick one..i assume the hei vac advance is run to the non emmisions port on the edelbrock #1405? buddy swears it goes to the port for emissions controled engines (left side of carb when standing in front of engine) seen many opinions on this...a tad confused.

 

The vacuum advance should be hooked up to the manifold vacuum port under normal circumstances, so you have max vacuum advance at idle and cruising. Seems very odd that it would have a problem starting at 8* BTDC but not at 20*. Mine is a mild 455, but I have no problems until I reach 15* initial, then it cranks slowly when hot. Your mechanical advance depends on the weights and springs inside the distributor, there were many different setups. The ideal is to figure out how much the distributor will add (or recurve it to add just the right amount) and then set the initial so that initial+mechanical equals about 35*. If the distributor adds too much, then you're forced to keep initial low, and if it doesn't add enough, your initial has to be too high in order to reach 35*, which is where recurving is handy and sometimes necessary if you want best performance.

Limiting vacuum advance to 10-12* isn't a bad idea, but vacuum and mechanical advance aren't being applied at the same times, so a theoretical initial+mechanical+vacuum advance could be as high as 45-50*. I have my vacuum limited to 13*, and with 14* of initial timing, it's fine.

 

Thanks for the informative post Intragration, appreciate your thoughts. I will be working on her today.

 

So i threw a set of NGK plugs in today hoping the previous owner had missed opening them up when he installed the aftermarket Summit HEI ignition..he didnt, they were set at .045 the car starts and idles well, exhaust smells clean, the timing is definitely close now...car runs fairly strong and very responsive on low end, but hammering it from say 35 mph it gradually picks up steam, nothing like the lower end performance (it will bake rear the tire as long as you keep your foot in it in a power breaking scenario) but the mid and top end is severely lacking....so much so that you cant hear/feel the secondaries kick in, but they do open manually, checked that. Distributor recurve sound or Transmission kickdown are my next targets. Where would you start? Btw trans is a "built" T350 with a shift kit and a stall speed set at about 2,300 rpm per the previous owner. Thats all the info i have on it..got a feeling it might be a vacumn issue....