i have a 72 350 .30 over with walker longtubes, holley 750, pertronix electronic conversion, flamethrower coil, and crane adjustable vacuum advance kit (silver springs, vac adv screw completely clockwise). the metering rods on the carb are set at two full turns out. the initial timing mark is set at 12*, that is if i'm reading the right mark. when i hooked up the light, i noticed two marks. one white or atleast shinier than the other. however the second mark was larger. this is my first time doing this, and i re-read the powertime thread, but cant figure out the whole 30* mark. from all i've read, 350's like mid thirties advance all in around 2k or so. at one point i did drive the car at 19* and it rode pretty good but something seems hugh about that number. any suggestions?
A timing light with a dial back knob is going to be infinitely easier... There should be a machined keyway in the balancer. That should be TDC. There may be other marks in the balancer from prior attempts at timing the car. Dont concern yourself with those at the moment. Just look for the factory mark. Put a little tire chalk inthe groove or white out to make sure you can see it with the light. Clean off the timing tab so you can actually read it. Plug the vacuum advance and set the idle. With the timing light on the tab, you should see what the correct timing is. Use the dial back knob and rotate it till the timing tab reads zero. The knob will indicate your inital advance which should be the same as what the tab is reading when the timing light knob is set to zero. Hold the engine at 2500 and do the same thing. Dial the knob till the tab reads zero. Read the knob on the light. Thats your total= inital+mechanical. You can play with springs and weights from there.
Do you have a dial back light? I need to know that first. Second, look at the balance, and determine what is the factory mark. Highlight it with some yellow or white paint.
no i don't have a dialback light. i will get one though, i believe NAPA here localy has one. i looked at the balance and have found these two possible marks...one that is small and lies on what looks like a tab of some sort, the other, a machined groce probably an 1/8th or so inch wide. so which is it? also, when making the 30* mark, where do i start measuring from for the 1.72 (or whatever) inches? i think so. maybe i have my verbage wrong. i'm talking about the two screws, one on each side, of the metering block on the holley 750.
The thin one that looks like it is on a tab is the one you need to highlight. If you are standing in front of the car, and looking down at the factory mark, measure 1 3/4" clockwise around the balancer. That will be where your 30* mark should be. I think you may find that the second wide groove you referenced above, may in fact be 1 3/4" away from the factory mark, and that may be a 30* mark for you. In any case, you do not need to make a 30* mark if you have a dial back light. Sears sells a very good light. Check there also. post back when you are ready to set your total timing, and we will go from there. The two screws are the idle mixture screws
right on Larry, thanks for the good info, as usual!!!! will post in a day or so with an update. i'm tracking the 30* mark is measured from 1 3/4" clockwise from the original factory timing mark i'm setting my initial timing with (the thin one that looks like it is on a tab)?
by tab i mean the part that is protrudeing from the circular balance and not the machined cut out that is in the balancer. i noticed two marks under the timing light. one that is on the part of the balance that is on a tab off the balancer (not the timing tab with 0-20) but off the actual harmonic balencer itself...i just want to make sure i'm doing this correctly..
went to tool around with the car a bit and was wondering if i have the vacuum advance hooked up to the correct port on the carb. one port draws vacuum at idle and one doesn't..currently my distributer is hooked up to the port that doesn't draw vacuum at idle. should i change it? is one better than the other?
I am pretty sure that that year the factory was using the ported vacuum source for the vacuum advance. Ported vacuum source for vacuum advance: With the ported source the vacuum canister only adds timing at part throttle cruise under light load. When under load or at full throttle there is not advance. The advantage to this setup is that your idle is not effected by any vacuum advance and you can set up your timing for a smooth idle with factory base timing. Manifold vacuum advance source for vacuum advance: The only difference is that this type of setup gives you vacuum at idle as well as at part throttle. The vacuum still goes away at full throttle. This setup works great to add off idle response due to the extra timing however sometimes PING will result when using stock spec timing. With custom timing curves and modified settings this setup can work great in many cases.
Yes, I am talking about the timing groove on the balancer itself. The timing tab is attached to the timing cover, and should have marks for 0, 4, 8, 10 etc. The thin line on the balancer does have a little tab though. You do not need to be concerned with using a 30* mark if you have a dial back timing light.
Sounds good Larry. I was only doing this to keep my idle hands busy and to practice the whole timing piece in general. Certainly whatever gains I would have seen by setting the timing will be rehashed once the TA284-88H and lifters show up tomorrow. can't wait!!!
thanks sean!! i think i'll try them both to see which is best for my ride. i got a dialback timing light today at sears (thanks larry) and will be tinkering with it all night. i should be looking for 12* initial right?
No, Power time it to 32*. The initial will be whatever it will be. First, install the yellow springs from the Crane kit in the distributor. Then, disconnect and plug the line to the vacuum advance. Loosen the distributor hold down just enough, so you can turn the distributor by hand. Highlight the factory line on the balancer. Start the engine and let it warm up. Connect the timing light, and turn the advance dial to 32*. Point the light at the balancer, and you should see the balancer line somewhere below the zero on timing tab. Slowly rev the engine, and watch the line on the balancer. It should move up. Slowly rev the engine more until you see the line stop moving upward. Note where it ends up. If it is above the zero, retard the timing a little and try again. If it is below the zero, advance the timing, and try again. What you want is when you rev the engine, and the line stops moving up, that it is even with the zero on the timing tab. You will have 32* total timing at that point (initial + mechanical timing) Tighten the distributor hold down. Stop the engine, and install, one blue spring, and leave one yellow. That is usually perfect for the street. You can check what your initial timing is at that point, but it shouldn't matter. You should limit the vacuum advance to 10* or less to avoid part throttle ping. You can make adjustments to the vacuum advance rate by turning the adjustment through the vacuum nipple, but you really should limit the vacuum advance to 10* or less before you make that adjustment.
i understand all larry and appreciate the step by step info. only issue now is the craftsman dial back i bought doesn't work. you push the button and it comes on for like a second or two then off. and it does it so speraticaly that i can't use it. it's going back to sears tomorrow. frustrated...but hey, ta cam and lifters should be here soon! silver lining....
And just like that another bug shows up. I'm changing plugs to fire it up and use the new dialback and voila--the brass screws on to of the bowl of the Holley springs a leak. I thought I'd make a new gasket out of some rubber making material and as I'm sure u know they dissentigrated. Fuel leaks profusely from the area around the screw and the gasket under the nut beneath it. What kind of gasket goes there? Both need to be replaced. Anything I can get locally w/o spending $46 on a Holley rebuild kit?
That is the float adjustment screw and nut. Maybe the bowl is flooding. Some dirt may have gotten into the needle/seat causing it to flood. Are you using a good fuel filter ahead of the carburetor? In any case, Jegs sells a 10 pack of the gaskets you need. I'm sure you can probably find them locally. http://www.jegs.com/i/Holley/510/1008-776/10002/-1 http://www.jegs.com/i/Holley/510/1008-777/10002/-1
He can get a needle and seat service kit also which has both gaskets, the screw, nut and o ring under Holley part #34-7
Got some gasket making material and fixed the leak. I'll get on the timing issue tomorrow. Thanks for the info. Oh and yes Larry, u caught me w/o a filter. It was only like that for about two weeks. Damn ur good. Situation rectified!
