Distributor & TDC, timing cover replace....

[ellisjay2]

I was told the distributor when installed, the vacuum port faces number 6 cylinder and rotor faces number 1. The person that did it said it didn't matter....I'm not too sure about that..he did the screw driver move and then dropped distributor in after we couldn't find marks on timing cover...



The timing cover on this 70s block doesn't have markings but has the one notch on balancer. I still have my old cover from 80s block with timing marks and balancer. can't I just swap em over??

[ky-donzi]

Yes you should be able to swap them over. Make sure the rubber ring in the balancer looks good. If it is bad the outer ring can move on the inter and the timing mark would be off.

The possible better solution would be buy a adjustable timing tab from summit and bolt it on your timing cover. You can verify TDC with an inexpensive tool that treads into you spark plug hole and you slowly turn the engine over by hand.

A far as the distributor goes,,, it can be anywhere you put it, it really doesn’t matter that much as long as the vacuum pod had room to rotate to set your timing, and the wires and rotor match the locaton you pick for TDC.

[ky-donzi]

https://www.summitracing.com/search?...ng%20tab%20sbc

[Dead Parrot]

The normal location for the vacuum pot is being placed so the distributor hold down bolt is hard to see and get a wrench on.

For a 75 350, the timing mark is at about the 2 o'clock spot on the balancer. IIRC, it was later moved to the 12 o'clock spot, maybe late 70s or early 80s.

A non computerized motor doesn't care about any of this as long as the distributor rotor points to the #1 wire post as the #1 cylinder is TDC. To make things easy for the human trying to set timing, it really helps if the timing mark on the balancer matches with the 0 mark on the timing tab when #1 is at TDC.

[ellisjay2]

So distributor would be fine in position it's in, the rotor would point to number 1 wire, and wire would just have to run around to number 1 cylinder??, is the whole point to keep wire routing easy???

The balancer has groove slash...if I just find/buy the bolt on timing mark and rotate with valve cover off and watch intake close and slash should land on 0° mark indicating right time?? That's how last person helping did it anyway.

[sick472]

A distributor can be put in any position so long as it has enough rotation travel to be timed properly and the rotor is perfectly positioned. The vacuum pod will usually dictate about where it needs to be, so long as your wiring reflects the proper firing order...it's good.

If it were me, I'd get a Top Dead Center Indicator to help verify your bolt on timing marker. You would insert the tool in the #1 spark plug hole (with the piston in a downward position, but on its way up into the compression stroke), slowly turn the crank to bring the piston up to touch the tool, mark your balancer where your new bolt on timing marker indicates "Zero"., then turn the crank the opposite direction until it touches the tool again, & make a second mark (at "Zero). Your real timing mark on the balancer should be exactly in between the two marks you made. This will get you as close as you can without using a more expensive TDC tool and a dial indicator. Close enough for 99.9% of us.

Chances are you could skip the TDC tool all together and just have someone look into the spark plug hole as you turn the crank and bring the piston up as the balancer groove approaches the "Zero" mark on your new bolt on marker. If it's close to being right, the piston will stop coming up as your balancer mark hit's the "Zero" and then start traveling back down as the balancer mark passes "Zero". This approach would be close enough for 95% of us. The timing mark might be off by a degree (or two), but I usually find that the final timing is a fuzz off from the books anyhow. Set it to the books to get it running and then fine tune off of the recommended book setting to run it's best.

[ellisjay2]

I reset every thing with valve cover off and watched number one intake close and hit 0
....set oil shaft piston to 11 and 5 o'clock and dropped on distributor with rotor facing towards number one.....does this look about right????

[Dead Parrot]

Looks good. Keep in mind that the cap is keyed and has no adjustment when you put it on. If you are lucky, it will fit so that a post is already matched up with the rotor tip. If not, you will have to turn the distributor body until you have a close match.

[ellisjay2]

Originally Posted by Dead Parrot

Looks good. Keep in mind that the cap is keyed and has no adjustment when you put it on. If you are lucky, it will fit so that a post is already matched up with the rotor tip. If not, you will have to turn the distributor body until you have a close match.

Would rotating crank to match up post with cap not work?

[sick472]

Originally Posted by ellisjay2

Would rotating crank to match up post with cap not work?

If I understand your question...the answer is "no". You need to have the #1 piston at TDC on the compression stroke. Then you have to install the dizzy so that the rotorbug points to a wire post with the cap on (at least very close). That post will be for your #1 wire. If you turn your crank off of 0° (otherwise know as TDC) you will have lined up the rotorbug with the post, but you are no longer at TDC and the timing will be off. So long as the rotor bug is pointing within a 1/4 to 1/2 inch of the wire post...you can rotate the dizzy to get it to point right at the post (given you have room to rotate the dizzy and not let the vac can hit anything). If that's not possible, you will have to pull the dizzy back out and rotate it the proper way by lining up the oil shaft and skipping a tooth or two on the cam. It looks like you have plenty of room in your pic to do any rotating to allow the rotorbug to line up with a wire post. Line it up with any post that is convenient and call that post #1...Then follow the firing order around the top of the dizzy with the proper wires. It should look similar to this...