Tdc? - Team Camaro Tech
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post #1 of 9 (permalink) Old Nov 28th, 18, 04:23 PM Thread Starter
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Tdc?

I am pulling the stock 327 2 brl & manifold and putting on Edelbrock 4 brl & carb so I won't have a reference mark on the new manifold to line distributor up.

I had always thought bringing the motor to # 1 TDC before I pull distributor would have the rotor also pointing to #1 cyl….but the #1 terminal on cap is pointing more towards #2 now on my running motor.


So with #1 at TDC (both intake & exhaust valves closed)...shouldn't the rotor be pointing towards #1 cyl?
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post #2 of 9 (permalink) Old Nov 28th, 18, 04:37 PM
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Re: Tdc?

If just replacing the intake and not rotating the motor just put it back in the way it came out. Remove slowly and make a mark on the firewall.

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post #3 of 9 (permalink) Old Nov 28th, 18, 04:46 PM
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In a perfect world , yes you are correct. That said it can be fired off of any cylinder. Mark the position of your rotor on your distributor with a sharpee. If you don't rotate the engine, it should fall back in in the same spot. Don't forget the distributor gasket. It should be that simple.

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1969 x-77 Z/28 orange/ white stripes, named by my daughter "Clementine ", M-22 close ratio, 4:10 12 bolt, CE 302. Hugger orange with white stripes. White standard interior. Restoration complete May 2018
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post #4 of 9 (permalink) Old Nov 28th, 18, 05:17 PM Thread Starter
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Re: Tdc?

I have pulled the dizzy before to put Pertronix kit in it and just put a reference mark on intake manifold and distributor base and one on lip of distributor base where rotor was pointing. My concern about marking the FW for example is that's about 3-4"away from dizzy and not as precise of a marking location so don't want to be off a tooth. But yeah I get it I do not necessarily need to be # 1 TDC if not otherwise rotating engine during the swap. Its just if there are issues in starting I want to know the distributor is in right


So if I do rotate the motor to #1 TDC...shouldn't the rotor also be pointing towards #1 cyl….the distributor cap does not for #1 plug wire

My accelerator pump is dead on the 2 brl Rodchester so not going to spend any $ rebuilding it and wanted to go 4 brl anyway. While that is a great anti-theft device getting tired of pouring a little gas in to start it every time :-)
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post #5 of 9 (permalink) Old Nov 28th, 18, 06:12 PM
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If you don't rotate the engine, the distributor will only go in two ways. Where it came from.. And 180 from where it came from. The oil pump rod prevents other positions. Marking the distributor where the rotor is pointing will make it easier. If it doesn't drop all the way down, its not where it came from. You say you did it once, you got this. No worries.
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1969 x-77 Z/28 orange/ white stripes, named by my daughter "Clementine ", M-22 close ratio, 4:10 12 bolt, CE 302. Hugger orange with white stripes. White standard interior. Restoration complete May 2018
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post #6 of 9 (permalink) Old Nov 28th, 18, 06:30 PM
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Re: Tdc?

Aim the firing tip of the rotor straight forward. Replace at the same point. Remember, the gear will turn the rotor as it both comes out, and is reinstalled, so make sure the oil pump drive tang is engaged when donw, and the rotor is pointing dead forward.
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post #7 of 9 (permalink) Old Nov 28th, 18, 08:25 PM Thread Starter
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Re: Tdc?

Thanks guys, been many years since I did anything on a Gen 1 SBC. Did the Pertronix kit last week so very aware about the oil pump engagement....and yeah the rotor does rack as the dizzy is pulled out

Just got the car.....no doubt I will have several other ?'s

This motor seems in good shape and "supposedly" rebuilt as stock "not long ago" according to seller (read we all hear that), vacuum steady at 19 in. at idle so likely stock cam, no noises or leaks. The Rodchester 2 brl was rebuilt not to long ago by its appearance. Will do a compression check before I pull intake to see if all cyl are common.

I have a Gen 2 LT1 that came out of my 96 Impala SS I put a 383 and T56 in. GMPP makes a carb manifold for it so it would be a candidate for transplant into the Camaro....although IDK if the Power Glide bolts to it....which could prompt a T56 swap, very familiar with that combo.

Ah I think that would be one deep rabbit hole :-)

Of course this stuff happens right after getting it. Accelerator pump puked when I got it off the flat bed after a 3 hr drive home at midnight. Poured a spot of gas in carb and it starts & runs. Drove it about 10 mi on street & fwy. Speedo was way high so I jacked up rear and rotated tire 1 turn to see DS turn 3.7 times so appears to have 37x's...and its a Posi, Whoopie. Got a 24 tooth speedo gear. It has a 20 in it now.

Undercarriage is bone dry, no rust. Front suspension has been gone through. All new ball joints, I see shiny new shims so alignment feels good, new shocks (Edelbrock), sway bar bushings & end links. New heater, complete new interior & paint.

Just gotta get it running clean and the new 4 brl "hopefully" should do that. Good to be back working on "simple" cars vs computer cars. Had a 70 Torino I put a 302 crate motor in with the same Edelbrock 600 cfm carb I got for this motor my son & I built about 10 years ago. A 70 Nova before that.

Glad to be part of the forum, thanks again for the help guys
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post #8 of 9 (permalink) Old Dec 2nd, 18, 09:41 AM Thread Starter
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Re: Tdc?

On further review I am going to first bring motor to TDC on #1 before I pull Distributor then make mark on distributor for rotor alignment and on rotor & FW. More to establish a clean mark on damper so I can see it when using a timing light. Going to paint the block, pulleys, damper during the intake manifold/carb swap. Want to use a timing light to not only confirm WTF the timing is now but too tweak it for the new carb. Instructions on the Edelbrock carb note I likely can run 2 degrees more timing

Using a stock distributor (with Pretronix kit) isn't stock timing about 15 degrees BTDC? (327)
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post #9 of 9 (permalink) Old Dec 3rd, 18, 05:14 AM
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Re: Tdc?

I'm going through a similar situation as you. My 327 had a HEI distributor, and to make the engine bay look period correct, I decided to remove this distributor and replace it with a points and coil setup. I first noticed that the HEI number 1 cylinder position on the cap pointed at an angle (the number 1 cylinder when the engine was at TDC). However, the points style distributor's number one cylinder on the distributor cap points more straight ahead (points straight forward then that of the HEI distributor). In doing research, this was due to the vacuum advance canister on the distributor; in order for the HEI's vacuum advance canister to clear an intake runner, the distributor was shifted slightly, making the number 1 cylinder on the distributor cap point more at the number 1 cylinder. For the points style distributor, number 1 points more in a forward direction (to the passenger side of cylinder 1) than the HEI.

You can basically install a distributor and have the rotor point to ANY position you want on its distributor cap, as long as you follow the firing order when installing the plug wires.

And as a tip, there is no need to worry about aligning the oil pump slightly counter clockwise prior to installing the distributor when installing; just install the distributor to get its gear and the rotor pointing where it needs to (number 1 cylinder location), then rotate the engine while slightly pressing down on the distributor (I use a socket and ratchet on the crankshaft pulley bolt) until the distributor drops and seats on the intake. Continue to rotate the engine to verify you have TDC (looking at the timing mark on the harmonic balancer and toothed timing bracket), and the rotor is pointing at the correct position for the number 1 spot on the distributor cap.

Never argue with an idiot; they'll only drag you down to their level, then beat you with experience.
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