jsmith98

it appears that the drive spindle has an offset 'keyed' end that aligns internally and setting the motor at #1 TDC allows for easy realignment. where is TDC for #1 cylinder? the spindle has a punch mark to align with the hole in the pump, is this hole in the pump shaft? i am deciphering the FSM and had no clue how to start at TDC. is aligning the drive spindle just trial and error? what is critical besides priming the pump? i think i am making this too difficult.

NismoPick

Welcome to ZDriver!

Click: https://www.zdriver.com/forums/showt...&highlight=tdc

rogerz

It is still somewhat hit or miss. You usually get within one tooth but i have never gotten it exact. Get a bolt about 3 or 4 inches long that is the same thread as the cover bolts. cut the hex head off it. thread it into one of the holes and use it as a guide pin to install the oil pump. makes installation easier. then remove it and install the remaining cover bolt. hardly any need to prime the pump it is below oil level and a positive displacement pump. once it turns it starts pumping.

NismoPick

Not true... the FSM states you must prime the pump upon install (same w/ the oil filter). It's also NOT below oil level... otherwise you would loose a lot of oil when removing it...

Priming the pump & filter speeds up the time it takes for oil to reach all locations... you don't want dry scraping metal parts.

jsmith98

thanks to all for your replies. it is good practice to prime the pump whether it needs it or not. i removed the pump without finding TDC. it is trial and error to put it back together (rotating drive spindle until it lodges correctly)? or should i find TDC as per NismoPick and try to slip it back in. as long as it seats fully, it appears that the offset key will only fit the dizzy one way.

NismoPick

The only way you'll ever get it set right is to put the motor to TDC on cyl #1 and install it.

So... TDC on cyl #1 is when the #1 piston is at TDC, and the crank timing mark is at 0. Pull the #1 spark plug if you aren't sure when the piston is at TDC (vs Bottom Dead Center).

When installing the oil pump, match the dots and install.

jsmith98

thanks NismoPick. it has been too long since i have done mechanic. been busy with. bought a clean 1979 280zx with 91k and my father and i are doing some mods so it can compete in autocross. no, the pump probably did not need changing, but being cautious and getting my feet wet. my first car as a 1971 datsun 1200...

jsmith98

thanks NismoPick. it has been too long since i have done mechanic. been busy with. bought a clean 1979 280zx with 91k and my father and i are doing some mods so it can compete in autocross. no, the pump probably did not need changing, but being cautious and getting my feet wet. my first car as a 1971 datsun 1200...

NismoPick

Yes... that is a problem. If it's not aligned, the timing will be too far off. This is a rookie mistake. When you align the shaft dots, make sure you don't rotate the shaft. I know it sucks (I've done a lot of oil pump pulls to fix timing). Install one bolt, hop up and make sure it's aligned right. If not, drop, turn one tooth, check again.

Skully

They matter!
At TDC, if you align the dots, and insert the pump, the shaft should line up at 1125, if it doesn't then you have issues, or you didn't set the engine at tdc, #1 piston. The dots, and setting the engine at TDC, is a means of proper install and verification that the engine timing lines up with the dizzy properly. If the dots are not aligned, and the pump does go in and bolt up, and you are at 11:25 up top, and you are at TDC, then I think the oil pump gear might have spun, because you shouldn't be at tdc with miss-aligned dots. Hope that makes sense, sometimes its hard to put on paper what you imagine in the head heh.

NismoPick

That looks 1 tooth too far clockwise to me. Install the distributor with the cap off and look at where the rotor sits (points to). It should be pointing just down from straight forward (about 8:30 position).