Hello all,

I believe my oil pump is one or two teeth off due to the alignment of the distributor pin when #1 cylinder is at TDC.  My question is whether or not it actually needs to be corrected.  Can simply adjusting the orientation of the distributor correct this?  My car is a 72 with SU carbs and I'm running a MSD unilite distributor on a Datsun Spirit 2.7 liter engine.  It runs pretty well, but is difficult to start and seems to pull/ let off at light throttle while cruising.  Thanks for any input.  

Cheers, Scot

As long as you can adjust the distributor position to get the ignition timing correct (as checked with a timing light), the real clocking of the pump and distributor does not really matter.

In other words... If you can get the ignition timing correct, the clocking does not really need to be corrected.

Edited April 30, 2024Apr 30 by Captain Obvious
more detail

54 minutes ago, Captain Obvious said:

As long as you can adjust the distributor position to get the ignition timing correct (as checked with a timing light), the real clocking of the pump and distributor does not really matter.

In other words... If you can get the ignition timing correct, the clocking does not really need to be corrected.

Thanks, I'll look elsewhere for the source of the inconsistencies while cruising with steady throttle.

Cheers,

Scot

2 hours ago, Montana Z said:

72 with SU carbs and I'm running a MSD unilite distributor on a Datsun Spirit 2.7 liter engine

Any more details about your setup?  Just for fun.  They make several different levels of engine.  Gear ratios and RPM would be good to know also.

 

https://www.datsunspirit.com/engines

 

Edited April 30, 2024Apr 30 by Zed Head

7 hours ago, Zed Head said:

Any more details about your setup?  Just for fun.  They make several different levels of engine.  Gear ratios and RPM would be good to know also.

 

https://www.datsunspirit.com/engines

 

Unfortunately it's nothing too exciting.  I got the SRT stage 1 engine which is an L28 block with P79 head.  I also went with MSA 6 to two headers.  The car had an automatic transmission in it when I purchased it 26 years ago.  I promised that as soon as it failed I would put a manual in it, but that little slush box just refuses to die.  I have a close ratio 5 speed and period correct 4 speed so when the day comes there will be some options.  Aside from that she's pretty much stock.

I can tell you first hand it’s a nite and day difference all the way around as far as power and driving experience when you swap it over to a manual transmission. Not trying to talk you into it of course 😂😂😂

10 hours ago, Montana Z said:

Thanks, I'll look elsewhere

Good luck with the hunt.

I'm not sure I understand what you meant with "pull/ let off at light throttle while cruising" What does that mean?

My simple answer.. A oilpump just needs to be driven by the engine.. there is no "timing" involved.  The pressure the pump makes is going up with the engines rpm's.. that's normal, if you have a warn engine the oilpressure can get to low.. a good check for that is looking at the oil coming on the casmshaft when you turn the engine rpm's as low as 500 rpm, the cam should stay lubricated at that enginespeed, check it through your oilcap opening when the engine is idling.

Your car is probably idling at a higher rpm as it is a automatic..

About that auto.. if you change to a 5 speed change the diff as well.. as a auto has a 3,5 diff of even 3,3?  A 5 speed needs a 3,7 or3,9 otherwise you use a lot of clutchplates as the 1st gear becomes very long.

8 hours ago, Captain Obvious said:

Good luck with the hunt.

I'm not sure I understand what you meant with "pull/ let off at light throttle while cruising" What does that mean?

It's hard to explain... What I think I'm feeling is an intermittent hesitation, but it's barely perceptible.  It pulls fine under throttle.

2 hours ago, dutchzcarguy said:

My simple answer.. A oilpump just needs to be driven by the engine.. there is no "timing" involved.  The pressure the pump makes is going up with the engines rpm's.. that's normal, if you have a warn engine the oilpressure can get to low.. a good check for that is looking at the oil coming on the casmshaft when you turn the engine rpm's as low as 500 rpm, the cam should stay lubricated at that enginespeed, check it through your oilcap opening when the engine is idling.

Your car is probably idling at a higher rpm as it is a automatic..

About that auto.. if you change to a 5 speed change the diff as well.. as a auto has a 3,5 diff of even 3,3?  A 5 speed needs a 3,7 or3,9 otherwise you use a lot of clutchplates as the 1st gear becomes very long.

I do have the idle set a little higher as the FSM calls for.  

Regarding the transmission swap, I do plan to change the diff at the same time.  One small hurdle is finding someone to rebuild it in my area.  It feels smooth in all gears and doesn't appear to have any metal in the fluid, but prior to putting it in I would like someone to go through it.  Transmission work is beyond my scope of mechanical confidence.

A wibeband o² sensor might help determine whether it's fuel related

1 hour ago, Montana Z said:

I think I'm feeling is an intermittent hesitation, but it's barely perceptible.  It pulls fine under throttle.

I would try pulling on the choke a little in the situation where you think you are feeling the hesitation. Give it a little more fuel and see what happens?

Did you put a timing light on it and verify that both the mechanical and vacuum systems are working correctly?