74VetteAZ

Hey Guys -


Almost done with the oil pan removal and rear seal on the 74 BB. It has taken me several months to find the time to finish plus I'm still learning this stuff so I'm much slower than you guys. Since it has been several months since the oil pan was removed and now I'm ready to put it all back together including a new oil pump. My service manual doesn't say anything about priming the oil pump but from what I've read lots of folks say you should. I have one of those priming tools (Summit Chevy BB specified) that goes onto a drill and into the top of the distributor. Couple questions - which way do I turn it - and do I do it with the ignition on until the gauge reads pressure? Also, anything else I should be aware of when working with the distributor since this is a first for me?


Thanks very much!

71VetteLover

Looking at it from the top you spin it clockwise and you'll know the moment the oil hits the bearings because the electric drill will begin laboring. Your priming tool must have the body on it that resembles the body of a distributor so it'll seal the oil passages that feed the lifters. Without that body your oil pump will spin and that's all it'l do.

cv67

You dont need to prime it. Look at it like you just parked it for awhile
Priming wont hurt...just saying if you dont its no big deal

resdoggie

Dynra Rockets

Is it nice to have peace of mind that your oil pump works and you are building pressure in the system though. pumping up new lifters is a plus too. I always do it.

71VetteLover

When you dump 5 quarts of oil into the pan it automatically fills the oil pump to the same level after it sits for a few hours. And when you crank the engine the oil gets pumped to the bearings within about 2 to 3 seconds. That's why it's pointless to pre-fill an oil filter because it gets filled before you could whistle the first three bars of Dixie.

REELAV8R

If you want to see pressure before you start it just don't pump the throttle or take the power off the ignition and crank the engine. You should see pressure in about 30 seconds or less.

On my 77 I have the choke removed. I crank it every time until I see pressure then pump the throttle to start the engine. So I essentially prime the pump each time before I start the engine.

HeadsU.P.

Its been said that 80% of engine (bearings) wear is in the first few seconds of start-up because, well, things are a little dry after sitting. Thats seems a bit extreme, but maybe.

If you have a good size mirror, set it on the drivers seat facing the gauge cluster. Then when you are running your electric drill with primer tool under the hood you will be able to see the pressure build up, hopefully.

jb78L-82

I do this procedure every time I start my 78 L-82 if it has sat for more than 1 day between drives. ^^^^^^^^^^^^.

I just did the same today when I took it out for a spin.......!

Either I don't set the chock and do not pump the gas after it has been sitting OR I pull the plug on the HEI for Battery and just let the engine crank. Oil pressure on the rebuilt/uograded L-82 355 shows 60+ PSI usually within 5 seconds of cranking. I stop cranking, let it sit for a few seconds, and then crank for another 5-10 seconds. After that procedure, I let it fire.

BTW- I always prime my 10C6Z06 before I start it as well. Foot to the floor on the gas, hit the start button, and the engine will only spin without firing...all GM Fuel injected cars have this feature to clear a gas flood condition.....just an FYI. On the LS7 following this cold start procedure, there is virtually NO valve train clatter starting a cold start 427 LS7 which is not the case if you do not follow this procedure.....

resdoggie

It may not be as extreme as you think. Wear will occur most with boundary lubrication. Little to no wear after the engine is flashed when hydrodynamic lubrication is established where there is no contact with the journal and the bearing surface.

7T1vette

If you want to prime it, just remove the central high voltage feed line from the distributor and let the engine crank over to pump up the oil pressure. Then reinsert the power wire and crank it to start. Slow crank over speed won't do any damage to bearings if they've had oil in them before.

resdoggie

It will wear the bearing surface because there is not enough oil film thickness to protect the bearing surface. It isn't much but after hundreds of starts, it becomes measurable and increases bearing clearances which in turn drops oil pressure etc and eventually you need a rebuild or a catastrophic failure occurs. This is why 80% of wear occurs at startup.

Dynra Rockets

For a clutch car one of the biggest wear surfaces at startup is the thrust bearing surface. I always prime a dry engine (fresh or not started in several years) and I have disabled the clutch safety with on almost every car I have owned.

OldCarBum

When you prime the pump using your tool from Summit Racing and before you pull the distributor, pull the distributor cap and using a marking pin or metal scribe, mark the exact direction the rotor contact is facing both on the cap lip of the distributor housing and someplace off the distributor. Then mark a line on the distributor housing base and onto the top of the intake manifold. Remove the distributor clamp bolt and slowly lift the distributor up. As you do you will see the rotor spin until it disengages the cam gear. Watch the direction it turns and then see the direction of the rotor when it stops spinning. When you replace the distributor locate the rotor in the same position and drop it in to place. Watch the rotor turn as you lower the distributor and ensure the marks at the base and intake perfectly line up and that the rotor marks on the distributor housing at the cap lip and your mark off the distributor perfectly align. This will ensure the cam gear, distributor gear, and rotor are in the same location and your timing is still set. If the pan has been off with no oil in the pump, I would prime it before starting. It won't hurt anything and it just adds some insurance that when you crank the motor there is already oil in the pump. Good luck.

cv67

not to rock the boat its only been 2 weeks, theres oil on th ebearings. Just turn the key no crazy seance needed.
Mines been sitting for 2 yrs. Gas, battery and turn the key
not like anyones trying to get 200k out of these?

7T1vette

My [original] engine has 217K miles on it. Pulling the distributor to pre-oil this (already operational) engine is like pre-washing the dishes before you put them in the dishwasher....

OldCarBum

If the OP feels better priming the oil pump and wants the added insurance, let him, and help him to get it done properly. As we always tell people, it's his car.

2airtime2

Correct, that's why we use assembly lube.


I recently started up my partial rebuild for the 1st time. I filled the oil filter before install. New cam and lifters with assembly lube, all bearings were re-used since the engine had been "gone thru" and everything was like new spec (oiled). New pistons and rings (oiled), new intake and carb with new mechanical fuel pump.


My engine did not fire immediately and I developed oil pressure on the gauge before it did. I'm not worried and she purrs like a lyon now.

jb78L-82

Yes!

Well documented that most engine wear occurs from cold starting...which makes logical sense as well.

I long ago abandoned engine manufacturer recommendation on oil weights for any type of gas engine, not just cars, but snowblower, lawn tractor, generator, etc. I follow 2 tenets for the last 25 + years:

1. Always use a synthetic oil...A REAL synthetic..not USA marketed "synthetics", most of which are Group III highly refined dino oils, but true PAO Ester based Group IV synthetics. Why? They offer SUPERIOR flow at very cold temps versus conventional oil...cold start up wear issue

2. Use the thinnest weight synthetic oil that will flow the best at very cold temps/cold start up temps and will meet the lubrication requirements at normal engine operating temp, since most wear occurs in the first couple of minutes of an engine's cold start operation....


All my combustion engines get Mobil 1 0W-40 European Formula only...this weight of Mobil 1 is a Group IV based synthetic, unlike the other weights of Mobil 1 that are called "synthetics".

68notray

I'll chime in - priming an oil pump is not at all necessary. Like said above it will fill on its own just the same.