Priming the rebuilt engine question

[Early a body]

I was recently talking to someone at a local shop who specializes in muscle cars as they were doing a cars and coffee. They do mostly fords and chevys some mopars. They are also well known in the area for doing great work. I was talking to him about how various things and he brought up how they prime engines that have been rebuilt. He says they crank the engine using the starter - no spark no fuel and watch for the oil to reach the lifters and rockers. I was a little socked by that as I always thought that was not a good idea on a rebuilt motor. But it did get me thinking as I have never thought about priming the motor like that. It certainty seams it would be quicker and easier to do.

What do you al think about priming the oiling system this way.

 

[Craig Burriss]

If it’s a got a roller cam, I don’t see it being an issue. A new unbroken in flat tappet cam though, I think that would be a different story

 

[TT5.9mag]

That is NOT how to prime an engine. Although lots of people do it that way because it’s easy and they are lazy. Regardless of make, Chevy, Ford, Mopar, etc you need to spin the oil pump (only) while rotating the engine by hand. It’s the only right way to do it. Unless of course you have one of those fancy preoilers plumbed in.

 

[67Dart273]

If it’s a got a roller cam, I don’t see it being an issue. A new unbroken in flat tappet cam though, I think that would be a different story

^^I agree^^ You are supposed to pre-lube bearings, pistons, cam, lifters when installing and a few seconds at slow speed on a drill will not hurt.

But with anything with a distributor, it's "usually" pretty easy to get or create a priming shaft. and that method is better

On a side note I always start with the filter REMOVED, and prime for just a second or two. Oil should immediately come up from the pump. This action removes the head from the pump and makes it easier to prime the pump. Then install a pre-filled filter, and with a hose, now get oil to the sender port, and then replace that with a gauge. You can FEEL the pressure on a drill because with that port plugged and oil pressure "up" the drill will pull very hard. A 1/2" drill is better

Then watch for oil out of the rocker shafts, and with a drill you will have to turn the crank so the cam oil holes line up

 

[dano]

Back in the beginning we never pre-oiled, but lubed everything well and never had an issue. Now my dad and I still lube the crap out of everything and pre-oil with a priming shaft until we get full pressure to the gauge then turn the motor over while priming then drop the distributor in and fire it up. If it doesn't fire quickly we stop and evaluate what is going on and not destroy the engine with fuel wash. Building an engine these days isn't cheap and having an issue can cost a lot of time and money to fix.

 

[Rapid Robert]

turn the crank to 90 degrees (1/4 turn) BTDC #1 compression & preoil the pass head with the hex shaft (some dampeners have partial marks (3 of em) in addition the the full TDC timing slit) or if not cut a strip of paper 5.694" to use as a ruler. then turn the dampener back around CCW to 20 deg ATDC # 6 compression & preoil again for the dr head. this will preoil both heads with minimal turning. then turn the crank back CCW a bit more to your preferred initial (IE 15 BTDC) & install the dist with the rotor under where the #6 plug wire is. It'd be a good time to check rotor phasing. and only vac adv not mechanical changes it (shifts it CCW on a SB) from its static position in relation to the cap terminal.

 

[1969383S]

The all important Hex shaft!

Any Mopar guy likely has one!

My first was a turned down Intermediate shaft with shaved Distributor gear. The latest a purchased unit from Summit! These are a must!

 

[my68barracuda]

I was recently talking to someone at a local shop who specializes in muscle cars as they were doing a cars and coffee. They do mostly fords and chevys some mopars. They are also well known in the area for doing great work. I was talking to him about how various things and he brought up how they prime engines that have been rebuilt. He says they crank the engine using the starter - no spark no fuel and watch for the oil to reach the lifters and rockers. I was a little socked by that as I always thought that was not a good idea on a rebuilt motor. But it did get me thinking as I have never thought about priming the motor like that. It certainty seams it would be quicker and easier to do.

What do you al think about priming the oiling system this way.

There are probably a couple of million new OEM motors built every year and I would bet that none of them are pre lubed prior to starting the first time by spinning the oil pump. Many new engines have crank mounted g rotor oil pumps meaning that you need to spin the crank to build oil pressure. Spin the oil pump with the crank stationary if you can and if you want, but using a quality assembly lube and having the parts and internal oil lines absolutely clean is a better way to engine start up success.

 

[RustyRatRod]

As long as the engine is assembled liberally with assembly lube and it is a fairly mild build with a mild to moderate flat tappet with relatively low spring pressure, it probably won't hurt a thing. I still like priming the oil pump though. If you think for one minute the factories primed engines going down the assembly lines back in the day, you gotta nuther thing comin. Ever seen the opening scene in Christine? That's exactly how it was done. Engine busted off, revved a few times, checked for leaks and then pulled out and parked in the lot.