'78 454 Oil Pump Driveshaft Help

[chevyguy285]

Howdy howdy,
First post here. Found this site looking for info/knowledge base for a rebuild I'm doing on a '78 454 engine for my old K20 pickup. I've done a complete tear down and rebuild on this motor over the course of several years (it's been a very VERY side project) and finally got to the point where it was time to prime the motor with oil prior for first start. When I pulled the dizzy to use the priming tool (i.e. hand drill running an oil pump primer bought off JEGS), I realized that the oil pump driveshaft has grown legs ( ). Not sure why, how, when, but here we are regardless. I went and bought what one local parts shop said was the correct oil pump drive shaft (Melling IS-77). Pulled the oil pan, unbolted the oil pump, slipped the drive shaft (bought one with an integrated collar so didn't need the nylon collar like the stock setup had) onto the oil pump shaft, and bolted the oil pump back up. I then stabbed the dizzy in and got it to engage with the camshaft gear (validated with the dizzy collar sitting flush on the intake, and the rotor wouldn't turn further than a few degrees before stopping when I tried to rotate the rotor with my hand). Now, to make sure that the dizzy was engaged with the oil pump drive shaft, I crawled back under the truck, and tried to spin the ~1" of exposed oil pump shaft that you can see even with the oil pump bolted into position. My thought process was that if everything was correctly engaged dizzy-to drive shaft-to oil pump, the oil pump shaft would not be able to spin by hand and would only spin with the motor running. However, the oil pump shaft spun when I rolled it between my thumb and forefinger. I really REALLY don't want to load the motor with oil and start it up only to get ZERO oil pressure because the dizzy isn't actually engaged with the oil pump drive shaft. I did a little more research with a local NAPA shop, and they said there were two other oil pump drive shaft lengths for 454s. The Melling shaft I have is ~6" end to end. NAPA says they have ~6.5" and ~6.75" length drive shafts. I'm confused here as to if my thinking is correct about the oil pump shaft, and if anyone else has run into this problem as well.

Any help would be greatly appreciated folks!

[Mike81K10]

I have built a couple of 350s and the priming tool would fit thru the distributor hole (distributor removed) onto the top of the oil pump and allowed me to prime the engine with a drill. I have never primed an engine by spinning the rotor. Perhaps you can do it, just have never done it that way. Seems it would be difficult to spin the pump with the distributor since you would need to spin the gears instead of spinning the pump directly.

[VileZambonie]

OMG stop saying dizzy! Save that for the Honda lovers.

There was a tall deck big block oil pump driveshaft which is probably what they were referring to. Are you sure the distributor is fully seated? It needs to engage the oil pump driveshaft before it will drop all the way in.

[chevyguy285]

I have built a couple of 350s and the priming tool would fit thru the distributor hole (distributor removed) onto the top of the oil pump and allowed me to prime the engine with a drill. I have never primed an engine by spinning the rotor. Perhaps you can do it, just have never done it that way. Seems it would be difficult to spin the pump with the distributor since you would need to spin the gears instead of spinning the pump directly.

Mike81K10 - to clarify, I was not intending to try and prime the engine by spinning the rotor by hand. That was me checking to make sure the distributor was fully seated and meshed with the camshaft. I'm using an electric drill and a oil pump priming tool that goes down through the distributor hole to do the priming.

[chevyguy285]

OMG stop saying dizzy! Save that for the Honda lovers.

There was a tall deck big block oil pump driveshaft which is probably what they were referring to. Are you sure the distributor is fully seated? It needs to engage the oil pump driveshaft before it will drop all the way in.

Yes. The DISTRIBUTOR ( ) was fully seated on the intake manifold and engaged with the gear on the camshaft - i.e. why the rotor wouldn't spin once I stabbed the distributor.

I guess I need to get both of the tall deck driveshafts and see if either one works. Just wasn't sure if this was a common issue for the 454s or not...

[VileZambonie]

Yes. The DISTRIBUTOR ( ) was fully seated on the intake manifold and engaged with the gear on the camshaft - i.e. why the rotor wouldn't spin once I stabbed the distributor.

I guess I need to get both of the tall deck driveshafts and see if either one works. Just wasn't sure if this was a common issue for the 454s or not...

You will engage the distributor gear without the distributor engaging the oil pump driveshaft so make certain that the distributor did in fact sit flush on the gasket. There is no reson the standard oil pump shaft shouldn't work unless it was boxed wrong. Try Sealed Power 2246154 6.82"

[JohnnyPopper]

Yeah, sounds like your driveshaft is coming up short.

The odds of dropping your distributor in seated without the driveshaft in a perfect position to receive it, are astronomic.

The spinny-town test is definitive-no connection.