'74 350 engine problem after rebuild

[Jack H.]

When priming with electric drill all rockers slow to prime, left bank starts to prime a little faster than right. Rockers on cylinder 1 exhaust does not prime, cylinders 2 & 4 both intake/exhaust not priming. Removed oil plug at top of engine next to distributor and oil shoots straight up, cam bearing were clocked at 2 o'clock. New bearings/lifters clearances checked & good. Rotating assembly spins at little less than 12 lb of torque. Using VR1 break-in oil. I have never seen this problem before & scratching my head trying to figure out this problem out. Anyone have any ideas or seen this problem before? Thanks Jack

[Mark E.]

Re: '74 350 engine problem after rebuild

Jack,

A couple of thoughts/questions:

- Are you using a priming tool (e.g. an old distributor housing)? Oil pressure won't build sufficiently without one.

- What's the oil pressure reading?

- How long are you priming? With a dry engine, it may take up to 10 minutes for all lifters to pump up. I prime for 10-15 minutes, rotate the crank 90 degrees then prime again, repeat 7 more times (one camshaft revolution).

[Jack H.]

Re: '74 350 engine problem after rebuild

Hi Mark,

Using an old distributor spinning for a good hour, have not checked the pressure yet on spin up with drill. I'm beginning to think internal leak...plug or cam bearings. Oil pump is a new Milodon .

Thanks Jack

[Jim L.]

Re: '74 350 engine problem after rebuild

Prime, rotate engine 90*, prime, rotate engine 90*,.... rinse and repeat.

Oiling of the rockers is not continuous. For any given rocker, it happens in pulses based on crank position.

[Jack H.]

Re: '74 350 engine problem after rebuild

Will do & let you all know...Thanks Jack

Prime, rotate engine 90*, prime, rotate engine 90*,.... rinse and repeat.

Oiling of the rockers is not continuous. For any given rocker, it happens in pulses based on crank position.

[Jack H.]

Re: '74 350 engine problem after rebuild

OK, no change on prime with rotate so took it a step futher and hooked it up to my run stand. Results not good...40 psi at startup, within 2 minutes dropped to less than 5 psi, reved it to 2500 & got about 35 psi and dropped back to 5 psi at idle...shut it down. Looks like I need to tear it down and figure out whats going on...Jack

[Jim L.]

Re: '74 350 engine problem after rebuild

What are the clearances on your mains and rods?

Is there any chance your engine does not have one or more of the front oil galley plugs, the ones behind the timing cover?

[Jack H.]

Re: '74 350 engine problem after rebuild

What are the clearances on your mains and rods?

Is there any chance your engine does not have one or more of the front oil galley plugs, the ones behind the timing cover?

Jim,

Main Bearings .002-.0022, rod bearings .002-.0023. Oil galley plugs are there if I'm getting oil to both sides although I guess one or more may be lose and leaking? Still scratching my head until I tear it down and start looking...has to be something simple stupid that I missed.

Thanks Jack

[Paul Y.]

Re: '74 350 engine problem after rebuild

Jack, every engine I have built had different characteristics on the oil coming out of the rocker arms and they all were hospital room clean with no debris. I had an odd kind of thing happen to me one time on a 327 that I had built. It was in a 63 short bed pickup truck with a 411 rear with granny gear 4 speed. I wound it up on a free way entrance and the oil pump ran out of oil and cavitated the oil pump. That was the last high volume pump I ever used. I tore it down to bare block and couldn't find anything wrong. The machine shop found that a freeze plug above the oil pump had moved and the oil was coming out of the pump and going right back into the pan. It of course does not apply to your situation if you have oil pressure but it proved to me that odd things can happen and that I can always learn something new. Good luck to you finding it and I would like to hear what you found out when you find it. Paul

[Jack H.]

Re: '74 350 engine problem after rebuild

Paul, I'll for sure post up what I find but not tonight...I'm beat and brain dead. Got an oil change to do then tomorrow is another day. Thanks Jack

Jack, every engine I have built had different characteristics on the oil coming out of the rocker arms and they all were hospital room clean with no debris. I had an odd kind of thing happen to me one time on a 327 that I had built. It was in a 63 short bed pickup truck with a 411 rear with granny gear 4 speed. I wound it up on a free way entrance and the oil pump ran out of oil and cavitated the oil pump. That was the last high volume pump I ever used. I tore it down to bare block and couldn't find anything wrong. The machine shop found that a freeze plug above the oil pump had moved and the oil was coming out of the pump and going right back into the pan. It of course does not apply to your situation if you have oil pressure but it proved to me that odd things can happen and that I can always learn something new. Good luck to you finding it and I would like to hear what you found out when you find it. Paul

[Jack H.]

Re: '74 350 engine problem after rebuild

Mmmmm still thinking...wondering if I missed a final torque pull on one of the rods. Could this be a cause? Jack

[Jim L.]

Re: '74 350 engine problem after rebuild

The machine shop found that a freeze plug above the oil pump had moved and the oil was coming out of the pump and going right back into the pan. It of course does not apply to your situation if you have oil pressure but it proved to me that odd things can happen and that I can always learn something new.

Not quite.

That small plug divides a vertical passage into "before filter" and "after filter" regions. Installed correctly, it causes oil from the pump to be diverted to the oil filter before it continues on up.

If it slips out of place, it can impede oil flow to the filter and that could reduce the pressure seen at the top of the block. However oil will not just spill back into the pan. There is no path by which that can happen.

One other point, that plug can be entirely missing and the engine will have plenty of oil pressure. It's just that none of the oil will go through the filter before circulating through the rest of the engine,.

[Jim L.]

Re: '74 350 engine problem after rebuild

Mmmmm still thinking...wondering if I missed a final torque pull on one of the rods. Could this be a cause? Jack

If the rod cap were entirely missing, maybe. But if it's present and simply not torqued to spec, no.

[Joe L.]

Re: '74 350 engine problem after rebuild

Is there any chance your engine does not have one or more of the front oil galley plugs, the ones behind the timing cover?

Jim-------


That's kinda what I'm thinking. These things need to be driven in and staked.

[Jack H.]

Re: '74 350 engine problem after rebuild

What are the clearances on your mains and rods?

Is there any chance your engine does not have one or more of the front oil galley plugs, the ones behind the timing cover?

Well Jim/Joe your the winners.

Finally got back to it about 30 minutes ago and guess what. Right front oil galley plug missing...what a dumb 1st grade mistake. I'm 68 & started rebuilding engines when I was a teen, goes to show you...check everything twice then once more just in case. This one is going the wall of shame.

Many Thanks to all who stepped and offered ideas & experence to solve this.
Jack