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PostPosted: Tue May 29, 2018 10:29 pm 
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Last summer and at long last I got my Sprint engine rebuilt and last weekend set about its first startup.
I’m not sure if there may be an issue with the oil supply to the rocker fingers and hope a few members can offer some advice.

I’ll start with what’s been done to the engine first.
Full rebuild, new +20 pistons, crank grind -10 thou, vandervell and AE bearings, brand new old stock AE oil pump, unipart filter - metal ends, STR91 cam.
After all machining was done, the head and block where fully cleaned out, all oil ways blasted with brake clean and 120psi air line after, checking everything coming out was clean.
I took the rocker shaft apart, which was the cars original with virtually no rocker wear to the pads, all fingers individually cleaned and oil holes blown through, I was going to use a new rocker shaft but found it had no plug in the end so decided to keep the original. I used our works degreasing tank and a very small bottle brush which went the full length of the tube and basically scrubbed it internally until no more black sludge came out, I then left the hose in one end with the degreaser being forced out all the little holes in the tube until I was satisfied all the dirt was out. This was then brake cleaned and blown out with and air line.

So, getting to the point, engine reassembled using thick engine assembly lube, it’s stood during winter, before cranking I wanted to prime the oil ways so welded a rod on to an old oil pump drive and used this on a drill to prime the engine, slow rpm, 2 or 3 turns per second. After a minute or so oil started appearing from the holes in the rocker fingers other than number 7 ( towards rear ). There seemed quite a reasonable flow from the others.
I then cranked the engine ( drive and dizzy back in ) but still seemed the same, so back to the drill, this time no oil seemed to be coming from some of the other rockers.

Eventually I just went for a start up....with the cam cover off! It looked like there may have been oil coming out of number 7 but very difficult to see and messy. Incidentally, the chain was absolutely flinging oil everywhere - normal? For the chain to have this much oil on it?
I then refitted the cam cover and ran it at 1500rpm max for about a minute, when I took the cover off number 7 hole appeared full of oil.
Any ideas on a flow check? Air line up the oil filter outlet, see what comes out? Normal some flow better than others?
I have a brand new Smiths electric oil pressure gauge which cold with running in oil read just under 50psi at approx 1500rpm, I assume this is good?

Any advice, thoughts, tips would be well appreciated, just don’t want to wreck newly built engine. It’s also a pain you can’t just unbolt the rocker shaft in a few mins and stick an airline down it! So looking forward to moving it under its own steam, it last ran in about 1995! :shock:

Look forward to some thoughts on this.

Thanks in advance,

Chris.


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PostPosted: Wed May 30, 2018 6:14 pm 
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I am in a similar position, but my rebuild was a bit more amateurish, so all I can tell you in my experience.

After running I found a good coating of oil all along the cam and oil leaking the length of the rocker cover gasket, till I tightened up. So I think as long as the whole cam has a decent coating of oil it should be OK. I think it is only meant to spray oil up there, it shouldn't be a flood.


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PostPosted: Wed May 30, 2018 7:00 pm 
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I know I keep banging on about this but the real Achilles heal of the slant engine is in fact the jackshaft and if its bore in the block is worn you are not going to get a good head of oil up to the top of the engine. The oil pump runs anti clockwise when rotated from the top.
I have just this afternoon stripped an oil pump to find that the valve spring was broken (poor manufacture?).

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PostPosted: Wed May 30, 2018 11:17 pm 
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I can remember the jackshaft seemed a nice snug fit, no obvious play at all. When priming ( anti-clockwise ) the drill was only going very slow 2 or 3 rpm and it didn’t take long for oil to come out of the fingers, a nice steady stream, just couldn’t seem to get any out of number 7, 8 was fine. Running with the top off it ‘looked’ like there was a splattering of oil coming out. I would have thought if there had been a supply problem to the head my fingers and cam would have been worn but where in excellent order!

Maybe I should just run it and see what happens.

Anyone any ideas on correct oil pressure reading when hot at idle and 3,000rpm?


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PostPosted: Fri Jun 08, 2018 8:50 am 
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Strange but I am rebuilding a Sprint engine at the moment and found for the first time a blocked finger on several arms! I drilled out the offending sludge and reassembled. The oil pump on this engine had a broken relief spring!!! so low oil pressure was the most likely culprit.

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PostPosted: Sat Jun 09, 2018 10:46 am 
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Quote:
Strange but I am rebuilding a Sprint engine at the moment and found for the first time a blocked finger on several arms! I drilled out the offending sludge and reassembled. The oil pump on this engine had a broken relief spring!!! so low oil pressure was the most likely culprit.
I think I may have found the problem, or not so much a problem but just how it operates, starting off at 1&2 you need to turn engine until the hole in the shaft and hole on the finger align then oil flows out. This is around about when the finger sits near the peak of the cam lobe. Turn past this point, no oil, so the cam just gets pulsed every time the holes align. Good news, no oil leaks sideways of the fingers so they obviously sit well on the shaft.
So number 7, the suspect one, holes aligned, compressed air down the hole, it can be heard going through the shaft, I re-primed with cam in set position, oil now flows out, however no 8 is slightly quicker to respond and I have noticed the hole is very slightly bigger. I’d also assume only a dribble should come out, a large squirt would miss the cam and end up leaving it dry. Highly recommend priming the engine with a drill, its surprising the resistance the pump creates, it only need to turn 2 or 3 turns per second. Hopefully panic over, it should be ok, original shaft and fingers which don’t seem to have much wear at all.
The cam cover is now firmly secured!
Oh, when ran with no cover, difficult to see the oil, I guess it turns to a spray mist, but omg the timing chain was absolutely smothered and throwing oil everywhere! So good supply there.
Found a photo of the flow after thorough internal scrub, which is essential, the muck inside was unreal.
Image


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PostPosted: Sun Jun 10, 2018 12:31 pm 
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Sometimes (almost every time) the blanking plug is pressed in by the factory too far and blocks partially the oil feed.

Jeroen


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PostPosted: Sun Jun 10, 2018 1:18 pm 
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Quote:
Sometimes (almost every time) the blanking plug is pressed in by the factory too far and blocks partially the oil feed.

Jeroen
Jeroen,

Looking at the plug from the outside, how far should it be set in? Ie from edge of the bearing cap.
The original cam and fingers ( still using the original fingers ) had done over 100,000 miles with virtually no wear, so I’m assuming the oil supply was probably ok.
Certainly a handy tip to bear in mind for the future.

Chris.


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