TOMMY GRANERT

No there was no bluing - just teeth looked broken on cam gear. The chain looked fine and also the lower gear. The wrist pin bushings looked hammered but i figured that was from full throttle extended runs.

Nordicflame

Smitty,
What did you end up doing here?
I was looking and wondering about this same thing last night on a Dart that I'm building up for a friend.
Also, I had to run a die over the galley plugs to get them to go deep enough to avoid the hitting torrington bearing on the back side. A tap would have been easier but I didn't want to chance any debrit getting into the galleys as it is in the assembly stage.
You would think the thread depth would be inspected at the foundry.
Dave

mrhorsepower1

I have a boat load of Dart blocks out there with Cloyes timing chain sets and ZERO problems. There is plenty of oil being thrown around were lubrication up front is not a problem.

articfriends

I drilled a .050 hole in one of the gallery plugs to spray oil on the back of the timing chain,I was worried about losing oil pressure but I was more worried abouit the torrington bearing and chain not getting enough oil. The one thing I would do different is use a different oil pump,I used a melling high volume blueprinted pump like I have used in my past motors,I'm not sure if its the tall lifter bores or what but even after having the crank polished even looser than last time (ended up with over .003 on the mains and .0035 on the rods) this thing had too much oil pressure,runs 100 psi unless oil is over 250 degrees. With same part number pump and exact same components in my merlin block I had 20-25 psi less cold and hot. I ended up having to run 5w40 or 10w30 oil vs 20w50 to get oil pressure reasonable,the thing is the thinner oil breaks down/thins out faster from gasoline dilution. I usually change oil every 10-12 hours,I ran the oil about 14 hours once this year and I noticed oil pressure DROPPING as you revved it higher after a very long run,I backed of and kept it below where it dropped off,cut the filter open (clean/nothing in it),changed the oil and problem was gone. I figure the oil was diluted by fuel (remember this is a 1000 plus hp blower motor) and was too thin to keep up with the flow requirements of the bearings. The same pump with a std or low pressure spring wouldn't be a good option either because it would just have the oil pump bypass open all the time aereating the oil and churning things up,Smitty

mrhorsepower1

Smitty,
So what is the problem?? You have great oil pressure, bearing clearence is perfect, and your worrying? I would run Pennzoil 25W50 racing engine oil with those bearing clearences. It would be ideal to see 80-85 PSI , but 100 will not hurt you. I run 165 psi oil pressure on blown alcohol applications. Oil pressure is your friend. I do not agree with your .050 hole theory. Your going to bleed off a ton of oil.

mrhorsepower1

Also a little note: The new Melling HV Blueprinted oil pumps do have a higher spring rate on the bypass valve and produce more pressure than earlier models.

Nova 26

This thread is interesting, I have the same problem with a 540 I built. At idle cold I will see 60 to 90 psi, anywhere off idle it pegs the oil pressure gauge at over 100 psi. I read in another thread that ideal oil pressure is 10 psi per 1000 rpm that you turn the engine. My engine is set up to turn a max of 5600 rpm, as propped now I see 5200 at wot. It would seem to me that anything over 60-70 psi is too much oil pressure. Not that it will hurt anything, but doesn't it rob hp to turn that oil pump? If I had 10,000 psi oil pressure, what hp would be required to run the oil pump then? I am thinking about putting a standard volume pump back in the engine just to see if my oil pressure calms down to 60-70 psi. Before I do this, what do you guys think? Is there any good reason to run real high oil pressure on an engine that never goes above 5300 rpm, n/a 540?

jeff1000man

Interetsting thread. I use the Dart blocks and use the regular High volume melling pumps out of the Summit catalog. Havn't seen any problems. Oil pressure is around 80 at 5500 rpms. I know there is no oil problem on the front because we had front seal pop out and oil was everywhere.

mrhorsepower1

I would keep the high volume pump. Where are your bearing clearences set at. . It will not hurt running where your at. The oil clearence may be on the tight side and even side clearence on the rods.

Nova 26

MR, I don't remember exactly, I think it was .003 on mains and rods. When I built the engine, a long time marine engine builder set it all up and I remember him saying that it had to be "loose". He even had what my wife would call a really "cute" little bore gauge that he checked each valve guide bore with and made sure that there was proper clearance between stem and guide. I used canfield heads and several of the guides needed to be loosened up. Anyway, I think the clearances are all correct for the marine use it was built for.
My question is about the oil pressure issue, I really do value the help from you seasoned engine builders, THAT I am definitely not! My oil pressure, as I said starts out at about 100 psi but if I run it hard for 5-10 minutes straight, it starts to drop. I've seen it go all the way to 30 psi. Gen 6 block, at first I thought it was the oil bypass in the pad. Changed that to the 30 psi bypass valve, no change. I thought that maybe the high oil pressure was causing the oil cooler and filter to be bypassed. At this point I am wondering if I should just go with a standard volume pump. Is there a reason to run high volume and pressure in an engine that only spins to 5500 rpm? As I posted before, I would think that a high volume and pressure pump takes significantly more hp to turn at 5500 rpm. If they aren't needed, why use them. Can I use a standard volume and pressure pump? What advantage does high oil flow give you?