Timing chain oiling on dart big M block
 

I'm assembling my 540 using my new dart big M block,there is no 1/2 dollar size hole behind the top timing chain gear like a typical big block has,I'm using a cloyes hex adjust timing chain and gears with a torrington thrust bearing behind top gear. I want to ensure enough oil gets to the chain and bearing,I have seen in the past where timing chain manufactures reccomend cutting a slot in the cam bearing with a hack saw blade to let oil come out to the bearing (I'm not keen on doing this on these fancy coated cam bearings). My other option is drilling a hole in the block or one or both of the oil gallery plugs to let oil squirt out,how big of hole should I drill? I know if its too small (like .035-.040 ) it could plug fairly easy but I don't want to make it too big and lose too much oil either. It doesn't look like enough oil would ever wash out of the main bearing and cam bearing to keep the chain and torrington bearing lubricated to me. Cloyes just says in there instructions to ensure enough oil gets to the chain with no specific reccomendations,what do the big name engine builders do? On a side note,for anyone considering using a cloyes hex adjust timing chain and gears the chain is a piece of crap with nasty seams where the outer rollers are crimped over the pins,I throw the chain in the trash and use a better chain with machined rollers with no seams,I used one of these "true roller" IWIS cloyes chains before that had these crimp seams and at 130 hours there was pits in the crimps and the chain wasn't looking too healthy,Smitty

your best bet is to call dart and see what they recomend for there block, I'm sure they will have some answers.
good luck:

Smitty,
I have never had a problem with a Cloyes chain. Personally, I would be more concerned that the other chain is not manufactured to the same exact specs as the Cloyes one and might not really fit the sprockets correctly. If you dont feel comfortable with the Cloyes set, find another brand, but I would use all matched parts from the same manufacturer.

Just my Opinion,

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

Bill,as far as using replacement chains on cloyes sprockets,manley chains and roll master chains have the same .250 dia pins,width and pitch,I have been using them for years on cloyes sprockets.On circle track motors and when freshening big blocks often the timing gears haven't started to exhibit any wear yet but the chain has stretched so you can replace the chain at least once before replacing the whole set. It sux that cloyes has a nice hex adjust timing gear set but supplies a chain with seams or crimps on the rollers. If you look at one closely you will see what I mean,a good timing chain has "true roller" sprocket bushings that spin on the inner pins(cloyes and most quailty ones do,cheap ones do not) but some but not all of cloyes chains have seams in the rollers where they are "crimped" from a piece of flat stock,a really good timing chain uses solid outer bushings that are machined vs crimped,I have had a crimped cloyes chain start to eat the rollers away at the seam where they are crimped,they are not even completey round at that point and bite into the sprockets,especially when running high spring pressures.This doesn't seem to happen on the bigger dia gen 6 chains but on the gen 4 and small block chains with .250 dia rollers.
As far as drilling oiling holes in the block galley plugs to help extra oil get to the chain,have you done this and what dia did you use? A stock block has the 1/2 dollar size hole behind the upper sprocket and some oil from the lifters/vallet area lubes the timing chain,on the dart big m this is casted out so the only oil the chain will see is the leak-off from the cam bearing and main bearing which I feel is not enough,some tech I have read says to slice a hacksaw width slot in the cam bearing to allow extra oil to flow out of the cam bearing but these cam bearings have a special coating on them and I'm not going that route,Smitty

Smitty,

I have 150 + hours on my 540 which has a Dart Big M block. I didnt do any modifications to the oiling system for the chain. To tell you the truth, I didnt even think of it, nor did I notice a potential problem. This winter, I am going to freshen it up, now you have me thinking of this as well. I am do to talk to Bib Madera this week. He is setting me up with his cam, lifters and T&D rocker set-ups. I will ask his opinion on this and let you know. Maybe he has some experience with it.

Vinny

Just went thru a 540 Big M Dart that had burnt 2 pistons and the double roller chain and the cam gear was missing 16 teeth. I wonder what caused this - was it from not enough oil? Gen 5 & 6 502's have those galley plugs with oil holes in them. This motor had about 95 hours on it.

Take it to a machine shop, have them put it in the mill and tap the hole in the lifter valley. I had to do the same thing on a Dart Iron Eagle small block for my drag car. This will allow oil to reach the front of the motor with no issues. One other thing to check......make sure the timing cover isn't pressed against the front main cap. If there isn't enough space between the two, your timing set will run wet and rob power.

My .02

I'm leaning towards drilling a .050 thousandth hole in one of the oil gallery plugs which will allow some oil to spray onto the chain vs the chain getting its oiling just from the leakoff from front main bearing and cam bearing. I know a guy who builds alot of 598/632's using dart blocks and said I'm worrying about nothing BUT he's a drag motor guy and measures life expectency of motors in passes not hours,Smitty

Did your chain show signs of lack of lube like bluing or extremely worn pins/bushings? You might have had other problems like your cam started seizing then the chain snapped o rvalve train bound up or hit causing a extreme load,you should have been able to tell when your motor was dissected,Smitty

---

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.

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

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.

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

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.

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.

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?

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.

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.

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?

Nova 26 do you have an oil temp gauge? It sounds like you are frying your oil if it is dropping pressure like that.

Don't get offended, but I have heard of this happening a lot. Do you have the oil lines going to the remote routed backwards? Have you noticed the oil filters collapsing?

Also, you said you were using DART blocks. I have never seen a genVI Dart BBC Block. THey are set up like gen IV. Do they make a 1 piece seal block?

High volume is good because of the length of time that the engine runs at high RPMs. 5500 for extended periods is actually pretty high. You don't need high Pressure. If you can get the guage between 60-80 you are just fine.

Where is the oild pressure at idle?

3 thousanths should be fine for crank and rod clearance. That is plenty loose.
Good luck.

patriyacht, yes and to double check it I used an infrared temp gun, stayed a little cool at about 180-200 deg.
jeff1000, no offense taken at all I'm greatfull for the help and input. I did check oil line routing, I run to the oil filter first and then to the cooler. Not a dart block, Gm gen 6 block with one piece main seal. At idle COLD, it will peg my 100 psi oil gauge, idles at about 850 rpm. Where can I get an 80# oil spring for the melling pump? Part number would make it really easy, Thanks for all the help so far!

I don't know the part number for the spring. I always use the pumps the way they come. I will get you a part number for the pump assembly.

You can call Melling and ge their advise if you wnt to rebuld. The whole pump is only around 100.

I gave some thought to your problm earlier.

What weight oil are you using? I didn't see it earlier.

If you are using multi weight it might be heaing up and be to thin for your bearing clearances.

Try runnung straight 40 weight for a little while and see if the presure range changes a little. It might not drop as much after it heats up. If that is the case, then it might just be about running the right oil. I need to read back on this thread and see if thi has been discussed all ready.

Filter first and then the cooler is right, but is it coming out of the right hole coming from the block. I know your probably OK, easy way to check is to take off the filter. Crank to engine over and make sure that the oil is coming out of the center.

Jeff1000, I use gold cap mobil 1 oil, 15-50. Have not tried a single weight oil, I can try that, but this winter, I have my engine out anyway and figured I'd try and correct this problem while it was easy to change everything. I may just buy a new oil pump, but the one in the engine now only has 50 hours run time on it and I was hoping a new pressure spring might just solve the problem.

airation, drop oil level 1 qt , see if this helps , just a thought , although when i got my 598 first back , id loose oil pressure just as stated , verry frustrating tryed everthing . ended up sendin g engine back to find out they didnt clearence the pan gasket enough and the crank caught the gasket and sucket it into the pump , thus causing the oil pressure to be great cold . but would run to 30 psi before id shut her down , dislodge and then suck back in , DAM I WAS PISSED , lost whole summer and was very frustrating too , good luck :evilb:

At a 100 psi I'm worried about scalloping the distributer gear and possible spark scatter from the distributer going crazy trying to turn the pump but I guess I'm worrying about nothing,thanks for the reassurance. Our water temp here is quite often in the 60's also and I run a 14qt pan,it takes a while to get the oil warmed enough where I'm comfortable that the valve springs are warmed up enough to run hard. If I'm just running around without long distance continous running I run 11 or 12 qts instead of filling the pan to the max. I do have a oil cooler with a thermostatic bypass. As far as the extra timing chain oiling,I had rollers on a good cloyes true roller set start to get small pits in the rollers when I tore the motor down to freshen it at 114 hours,I figured they were galling from a lack of lube. In the past I have used rollmaster premium timing sets on small blocks and they always insist that you make some kind of a provision for "extra" chain/thrust bearing oiling,either a small oil channel in the cam bearing or a small spray hole in the face of the block over a oil passage or a gallery plug.
In the past (before this dart block)I used 20w/50 kendall (I know its no longer as good as it used to be) or ran mobil1 vtwin 20w/50 and ran straight50 wt if running in real warm water on vacation. I have never had any bearing problems,everytime I have freshened/rebuilt my 540 they looked like new (120 hours or so) but I'm not trying to get 200 plus hours out of it either,Smitty

Nova 26 I would agree oil aeration. High rpm running for long periods of time require good oil control. A deep Dooley oil pan. windage tray and a scraper are what I'm using along with the high volume oil pump. This is what I'd like to get. http://www.billetfab.com/index.htm 100 psi at cold idle is nothing to worry about.

Patri and all the others, thanks for all the input, I think my next step will be to replace the stock 6 qt oil pan with a 10-14 quart pan. Anybody have one for a gen 6 block cheap?