Will a 6 qt be enough?

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swinger340

swinger340

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Building a high reving (7000 - 7500 rpm) 340 for my swinger street/strip car. Have drilled everything 1/2 from oil pump up to oil filter and back over to rt lifter bore, drilled diagonals from rt lifter down to mains 5/16, cleaned up casting on upper end (under intake)w die grinder, drilled 5/16 holes between every set of lifters (for quicker oil return to pan). Going to be running a melling high volume oil pump. Would a 6 qt. pan be enough oil or should i go w a 7 or even 8? Had this engine togeather once w a stock pan. That was not enough oil. Spun #5 rod bearing by sucking pan dry and oil not draining back down to pan quick enough. Was able to clean crank up this time but dont want to make a habbit of it. LOL! Thanks for any input, Kevin
 
I don't think you sucked it dry. Unless you put in a high volume pump, which would do that. I would really like pics of the internals, as you took it apart.
 
When my car was being raced it ran with a stock pan and standard oil pump. That was with an 8000rpm shift point.

20 years later it still has the same bearing in it.
 
Sucking a pan dry is impossible (Mopar ran tests on this back in the 70's and proved a stock pickup, even with a HV pump won't suck a pan dry) unless you run a real good aftermarket oil pickup like the kind that bolts to the pump cover. More times than not the reason for a spun bearing is from oil starvation because the stock pan has no baffles to keep the oil where it belongs under acceleration. Since you've obviously put a lot into this engine and are revving the snot out of it I'd say go for the biggest pan you can fit in the chassis. You may also want to run an accumulator for added safety.

BTW: are the rods stock? Have they had good aftermarket bolts installed and been re-sized?
 
All my oil passages have been drilled bigger for more oil flow. Melling high volume oil pump was used. All mains and rods were almost black when pulled, except for the spun one. Would lead me to believe they were definately not getting oil. If pan was not dry there was definately no oil around the pickup. This was a stock pan w baffles welded in. Have also thought w pumping so much oil that the windage tray and welded in baffles slowed the oil from getting back to pickup quick enough. Eighter way stock pan was not enough oil for this engine. Your lucky if your 340 w stock oiling system stayed togeather w 8000 shifts. Have seen alot of spun rod bearings w only 7000 shifts. I actually have a buddy w a 70 plumb crazy duster that used to be dragged hard in the 80s. This car alone has blown up over a dozen 340s shifting @ 7000. Leads me to believe the oiling system in the 340 is its weak point. And im a 340 nut.
 
fishy68 said:
Sucking a pan dry is impossible (Mopar ran tests on this back in the 70's and proved a stock pickup, even with a HV pump won't suck a pan dry) unless you run a real good aftermarket oil pickup like the kind that bolts to the pump cover. More times than not the reason for a spun bearing is from oil starvation because the stock pan has no baffles to keep the oil where it belongs under acceleration. Since you've obviously put a lot into this engine and are revving the snot out of it I'd say go for the biggest pan you can fit in the chassis. You may also want to run an accumulator for added safety.

BTW: are the rods stock? Have they had good aftermarket bolts installed and been re-sized?
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My rotating assy. consists of stock forged (heavy) crank, Scat H beam rods w arp bolts, JE forged pistons. Was balanced by a local machine shop.
 
The oiling system on a stock SB Mopar does need improvement such as you have done. Some aren't as bad as others. Maybe that's why some guys are lucky enough that theirs survive and others don't. I just did a 340 for a buddy last summer and I found the oil pump feed hole in the main cap was only 3/8". Should've been close to 1/2" if I'm not mistaken. Don't know what happened on his but it seems like they missed one last machine process when they built it. Or they used the wrong size drill bit. I opened it up to 1/2".

BTW: did you do any mods to help the windage tray drain back faster?
 
Engine had the stock 340 windage tray in it when i spun the rod bearing. Should this be modified or replaced with a better designed aftermarket one. Local machine shop told me to throw it away. I dont think ill go that far. Thanks for any input. I realy dont want to do this engine a 3rd time. It probably would be fine if i kept it 6500rpms or less.
 
Back in the day Mopar recommended that you pry open the slots in the tray to about 1/4" to help oil drain out of it. I'd imagine they still do.
 
swinger340 said:
Engine had the stock 340 windage tray in it when i spun the rod bearing. Should this be modified or replaced with a better designed aftermarket one. Local machine shop told me to throw it away. I dont think ill go that far. Thanks for any input. I realy dont want to do this engine a 3rd time. It probably would be fine if i kept it 6500rpms or less.
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If you go with a real deep pan, like the 8 qt. that gets the oil away from the crank the windage problem pretty much goes away. I'm not positive but I think it was one of our members (OU812) that's a highly regarded engine builder did some dyno testing and found with a deep pan a windage tray is no longer beneficial. You might try a search for him and send him a PM and see what he thinks. Or if you prefer to run a tray you can do like 64 said and open the slots to help it drain back quicker.
 
Not saying Brian OU812 is wrong but couldnt the stock windage tray help out alitle keeping the mains tied togheter? may not make a big diference but every litle bit of help could be of use
 
be sure to run good clearances on the crank we ran 3thos. rods and mains with strate 50wt.oil on dirt twisted her 7500 to 8000 with no trouble.. and make sure you are running breathers in both valve covers....Artie
 
I was just gonna say... What were the oil clearances set at on the old motor? As the rpms get beyond 6500 I feel two things HAVE to happen. Neither really have to do with oil sump volume or delivery. IMO, HV pumps are not needed unless you're running a road race, and the control of oil getting back to and in the sump is much more important than just more oil.
1. You need to add a little clearance. I run .0025 on the mains and .003 on the rods. Not plus or minus.. that is what needs to be there.
2. There can be no taper on the crank journals. None is acceptable. Factory specs are up to .0005" but once the rpms climb you have to make sure there is no taper.
 
green1 said:
A piece of 20 gauge sheet metal tie the mains together?
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like i said everylitle bit to help out may make a diference my old stock windage tray is very stiff compared to how thin it is and when a piece of metal is clamped down solidly it can act alot stiffer than it looks. i doubt it make a big diference but i dont doubt that it makes a diference,the caps are far out of the rest of the suporting structure of the block and that would indicate to me that there is alot of leverage on them and the tray is even further out making even something fairly thin alot stronger than it looks. but i dont know how much of a diference it makes in the real world..
 
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