I am going with this setup , 6.125 H beam rods, J E forged pistons, 383 scat crank , ch7 dough herbert cam,dart pros 215cc 2.05/1.6 valves, professional products single plane, holley dp and need to decide if I should go with a high volume oil pump or stick with the m55a melling . My oil pan is a moroso 6qt . This cam is good up to 6500 rpms on a stroker!! Any input appreciated

 

The oil pump needed will be determined by the bearing clearances, engine temp and application, and the oil you intend to run among other things. Tell us about these things. Have you allready bought the rods and pistons? If not I would take a second look at things. Your combo gives a 1" compression distance assuming zero deck. This crowds the ring pack and has less stability in the bore than a 5.7 or 6" piston. This is less than optimal on a street or mild race engine which I assume is what you have due to the parts list and RPM range.

 

As long as you're not running alot bigger than recommended clearances, I don't think you need a high volume pump. Last summer my pickup loosened up, and to make a long story short, I installed a new M55a and I'm happy with it.

 

At this point it looks like I will be going with a solid roller lifter nstead of hyd. roller lifters and also decided on a different cam dough herbert cc6h . My b earing clearances I will post later tonight or tomorrow morning, I will be running 20-50 motor oil, will see more track time than street although driving it on the street once in a while is a must. The pistons and rods I got already I still need to buy the cam and lifters . Oh and sorry for the parts constantly changing. It's just that right now I am undecided on cam selection. The parts that are not going to change are the rods and pistons.

 

Your compression height is a bit small to get a good size on your ring pack. There will not be enough material betmeen the ring grooves to get a good seal,especially if you run a power adder.The top ring will be very close to the top.
A big HP 383 should have .0025-.0027 Rod's-.0027-.003 on the mains and you NEED a pump to keep up with the clearances.A standard pump won't work.You will also need a good pan.
Don't run restrictors to the lifters with a mech roller unless it's a trailer queen.

 

Thanks for the response. I will take note on your information and make sure on the clearances. I will get a 7 qt oil pan I've got a 6 qt moroso now but since I will be running a high volume oil pump I know I will need a different oil pan.

 

The 6.125" rod is definately long in a 383, but it's not impossible. I've run some motors with 1.000-1.100" compression heights and you can get good ring seal out of them, but it's better to space the ring pack out if you are running pistons really loose in the bore. Like a 4032 Forged piston.

As for bearing clearance.... if the motor is NA then you can get away with .0020-.0025 on front four mains and .0025-.0030 on the rear. A standard pump will keep up with this and 600 hp easy. I honestly don't think you are going to need .0025-.0030 on the mains until you get into the 700-900 hp range. A tighter bearing clearance and lighter oil is going to make more power.... but like captaindbol said "The oil pump needed will be determined by the bearing clearances, engine temp and application, and the oil you intend to run among other things." that is very important as well.

Bret

 

The 20-50 is heavy.... oil choice should really be dependant on bearing clearances and how hot you are going to run the motor.

Bret

 

[QUOTE=SStrokerAce]The 6.125" rod is definately long in a 383, but it's not impossible. I've run some motors with 1.000-1.100" compression heights and you can get good ring seal out of them, but it's better to space the ring pack out if you are running pistons really loose in the bore. Like a 4032 Forged piston.

Bet ya aren't getting many street miles out of a 1.000-1.100 ring pack.
I have run that too but they were trailer queens.

 

Why run 20-50 oil? A 6" rod is a better choice, longer is not always better (when it comes to connecting rods, anyway). HV pump and a 6q. pan may not be a great idea. I learned this the hard way.

Rich

 

First I have to ask "why" you chose a 6.125" connecting rod?

I can't point to any advice given on this board, ever, which would steer you in that direction. I'd swap them for a set of 6.0" and get the right pistons.

-Mindgame

 

Let's see, why did I choose a 6.125 rod? Well, first I saw a car at the track with the setup I am going with and it ran low 11's n/a at 4000ft elevation in the middle of summer. His car was mostly trailered but I did see him drive it on the streets. Granted I did not completely get "all" the specs(oil clearances,oil pan type,oil pump type,running engine temp, etc.) but I saw enough that I wanted the setup to. I rememeber his top end was wicked and him telling me his stroker was spinning above 7000rpm As far as going with 6.0 rods and different pistons , well can't do that seeing as to I am set on running this setup and the parts have been bought. Now if this car is not able to be run in the street I will be ok with that.

 

The rings on that puppy seal up like a champ and there is about a 1.786 Rod/Stroke ratio so it has very little sidewall loading.... OTOH A 6" Rod 396 is a 1.548 Rod/Stroke and that combo can last a decent amount of time even with that crappy R/S and tight ring stack.

Big454blockchevy,

A long rod setup in a motor is used to make the head port think that there are less cubes under it. This is why the old guys like Grumpy and Smokey loved them because they had very small head ports that they had to deal with. You'll also see them in drag and circle motors that are not restriced by rod length but are restricted by are restricted buy cylinder head volume. Basically your setup is going to make those Dart 215cc heads act a little bigger but that's not a bad thing if you want to twist that 383. It's still a odd combo because if I had the choice I wouldn't run a compression height that small, but then again I have so it's like the pot calling the kettle black. Mostly you just have to work hard at getting the ring seal correct.

Bret

 

Why do you need a 6.125" rod to spin a 383 over 7,000rpm? I've seen it done with 5.7" and 5.85" rods.

 

I 'm not saying you need a 6.125 rod to spin to 7k plus rpms . I stated my reasons for going with this rod. I would never say you couldn't do it with a shorter rod either because it's been done before. Both long/short rod setups have been used before and both have had good/bad results. People will argue the long rod/short rod issue forever. My setup will be off for balancing Monday morning.