383 stroker questions...help requested

[goingballistic]

Ladies and gents been off the board for a while due to work but bakc again.

As some of you are aware I'm building a 383 stroker for my '81 and made quite a few strides......much research, engine desingers involved etc.

One question they can't help me with is this:

I am planning a high volume oil pump not sure the cfm YET but the question is what size pan can you put on the block and stay clear of the frame ( ie no mods to the undercarriage) so the engine just drops in with the new pan. Part numbers would be greatly appreciated if you have dealt with this.

I decided to stay with the 5.7 rods due to the attack angle in the cylinder. With a 383 crank this required a custom grind on the cam and some modifications to the block to accomodate the rod bolts on the rotating assembly, basically clearing casting off the block so the bolts don't hit. THere is about 50 thous clearance between the rod bolts and the cylinder shoulders and also the rod bolts and the cam lobes.

So step one is complete, clearing the rotating assembly, so the engine is apart again and is now ready to go the shop for zero deck, 30 over etc.

Any help or guidance here would be appreciated. Thanks.

Paul.

 

[tomtom72]

Hi Paul, I have a question. On a C3 frame the only thing in the way of the oil pan is the P/S piston linkage. I had a 72 and there was nothing under the oil pan at all. My 72 was a LT-1 with a 4 quart pan & hi-volune pump. The early 70 LT-1's had no P/S and used a 5-quart pan and same hi-volume pump. When P/S was avalible late in 1970 run chevy did away with the 5 quart pan cause it got scraped by the P/S cylinder linkage. My point is an LT-1 was fairly stressed motor and chevy still used a 4-quart pan. I am wrong if the frame on your vette is different than the frame on a 72. If the frames are the same the only two factors that need watching is the ground clearence and the P/S system if it is the same as the 72's. I used a 70 LT-1's pan on my 72 with P/S, but I had to modify the front of the pan for clearance. The only reason I chose the 5 qt pan is because of the oil drainage (or lack there of ) in a SB chevy. Too much oil stays in the heads & cam valley with a hi-volume pump due to bad drainage. I also remember 'experts' being negative about using hi-volume pumps back in the 70's when I rebuilt my motor, but I figured chevy knew what they were doing so I used the 70 5-qt pan and the stock hi-volume pump. Just my two cents. tom

 

[goingballistic]

Tom you bring up an interesting point and observation.

Having to "modify" the pan is what I'm trying to avoid, as far as the oil return problem I have been told that the reason for the poor return is the oil return holes in the cam valley and the fact that the pickup under the journal is not rounded.

I took a dremal tool and rounded those out all the way to the casting around the complete hole removing almost a 1/4 inch in some spots of "flashing" so the holes are now open considerably better than they were ( almost twice the size of the original hole!!!). I was also told that the oil pump return hole in the main journal needed to be deburred and rounded out to act more like a venturi than just a return "hole".

The standard pan is 5 quart, I would like to go to a 6 quart and have heard horror stories about sucking the pan dry. Sinking over $4K in parts into this......sucking it dry is NOT an option, so I am trying to do everything I can to make sure that doesn't happen.........this includes paying a Delphi Engine designer for his time. Everything else seems OK, I'm just worried about the clearance under the car and not sure if I NEED to be worried??????

I've already got clearance problems on the top end with the manifold and carb combo ( that I can easily deal with) oil pans getting holes in them.....I can't deal with.

If I blow this up my wife will never speak to me again..............wait a minute I may be onto something here............just kidding dear:L

 

[JohnZ]

Sucking the pan dry with a high-volume pump is an "Internet Urban Legend", unless your oil drainbacks are seriously restricted; that said, there's no reason to use a "high-volume" oil pump - the stock pump will work just fine (unless you're building a roundy-round track race motor).

 

[Checklst]

I agree with John just use a good quality stock pump unless you are going to turn 7000 RPM for long periods of time like the round track boys.

 

[goingballistic]

"internet Urban legend" my butt, I know two guys who have done this with 383's due to restrictions in the lifter cavity valley. I've bored those out all the way to the block to ensure that I have good return and rounded out the oil pump return hole to create a ventrui effect in the pump on the number four journal.

If it does or doesn't is kind of immaterial, I'm looking for info as the wheather a LARGE pan fits under the engine with no contact to the frame or associated components,I would like to put a high volume pump in the pan and am concerned about "sucking" the pan dry with a "stock" pan, so if someone can help with the clearance problem, I'd appreciate it. Thanks.

Paul.

 

[bossvette]

when I built mine I had a 7 qt Moroso circle track pan laying around and used that it has kickouts and is the same depth as a stock pan. Been on there over 4 years.

 

[goingballistic]

Bossvette, thanks for the reply, just what I needed to know


paul.

 

[JohnZ]

"internet Urban legend" my butt, I know two guys who have done this with 383's due to restrictions in the lifter cavity valley.Paul.

Exactly what I said - if you have restrictions, you'll have problems, and it doesn't matter if it's a 383 or a 283 - the oiling systems are all the same. I've been building SB Chevy engines for 40 years (including 383's), all with stock oil systems, and have never had one "suck the pan dry". Also spent 21 years with Chevrolet Engineering, and never saw one suck the pan dry during 400-hour dyno durability runs. The oil pump hole mod you made is always a good idea, to minimize pressure-side flow restriction.

 

[bossvette]

your local Chevy dealer has a book called the "Power Catalog" it is not so much a catalog, but a How to with part numbers I recommend it to anyone building a Chevy it has specs torque sequences and lots of tricks; it will be the best $9 or $10 bucks you spend!