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Z/28's used standard volume pumps with high pressure springs. The bearing clearances were specified bigger on the SHP engines but no where close to being big enough to require a high volume oil pump. You can make a case for a HV oil pump with roller cams to help feed the lifters but I never go there personally.
NOBODY "wedges an oil pump bypass open". That is nonsense. Your builder might have plugged the oil filter mount bypass closed? Oil pumps have pressure regulating valves inside them that control the pressure and bypass the excess oil flow back to the inlet side of the pump. You might want to have another conversation with him about that to clarify what he actually did there.
Build a longer stroke engine if you are firm on your power goals. It will be easier to get there with more stroke. Use 6" rods and internally balance the rotating assembly. You can keep it 100% stock looking.
Brzezinski can build a set of "double hump" Dart cheater heads that look stock but are modern chambers and high flowing ports. The machine the ends of the castings and cut the valve cover rails down so they look like GM fuelie heads. There are other options for "modern" double humps.
Stormin Norman,
A real engine builder would not wedge a by-pass open, but would rather buy the "Non-By-Pass adaptor that bolts to the block for $35.
However, the over-whelming vote on this practice is: NAY. This procedure can actually burst a thin-walled oil filter.
And with cold starts, it can deny oil to flow to the bearings immediately.
Back to the empty oil pan story:
So your engine builder thinks its possible after 50 yrs of knowledge. I did a complete tear-down / rebuild on a 283 two barrel in 1969. I have been around the block once or twice too. I have owned and worked on more SBC than any other engine.
Try to visualize this:. You have 4-5 Qts in the pan. You are turning 6 grand. Oil pump is humming. But where is 4 -5 Qts going to stay and not return to the pan?
In the heads? No. In the lifter valley? No. So where? There are dozens of drain holes everywhere. The oil will not stay "top-side".
That, pump a oil pan dry is an old wives tale. I file it in the same category as damaged valve seats without leaded gas. Still waiting for proof on both accounts.
Well, not entirely true. If one were to plug all drain-back holes in the head and lifter valley so that there was absolutely no oil return, then yes, the pan could . . . . . . .
All mine in the lifter valley are except the large one in back.
Op a 383 can handle high rs no problem. Your engine doesnt have a true 11:1...if you use say an AFR or Dart head with that nice shaped combustion chamber you can run that much even a little more without pinging they dont need that much timing. Very efficient.
Cant really recommend a cam with that 3.36 gear; maybe why some recommended the engine with the larger stroke
If it was me Id put some 195 Afrs maybe even the race port...kick *** heads
Spend the $ on a steel core cam, good pushrods,springs & lifters. You will absolutely love the way a solid roller runs.
Z/28's used standard volume pumps with high pressure springs.
I have one of these in my old parts box. The gears are taller and it's some kind of chevy over the counter higher volume and pressure pump. very common back in the 80's time frame. They even came with a steel collared pump rod compared to the nylon stock junk.
Oh for the record both of my solid roller motors have Allen plugs in the oil bypass. Yes I run WIX or K&N high pressure one quart filters and 7 quart road racing pans for a total of 8 quarts.
My max pressure is about 75 psi hot. Solid roller need lots of oil.
Originally Posted by gkull View Post
how can you get 11.3 out of a 383? I don't think that you understand how the bypass actually works.
What does bypass have to do with compression, I think we are talking apples and oranges?? I'm running 4cc flat tops .008 in the hole with 62cc (measured average) chambers which is 11.3:1 with a .041 head gasket.
How can you get 11.3 out of a 383 is a legitimate question. Things like .008 in the hole isn't a normal engine. It tends to mean that the block was really warped to require that much surfacing, vs your typical .025 in the hole. minus 4 cc valve reliefs is also not a normal performance forged piston. Because they are made to accommodate larger valve diameters and higher lifts. generally they will list like -7 cc and then add in the amount of gasket to block diameter and the distance to the top piston ring. .041 head gasket isn't the best choice ending up with .049 quench.
As to oil bypass. If you open up a pump and look inside the size of the meshing straight cut gears determines the volume of the oil pumped. So way back when we used to buy the Z-28 oil pumps because they were taller pump gears. Then melling came along and made high vol pumps. The pressure coming out of the pump is limited by a spring and ball check valve. as pressure opens the ball the flow is dumped back in the oil pan. Bypass.
Some of those 50 year shop workers never keep up on new things. I've had bubba experiences in both Wyoming and South Dakota supposed drag racers and race shops that screwed up perfectly running complete race motors that I delivered to them. The bubba people could not figure out me delivering distributors that idled with 22 degrees of advance with only 12 degrees of mechanical advance for a total of 34 degrees with AFR 227 cc heads. So they put stock distributers on them to get 10 - 12 initial and 38 total just like the 1970 chevy manual. One of the motors had a bench flowed AED 950 cfm on single plane a 421 ci. I had set the pressure to less than 5 psi with a return type pump. They thought that the fuel pressure was too low so they put on and electric with 9 psi and the first time all the bubbas fired it up it was blowing gas out of every vent hole. It filled some cylinders with gas cranking it over causing the motor to hydraulic lock ruining the motor. It destroyed the NASCAR anti foaming big diameter higher flow needle and seats and then told everybody that I didn't know how to build motors and carbs. This was a dyno tuned boxed up motor ready to install in a drag car.
It's like talking to rock explaining things to them. I said that I would like my dizzy back and the shop told me that they had thrown it away because it didn't have enough advance. I set it up on a machine to only have 12 degrees.
My block was line honed and decked to 9.007. Initially we going to use 12cc dish, but they were unavailable at the time so I used DSS flat tops which landed .008 in the hole. Those DSS flat top pistons are 4cc. Normally I think he would have final decked it to 0 or -.001 and ran a .041 gasket but I was really sweating the compression. .040 is close to minimum head to piston clearance anyway unless you like playing with fire. The oil pump is a melling HV pump with a standard pressure spring, 055A I think. With 10-40 it idles at 40 psi and 80psi at part throttle. Blocking the filter bypass is how he does it, just don't flog on it when it's cold. I think the stock 4qt pan was a concern with the HV pump and the high pressure spring if I recall correctly, he recommended a 7 qt pan for the high pressure but I didn't think it would clear the steering. My builder is really old school, but his stuff holds together which I can't say about some other builders. Sometimes the old guys know what they are doing from experience even if internet lore disagrees.
Build a 400 block w/ a 327 (3.25") crank & spacer bearings. The bigger bore breathes so much better; CUP style.
Yeah, we're not popular at parties... but i second this idea. However, can you not just buy 400 cranks with the shorter throw for relatively cheap now? Last i checked you could, or at very least a 350 crank with the 400 mains. Nothing wrong with a 377 either. However however... you really dont even need that to move a Corvette. A 350, even with a powerband moved well north, will still motor around decently enough at part throttle. Everyone has this asinine notion that big cams and heads and high revving powerbands will be undrivable on the street. the OP has already stated he doesn't want a typical car (read: 383-400 street torque beast that you can mash off-idle), so dont build him one. Even a 7000rpm 350 will move a 3000lb Corvette from light to light as good as a stock one. And when you hit that powerband... POW!
To the OP. With Twisted Wedge or AFRs and a solid roller, you'd have to screw something up to only make 425HP. You could get close to that with stock Vortec heads. I say dont bother stroking anything, and aim higher. Get either head that works best for you, paint it orange if you have to, match 'em with a solid roller, run as much compression as you dare, with tight quench, and with quality modern rods/pistons... and a good single plane/carb/exhaust... and you'll have a dream car. Whew! Lets hope it runs on as well as my sentences...
Edit: Just saw that you want to use your stock block. You can still hit those numbers with a 350. Anything you give up in torque you'll make up in HP. Guys are getting 900HP and 550tq out ov engines that size with full-aftermarket and every trick in the book. You're only asking about 3/5 ov that. The Chevy aftermarket is a dizzying magical wonderland... and for every Mopar engine expert, and every 3 Ford engine experts, you have 10 Chevy experts. Many ov these guys will give you their knowledge. You're really not asking a lot. Though... perhaps asking a high-winding 350 to play nice with that 3.36 rear gear might be a fun challenge...
Someone else above mentioned to skip the sidepipes. I second that too. Race wise, the only good thing about sidepipes is the weight reduction. A true 3" mandrel dual with a properly designed X-pipe (and maybe a modified crossmember to fit it) and some modern zero-loss mufflers would be FAR better. And they'll sound better too. Exit them out the side for nostalgia's sake. Thats what i'm going to do.
Last edited by Pale Roader; Sep 20, 2021 at 03:58 AM.
The big issue with building a 355 (3.480) engine to make serious power is using a stock block. The GM block must be modified not only for strength in the main cap area......but also every oil passage in the block needs to be enlarged for sustained 7000 rpm operation. Even the GM "Bow Tie" blocks need to have this done. Going with a Dart or World block does away with all of that. The oil passages are bigger and the blocks have priority main oiling.
You can definitely modify your block, but it is costly and you need to find someone who knows what I am talking about.
Besides that, a short stroke engine has a higher powerband but needs to live there too.....so the 3.36 gears are 100% out of the question.
If this were my car.....I would build a 406 for it. It could be built to 500hp with almost no strain as you can cap RPM's at 6000......it can also be built with a GM block for a super sneaky setup.....even the stock LT-1/DZ intake could be used with some mods......this engine would be a lot easier to live with at 1.25 hp per cube than the 355's 1.4....a flatter torque curve and less wear overall.
But....if you absolutely need to use your stock block and L-46 crank.......all you have to do is turn back the clock and use the tricks the TRACO did to these 40+ years ago......this is a long list.
BTW...I have never seen a SBC pump the oil pan dry, but I have seen them hold a lot of oil in the heads.......It was notorious in Big Blocks for many years.....in road racing applications the oil drainbacks need to be enlarged and radiused....and restrictors used on Mark 4 blocks. Small block oil drainbacks should be enlarged and radiused as well as the holes are small and most of the oil only has two places to drain....the rear two holes.
Once again....the aftermarket blocks do not have this problem due to priority main oiling.
The concern about running the pan dry is not really a fairy tale. Running extended high RPM small block with bigger bearing clearances during a lively race track event CAN run a pan dry and expose the pickup. Obviously it is not good to have that happen. High RPM and high pressure slings more oil out the rod bearings and with excessive clearances it becomes an issue. This concern was mitigated with proper racing (sensible) bearing clearances and running stock volume pumps with high pressure springs along with the baffle tray and the matching pan. They advised running 1-2 quarts over full for competition events, as required.
A page from a GM "Camaro Chassis Preparation" packet. This was provided to SCCA racers who asked for it 50 years ago.
Comment on running the pan out of oil. As tire technology and suspension increased turning and braking "G" forces started exceeded "ONE G" This would cause the pump pickup to become exposed. I remember the days of running an extra quart or two before the proliferation of aftermarket baffled larger volume oil pans. There is still a point with the best Road racing pans are not enough. With my 8 quart setup I would have my oil pressure red light come on in long high "G" turns.
The cheaper answer is to install an Accusump oil tank that feeds pressurized oil when ever it senses a loss of oil pressure. I had actually installed a few at work, so I bought the 4 quart system for my Vette and never had an oil loss again.
Running 7000 rpm all the time is not a big deal on stock block class racing. You have to address the oil issues to make it more of a priority mains oiling system. My road racing 383 and later 396 used the 8 quart system with melling high volume pumps. I used drilled out to .110 Morroso top end oil restrictors in the back of the block. The heads also have machining to increase the oil return. I've tried restricted oil flow push rods in the long ago past.
The bottom end is just your typical 4 bolt block, but using ARP studded main caps. You can also add billet steel main caps to the studs. I have never been a stock 400 block person, way too many failures.
My Morroso big pan is made for up to 4 inch stroker stock blocks. I only build 396's I won't build a 383 because the cost of the quality rotating kits are the same. So my original L-82 has morphed into a 396 with as big as cnc factory ported dart 227cc heads with 2.10 intakes and 1.625 exhaust . It easily has done years of road racing banging off the 7500 rpm rev limiter in ever gear lap after lap. Even a 6 hour endurance race with three drivers. It just gets refreshed periodically.
Arent these cars closer to the 33-3500 range? Wtih that gear Id want that extra stroke to get it moving.
The OP is talking a race-inspired, stripped down car. Even with the performance upgrades it should still be nowhere near those numbers. Hell, those cars were barely over 3100 stock to begin with.
Jebby and Pale Roader, thanks for the info. This gives me some stuff to think about. I should have mentioned in my initial post that I don't mind changing gears if that makes sense. I planned on rebuilding the rear end anyway, and gears are cheap. I didn't know about needing to open up the oil passages or beefing up the block to run high RPMs. I guess I can talk to the machine shop I plan on using and see what the cost would be. I would think they are familiar, they build racing engines and have been well regarded here in DFW for decades.
I would consider a different crank, but I really don't want to have to buy a new block. Not just for the cost factor, but I just don't have anywhere to store a complete engine without it constantly being in the way. If this idea is just not practical, I'm open to going a different way.
I would consider a different crank, but I really don't want to have to buy a new block. Not just for the cost factor, but I just don't have anywhere to store a complete engine without it constantly being in the way. If this idea is just not practical, I'm open to going a different way.
That's what I did. I had my stock 4 bolt bored out .030. I bought a complete 6 inch rod, fully forged, 4340 3.875 internally balanced rotating kit. They used to be about $2500 complete with bearings and rings. So all you need to buy is a damper, timing double roller chain kit, cam, pushrods, roller rocker arms, gaskets, 7 quart road racing kick out pan, aluminum heads and intake. at least a 750 double pumper carb. Oh the list goes on.
Especially when you find out your vettes short comings!
My favorite stock 4 bolt block motor is the 396 ci with a 3.875 stroke light weight crank. My vette has one that does 7500 rpm all the time and is in the mid 500 hp range. Solid roller with AFR 210 heads.
Is that the one you mentioned here? I thought you were referring a 396 big block. What valve train parts are you using to rev that high? And yeah, I understand the "one thing leads to another" aspect of messing with cars. :-)
^^^396 sbc. Shaft rockers are foolproof, but depending an ARP 7/16 stud and good rocker arms arent bad
Sounds like you need to talk to your builder tell him your goals. Perhaps the track you run on to optimize your powerband/gearing so it works for you.
Anyone can build a hp # but that doesnt mean it will work for you. A good quality oil cooler & oil pan will serve you well
Dont want your oil climbing the walls in a hard corner uncovering the pickup.
Yes, I will talk to the builder, although he won't really be the builder. I'm going to build it myself, but the machine shop I'm using does build race engines, and has quite a good rep around here.
Yes, I will talk to the builder, although he won't really be the builder. I'm going to build it myself, but the machine shop I'm using does build race engines, and has quite a good rep around here.
I'm not racing this car, it's just for fun.
If you are not racing it then a stock block with no oil mods will probably do what you want......
You have to at this point choose what you want.....a peaky high revving great sounding unit with a lot of gear.....or pure grunt and power. Decide on a power level for your build. Is an 11 second 1/4 car fast enough for you?
I can tell you this much.....if you drove a 355 then drove a 406 back to back......you would never look at another 355 again...Lol.
I am restoring a 70 L46 coupe....... But it will be a street car, not a race car, so I don't want to totally kill the bottom end either......My goal would be to get in the 425-450 range for HP and torque. I want it to look as close to stock as possible, so I thought maybe use those Trick Flow heads that have the double humps. But from what I read, the AFR heads are probably better. Not sure if I need them to get to the goal though. And I see the AFRs are raised port, so I don't know what that does for header selection. I had planned on using Doug's side exhaust headers.
I'd also like to go to solid roller lifters for the higher RPM stability. I don't mind the extra maintenance, actually I enjoy it. Are there are rockers suitable for use with a solid roller valve train that will let me use the stock ribbed valve covers? The engine already has a Performer RPM manifold on it, so I can use that or not. ...Going to do the electric headlight conversion, and I have manual brakes that I'm going to keep, so I don't need tons of vacuum. Keeping the Muncie, and I think the gears are 3.36......I will rebuild the bottom end. The L46 used a forged rotating assembly, right? I'd like to keep the stock crank. The rods I don't mind replacing if it makes sense, but if reconditioning will work for that HP level, that's fine too. I'm expecting to have to replace the pistons as I'm thinking they will have some degree of wear, or I'll have to bore, but I haven't opened the engine up yet.
So what would your recommendations be for this engine?
On second, or third thought ...
Build a ~355" w/ Your block, ... it'll easily make 425-450 H&T with good heads & cam-valvetrain. Probably No sustained hi revs in practical use (so no need to open oiling up nor have squirters for valve train or pistons etc). Use Your forged GM crank but have it magged etc. But lighten assembly via 6" or 6.125" I-beam rods w/ cap screws e.g. Scat/Manley, appropriate compression height forged pistons (shorter = lighter) w/ thinner metric ringpak e.g. Mahle/JE, Heads either TFS hump, Dart P1, or AFR enforcer are plenty capable (No matter which heads/springs; absolutely ensure you have adequate springs (e.g. PAC) according to Cam maker), New damper, good RoadRace pan w/ windage tray, Cam pick that once you've settled on RA specs, upgrade oil pump to later M155 (has stock P&V but larger inlet). JMO, I do Not care for "RA Kit" because Kit seldom best meet YOUR needs/requirements. Have a trusty proven local shop balance Your RA. YMMV
Last edited by ebbnflow; Sep 20, 2021 at 05:43 PM.
I bet the typical Scat forged bottom end with Ibeams would be more than sufficient for him
A good 195+-cc head, headers the usual stuff. Wtih a solid roller I wouldnt be surprised if he snuck up on 500hp
Its not too hard to make these days if you have a good cyl head. Good 750ish DP carb, HEI hes set.
On second, or third thought ...
Build a ~355" w/ Your block, ... it'll easily make 425-450 H&T with good heads & cam-valvetrain. Probably No sustained hi revs in practical use (so no need to open oiling up nor have squirters for valve train or pistons etc). Use Your forged GM crank but have it magged etc. But lighten assembly via 6" or 6.125" I-beam rods w/ cap screws e.g. Scat/Manley, appropriate compression height forged pistons (shorter = lighter) w/ thinner metric ringpak e.g. Mahle/JE, Heads either TFS hump, Dart P1, or AFR enforcer are plenty capable (No matter which heads/springs; absolutely ensure you have adequate springs (e.g. PAC) according to Cam maker), New damper, good RoadRace pan w/ windage tray, Cam pick that once you've settled on RA specs, upgrade oil pump to later M155 (has stock P&V but larger inlet). JMO, I do Not care for "RA Kit" because Kit seldom best meet YOUR needs/requirements. Have a trusty proven local shop balance Your RA. YMMV
This is kind of what I envisioned.
Jebby, I know what you're saying about the 406. I just built a stroker motor for my son with a Mopar 318 polysphere engine (yes, you read that right) and it's night and day. But I have two other big block Mopars that I'll be restoring next. One is a 383 that I'm going to stroke and build to 500+ hp. The other will be closer to stock, but it has a 440 and they are no slouch. So those cars will be built for low to mid range monster power and torque. I want the Corvette to have a different personality, so I have some variation in my "stable".
