Okay, time to unveil my Corvette.
I've been working on this for about 2 years now, and I'm one Muncie rebuild away from completion.

My Vette was a 355-powered 1968 convertible, with an M21 Muncie with Hurst shift kit option, and 3.36 posi rear end. The original 327 threw a rod when the car was 7 years old, so that's long gone.

New engine: 433 cubic inch BBC.

Suspension: 550 #/inch front springs, 340 #/inch rear glass spring, urethane suspension components, front and rear sway bars, Bilstein high pressure gas shocks.

Transmission: Trying to secure a deal on an M22 Muncie. Otherwise will rebuild stock M21 Muncie and hope for the best. Would like to upgrade to a future Jerico 4 or 5 speed.

Performance: Best estimate, untested, is by Mr. Gasket's Dyno2000 software. 630 hp at 6500 rpm, 591 lb-ft at 5000 and 5500 rpm.
Reality will be less, I'm at 5,800 ft ASL and Dyno2000 software I believe is a little optimistic. I'm hoping for the approximate performance of an original L88, but with less compression and more modern technology.
Will be tested on a chassis dyno after engine break in.

Intended use: Weekend warrior, mountain cruiser, classic racer in road and track events. Ultimate goal is a run in the Silver State Classic.
NOT a drag racer, but should be capable of respectable et's.

Engine Details: (The good stuff)
Block is a 454 4-bolt main with nodular iron main caps and ARP studs.
Crank is a GM 427 forged crank.
Rods are GM forged steel I-beam, std length, shot peened and polished.
Pistons are 0.030" overbore forged TRW, "435 horse" pressed pin type.
Compression ratio with 109 cc heads is about 11:1.
Camshaft: Crane SR-246/362-2S-10 solid roller. Duration is 246/254 @ 0.050", 296/304 advertised, 110 LSA, with 0.615/0.636" lift.
Valvetrain is full roller, extruded aluminum.

Heads:
My machinist, and many racers convinced me to try these.
They're oval port 063 GM iron heads, for excellent torque but ported to flow well.
They are fully ported, polished, bowl blended, 3-angle valve job. Machined for 2.30" intake and 1.88" exhaust valves. Combustion chambers are unshrouded, which brings it to 109 cc's measured.

Head Flow:
(How's this for an oval port?)
Measured at 25" H2O pressure drop using a Superflow Model 600.
Intake:
Valve Lift CFM
0.100" 63.9
0.200" 132.5
0.300" 198.5
0.400" 232.8
0.500" 261.4
0.600" 272.9
0.700" 272.9

Exhaust:
Valve Lift CFM
0.100" 52.4
0.200" 104.8
0.300" 137.1
0.400" 169.8
0.500" 192.3
0.600" 201.9
0.700" 208.2

Maximum exhaust flow is 76% of maximum intake flow.
Machine work and flow testing performed by Ridge Reamers, Inc. (303)420-3543.

Redline: 7400 rpm, but shifting will occur at 7000 rpm for maximum torque transfer.

Carburetion: Barry Grant Gold Claw, double pumper type, with removeable venturi's. 775 cfm sleeves for high altitude work (Colorado).

Intake: This is experimental. I have experienced very good results with the Torker and Torker II designs. So will try a TII with exhaust crossovers blocked and a 1" HVH Supersucker carb spacer (if it'll fit).

Hood treatments: Stock small block hood with 1967 style 3 1/2" stinger scoop. Cowl induction for the carburetion, and ram air for intake cooling.
filtering will be courtesy of K&N.

Fuel: Will have to experiment here. I'll start with half a tank of av-gas or race fuel, and the rest pump premium. 11:1 on iron heads will need some increased octane, even at this altitude. Fuel will go through an air-air and an air-liquid cooler with fuel bypass back to the tank. Electric fuel pump.
No nitrous will be used. They won't allow it for the kind of racing I want to do.

Oil: Remote filter mount, with oil lines to air-air and air-liquid coolers.

Cooling: Custom radiator, 4 core, no radiator support. Radiator will mount directly to the sides of the engine bay.

Exhaust:
I had explored two options. I have a set of Hooker Supercomp headers and a set of Hooker big block sidepipe headers with sidepipe extensions.
I will not be using the stock Hooker inserts, but rather a custom muffler insert that flows much better. The Supercomps are under-car headers, and I will save them in case I change my mind. They would have employed a Dr. Gas X-pipe and a pair of Flowmasters.

Rear End: I'm keeping the 3.36 for top end capability. The torque of the 427 will move these gears well, but they don't really shine until you're over 100 mph, and then up to 180 mph, they are beautiful gears.

Driveshaft: Custom chrome-moly 3" with Mark Williams billet yokes.

Body/chassis modifications: There will be frame stiffening. I'm designing a cage that stays under the bodywork to allow use of the OEM soft top or a hard top. There will be a rollbar which must be 2 1/2" over the top of the helmet (which wouldn't allow use of the OEM tops if fixed, so it will be removeable...obviously not NHRA legal).

Tires: BF Goodrich Comp T/A R-1 tires, 255/60-15, on aluminum wheels. I bought two sets of these and now they are no longer available. After these go, I'll have to upgrade to 17".

So let's hear it. Constructive criticism is preferred. How will it run?
No :troll please.
I've worked hard and invested much money on this shark. What would you do different, or would you keep it just like it is?
Some things are variable, if I choose. Intake and exhaust can be altered based on experimental results, but I think I've got it pretty well optimized for powerful midrange and very good top end performance, up to 7000 rpm.

Let's hear it.
:cool:

 

nice ride momo. even with the porting, the o port heads might not make power much past 6500 IMHO. I have the Performer RPM O Port heads which have bigger "baby square port" heads and will make power to 6400.

your build up is very well thought out. FYI, there is a company (see this months hot rod) that is make NEW M22 trans. a doug nash or T56 6spd will really MAKE the car. the BB going down the highway revving high gets annoying. mine doe 3K at 70 mph crooze, the zr1 I have is only 2200 RPM @ 90!!!

the alum heads are a "down the road" upgrade. I would also suggest a lightweight alum water pump, gear reduction starter, and a high quality alum radiator with dual high flow electric fans to keep the beast cool. in the summer, run distilled water with some redline water wetter.

a roll bar is a good idea as well as some "corner gussets and strategic bracing to stiffen the frame. I wanted to box the frame and use some structural foam to stiffen things up.

cool project, keep us posted.

:yesnod:

 

Momo, using AFR's flow vs. hp formula (hp=cfm*0.2575*no. of cylinders), maximum hp would be around 560 with your flow numbers. That is with everything optimized as well. Still very good numbers though!

Also agree that a overdrive tranny would be better for the applications you are thinking of. I have 3:73's in my car and loathe highway driving. Before I changed to 3:73's, I had 3:36's, and I always wished I had another gear for the highway. My next mod is a OD tranny. You might consider 3:08's.

For sustained high-speed running, you might want to consider aux. coolers for the diff and tranny. At least use synthetic. The m-21 will run hotter than the m-22 ( at high sustained speeds) due to the increased thrust loading from the 45* gear cut.

Sounds like a well thought out car (although the cam will be pretty lumpy for putting around). Have fun with it :cheers: !!

 

Pirelli makes a tire that size with a VR speed rating if that helps

 

Sounds great MoMo!

The chassis dyno results should be real interesting. I'm curious to see what rpm your heads and intake will support. This should end the debate for good!

Why the M22? I would think a TKO or Richmond 5 would be a better choice for similar money depending on your preference for tight ratios or overdrive. I can certainly understand if it's a nostalgia thing or a real good deal on the M22.

3/8 or 7/16 rod bolts?

-Joe

 

I'm learning to use my new copy of Engine Analyzer, so I thought I'd give your engine a try. You can download the report here: http://members.bellatlantic.net/~kayser/temp/MoMo.pdf

This program is supposed to be more accurate than DD2000. It says 570 hp at 6000 rpms with open exhaust. Interestingly, it also lost around 80 hp when I added 2.5" dual exhaust!

 

MoMo, that sounds like a bad **** ride! I'm interested in your removable roll bars. Do you have picts? I want to do something similar on my '58 someday.

It sounds like you have really planned out everything, that's why I hesitate to bring this up... can you tell me how you got 11:1 cr?

Here's what I get:
433ci/8 = 54.125 ci per cylinder
16.36cc = 1 ci
109cc/(16.38cc/ci) = 6.65 ci

(54.125ci + 6.65ci)/6.65ci = 9.1 --> 9.1:1 cr.

I hope I'm wrong... let me know. :chevy

 

:cheers: :chevy

 

I don't know much about big blocks. But I'm surprized at how small the CFM numbers are. All you need is ceramic coatings and don't worry about having to use higher octane fuel.

 

Sounds like a nice ride. Like others have already stated I would want better head flow numbers and a overdrive transmission. I have a roller cam close to those specs and it falls a little short by about 6000-6500.
Good luck with your new ride.

 

Nice ride. A car this powerful needs to handle. I would go w/alum heads, manf and anything that would reduce weight. You will spend more time cruising than anything else. Get the 3:08s, you have enough tq to pull hard through grars. Tires are a little small, you will need more rubber, just to stay in control. W/ your cr, I would step up to longer rod. Having to find special gas is a PITA. Other than that I think you will be very happy.

 

I believe the 435 pistons have a dome, but I'm not sure how big it is. Now that I think about, weren't the 435 HP cars around 10.75:1 with closed chamber heads? (under 100cc chambers?) Maybe the deck is milled?

 

MoMO it sounds like you've done your homework. Should be a very fun ride :D !

 

Thanks guys.
Let me see if I can remember everyone's questions.

First of all, yes, the 435 horse pistons have a dome, in fact, a large dome. On closed chamber 105cc heads, they would have been 11.4:1, but with the unshrouding of the valves, which bumped them up to 109cc's, that dropped compression down slightly to about 11:1. And that's according to the machinist I worked with.

Next, I agree, aluminum heads would be a natural future upgrade. If I find that the heads are the limiting factor above 6400 rpm, I could someday upgrade to aluminum. We'll see how it goes.
I had to work on a compromise. I live at over a mile in altitude, and the air is thinner here. Rectangle port, small-displacement big blocks that run at Bandemere seem to lose too much torque in this thin air. The large valve oval ports are an experiment of mine to see how well I can maintain high torque of an oval port design and still get it to rev. Sort of have my cake and eat it too.

I thought the flow was better too, but I see that most of the aftermarket oval port heads are advertised to flow a little bit more than these. So there may be room to improve down the road.

Also, I do have an aluminum water pump, to save what weight I could.

The choice for the M22 possibility is because it is an unbeatable deal. This guy installed it behind a carbed 305 in an '82 Camaro, and he knows it's way too much transmission for him. He wanted my M21 in trade because of its quieter operation, and knows I need the strength of his M22. So the deal is a straight trade...pretty good deal.

I saw that article on a company that makes M22 stuff. Very interesting. I wonder what they charge. I should look into it.

Last question that I can remember is, yes, I do plan on having auxiliary cooling for engine oil and fuel. And I'm planning on a custom radiator that spans the entire width of the engine bay.

This car I want to be very strong in the midranges, which I know the oval ports will give me. I also want it to be capable of higher revs, which the low-rise single plane intake and bumpy solid roller cam will give me. And the 3.36 gears, although not great for off the line response, are really good gears at higher speeds, although you're right, I've always wished for an extra gear to grab.

So that's a future upgrade option too.
However, with a torquey engine, taller rear end gears feel alright. It won't be a slouch off the line.

Oh, exhaust came up. If I were to go to undercar exhaust, I would keep it 3.5" into an X-pipe crossover, and 3" out of the crossover and all the way back. But because I'm going to try the Hooker sidemount headers/sidepipes first (because of their knock out looks), I will have a 4" collector pushing exhaust gasses through a customized pair of 3" inlet/outlet Purple Horny glass pack headers sitting inside the sidepipe extensions.

570 horse is believeable. In order to break the 600 horse range, I'd have to be capable of those high rpm's. And we'll see how those heads do on the top.


[Modified by MoMo, 3:37 PM 4/23/2002]

 

Well, I guess you can't argue with a free M22 :lol: :cheers:

 

Call back to your head porter and make sure they really used 25" as the std. Many heads are rated at 28" which will drastically affect the comparison to most aftermarket heads. There is a conversion factor but off hand I don't have it. Your head porter should easliy be able to give you comparison numbers.

At 25" they don't seem too bad. The I/E ratio is very good. Will help with your closed exhaust running and shouldn't need as much overlap to make it work. With 2.30 valves in a 4.280 bore, you might want to seriously consider using .030 or .050 offset head dowels from Moroso to "scoot" the head slightly to get the intakes further from the wall. The close proximity to the wall will kill all that nice flow. You really need a big bore to allow that size valve to flow.

I'm interested also in how you like that cam. I believe it will be a pretty good choice, but that 2.20 low and 3.36's is going to be tough to get moving.

Save up for a Richmond to get another gear in it. As much as I love Horsepower, I think some gear multiplication will be in order before better heads.

Don't worry too much about your heads. I rode in a 502 street race type car the other day that a buddy has. Runs pump gas, 10.0 comp. Crower hyd. roller cam, Dart intake, 950 CFM carb and heavily ported GM iron oval ports.

So far he has run a 10.31 at 131 mph on MT ET streets with a 2500 converter, 3.73's and a 3200 lb race weight with him in it. No bottle or power adder. It pulled 6700 rpm easily here at sea level in high gear!

Good luck and keep us informed!


Jim


[Modified by 427Hotrod, 6:46 PM 4/23/2002]

 

Jim, I sure wish I photographed those combustion chambers before I bolted them on the engine block. The machinist did some significant work around the 2.3" intake valves to unshroud them. So they're not right next to the wall, because the wall has been...well, cut back pretty far. Probably about an additional 1/3" further back from that side of the valve, or more. He did that because just like you said, he was worried that the bigger valves would be too heavily shrouded to achieve the desired results otherwise.

I wasn't looking for a king of the hill motor like some probably thought (Mountain Motor). What I wanted was the feel of an L-88 using a little modern technology, and I think I'll have that.
My neighbor runs that exact cam in his 468 BBC-powered 69 GTO, and it's pretty hairy. But get that stick wrapped up tight and it pulls damn hard past 7000. I've been in his car and it's intoxicating...really really quick.
It'll be bumpier in 35 less cubic inches. Kind of an enormous cam for a street-legal car.

Thanks for your input. As always, you're very helpful

 

suggest you talk to Guldstrand to optimize your suspension: bigger is not always better with C3s.

 

Wow-eey :eek: