396 SBC Stroker for a corvette

[guru]

Here are my thoughts.

I am slowly collecting the parts I need for a 396 stroker for my old corvette. I have drawn my inspiration for my hot rod based upon old racing corvettes of yester-year.

I purchase my parts by and large by what I can find used and I am running out of stuff that is readily available used.

I want to use Hooker Super Comp Side Mount headers which have 46" long and 1.875" diameter primaries, with a 4" tube which accepts a variety of slip in mufflers. The downside of this header selection is two fold, 1.) requires the use of a stock location exhaust port which really limits head selection and 2.) Primaries really dictate a Low RPM motor. This leads me to Dart heads as the cream of the crop with stock location exhaust ports.

I also intend to use a weber DCOE sidedraft setup with 48-55mm weber carburators. I will bother pierce Manifold about the appropriate selection of weber carb as they are the only company who really sells Chevy DCOE setups in the larger diameters. I guesstimate that the smallest choke tube I could use would be a 42mm venturi which requires at least the 48mm weber.

I intend to use my later style OE hyd roller block, and I guesstimate that I will need a camshaft in the 230/236 at .05 range. The major problem with the Weber setups is that they do not tolerate reversion, so I need to use short duration camshafts which limit compression, and this also leads me to Dart Heads with their 72cc chambers which will go quite nicely with my flat top pistons. I may even have to go shorter than the 230/236.

Since the motor does not really dictate the rest of the car, I am thinking that I want a ROD 6 speed transmission with the 3.27,2.13,1.57,1.23,1,.8 gear ratios with a 3.36 rear end. This should use all of my spedometer at 160mph at 5500rpm in 6th gear and cruise very nicely between (55-75mph) 2241-2585 rpm. The .8 final gear is the most durable road race gear. I think the 3.27 first gear is inherantly useless to me, but there isnt really as nice of a 5-speed out there that has a durable final gear and good ratios in between. I could go down to a 3.08 and still use the durable eaton 3-series carrier, but that doesnt really make first gear any more useful. Its not like the car is a truck or anything. My car goes just fine with the muncie first of 2.2.

I think I want to use 255/50-16 tires as I can tires in a road race compound, an autocross compound, and street tires. Plus they are 26.2" tall which isnt quite the 27.1 tall 255/60-15s I have now but are pretty close to the 245/60-15s that I think were an offered performance tire back in the day, which were 26.5" tall.

So I need to find the right heads. I am leaning towards the Dart 215cc heads which the local circle track engine builders can make be all they can be. I am leaning this way because the hyd roller cam will leave my fairly lift limited and the larger valve should help feed the big 396 small block. I mean think of the big ol valves that fed a 396 big block. The only thing that concerns me is that I really want to keep the RPMs down to around 5500rpm and maybe only see 6000rpm max on a rough day when I am really pushing it in 2nd for an autocross or something (gets my 65mph). Though maybe perhaps the Pro 1 200cc heads would probably do the job nicely as well for such a low rpm motor.

So another thought struck me after a couple ounces of scotch. Seems that Dart spent a lot of time working on this speed flow stuff, and it would probably be a shame to mess with that in the quest for flow numbers. So I am wondering if the good money is in just cleaning up the casting with some emery paper like GM advertises with their fastburn heads.

I really like this motor idea as it harkens the 377ci motor with the big ol webers in the 1963 grandsports and the later hilborn get ups. Its purely an affectation but I think its cool.

Thoughts? Criticisms?

[Awesome Bill]

This, sounds like a mess. If your thinking of running the Webers around 6000 rpm with that stroke, and try to make power, you should rethink it again. Your wanting power from a head, then put restrictors on top and then say maybe 6000 rpm when I need something? I don't know what thats about, like there is some hidden power if you turn the little hydraulic under cammed engine up there it will make power. You say all this like if you say it, it will work because you have picked this out of some dream. First of all, you need air to make power, your bore and stroke will demand a certain amount. Figure that out first and then go with a cylinder head that will supply that air at that rpm or power level you have to have. Then put a carb or carbs on top that will give you @ the very least 90% of the air you would need being your going to hurt the VE of the engine with exhaust, air cleaners and anything else you wish to use. I would not even begin to think about RPM until you add into your equasion of renting a dyno for a day or 2 and then you might have a chance @ having a competitive combination. If you want old school, Hilborn is the way to go!

[Dart Vader]

This, sounds like a mess. If your thinking of running the Webers around 6000 rpm with that stroke, and try to make power, you should rethink it again. Your wanting power from a head, then put restrictors on top and then say maybe 6000 rpm when I need something? I don't know what thats about, like there is some hidden power if you turn the little hydraulic under cammed engine up there it will make power. You say all this like if you say it, it will work because you have picked this out of some dream. First of all, you need air to make power, your bore and stroke will demand a certain amount. Figure that out first and then go with a cylinder head that will supply that air at that rpm or power level you have to have. Then put a carb or carbs on top that will give you @ the very least 90% of the air you would need being your going to hurt the VE of the engine with exhaust, air cleaners and anything else you wish to use. I would not even begin to think about RPM until you add into your equasion of renting a dyno for a day or 2 and then you might have a chance @ having a competitive combination. If you want old school, Hilborn is the way to go!
If you think guru's plan needs some adjustment that's fine, but there isn't any reason to be rude about it. Please share your thoughts without insulting...

[guru]

Thank you for your thoughts.:)

I wasnt thinking about magical power, just that because of gearing considerations there may possibly be a circumstance however unlikely that I may need to exceed 5500rpm.

[guru]

I will try and craft a less stream of conciousness plan after work. In hindsight I can see how that would be frustrating.

[guru]

OK as a more to the point post.

I would like to have a 396ci Small Block with a Quad DCOE induction system. I readily admit that this is purely for the sake of appearences and less about performance. The intent of the vehicle as a whole is a general purpose street and motorsports car for whatever event is around for me to attend ie. Drag Racing, Autocross, and HPDE events and road courses. The intent ultimately is to have fun, and open the hood and say "cool."

Because of a variety of reasons like gearing and exhaust, I would like to keep this is a relatively low RPM motor. I would be pleased if the top rpm was around 5500 RPM, with a 6000RPM redline.

I think my engine combo should be:

Quad DCOE 48mm webers with a 42 or 44mm venturi.
Dart Pro 1 200cc Platinum heads w/ 72cc chambers for a nice 10.47:1 compression
Flat top pistons
6" Rods
3.875" stroke crankshaft

The camshaft is a problem right now as I have not looked to far into the issue past the need for very little overlap to prevent reversion. Reversion can cause some pretty severe problems, like spitting fuel out of the carburator. So I am thinking about that. I 'think' that as a starting point a camshaft around 230/236 at .05 with a 114 Lobe Seperation would probably be a good start.

I do not expect the motor to exceed 450hp.

To me this is what a corvette engine should look like, and please bear in mind that it is purely an affectation.
http://www.grandsportcorvette.com/gs/004/004-19.htm

I fully understand that many will have a reservation about the DCOE setup, and agree that there are more efficient means of doing it. It is purely for my own enjoyment and the "cool" factor

If I had the cold hard cash I would buy this setup (just for you Awesome Bill)

http://www.kinsler.com/mel/MalissaManifoldExtracted.JPG

[guru]

While reading many of the posts here attempting to learn more.

I have determined that at 100% VE at 5500rpm my motor would require 630CFM, at 90% as above, I would need 567cfm.

From what I took from Awesome Bill's post, and another thread I located, that because of the restrictive intake system, larger heads may not play a very important roll in making power. So the conclusion I feel I should take would be look at perhaps smaller heads.

[Awesome Bill]

With that stroke, I would not go under 200 cc. The fact that I now understand you want something that is totally cool, there is nothing better to pop a hood and see what your thinking about fire and run. I would do exactly what your asking and thinking if you prepair it like you have listed.
It is true, the fuel will spit right out of the tops while idling so I would not exceed anything in the 40's with duration. You don't need it anyway. I would not want to see your air filters or anything under the hood go up in a real quick blaze!
The lobe sep is perfect and I would use the same thing. Now the lift, I would get it up to .600 and even .630. Comp has some really nice small base circle hyd roller cams that will work very well.
Remeber it has to be a SBcircle or your 1256 cam journals will be junk real quick. You still have to clearance the rod to cam even with the 3.875 crank and H beam rods. You could use the 2" rod jouranl cranks that are available and not worry about notching anything. We now use that even in the 4" stuff. Works well. We still have to touch the rod up a little but nothing like cutting into the rod bolt and compromising the bolt which every other rod company does. They will break, seen it more than once.

I would most likely use the Engler Set up or Hilborn. Kinsler is top quality also but never could get any more power out of their stuff over the other 2 and the lady never shows up. So they should be a little more descriptive when they advertise, I think I may had to dispute my last bid on Ebay because they did not list her as not in the package. lol. All top quality stuff. The new electric fuel injection is the only way to go with the stacks that Hilborn has. Now that is the sweet stuff. Did not mean to come across rude. This political awareness crap is really making our whole world a lot better, Can't you tell? Good luck

[guru]

Thanks Bill.

If I use the 200cc heads I can use the ferrea 6000 valves I have on my shelf. That will work out nicely with some beehive springs.

As I read what your saying, I just wanted to make sure I was understanding you right. You think I would be alright with a camshaft in the 240ish duration range and still not worry about fuel spitting out all over? I look at the camshafts below and the overlap is really small like 44ish degrees.

Inglese(compcams) offers a couple of camshafts but they seem just 1 step to mild.
272/276(222/224) .536/.530 115LSA
http://www.compperformancegroupstores.com/store/merchant.mvc?Screen=PROD&Store_Code=IN&Product_Code=12-491-8&Category_Code=ChevCam

After I read your post I could see that you were more frustrated with my poor writting, more so than anything else, so I didnt make anything of it.

Kinsler lost me at the 9 grand thing. Now if I come across one on ebay for $800 or so that may be different.

[want-a-be]

Try Cam Motion for your cam. They will grind you about anything you want.

Thanks, Don

WCRE

[guru]

Try Cam Motion for your cam. They will grind you about anything you want.

Thanks, Don

WCRE

I have bought a cam from cammotion before, I do like calling them a helluva lot better than calling compcams.

[guru]

Looking over the compcams lobe catalog I came across these lobes.

3192 276 224 152 .378 .069 .056 .567 .605 .643
3194 282 230 157 .389 .078 .064 .584 .622 .661
3196 288 236 162 .390 .090 .075 .585 .624 .663

So I can pull this off with OE hyd rollers and 1.6 ratio rockers

I could have 224/230 and .605/.622 lift

According to their lobe catalog that low RPM and higher spring pressures can make these work. Since I have a 5500rpm motor that shouldnt be that hard should it? The question is the normal lobes are .536/.544 or so, is there really a benefit to more lift?

[guru]

Ah Ha a compromise

http://www.twminduction.com/v8_kits/chevy_350_crossram.html

[Awesome Bill]

Low 40's would be it, 234/244 combo would be good. We built one of these engines years ago for a road racer and the engine never quit pulling. I can't remember how fast his car would go but in front of the shop, I run over 160 mph and got out of it because the car was un stable. We used the GM fast burn heads on a 355 with a Richmond Gear box and his 81 Camaro with all the goodies would fly. Under 5500 engine would not quit pulling. and from 2000-4500, it felt like NOS was on it.

[guru]

Thats awesome to hear.:)