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Author Topic:   New engine rules??
UFnARacing
Dirt Full Roller

Total posts: 68
posted December 04, 2002 08:58 AM
Our hobby stock rules have changed a little for the up coming year. Right now we have flat top pistons and stock heads, only. No machine work. Max .460" cam, measured at valve. I'm going to get a new cam this year, because the one in there I'm not sure of. My question is: this year we can run either flat top or domed pistons, forged or cast. Cranks and rods must be stock. Heads must be stock type, exact words "Bow Tie heads, high performance heads, angle plug Chevy heads,etc...shall not be allowed. Angle milling shall not be allowed...1.94" Chevy heads may install 2.02" valves and blend bowl 1/2" below valve seat. No titanium valves" Cam still hyd, .460" max lift at valve.

What set up should I go to, as far as pistons and heads. We must use Holley 4412. Still not clear on intake, but probably stock. Exhaust manifolds must be stock. 1/4" mile, rpm-3000 up to about 6200.

Any suggestions would be greatly appreciated.

Thanks,
Randy


KPLugnut
Dirt Freak

Total posts: 408
posted December 04, 2002 09:42 AM
Vortec heads, mill them .040", and either install 2.02 valves, or just do a good valve job on the 1.94's.
Run flat tops and deck the block to .005" down in the hole.
As for the intake, I'd go with the Vortec cast iron quadrajet intake and a 1" phenolic slider spacer under the 4412 carb. Slide it about 3/4 of the way to the rear and that'll work the best.

Hope that helps. there's tons of other ways too, tho, to make a fast motor with those rules. Other heads that'll work will be the World Products straight plug designs or the Darts too.
But on a short track like that, the Vortecs will make great power in that range of rpm with that cam rule.


UFnARacing
Dirt Full Roller

Total posts: 68
posted December 04, 2002 02:23 PM
My rules allow machining of the heads for "normal warpage", so I could probably get away with taking .040" off the heads. The rules on the block say's the same thing. Would decking the block be grinding to correct "normal warpage" of the block? How much compression would this combo produce? The bottom end has to be stock, except you can use better rod bolts. We can use aftermarket pistons.

One more question (for now), Did the vortec cast iron quadrajet manifold come on factory produced cars?

Thanks for the help, and keep it coming.

Randy

istock59
Dirt Freak

Total posts: 237
posted December 04, 2002 02:34 PM
Regarding the cast-iron vortec intake. No, it never came stock on any GM production car. According to what I've been told, it was built for an "industrial" application. Like a grain truck, cement truck or something along those lines.

It's kinda one of those grey areas, perhaps you can slip one in....

Compression? Depends on the bore and stroke. The toolbox here has a calculator, that should get you close.

[This message has been edited by istock59 (edited December 04, 2002).]

KPLugnut
Dirt Freak

Total posts: 408
posted December 04, 2002 02:55 PM
yes, like Istock says, the intakes are available thru GM but weren't put on cars.
And based on a 40 over flat top motor, generally, the compression will be around 11:1 or just a bit under.
Dynamic compression (in lbs) is the more important thing, and cam choice will have a lot of say in that one...

Hope that helps,
KPLugnut

ray14
Dirt Full Roller

Total posts: 67
posted December 04, 2002 05:09 PM
well i run a 350 thats b0red 40 over with 58cc heads that has been milled 30" and block has been decked 20" with hyperutectic pistons and bye the calculator it is 11.2 compression not sure but i know on compression gauage it reads 240 in every cylinder i also run a crane 465 lift hyd. cam with a 280 dur. an a 108 lobe sep. well thats my 2 cents hope it helps.

[This message has been edited by ray14 (edited December 04, 2002).]

UFnARacing
Dirt Full Roller

Total posts: 68
posted December 05, 2002 09:41 PM
I'm defintely leaning in the direction of vortec heads. But, I'm not sure that I could get away with decking the block that far, I'd think the tech guys would catch it during a tear down. I also have to find a way to convince them that the iron quadrajet manifold came on production cars, any ideas??

Thanks,
Randy

istock59
Dirt Freak

Total posts: 237
posted December 06, 2002 07:34 AM
The intake's have an 8 digit part number on them. Looks like a GM number.

I sent you a couple pics on the side of the intake I have.

UFnARacing
Dirt Full Roller

Total posts: 68
posted December 06, 2002 07:39 PM
I talked to the tech guy tonight and it was good news for me. I can run the cast iron vortec intake. So.....will the stock vortec valve train handle a .460" lift cam? Or, do I have to have some work done to it? I'm still planning on flat milling it.

Bob0092
Dirt Roller

Total posts: 16
posted December 06, 2002 07:44 PM
heres the intake we use http://www.sallee-chevrolet.com/Intake_Manifolds/Cast_Iron_Vortec.html

Eljojo
Dirt Freak

Total posts: 273
posted December 06, 2002 09:27 PM
UFnA, you shouldn't be in trouble with the vortecs with that valve lift. Just be sure the machinist who sets the spring pressures knows what type and lift camshaft that you're running. Circletrack.com has an engine re-build guide that says to leave about .050 between the top of the piston and the bottom of the head (in the quench area) I've always thought that .038 was the majic #. If you're worried about tech giving you grief about the deck height, why don't you consider using a steel shim instead of a head gasket? They compress to about .017 whereas a head gasket only flattens to around .040. Remember that domed pistons and vortec heads make for ugly problems! The spark plug location and the heart shaped combustion chamber of the vortec requires a specially designed dome. Maybe one of our local motor guru's will jump on in...

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