602 GM Crate vs. Built Engine

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1997bird
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Re: 602 GM Crate vs. Built Engine

Post by 1997bird » Fri Mar 23, 2012 4:19 pm

MidgetMotorsports07 wrote:
1997bird wrote:
dirtracr5 wrote: you must be looking at the wrong rules. open engine gets worse heads (smog 76cc heads no work allowed) spec intake (edelbrock 2701 no work allowed) limited flat tappet (.842 roller tip rockers and 3/8 studs only) non oxygenated gas only no ethanol or methanol. compression rule is 9 to 1.
Which class are you looking at? I assume your looking at a hobby stock, but the rules tha were kind of outlined are for a Sport Mod. The Sport Mods are limited by 175 psi cranking compression after 5 revolutions of the engine. You can almost get 11.5:1 SCR if you know what your doing and still be IMCA legal. IIf you look at the rules there is an advantage to stay with a GM 487 or 487x head castings over the IMCA EQ head that can have nothing more than it being flat milled. If you can't crack more than 400 HP with a 0-4412 carb then you may want to start consulting another builder, with last years rules of having to have 12" of vaccum @ 1200 rpm & a hyd flat tappet cam we were seeing 410-425 HP. With being able to use a solid cam and no vaccum rule this year that opens up even more HP to be had over the crate engine.
Maximum compression ratio is 9.0 to 1, no tolerance. Compression ratio checked using Whistler and cubic inches checked using pump, OR by visual inspection of part and/or casting numbers, pistons.



That is directly from the website!!!!
I had asked on the first page which class the rules were for and they looked like Southern Sport Mod rules, which is what I build for the local CT racers around here.

1997bird
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Re: 602 GM Crate vs. Built Engine

Post by 1997bird » Fri Mar 23, 2012 4:21 pm

dirtracr5 wrote:
1997bird wrote:
dirtracr5 wrote:im looking at imca northern sport mod rules which is what the OP is asking about.

https://imca.com/wp-content/uploads/201 ... rtmod3.pdf

rules clearly state 9 to 1 and solid cams have always been allowed. never had a vacuum rule either. not sure what rules you are reffering to?
IMCA Southern Sport Mod

gotcha thats a totally different ballgame than what we are talking about. dont they allow quadrajets down south?
Yeah they do but you can not run a 1:1 linkage for the secondaries, which puts them at a disadvatage coming off of the corner or in traffic.

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Re: 602 GM Crate vs. Built Engine

Post by Brian W » Fri Mar 23, 2012 4:23 pm

CamKing wrote:With Wistler, 9.2:1 checks as 9.0:1

Do they CC the heads?, or do you just have to check at 9:1
Depends how they check it... If they put car in gear a rock it to find TDC then yes it will usually check lower comp then it is. However if they turn engine over by hand and stop @ TDC it will check closer to actual comp. At least that is my experience with the whistler.

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Re: 602 GM Crate vs. Built Engine

Post by MidgetMotorsports07 » Fri Mar 23, 2012 4:30 pm

Well as lazy as the Techs are around here, we could probably run domes and get away with it. I try to push the rules as far as I can, but I'm not trying to get any of my drivers a fine.

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Re: 602 GM Crate vs. Built Engine

Post by IMCADW » Fri Mar 23, 2012 6:20 pm

I have always felt the Weiand was better with some work.

Now onto the other part of the discussion... 6" or 5.7" Rod?

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Re: 602 GM Crate vs. Built Engine

Post by MidgetMotorsports07 » Fri Mar 23, 2012 7:22 pm

5.7 no question. I like torque and shorter rods make more of it.

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Re: 602 GM Crate vs. Built Engine

Post by raceman14 » Fri Mar 23, 2012 8:10 pm

If your tech man can't find a cheater on compression with a Katech Whistler he must be a retard.
Rocking the car back and forth is for Hilbillies.
You need a 3/8 or 1/2 drive ratchet to turn the engine with and you are supposed to remove all the spark plugs and take the rockers off the cylinder to be tested.

How simple can that be, I have done it a thousand times.

There are ways to cheat the whistler but you have to be pretty smart to do it and I have seen and caught just about every way folks have tried, from cigarette butts in the cylinder to threaded inserts in the head to leak air volume.

Wow, someone else in the world likes short rods...good on ya mate !!!

Sold some tooling to an Aussie customer this morning and he always says that...
More is always better!!! Most of the time.

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Re: 602 GM Crate vs. Built Engine

Post by 2xmod » Fri Mar 23, 2012 8:33 pm

ive heard the crate guys are runnin a jumper wire on the rev box some how, and take it off and put it in their pocket after the checkered.........then theres the spec guys athat claim theyre turnin 7500-8000 with a stock gm smog head :lol: ....... if no one has mentioned it, the northern sport mods have to run a 3/8 rocker stud also. also roller tipped rockers..... how much valve spring can u run with them?

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Re: 602 GM Crate vs. Built Engine

Post by MidgetMotorsports07 » Fri Mar 23, 2012 8:41 pm

2xmod wrote:ive heard the crate guys are runnin a jumper wire on the rev box some how, and take it off and put it in their pocket after the checkered.........then theres the spec guys athat claim theyre turnin 7500-8000 with a stock gm smog head :lol: ....... if no one has mentioned it, the northern sport mods have to run a 3/8 rocker stud also. also roller tipped rockers..... how much valve spring can u run with them?
You can run some pretty nasty springs if you run good studs, and I have built plenty of 355s that turn over 7000rpm with smog heads and a 500

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Re: 602 GM Crate vs. Built Engine

Post by IMCADW » Fri Mar 23, 2012 8:52 pm

I'm thinking the shorter rod is better as well.

Guys run the crate because they know it's working. They don't want to take the time to build a correctly cammed 9-1 engine. They'll slap the good ole shelf piece in it, because it says "high torque" and go racing. Instead of correctly matching the camshaft to the engine, they go the cheap route. It's ok in a spare engine, but when you're racing for all the marbles, you gotta spend the extra $100.

Interesting Mike, on the OEM Heads. The EQ's have shown to flow better than the GM heads. Of course, you are stuck with the 1.94's in the EQ's. Do the OEM's flow better with the 2.02's?

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Re: 602 GM Crate vs. Built Engine

Post by raceman14 » Sat Mar 24, 2012 1:45 am

I'll be glad to flow test some 487x's if someone send them to me.

I think the potential is in the extended RPM range you can get from the open flat tappet and no rev-limiter. 3/8 studs are plenty strong for 7500rpms if you get the right ones. You can easily run 150# on the seat and 400# open if you need to. Guide plates and good pushrods, light retainers, locks and valves and it will be no problem to scream a built engine even with a 4412. Rules say 1.250" max OD on the springs so I will have to OD grind my outlaw springs a couple thou just to make sure they pass.

With the right valvetrain parts you can turn even higher if you can get the carb to suck air down at that point. In most cases 6800-7000 is the max on that intake with a smog head and then you are really pulling on it hard but it helps coming off the corner 1000rpm higher even if you run past the power peak, think of it as compression braking.

I know it is possible cause we did it with double humps, 2101 and a 7448 and we qualifed at Lanier for an ALL-Pro race with NASCAR 9:1 engines making over 600hp. They allowed the winner of the Late Model Stock race to pass into the big race and we finished 7th on the lead lap of a 250 lap race, we never pitted for tires and ran the whole race on one tank of gas...that was the last time they allowed a "TURD/Stepchild" 2bbl car to run with the ALL-Pro cars. The kid who did it was Jonathan Buckner who gave up racing the following year to work a paying job on rich kids race cars.

DW or Midget, can you pm me the flow number you have on the 487's -vs- EQ's ???
More is always better!!! Most of the time.

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Re: 602 GM Crate vs. Built Engine

Post by MidgetMotorsports07 » Sat Mar 24, 2012 2:00 am

raceman14 wrote:I'll be glad to flow test some 487x's if someone send them to me.

I think the potential is in the extended RPM range you can get from the open flat tappet and no rev-limiter. 3/8 studs are plenty strong for 7500rpms if you get the right ones. You can easily run 150# on the seat and 400# open if you need to. Guide plates and good pushrods, light retainers, locks and valves and it will be no problem to scream a built engine even with a 4412. Rules say 1.250" max OD on the springs so I will have to OD grind my outlaw springs a couple thou just to make sure they pass.

With the right valvetrain parts you can turn even higher if you can get the carb to suck air down at that point. In most cases 6800-7000 is the max on that intake with a smog head and then you are really pulling on it hard but it helps coming off the corner 1000rpm higher even if you run past the power peak, think of it as compression braking.

I know it is possible cause we did it with double humps, 2101 and a 7448 and we qualifed at Lanier for an ALL-Pro race with NASCAR 9:1 engines making over 600hp. They allowed the winner of the Late Model Stock race to pass into the big race and we finished 7th on the lead lap of a 250 lap race, we never pitted for tires and ran the whole race on one tank of gas...that was the last time they allowed a "TURD/Stepchild" 2bbl car to run with the ALL-Pro cars. The kid who did it was Jonathan Buckner who gave up racing the following year to work a paying job on rich kids race cars.

DW or Midget, can you pm me the flow number you have on the 487's -vs- EQ's ???
I 'm not sure what they flow to be honest, I think the EQ will probably outflow a 882 or a 993 but the 487X is pretty interesting. I think they will flow as much or more than a EQ.

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Re: 602 GM Crate vs. Built Engine

Post by CamKing » Sat Mar 24, 2012 12:24 pm

IMCADW wrote: Do the OEM's flow better with the 2.02's?
Yes, and if you go to someone who works with those heads a lot, you can really pick up a lot of flow, going to the larger valves.
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Re: 602 GM Crate vs. Built Engine

Post by IMCADW » Sat Mar 24, 2012 3:14 pm

Since the rules are pretty strict, who do you suggest on the heads MIke?

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Re: 602 GM Crate vs. Built Engine

Post by CamKing » Sat Mar 24, 2012 7:11 pm

There's plenty of guys. Look in the New England area. They've got 30 years experience with these rules.
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