IMCA 500 cfm engine option, what heads?!

Ive built several Southern Sportmod engines using the EQ stamped head/882's/993's and 487's.
The southern sportmod class has a cranking compression rule of 180lbs and 12" vacuum @1,200 rpm.So squeezing all the compression out of it is not an issue.
On these engines the 487 casting seems to have a little more down low and the EQ head picks it up on the top end a little. Not very much difference at all after they are both cleaned up a little because the EQ IMCA stamped head is a copy of the 487 casting. The EQ is more consistant in the casting.
If you have a good set of 487 heads then depending on their condition it might be cheaper to build them but if you have to buy a set then do all the machine work to them the EQ might be cheaper.
Hope this helps.

Really a moot point. To be legal.....the most compression you will ever get with this combo is 11:1 and that is a stretch. A good 406 with a 350 carb will destroy this spec engine. IMCA's only option will then be to outlaw the open engine. Once they outlaw the open engine....and find out how everyone has 11:1 compression. They will then change it to 9:1 or bring in a crate.

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Originally Posted by stock car driver

Thats makes zero sense...

You clearly must not know IMCA stock car rules.

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Makes perfect sense. Since IMCA very seldom ever pulls a head off...can get by with quite alot.

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Originally Posted by parrot69777

Makes perfect sense. Since IMCA very seldom ever pulls a head off...can get by with quite alot.

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What head would they have EVER needed to pull for IMCA stock cars?

Thats the topic of discussion here.



Now that youve read the rules you predict the 360 wont work, lol...

Not a prediction....it's a fact. No different than an IMCA late model going up against an open late model with a 390 carb. 14:1 compression against 10.5:1.

Going to be alot of arguing with this IMCA spec engine this year. Too many loop holes. Too many ways to read inbetween the lines. This stock car engine isn't cut and dried like the sport mod and hobby 9:1 engines are.

IMCA has quite a few other classes that use the EQ or GM heads and other than Boone....have never seen them pull one yet.

"Now that youve read the rules you predict the 360 wont work, lol..."

If you go back to a post I made on 11-30-2010.....I said the same thing about this spec engine not keeping up with the open engines. Stockcar5 had the next post right after it and agreed 100%.

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Originally Posted by parrot69777

Not a prediction....it's a fact. No different than an IMCA late model going up against an open late model with a 390 carb. 14:1 compression against 10.5:1.

Going to be alot of arguing with this IMCA spec engine this year. Too many loop holes. Too many ways to read inbetween the lines. This stock car engine isn't cut and dried like the sport mod and hobby 9:1 engines are.

IMCA has quite a few other classes that use the EQ or GM heads and other than Boone....have never seen them pull one yet.

"Now that youve read the rules you predict the 360 wont work, lol..."

If you go back to a post I made on 11-30-2010.....I said the same thing about this spec engine not keeping up with the open engines. Stockcar5 had the next post right after it and agreed 100%.

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Yes, stockcar5 did and I been laughing about it since. He also put new eq 64cc heads on ebay for a loss of $$ when the 360 rule came out. I believe hes not as dumb as hes playing and knows a 360 at his home track will dominate.

Where do you race?

Have you raced IMCA legal against 360s with 4412's? I have for 4 years.


Oh yeah last I knew the IMCA late model package was the package of choice at our local Nascar track vs a 390 carb open motor, lol.... So not sure what your comparing there. A little more air thru the carb effects a motor all the way down the straight..

None of our big cube motors pull to the end of the straight, they all drop in hp from 5k on. A 500cfm carb motor will pull till near 7000 without any drop in hp.

Pretty simple to comprehend if you can keep gaining speed on the straight over a guy that cant you will win.... Unless you cant corner I suppose since there are 4 corners and two straights!

I don't race anymore....gave it up because I was tired of wasting money and just didn't have the time anymore. Most of the help I had decided education, families, etc. was more important than racing and I got tired of doing it all myself. So I just build engines now and it has been taking up all my spare time. I have been building since 1987 and yes all the 383-420's I build on a 350 cfm carb pull out of the corner, all the way down the straights, and never have to get over 6200. And I don't use dyno's or flow benches.

Never have had the chance to run against the 360's on the 500 carb because this is the first year IMCA is doing it in the stock cars. Never have claimed to know everything...maybe there is something better....but I don't believe in ghost and I don't believe anything on a race track until I have seen it personally.

Since the IMCA late model package is so great.....that is why the Corn Belt series has to give the IMCA guys something like 5 different rule changes to make them competitive.

no 360 motor for me. the 350 carb is low enough on power..i dont need any less. lol

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Originally Posted by stockcar5

no 360 motor for me. the 350 carb is low enough on power..i dont need any less. lol

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Good luck with that at Jackson.

I don't think that the 500 engine would get smoked by the open motor, I ran a very mild 355 with the 350 carb this year, and ran with big 406 and 434 powered cars. It gets REALLY slick out here, and when those big motors even touch the gas, they just spin the tires off!

Putting a bigger carb on it is gonna change everything. Your getting not quite twice the airflow into the engine, take any engine and run half the air through it...be surprised!

So is stockcar5 still running a 350 Carb motor? And is parrots prediction of the spec motor still true?

Lol.. Stock car 5 went to a 360 in 12 and won around 20 races... Not sure about this year, never saw his name anyplace but did notice he won a championship at one track on a sheet I saw.

Good info! So if you had to run a 500 cfm and had no head or cubic inch rule, are 406 & 421s the best engine to use with the limited carburetor?

yea i switched in early 2012 after getting second all the time to a couple of 360's lol. on the 1/2 mile tracks it's amazing how much better they are. and jeff is right. 20 wins and 5 track championships in the last 2 years.

What kind of HP are the spec engines making?

380-390hp 400-420tq is a good one where i dyno.