Restrictor plate engines

I would like to know who to begin conversations with. Someone having experience building engines with limits on air flow. We are in a class that allows only factory iron heads and intake manifolds, a 6000 chip, and a 650 Holley carb. We are resticted to flat tappets and non-roller rockers. I really hope to find someone on here with us having experience designing and building something similar.
Perry

I've done a lot of circle track engines with 2 barrel carburetors and restrictive rules. If you can run a 650 four barrel carburetor you are not all that restricted at 6000rpm. You need to find out what you can do to the carburetor and the rest of the engine. How big can it be? How do they gauge the carburetor?

You are probably going to strike out here at this site. I would suggest going to: www.speedtalk.com. Also I would suggest checking with some of the NASCAR guys. Another possibility is is Brzezinski Racing Products in Pewaukee, WI. www.castheads.com

Hope this helps,

Charlie Evans

Did i read that right in saying you must run a factory iron heads AND intake?

I was just thinking back to when we were messing around with Wes' cousin Shannon's 460 on the dyno. We ran it with a 4412 two barrel and that's 1/2 of a 750. It made 425 horsepower. Going to a 600 Holley 2 barrel which is still 40% smaller than what you can run gave us 485 horsepower so it's not going to be all that difficult to get it to run well with your 650 carburetor. We were running on a Victor intake but NOTHING on the engine was optimized for restricted induction and the compression ratio was only 11.5:1 with a home ported DOVE head.

Yeah... we must run factory iron. 500 c.i. max. I'm currently running a set of Speed pro domed pistons -.005 in the hole, with Dove-C heads that have 69 c.c.'s, three angle valve job, port matching and a Crower cam w/ .520 lift , 240 degrees @.050. We have one season of good success but I am ready for more. We are not allowed carb modifications beyond tuning, i.e. no polishing, changing boosters, flattened shafts, etc. We are checked often with a set of plug guages. I don''t want to cheat, just run stronger. Thanks to you all, 'specially Charlie and Dave. I'll check out the links you've suggested and if you come up with anyone else, give me a shout. Thanks again.
Perry

Carburetor and cam package are CRITICAL on a restricted deal. Believe it or not fuel curve is more important than airflow in this application so I'm not talking about cheating. You will probably be able to pull over 5 inches of Hg under the carburetor but you're restricted to 6000rpm too? 240 degrees isn't near enough cam duration unless you also have to meet a vacuum requirement.

DaveMcLain wrote:Carburetor and cam package are CRITICAL on a restricted deal. Believe it or not fuel curve is more important than airflow in this application so I'm not talking about cheating. You will probably be able to pull over 5 inches of Hg under the carburetor but you're restricted to 6000rpm too? 240 degrees isn't near enough cam duration unless you also have to meet a vacuum requirement.

X2

hpwdboss1 wrote:Yeah... we must run factory iron. 500 c.i. max. I'm currently running a set of Speed pro domed pistons -.005 in the hole, with Dove-C heads that have 69 c.c.'s, three angle valve job, port matching and a Crower cam w/ .520 lift , 240 degrees @.050. We have one season of good success but I am ready for more. We are not allowed carb modifications beyond tuning, i.e. no polishing, changing boosters, flattened shafts, etc. We are checked often with a set of plug guages. I don''t want to cheat, just run stronger. Thanks to you all, 'specially Charlie and Dave. I'll check out the links you've suggested and if you come up with anyone else, give me a shout. Thanks again.
Perry

Perry,

Just because you are restricted in some areas, doesn't mean you don't need to be optimized in other areas. IMO you don't have a good set of pistons with those heavy Speed-Pros the 5/64th ring package, so there's room for improvement in your shortblock. Additionally, I would suggest fully ported heads, with max. effort exhaust. Also you can make a lot of improvement with your factory cast iron intake manifold, especially in the plenum area. I just had a cast iron CJ manifold that I'm doing, up in the Bridgeport and with the changes we've made, the two planes are going to be able to crosstalk much better. This will help the carb think it's bigger. At the end of the day, you can "crutch" your engines ability,,,, or inability to breathe, via the camshaft.

Hope this helps,
Charlie

Charlie is right in that there is power to be found in the short block. Really just trying to make it as efficient as possible to save power. I think you'll find that the engine will be relatively insensitive to changes in the exhaust system overall but what are the rules in that area?

On the carburetor are they checking for a stock booster? The 650 that I have on my pickup is a down legger and I'm not sure if all 650's are set up similarly. If so you might want to see if you could get by with a down leg stepped booster like used in the 950HP. This won't help airflow to any degree but it can make the fuel curve and atomization more effective and this could help negate the effects of the poor intake manifold.

See what Dave is Eluding too, Do the Rules Specify a Part Number for the Carb or Specify certian dimensions and how will it be verified?

Let's see now... yes I am limited to 6k with a MSD box mandatory.
Our carb must be a 4777 Holley with stock boosters, veturi, no visuals except for removal of the choke plate(only), etc. We can run any type of spacer max of 1.00" thickness.
We run Schoenfeld upright headers with 2" primaries and 4" collectors.
Any valves, porting, and flat tappet cams, no vacuum rules.
We actually produced enough torqe last season to pull a taller gear than most of our competition. Last year we ran direct in the tractor rear and low in the C6. We are building a new gearset to let us shift up into our gear with hopes of a better launch this season.
Perry

ok it says you can use a factory cast iron intake? does it say you can or can not use a factory SCJ intake it is cast iron and has bigger runners and ports? I just happen to have I think one of each.... if they just say cast iron it is that for sure....


Randy

Just a thought, not knowing how this would be of assistance, but FoMoCo actually made several sets of Hemi Boss heads in a cast iron configuration. Connie Kalita used them in his dragster in the late 60's. They were originally used in marine applications and can be found. They are a full hemi chamber rather than the heart shaped chamber used in the aluminum Boss 9's. I doubt you could get the full potential out of them with the limitations of the class, but you would definately make some serious power.

hpwdboss1 wrote:Let's see now... yes I am limited to 6k with a MSD box mandatory.
Our carb must be a 4777 Holley with stock boosters, veturi, no visuals except for removal of the choke plate(only), etc. We can run any type of spacer max of 1.00" thickness.
We run Schoenfeld upright headers with 2" primaries and 4" collectors.
Any valves, porting, and flat tappet cams, no vacuum rules.
We actually produced enough torqe last season to pull a taller gear than most of our competition. Last year we ran direct in the tractor rear and low in the C6. We are building a new gearset to let us shift up into our gear with hopes of a better launch this season.
Perry

What tractor rear end are you using?
Massey or Oliver/cockshutt?

I like this topic and I for one am glad you brought your search for performance to the 429-460.com site. Dave and Charlie are pointing you in the correct direction as to your engine's possibilities, as you have presented them. A question that I always ask of your application and the environment you compete is, tire limitations and size and configuration of the primary track you wish to compete. As Dave and Charlie mentions, an efficient short block, professionally ported heads, intake manifold and making the most of the carburetor are an absolute. The camshaft can make a huge difference where or how you position your car at the end of the stretch! A tight corner may need a little less duration as long as you can keep the car hooked up. A slick corner may benefit with a bit more duration, allowing you to use the power a bit farther out of the corner or near the end of the stretch. Many things to consider! Remember it's the package that will prevail, not one part of the engine or the car!

Dave.