View Full Version : IMCA Hobby Stock

Dirt Track Dodge
01-21-2000, 06:03 PM
Who runs in IMCA Hobby Stock? Which Mopar fits the class best,what suspension mods , bars and springs ,requires109"wheelbase. Engine combination; 360 or 318 ,which iron intake,I have 2-bbl int from 273 and the 360 that are like the marine with equal length runners or could use the more common style from passenger cars,also have special int from Chry Imperial, carb-no Holleys, exhaust manifolds:340 or Magums, must be rear dump,RPM range, camshaft(hyd or solid) lift-dur@.050 lobe-sep,can use adj rocker,904 automatic or 3sp stick, what converter, 6-cyl flywheel and clutch assemble(could use HD springs in pressure plate). We will be running on 3/8 high-banked dirt,usually dry by feature.Suggestions Appreciated

01-22-2000, 01:36 AM
There are some guys that oval track race that post on these boards. What they race I don't know but I'm sure you will get some help. I race on asphalt, so I'm not much help as far as setup goes. Engine help yes, I run a 318, and the trans question, I run the 904, it has been bullit proof. If you build a torque motor, you can run a stock or very low stall speed converter. I would suggest a big trans cooler if you go the 904 route. We also use 6 clutches in the front instead of 4. To get 6 in you just use the thinner ones, like in the rear. This will give more holding power. Our 318 is nothing special. If you elect to use a 318 I'll let you know what we did with ours.


01-22-2000, 01:41 AM
I would look for a Challenger. The wide track width can make for good handling on nearly stock suspension. The 110" wheelbase fits the class. Another choice might be a Duster. The only drawback I see in the Duster is the light duty suspension components. They may not last in a hobby class. The narrower track width of the Duster may help on dry slick with weight transfer.

You might still be able to find the kit car bars for the front. Also, there are aftermarket manufacturers for bars now.

In a stock type class I would prefer the 360 engine. With a 340 4bbl intake with a 2bbl adaptor. Get the adaptor that allows placing the carb over the secondary ports in the flange.

You should be in the 5500 rpm range with a cam change. I would err on the smaller side with a 2bbl, less than 245° at .050". Get the KB flat top cast pistons for better compression. I would run the 3 spd if you can't direct couple the trans. Get the right gears for your track and run in 3rd. I assume they would be in the 5.67 or 5.43:1 range, depending on the track size, tire size and final weight of your car.

I build my cars in this order. 1. Safe., 2. Fast., 3. Durable. and 4. Pretty.

01-22-2000, 06:23 PM

01-23-2000, 01:56 AM
I run a Dodge Ram in the American Race Truck Series. So we run on tracks from 1/4 to 1/2 mile. Banking from 0 to 15 degrees.
The motor we built has always been built for torque. This year we are going for alittle bit more horse for the bigger 1/2 miles. We found our corner entry speed was about 4MPH off of everyone else, which made me have to brake real late into the corner to stay with everyone. The trucks great off the corners, motor made 352lb of torque at 3000rpm. We gear it right for that and we are good to go!!. Motor combo is late model 318 heads, casting "302", edelbrock rpm manifold, Holley 2bbl, custom 1 5/8 headers, into a Dr Gas "X" pipe. With the heads we put in 5/16 valve stem sized valves. This picked up lots of flow, as these heads are great on the exhaust but need help on intake.
Someof the above is dictated by the rules.
I feel we have done our homework and have the winningest ART in the country the last 2 years, along with the championship. Let me tell you the Chevy and Ford guys hate it, but the Fans love cheering for the underdog, and that is Dodge. IU can't help you much with chassis because all ART's trucks are built on the chevy metric chassis. I can help put you in the right direction if you have a chassis question, i.e. loose? tight, springs, shocks, etc. Hope this helps


Dirt Track Dodge
01-24-2000, 01:36 AM
Finding a Challenger might be difficult but,
would be a great looking stock-car.What is the wheel base of a Diplomat? They're not as great looking but,are more plentifull.They use transverse bars,I've measured cop bars and standard bars and found they are the same. Can these cars be made to handle? What
would be the approximate weight differance,
they look heavy? We race on 3/8-1/2 mile dirt.

[This message has been edited by Dirt Track Dodge (edited January 23, 2000).]

jason hilbrands
01-24-2000, 02:16 AM
i would recomend a 360 with a 904 trans. i have taken a converter and machined it to be a direct drive by retaining the ringgear and the snout only. this reduces the weight to about 7 lbs.


01-24-2000, 02:44 AM
hi guys i race a 72 dart in street stock on dirt and superstock on pavement ! i use a 360 with 3spd 2bl holley 500 cam !! the dart is probally the lightest of the bunch and u can get t-bars and springs for it !! u can also get a front sway bar too ! and if u want u can get a rear sway bar off a cuda or dimpolmat cop car !!
anyone have any a-body torsion bars for circle track for sale ? let me know if i can help !! david

01-24-2000, 02:57 AM

01-24-2000, 04:45 AM
There is a guy in Rapid City, SD that has run the same Challenger for 14 years as a street stock. He has taken a few years off from driving the Challenger along the way, even driving a Chevy. He won a couple of track championships with the Challenger. He even end for ended it about 10 years ago and straightened it out for the next week.

The front suspensions on the cross mounted torsion bar cars is junk in my book. In J-body's Mirada, the top A-arm mount would move in and out about 1/4"-3/8" when uloaded and loaded. That was really wild to watch. Made a guy leery about stuffing a RB into it.

Jason, did you get the pump valve deal figured out? I wondered if you guys were doing your own trannys since I didn't hear from you for some time.

If you can use a direct coupler for an automatic, then you can use the method Jason uses. If you have to be able to stop the car in gear, you can bypass the pump pressure into the pan pretty easily with a 1/2" ball valve and some hydraulic line.

Hey mother, we need us a circle track page here!

01-24-2000, 07:03 PM
I have run an 85 plymouth gran fury for two years in a bomber type class and we had lots of success. the car has the torsion bars that go cross ways on the car. I run on a 3/8 high bank and I can keep up with a wissota street car and these are the national point champions not just a bunch of morons. On a 3/8 you should run 6.20 gears but I ran 3.91 in the car and I ran the car in second gear. I had the cop car version and it has all the coolers on everything. When I first raced it the car would push a little so I messed with the rear stagger and I found that an inch of negative stagger(smaller on the outside) actually worked well when it was dry. I know it sounds odd but it did work. It loosened up the rear just enough to let the rear of the car slide out a little bit and set yourself up for the exit. I raced it a few times on a high bank 1/4 mile and it was dry slick every time we were there. The car worked well on the high side of the track where I could keep up momentum. I still ran it in second with the 3.91 in it. These cars are plentiful unless a blues brothers movie was filmed in your area. ha ha ha. I picked up my car in a salvage yard for 100$ and it even had current registration on it. The car worked well. I drove the hell out of it and I even rolled it the first season. I would suggest boxing the lower control arm to stiffen it because it is a single arm not an a shaped like GM. Spare the challenger because if you wreck it and you want to reskin the body after the season you wont be able to find parts. The wheel base on the four door fury is 112 inches. I am pretty sure it will work for every entry level race class so you can race it at a lot of tracks unlike the shorter challenger. I hope this helps you out and good luck.

YOU must be fast, Because I was haulin a$$ when I passed you!

[This message has been edited by cageman (edited October 25, 2000).]

Dirt Track Dodge
01-25-2000, 03:39 AM
Imca rules require working torqueconverter. Do you know of a tighter or smaller converter for the 904?Also at PJ,
they have to discuss the body and frame rule,I'll let you know.Thanks for the help. Originally posted by jason hilbrands:
i would recomend a 360 with a 904 trans. i have taken a converter and machined it to be a direct drive by retaining the ringgear and the snout only. this reduces the weight to about 7 lbs.

01-25-2000, 04:54 AM
Can you use a lockup convertor for a newer 904 based lockup tranny. All you would have to do is wire it on a switch. Just food for thought. I don't know how well the lockup works in high performance applications.

If you can find an aluminum 4 spd or 3 spd overdrive trans, it would not be too bad for weight. I have the aluminum 4 spd and it is lighter than the cast iron 3 spd I have.

01-26-2000, 01:29 AM
The alum. overdrive tramy we use wieghs 80lbs. Most of the handling problems I have seen a the dirt tracks we race is that most poeple over tighten the right tortion bar making it to stiff causing the car to push in the corners. Keep the car at stock height on the right and lower the left. If it rolls to much, put the next higher rated bar in. Play with differant heights on the rear spring shackles. Last differant rim offsets will also change the handling. Hope this will help some.

01-26-2000, 01:46 AM
I race a street stock class on dirt quarter mile and have been using A bodies. Dusters are 108 inch wheelbase, so that's out for you. But, Dart Sports (like a 74 or 75) are 110 inches and look exactly like the Dusters. You can also use some two door Darts of the same year (plus the '73's I think) that are either 110 or 111. These are good years to use because the suspension already has the big wheel pattern (5 on 4.5). I agree with 340 King, a Challenger would be good to run, but they're getting hard to find. Darts and D/S are plentiful.

I have used the cross-ways torsions like those found on the Diplomats, Volaries and Aspens. I personally don't like them, but they can be made to work on a circle track. They're harder to take apart and reassemble (picture yourself under the car at the track between the heat and the main having to change the right side lower control arm) and don't have bigger torsions available (that I know of). To make them work you must absolutely have a good racing shock on the right front as a minimum. Carrera's the only one I know of who makes them and they aren't cheap. Plus, the shocks are so small on these cars that it would be very problematic to adpat something else to work. In short, they're more trouble then they're worth.

A bodies do have weak front end frames, but the suspension pieces are plenty strong to handle circle track racing. The key to racing a stock bodied mopar circle track car is to stay off the wall and other cars. This holds true for any mopar model as the lower control arms will bend in a second. Without the lower "A" arm design like a Chebby, they'll peel right back on contact. When building an A body, go over every body seam on the car with a wire feed welder and then reinforce the front frame rails with some angle stock.

I use the MP 1.04" Torsions and Landrum springs, 200 LR and 225 RR. I don't think It'd hurt to go softer on the back, but it works fine this way with 53 percent rear weight. I don't use a front sway bar with those bars.

Regardless of the rear springs you use, you've got to get the rear weight percentage up there past fifty. Otherwise, you'll get left behind off the corners. I think my left spring on the back has an inch more arch than the right, but that's no big deal. Regardless of the arch difference, you can adjust your rear ride height and crossweight with lowering blocks as necessary.

I run 360's with KB pistons, cast iron in and out. Since I busted my last set of 340 exhaust manifolds, I went to the magnums off the new trucks (you can get them from the dealer). The engine has to be raised two inches to accomodate the magnum exhaust manifolds. I added two inches to my motor mounts and everything fit. Having the engine that much higher didn't seem to affect my handling at all.

I have one engine with a Hydraulic MP 284 484 grind with the 108 centerline, zero deck KBs and J heads. Ran very well. I race against Chebby 406's predominately and give nothing away. My other engine uses the KB .050 above deck height pistons with a solid MP 284 520 106 centerline cam. Haven't tried it yet.

Once you've got it set up right, you'll have the Chebby guys scratching their heads trying to figure out just how you get through the corners so fast. Good luck!

02-29-2000, 01:08 AM
I run an IMCA Hobbystock. You can see it at www.Galynx.com/Harvey (http://www.Galynx.com/Harvey)

You aren't suppose to change the wheelbase length. IMCA has a wheelbase rule... Unibodies = 109" minimum
Full Frames = 107.5" minimum
( Makes no sense to me, ask IMCA why. )
But I have a couple of friends that have been talking to IMCA tech about the 2 DUSTERS that they are building right now. Sounds like we are going to get to move the wheelbase back 1" on IMCA Hobbystock dusters, ect by changing the leafspring mounts. This will effectively move the back tires back 1". I don't know for sure on any rule with the IMCA. Last year we could run the stock Holley off a 360/400 mopar. This year they outlawed them. This year... no rivits allowed in doors or front fenders. They change the rules often.

I personally run a dodge dart. I tell IMCA that it is a 1977 Dart. (VERY rare, Indead)
IMCA hasn't caught on to that one yet, or the DODGE stickers on MY duster. <grin>
P.S.-What is the wheelbase on a '77 dart?

Dirt Track Dodge
02-29-2000, 05:01 AM
Thanks Trat for answering my question and others here on Mopar Chat.I beleve the 108" unibody rule was to keep camaro's and firebird's out of the class.I think it's great that IMCA will allow A-body's now in Hobby Stock.I'm planning to build a Hobby in the near future,been gathering info. Just got this computer outfit a couple of months ago for the kids,I've been using it up , already fried the printer.I run a 67' Barracuda in Street Stock with 74'Duster front suspension. I race Park Jefferson,it's 1/2 mile dirt,about 15 deg banking.The car is ok on wet or dry,but tacky,it pushes in the middle after it takes a set and you pick up the throttle.The car is 3300#,50%rear,52%left and 48%cross,1.170 bars,180#leaf-L,200#leaf-R,ride height is 7", 8" wheels,265Mc,Caster;R +6,L +2 Camber; R -3,L +2 , toe out 1/8". Is your front end as factory produced or do you move anything around? Do you think production geometry is ok? Also does anyone understand the Basic Race Car Chassis Set-Up For Short Ovals section in the Oval Track Mannual ? It talks about spring combinations and using the swaybar chart on the next page.What does #24Lt./#25Rt.mean? How do you find the spring rates?What is 1.140/1.10 #14/#15 ? Why is the bigger bar on the left? Who do you contact that understands this ?Is it a lost cause trying to find out? Certinlly this information was gathered through research by engineers? Calling the tech line seems to be a waste of time,if you get through they don't know much.
What baseline setup would any readers start out with? Then what would be adjusted to set car for muddy heat race and then to tacky feature? What about dry slick feature with a little moisture at the top ?

03-01-2000, 07:15 AM
Well, an easy way to get half way close is to talk with the track champ (and a few other front runners). Convert their shivvvy front spring rates into wheel rates. ( The easy way to do this is to just divide his numbers by 4 - close 'nuff for you). The MP Tech line guys are mostly drag racers, but they CAN look up the wheel rates on the torsion bars that they sell. Ask 'em for ALL of the wheel rates. (And ask 'em why they don't just put these numbers in the catalog?!?)
The Mopar Performance leafs may put you right in the ball park. A lot of people have real good luck with them, even a few shivvvy freaks. IMCA can't say thay aren't "factory" leafs, either. <grin> Or you can call up Landrum, Afco, Flexiflyer or Flexiform. Tell them your percentages, weights, track conditions... and they will help your buy what they think will work for you.
That #24, #25, #14 ect. are all old leaf spring numbers that Chrysler used to sell during the 64 - 70's NASCAR Championship years. A lot of those same leafs and torsion bars were sold for use on the Chrysler Kit car. That was kind of like an IMCA Stockcar (Only with a quick change & a 4 barrel 355 Mopar smallblock).
Try to keep your overall weight down when building your car. IMCA has no minimum weight for hobbystocks. A lot of the shivvvy guys lie about what their car weights. (Had more that one tell me that their car weighed less than a IMCA Modified!) If your car is under 3000# without you in it, you are in good shape.
Claim one of those big School Bus/Grain Truck Rottenchester carbs off somebody you don't like. Make sure you have the BIG one. (1/2 inch between dividers at the top). I think they have 1 9/16" butterflies.

03-03-2000, 01:26 AM
OK wet or dry, but pushes when track is tacky. Hmmmm.... That means it's pushy. It's ok when wet, 'cause your right foot makes it ok. Same for dry slick. You have a push. The hard part is making a car work on dry slick or sloppy mud. Anything can work on tacky. Why is it pushy? Check these things first...
Tire Pressure?(go by tire temp-hot in the middle of tire=overinflated)
Too much cross Wt?(go by tire temp-LF 10 to 20 degrees cooler than LR is good)Less Cross=More LF temp.
RF Camber Wrong?(go by tire temp-Hotter inside=lean it out,Hotter outside=lean it in)
Wrong spring?(go by shock travel - rig up something to get shock travel measurements)too much travel=not 'nuff spring. Not 'nuff travel=too much spring.
And make sure you have GOOD TIRES. On a tacky or wet mud track I like Continential Conti-tracks (General Grabbers). No less than 5/32 tread depth. Keep all 4 tires within 1/32".Hope this helps.