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Author Topic:   everyones thoughts
19J
Dirt Freak

Total posts: 370
posted April 18, 2005 08:53 PM  
I have an 83 Dodge Challenger. Last year i ran a head that had a lil taking off of it my guess is about .010 or so. From what i heard the guy will do the bare minimium and i only had it flattened out. So my guess is about .010 with a stock mikuni carb and a stock intake this year we took a "hi rise" intake off of a d50(supposed to flow better) and made an adapter tip welded it to the intake got rid of all the vacuum holes then put on a 2 barrel rochester and took a diff head and milled it a hundred. We thought it would give more power but i gotta disagree i think. I changed my tires to get more gear. I turned about 4200 at the end of the straight im pulling that off the corner now and i think it is doggier. Well i guess what im saying is it dont pull of the corner. My question is what would be the first thing you would do and why. But one thing im not switching to a ford or switching cars period lol. I was fast last year i had some problems but first 2 nights out were top 5 this year i dont even think im top 10. We played with the carb but im wandering if it is smaller than the mikuni. We might switch back. Im almost thinking that my cam wont pull hard up high which it really dont. It has great power on the lower end. Thanks.

bigcityracer
Dirt Freak

Total posts: 431
posted April 18, 2005 09:13 PM  
First off has there been any other changes besides head cut, intake, carb and tires?
Cam? Gear? ect?

What is your top rpm right now?

Do a basic check first. Cam degreed? Timing set? Compression check? If all is well there, I would first change tires back and carb. Run and note changes.

I don't know a lot about the Dodge motors, but if cam is in head and head is cut you most run a adjustable timing gear to degree cam. That could be the hole problem.
Good luck!!

19J
Dirt Freak

Total posts: 370
posted April 18, 2005 09:26 PM  
Its actually a mitsubishi motor. A 2.6 It doesnt have an adjustable timing gear the cam has a hole in it the timing gear has a peg. Gear only has one hole for the peg. It has a tensioner built into the oil pump to keep them tight. I changed the tires to get the rpm. Thats all the changes made. Intake carb tires and more off the head.

Oh yeh rpm last year about 4200 at the end of the straight. This year about 4200 off the corner and about 5300 or so at the end of the straight.

[This message has been edited by 19J (edited April 18, 2005).]

bigcityracer
Dirt Freak

Total posts: 431
posted April 18, 2005 11:07 PM  
quote:
Originally posted by 19J:
Its actually a mitsubishi motor. A 2.6 It doesnt have an adjustable timing gear the cam has a hole in it the timing gear has a peg. Gear only has one hole for the peg. It has a tensioner built into the oil pump to keep them tight. I changed the tires to get the rpm. Thats all the changes made. Intake carb tires and more off the head.

Oh yeh rpm last year about 4200 at the end of the straight. This year about 4200 off the corner and about 5300 or so at the end of the straight.

[This message has been edited by 19J (edited April 18, 2005).]



WITH THIS INFO I WOULD LOOK AT GETTING A ADJUSTABLE TIMING GEAR OR OFF SET PIN TO RESET TO DEGREE CAM BACK TO CRANK. I THINK THAT'S THE MAIN PROBLEM YOU ARE HAVING.

19J
Dirt Freak

Total posts: 370
posted April 19, 2005 08:43 AM  
I guess im lost. Why would i need that? The cam and the crank would already be degreed to each other factory specs and couldnt change. So i dont get it. Thanks.

bigcityracer
Dirt Freak

Total posts: 431
posted April 19, 2005 08:45 PM  
I may be talking out my a$$ if you don't have cam in head???
I don't know much that motor. Just thought it would be over head cam.

19J
Dirt Freak

Total posts: 370
posted April 19, 2005 08:47 PM  
Yes it is overhead cam. But im just lost on why i would need to degree it in again.

popeye14709
Dirt Forum Racer

Total posts: 86
posted April 20, 2005 06:20 AM  
First i think what Bigcity is tryin to get you to do is double check your cam(degree) 1 degree off means alot also is this a stock cam or an aftermarket? Im sure you know that with all cams there is a power band in wich you need to run your car to get the optimal performance outta the cam...another thing to check is your rochester carb was this a used one you had layin around or a slightly(lol) modified card? check the jets that your mikuni has and the jets in the Rochester but if you already messed with carb i would think you already did...also whats your timmin advance? another question is the motor getting hot? also at the end of the straight @ 5200 rpm is the motor at its limits or is there more there?? like bigcity not to knowledgeable about the mitsubishi but possibly with a little more info and a check list we could help figure this darn thing out....

19J
Dirt Freak

Total posts: 370
posted April 20, 2005 08:04 AM  
I get that he is trying to say that but what i dont get is how it can change. Im not questioning what he knows. Please dont take it that way. I just want it explained cuz i dont get it. You could say it is slightly modified lol. On a mikuni it has 2 diff size butterflys primary and secondary. We made the carb a hair smaller than the biggest butterfly. It has awesome low end power you step on it its there. But im thinking that my cam is done up that high. I think it pulled better off the corner last year. This carb is "fresh" we rebuilt it. It almost seems like it has more but yet it just dont wanna pull very good. I mean rpm wise it has more but the power of the cam i think is done. Im trying to get a new cam now. yes it is stock. Yes it is getting warm with a good solid steel racing fan and a shroud. I thought it might be too small of a restrictor so we put another one and havent got to try it yet. THANKS!

Festy46
Dirt Full Roller

Total posts: 59
posted April 20, 2005 09:37 AM  
quote:
Originally posted by 19J:
Yes it is overhead cam. But im just lost on why i would need to degree it in again.


Visualize this: With a stock cam, stock non-milled head, the timing marks all line up and the timing belt is tight on the "drive side". Now mill a lot off the head. Since the cam gear is now closer to the crank gear, the timing belt has slack in the "drive side" where it was tight before. The only way to take out the slack is by rotating the cam backwards so that the tensioner pulley can take up that slack. When you turned the cam to remove the slack in the belt, you changed your valve timing. See how it works?

------------------
Gas right. Brake left. No bumping.

19J
Dirt Freak

Total posts: 370
posted April 20, 2005 10:40 AM  
Ok got it. Where could i get one of these at? Thanks.

bigcityracer
Dirt Freak

Total posts: 431
posted April 20, 2005 05:28 PM  
Festy46 Great job explaining what I'm talking about.
19J I don't know were to buy for that motor. I am looking and will post if I find one.
I just make my own off set pin.

19J
Dirt Freak

Total posts: 370
posted April 20, 2005 11:08 PM  
How do you do that. I mean i guess i understand how to do it just how do you get it precise and do you drill a new hole in the cam or gear. Thanks.

bigcityracer
Dirt Freak

Total posts: 431
posted April 21, 2005 02:11 PM  
REMOVE THE DOLL PIN FROM THE CAM. THEN SET GEAR OPPISITE OF ORIGINAL HOLE AND DEGREE TO ZERO AND DRILL NEW HOLE, IN STALL DOLL PIN AND YOUR SET.

OR IF YOU CAR SET THE GEARUP ON AN INDEX TABLE AND DRILL 3-HOLE SLIGHTLY OFF, YOU NOW HAVE AN ADJUSTABLE TIMING GEAR.

FCRA
Dirt Roller

Total posts: 14
posted April 21, 2005 02:28 PM  
You may try www.racetep.com I know that thye have some performance parts for that engine. Good luck!

Nate Stevens
Four Cylinder Racing Alliance

rnoswal53
Dirt Maniac

Total posts: 120
posted April 23, 2005 08:59 AM  
If you run a stock cam then the specs for it may be in the repair manual for the car, but more than likely not. If you are going to go through the trouble of trying to get the cam in the correct position, you may as well check to see what your rules allow and go with a new cam. They always come with the numbers needed to get the cam set up right.

There is not a lot to setting up a cam, but it really helps if you had someone that has had some experience in setting one up properly there to help you. If you mill the head too much then you may have problems with the valves getting to close to the pistons or even hitting them.

Another thing is the carb. If you can run up to a 350 cfm then I would try to find a 2 barrell off a Ford V-8 engine. Look for the number 121 on the side with the accelerator pump rod. There is another carb that has the number 108 and is smaller, but still a good carb. The 121 flows around 350 cfm and there are many out there so when you need to make jet changes, just take them from the other carbs and try drilling them out to match some of the Holley jet sizes. The 121 motorcraft carb will get you off the corners pretty good, the Rochester may be too big and hurting you off the corners.

Russ

19J
Dirt Freak

Total posts: 370
posted April 23, 2005 09:40 AM  
This is what ive decided to do. Im gonna get a new cam. And then hes gonna tell me how to do it. He said that to his knowledge there is no adjustable cam gear. Then if all else fails yes i am switching carbs. But i dont think it is too big just by the way it responds down low. It should be better up high then down low you would think right? Its good down low im getting holley jets put in it then getting the right jets and going from there. Thanks.

bigcityracer
Dirt Freak

Total posts: 431
posted April 23, 2005 02:46 PM  
quote:
Originally posted by 19J:
This is what ive decided to do. Im gonna get a new cam. And then hes gonna tell me how to do it. He said that to his knowledge there is no adjustable cam gear. Then if all else fails yes i am switching carbs. But i dont think it is too big just by the way it responds down low. It should be better up high then down low you would think right? Its good down low im getting holley jets put in it then getting the right jets and going from there. Thanks.

A new in the same position with out proper degreeing will not be any better, if not worse! Get the cam degreed in and go racing. A race cam would be great, but either way it must be degreed in correctly!!



19J
Dirt Freak

Total posts: 370
posted April 23, 2005 10:57 PM  
Im getting a race cam then the guy is gonna tell me how to degree it as close as possible.

rnoswal53
Dirt Maniac

Total posts: 120
posted April 23, 2005 11:36 PM  
You would be amazed at how much a few degreees can make a difference in how the engine responds. You can get it spot on but you do need some sort of degree wheel or crank pulley with degrees on it. With my Toyota, before I got my adjustable cam gear, I used the offset dowel buttons that are used on the Ford and Chevy cams. A decent race part shop should have them in stock. There are several dowels that represent different degrees. A lot of guys will adjust there cams to the track conditions and it may be only a few degrees that can make a difference. Advance for low end and retard for high end power.

Most chain tensioners can accept quite a bit of milling on the head before you need a shorter chain, but if it is close, put on a new chain and gears, that will tighten up a lot of play in the chain.

I think I recall a few racers on the 4m.net forum that had experience with the 2.6 or do a search for mini stock tech. Also check to make sure your ignition timing is working right. Put it around 34 degrees advanced at where ever your timings stops advancing and lock it in. Make sure your advance is working unless you locked the plate. Any type of flutter there will hurt performance.

I had an old Corolla that was off one tooth on the timing chain and it would not reach anything in the upper rpm range. You could rev it up and watch the top of the carb and see the blow back above the carb. Good luck.

Russ

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