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Author Topic:   RPM question/Help with ideas
Winland Racing
Dirt Maniac

Total posts: 122
posted May 16, 2005 12:26 PM  
Ran an enduro yesterday on asphalt. I have a 350 motor, good set of 041(194)stock heads with the z28 springs(or whatever they are called), and a decent cam from camcraft,1.6 rockers, stock intake 4bbl with a quadrajet(recently rebuilt). I also have a Mallory racing distributer without vacuum. Total timing was 35. I run a powerglide in 1st gear and 373 rear end gears which should be around 678 final on a 1/4 mile track.
I was only able to get the motor to go up to about 4200 rpms before I was letting off for the turns. If I went to 2nd gear the rpms obviously went down. I was getting passed in the straitaways by the 4 or so fastest cars.
Am I over geared or just under motored?
Never hesitated, did not float the valves, car ran well.

any ideas???
I want to be able to compete with the fastest of the fast without having to build a stroker.
WR#66

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Winland Racing
http://www.freewebs.com/winlandenduroracing/

bubba0six
Dirt Maniac

Total posts: 146
posted May 16, 2005 04:39 PM  
is your throttle opening all the way with the pedal? get in the car and mash the gas all the way down and have someone see if the throttle is all the way open on the carb. i run a 624 on a 3/8 mile track i dont see why a 6.78 wont work on a 1/4 mile!

[This message has been edited by bubba0six (edited May 16, 2005).]

Winland Racing
Dirt Maniac

Total posts: 122
posted May 16, 2005 09:48 PM  
How many R's are you pulling in the straits?
Good call on the throttle opening. I will check that. It makes sense, even when I shift into second it dosent seem to want to go faster, just less resistance (backpressure) from the gearing.

Any other ideas?

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Winland Racing
http://www.freewebs.com/winlandenduroracing/

racer17j
Dirt Forum Champ
Total posts: 5390
posted May 16, 2005 10:41 PM  
I run 225/70/15, not sure of the actual roll. My tires were gripping the track well in the straitaways. I am hoping that it is a carb/cable issue. I run the stock bracket off a quadrajet that bolts into the 2 holes on the back of the carb. I have been using the same bracket for 10 or more years. I am going to check the adjustment tonight.

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Winland Racing
http://www.freewebs.com/winlandenduroracing/

racer17j
Dirt Forum Champ
Total posts: 5390
posted May 17, 2005 03:51 PM  
What size tires do you recommend? What is the lowest gear made for the metric 7.5?
Thanks for the ideas,
WR#66

quote:
Originally posted by Winland Racing:
I run 225/70/15, not sure of the actual roll. My tires were gripping the track well in the straitaways. I am hoping that it is a carb/cable issue. I run the stock bracket off a quadrajet that bolts into the 2 holes on the back of the carb. I have been using the same bracket for 10 or more years. I am going to check the adjustment tonight.



racer17j
Dirt Forum Champ
Total posts: 5390
posted May 17, 2005 07:27 PM  
I checked my throttle and it appears to open all the way. I did this with the motor off. I noticed that the accel pump dowell does not completely go flush with the top of the carb, it still sticks out 3/8 of an inch and my back barrels do not open. DO I need to adjust the linkage to get the dowell to seat further in the carb? Do Rochester quads use vacuum to open the 4 barels or is it mechanical.
Thanks again,
WR#66

speedwrench
Dirt Roller

Total posts: 16
posted May 18, 2005 09:08 PM  
have you removed the choke and related items like the secondary lock located on the right rear of the carb? it will keep the secondaries from opening and cut into your rpm.

speedwrench
Dirt Roller

Total posts: 16
posted May 18, 2005 09:11 PM  
both the butterflies are mechanical and the secondary jets are kicked open by vaccum

petordragon
Dirt Maniac

Total posts: 167
posted May 19, 2005 01:51 PM  

 
depending on the rules of your track if you have to run a stock carb there is a adjustment on the passenger side of the top of the carb that goes from the top of the secondaries to the vaccume pod. either remove it or adjust it to where when it is started you can open the top of your secondaries with your fingers. then look where the rod attached to the top of the secondaries there will be a small flat headed stop screw on the side and a allen screw an the bottom loosen the flat headed screw then loosen the allen screw till the top of your secondaries push open easily then tighten the flat headed stop screw back tight. Drive it if it bogs when you stomp the gas tighten the allen screw just a little till you get the response you want.

Winland Racing
Dirt Maniac

Total posts: 122
posted May 25, 2005 12:59 PM  
In follow up,
I have found 2 issues.
1) secondaries appeared to be stuck closed, forced them open now they open freely, may have been hanging up on the gasket.
2) We heard a rattle during the intermission, couldnt figure it out, then tranny stopped working. Pulled it off the trailer and found that all 3 bolts from flywheel to converter were missing. What effect would loose or missing one or two bolts have?
I will be racing Monday so I should know if the carb issue fixes my problem.
Thanks
WR#66

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Winland Racing
http://www.freewebs.com/winlandenduroracing/

te33
Dirt Freak

Total posts: 237
posted May 25, 2005 04:45 PM  
sounds to me like you have several issues.a good place to start i think would be to spend an afternoon just wrenching the car.just put a wrench on every nut and bolt you can see ,or feel front to back,top to bottom.it always amazes me when i see what the stress of racing will make come loose!after everything is good and tight,it gives you a good sound base from which to attack the other issues.good luck.

[This message has been edited by te33 (edited May 25, 2005).]

petordragon
Dirt Maniac

Total posts: 167
posted May 31, 2005 01:00 PM  
good idiea on the tighting every bolt. Seen a guys water pump fall off the front of his motor last week

Winland Racing
Dirt Maniac

Total posts: 122
posted May 31, 2005 05:39 PM  

Ran on a dirt track yesterday, real muddy at first then started to get fast. Pulled 4500 in the straitaways. Car was working ok, it fluttered a bit if I used the throttle to quickly, had to kind of feather it to get max speed, it seemed to bog down when I pressed it. I think it was the 4 barrels opening, I readjusted timing at the 100 lap intermission and it seemed that the fluttering went away, then overheated for no apparent reason. May have been too aggressive on the timing?
Thats racing....

te33
Dirt Freak

Total posts: 237
posted May 31, 2005 05:45 PM  
to much advance will cause it to get hot quick.hows your fuel pressure?

Winland Racing
Dirt Maniac

Total posts: 122
posted June 01, 2005 02:28 PM  
I do not know how much fuel pressure I have, how much should it be? As far as timing, I may readjust back to the 32-34 range.

Ken

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