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Author Topic:   Redhot exhaust
backwoodsracer
Dirt Forum Racer

Total posts: 88
posted May 09, 2004 09:33 AM  
Last week my crew noticed my exhaust manifolds glowing.After the race we pulled a plug and it showed very rich I mean black.The carb is a rochester 2bbl from jet with 70 jets.I have to run stock manifolds and I run 2 1/4 straight pipes no muffler.I went down to 68 jets this week and same problem.I dont know if this is a carb or exhaust problem or something completely different.Engine temp doesent go over 200 and pulls real hard on the straights.Any suggestions would be greatly appriciated.

foxracin11
Dirt Full Roller

Total posts: 26
posted May 09, 2004 11:35 AM  
i would check your timing it sounds like to me that it is retarded somewhat and it is burning fuel in the exhaust manifoldsit is firing to late timing to low i would put money on it check and see

joetaylor
Dirt Forum Champ
Total posts: 640
posted May 09, 2004 11:58 AM  
check your float leval it sounds like that it is over fueling

Wind Walker
Dirt Full Roller

Total posts: 37
posted May 12, 2004 09:47 AM  
Retarded timing!

Set it at 34-36 degrees (total), and see what it does then.

backwoodsracer
Dirt Forum Racer

Total posts: 88
posted May 12, 2004 04:53 PM  
I have had my timming at 34 degrees so far this season.I am going to work on the float level for this weekend.Does anyone have an easy way to set float level in a rochester 2bbl or is it just trial and error?Thanks for the replies so far.

racer17j
Dirt Forum Champ
Total posts: 5390
posted May 12, 2004 07:43 PM  
still ck the timing. cant tell ya the number of times we fixed a car that way after the owner swore the timing was right on

racerman707
Dirt Freak

Total posts: 374
posted May 13, 2004 10:31 AM  
I agree with the timing deal. Are you using a stock damper?, they have been known to slip the outside ring. Have you properly found tdc, what kind of timing light do you use? Never will forget a guy at the track set his timing at 32 degrees with an adjustable timing light and had timing tape on his damper. He set the light on 32 and checked it on the 32 mark!

juliaferrell
Dirt Freak

Total posts: 370
posted May 13, 2004 02:01 PM  
Very critical to know where true TDC is on the damper. I with 707. They don't torch the header like that unless something is haywire. Just a few jet sizes or timing degrees don't fix that. I'd say way too retard on the timing.

joetaylor
Dirt Forum Champ
Total posts: 640
posted May 13, 2004 07:04 PM  
I don'ttrust the dampner I find true tdc then make a mark on the pulley that will not slip like the balencer and then you can watch the balencer to see if it moves

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U LIFT U LOOSE

widebody
Dirt Freak

Total posts: 296
posted May 14, 2004 08:20 AM  
Hey there red header guy!!

These were the numbers I ran on the street stocks for the V-Boys, I looked in my old notes just for you!!.

Carb float levels:
Float Level: 1 1/32
Float Drop: 1 19/32
Those Rochesters need to be measured from the gasket surface with the gasket off, And if I remember theres a little lip or seam at the end of the float that where you measure from..
I always wipe a new gasket with grease and that allows it to come off without sticking..

Holleys are so much easier!!

ltd7blue
Dirt Roller

Total posts: 18
posted May 15, 2004 01:10 AM  
what are you running, ford or chevy??

backwoodsracer
Dirt Forum Racer

Total posts: 88
posted May 15, 2004 07:49 AM  
I am running chevy.Thanks guys for all the replies.I spent a couple hours working on the floatlevel and with the numbers from widebody and what I found in the archives my float was way off.Now I have to do a plug check at the track and hope I dont have to pull it apart down there tonight.

foxracin11
Dirt Full Roller

Total posts: 26
posted May 16, 2004 01:44 PM  
was wonderin if the float level fixed it or not and if you did check your timing like we suggested

iowa_dirt_track_girl
Dirt Freak

Total posts: 461
posted May 16, 2004 05:27 PM  
this same thing happened at osky to us last year everryone there says dont worry about it the motor is working hard plus the manifolds we were running was the over the top ones and they are thinnner anyways
If your plugs look good and your timming is not way out of bounds and its not getting hot DONT wory about it Kind of like the saying if its not broke dont fix it

backwoodsracer
Dirt Forum Racer

Total posts: 88
posted May 16, 2004 07:32 PM  
We got rained out so I wont get to try it untill next weekend.I checked the timming and it is still 34 degrees.I also checked the balancer at tdc and it does not look like it has walked so I think the timming is correct.Thanks again for the replies.

Busch
Dirt Full Roller

Total posts: 46
posted May 18, 2004 07:33 PM  
Have seen this before and it was really crazy and you would have a hard time believing this but there was a crack on the under side of the intake manifold. This gave us problems for a good while. We found it by using a vaccum gauge while the engine was warming up. Hope this may help.

backwoodsracer
Dirt Forum Racer

Total posts: 88
posted May 23, 2004 09:08 AM  
I got to race last night with the new carb settings and after warmups we pulled plugs and it was pretty lean so I decided to go up three jet sizes from 68 to 71.The engine ran well in the feature water was 200-210 but one time down the back strait it seemed to lean out on top end.I had my foot to the floor and it just laid down like it ran out of gas.I pulled in to see if the crew saw any smoke from the exhaust and everything seemed ok so I went back out and only ran it up to 3/4 throttle or so and still finished sixth.Pulled plugs after and they still looked slightly lean but not as bad as warmups.The exhaust manifolds did not glow so thats one problem solved and the carb seems close.A couple guys told me to raise th float a little an up the jet to 73 and maybe bump up the timming a couple degrees.Well what do you guys think?Thanks in advance.

cd2
Dirt Maniac

Total posts: 161
posted May 23, 2004 09:55 AM  
Backwoodsracer Has the block been decked and has the heads been cut? If so did the machine shop cut the intake to match if not it could be pulling air at the inside by the lifter galley. cd2

    

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