4150 likes to die on hard acceleration

1609 Views 22 Replies 10 Participants Last post by 406monte, Jul 7, 2009

406monte

Discussion Starter · Jul 3, 2009

I need some help on my 750 Dp it is a 4150 and i just rebuilt the carb and installed it and it runs really good till i get at around 2500 rpm and then it starts to surge and stutter. I don't know why this is happening i have checked everything i know to check. I starts right up and idles fine. I have checked the floats and they are good and the fule preassure is set at 6 lbs. I have 30cc pumps and 6.5 power valve and 67 primary and 72 sec jets in it. I have 31 primary and 37 sec downleg squirters. I put them in there from the 31's that were in there both front and back. Also, if i am taking off fron a dead stop and hammer it down it takes off really hard then it seems to stumble and act like it is trying to float out on me and i have to peddle it to keep it from dying on me. It has done this to me once yesterday and it tried to die on me once today as well but i kept it going. Any help would be apprecitated i want to take this to the local midnight madness and see if it picked anything up from the old 750 vac sec Holley that i had on it.

Eric

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406monte

Discussion Starter · #3 · Jul 3, 2009

I checked the fule filters and they are not blocked. i may try and up the jetting to help it and see if that helps. Thanks

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406monte

Discussion Starter · #5 · Jul 3, 2009

I went and checked the floats again and the rear one was way off some how from the initial settings. I went up to 72 prim and have 73 sec jets in it. I checked the power valve and it is good. I went and readjusted everything and took it down the street and it ran fine now. It has just a slight hardly noticeable stutter and then it is gone. I only felt it cause i was really trying to feel for it. I barely noticed it after a few minutes. I think maybe some more jet and it will be good. Well, i am off to hit the Midnight Madness tonight and see what happens i took it down the steet with my Mickey Thompson Street E.T.'s on it and it hooked so hard and reacted so different that i can't wait till tonight. Wish me luck.

I know some take out the power valve all together and jet up. How much should i go up in the jets and i should make them squared right? I think i might try that and see what happens. I am only running the power valve in the front also.

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406monte

Discussion Starter · #7 · Jul 4, 2009

Well, i it all came back to haunt me at the track. I got two decent runs out it and then the loading up came. I was on the third pass and when i came out of the water box it died. It took me forever to get it started again. I felt like an idiot sitting there holding everyone up. I finally got it started and cleaned up the carb. I made a pass and it only ran a 12.69 but i did short shift it on that pass to. The 4th run and it died again out the box and wouldn't stay running no matter what i did. I just backed it up and took it to the pits. I pulled the screws to check the fuel level and both were right at barely dripping out the screw hole. So, what gives i have no clue as to why this is doing this. Can anyone help me on this huge issue?

I did take my Demon with me as a back up and wouldn't you know it i needed it. I wanted to redeem myself and finish strong. Well, i did and ran my fastest times with it. I had some pretty good sixties as well. I did however have on time with this carb to that died coming out of the box. I got it started and cleaned it up and ran my second fastest of the night. So, all in all i did have a good time and then came home. I just want to get this other carb to run right. I guess i need to do this one the dyno and figure it out there. I did cut a perfect light on my second pass with the Demon. I felt good about that and was the only one tonight to do that.

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406monte

Discussion Starter · #13 · Jul 5, 2009

I am going to go and jet the carb 73 prim and 83 sec and see what that does for me. Then i am going to take it back down the street and see how that works and hopefully it won't die on me on a hard load.

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406monte

Discussion Starter · #15 · Jul 5, 2009

Can't it has been raining here off and on. Did the carb but must wait to try it out.

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406monte

Discussion Starter · #17 · Jul 5, 2009

Well, i have a similiar set up as you do MANIC. I am running a 406 with Trick Flow heads and a hyd roller .558 lift at .246/.254 @.50 on a 112* seperation. I am running 34 degrees total and all in by 2800 rpm. I am footbraking it also with a TCI Streetfighter and a 3.73 gear and i ran in the lower 12.10's to the best Friday night in the low 12.03. My best time is also a 11.96 at 115. Wow, our times and engine combo are really close. I will try and turn the screw out some more as well and see what happens. I wonder what causes the sudden lack of fuel when i get off the throttle to cause it to die.

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406monte

Discussion Starter · #19 · Jul 6, 2009

How did you fix the issue.

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406monte

Discussion Starter · #21 · Jul 7, 2009

I have never had any issue with the Holley Black Pump and when i put the Demon on i had no issues with that carb.

Yes, the pump cam is in the number one position, and it looks to be the pink cam to.

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406monte

Discussion Starter · #23 · Jul 7, 2009

You know i have never thought of that. Most of the time that is for the off road guys that are at some rediculous angles. I might just try i though.

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