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  #1  
Old 06-28-2003, 02:01 PM
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Gripe High end troubles...

The good news is, with a set of cheater slicks on the truck, 14.96 has been achieved.

YAAAAAAY!

The bad news, is that the really good launch, has made my high end problems more obvious. At last nights "secret street" thing at the track, I ran 4 times, against cars that were all runing mid 13 to 14's. I beat every one out of the hole and for 330 ft. Then they all passed me. Even at 14.96, I only hit 88 mph

Ive chased carbs around and around, and now I'm working on a new theory.

I'm using 2 1/2" shuttleworth style truck mufflers. These mufflers sound great, nice deep rumble. But they are full of perferated little baffles. No chambers as you see in performance mufflers.

I think I'm choking the exhaust,(using headers before the muffler) Not enough to hurt the launch, but it sucks in the high revs.

My other reason for thinking this, is readings I've gotten from my G-tech. When this engine was in the van it made the same hp it makes now(on the G-tech)

Which is kind of odd, because the van had motorhome manifolds, and 2 1/4 dual exhaust. (vs headers and 2 1/2 in the truck now)

I also noticed that if I short shifted the engine at 5100, or reved her out to 6200, it makes no difference in my time, or mph.

My question is simple. Does this theory make sense to anyone other than me? And if so do you have any examples or reasoning, as to why?
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Old 06-28-2003, 02:06 PM
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Have you got the high rpm lean condition fixed on that Eddy? At what rpm does it quit pulling?
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Old 06-28-2003, 03:54 PM
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That's what I mean. I'm starting to doubt it's a lean condition after all.

I put the biggest jets I could get (.119" I think) in the secondarys, and it runs exactly the same. No better, no worse.

Running the holleys did seem better, but further analysis of the time slips shows me running the same mph, no matter what carb I have run.

Seems to stop pulling about 3800 to 4200.
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Old 06-28-2003, 03:56 PM
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Do you have a fuel pressure guage? What pump do you have? What color are the plugs?
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Old 06-28-2003, 03:59 PM
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Very well could be the mufflers. Just unbolt the pipes at you next test and tune and it will answer that question. Definately too much back pressure and turbulence in those preferated type mufflers. Chambered type are much better.
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Old 06-28-2003, 09:45 PM
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I have run it with a gauge, right up to 6000 rpm, with no pressure drop off.

I'm using a carter super pump, with 3/8 fuel line.

The plugs do indicate a lean, but I'm wondering if excessive back pressure would cause a similar reading.

Not enough air flow through the carb, therefore not enough fuel drawn in, plugs look lean. ?

I was planning to make up a straight section of pipe with some header collectors to test the theory.
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Old 06-28-2003, 09:50 PM
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It can effect the a/f ratio. For example I went from a long tube 1 5/8 header to an 18 inch zoomie on one of our dirt cars. It went rich due to less restriction in the exhaust sytem.
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Old 06-28-2003, 11:02 PM
Blygy Blygy is offline
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Default Considering a move????

Dave man you gotta move closer to Edmunchuk..LOL..

Then I can hang with someone who understands the "lifestyle".

LMAO.

anyway..

Good luck with the pipes..

Blygy
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Old 06-29-2003, 12:32 AM
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Blygy:

No man, YOU'VE got to move down HERE. Lol

We get way less snow than you guys.

I haven't shoveled any for at least a week!

Speaking of the lifestyle, I looked a 74 shorty van today. SB and it's a 4 speed!!

500 bucks. The potential I see in it....(sigh)...unfortunately potential costs money.

And the wife wouldn't be too happy either
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  #10  
Old 06-29-2003, 02:34 PM
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4-spd on the colum? I'd have fun with that one!
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  #11  
Old 06-30-2003, 02:00 AM
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No, it's on the floor! Shifter reaches up beside you.

It's kind of weird
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