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914World.com _ 914World Garage _ On Topic: Missing above 3k rpm

Posted by: djm914-6 Apr 6 2004, 08:54 PM

So, I'm cruising down the road and step on the gas to pass a few cars but the car doesn't go anywhere. Instead of the usual vrooom to red line, I gat a bunch of flat sounding sputters. When I let the car cruise, it runs fine. Of the line is good also untill I reach ~ 3200 RPM. No mater what I do, I can't go past 4k, even nursing it.

I'll see what happens tomorrow when I put the muffler caps back on, but I can't see how 3 exits would run worse than one exit. What should I be looking for? My boss thinks plug wires, but he's a Healey guy so of couse he'd guess electric faults.

I'm looking for some real basic pointers here is you got 'em. I'd love to fix this one myself.

Thanks All, pray.gif

Posted by: campbellcj Apr 6 2004, 11:00 PM

My first guess(es) would be ignition related, just like your Harley friend smile.gif

Timing, dwell/points and plug wires... check the simple stuff first!

Assuming the car is carbed it might potentially be an issue with the idle-to-main transition i.e. clogged main jets or other carb farkups?

Posted by: Curvie Roadlover Apr 7 2004, 04:06 AM

Also could be the throttle position sensor

Posted by: ArtechnikA Apr 7 2004, 04:45 AM

QUOTE(Curvie Roadlover @ Apr 7 2004, 02:06 AM)
Also could be the throttle position sensor

Dave's car has two throttle-position sensors, and they're both triple-throat Weber's :-)

Posted by: Tom Perso Apr 7 2004, 06:24 AM

I would thing ignition as well... Check the cap for misfiring (burn marks), wires, plugs, etc...

I would have a hard time believing that you lost all 6 transition circuits on your webers at the same time...

Ignition... wink.gif

Later,
Tom

Posted by: Justin Fischer Apr 7 2004, 07:10 AM

agree.gif Sounds like ignition.... Have you adjusted the timing lately??? Make sure you tightened the distributor back.....

Posted by: djm914-6 Apr 7 2004, 08:32 AM

I reattached the caps over the middle two exhaust exits for a quite(er) ride this morning. What do you know... no problems! The car pulled strong to redline each and every time I tried it.

So, how does this effect the engine? Mixture?

Posted by: ArtechnikA Apr 7 2004, 09:17 AM

QUOTE(djm914-6 @ Apr 7 2004, 06:32 AM)
So, how does this affect the engine? Mixture?

yup - i always had to run bigger main jets with open exhaust.

intake and exhaust has to be a balance. you could probably run bigger mains (or smaller air correction) if you wanted to keep the free-er flowing exhaust...

Posted by: mskala Apr 7 2004, 09:43 AM

Distributor advance is stuck or can't get past a certain point.
Easy to check with timing light.

Posted by: cary Apr 7 2004, 06:07 PM

Ground strap on the distributor plate is broken. Once you get to a certain point in the curve it looses contact. And you go to ZERO .............no ignition.

Posted by: 94teener Apr 7 2004, 06:50 PM

Your engine may be suffering from fuel starvation under load (can't pump, can't get the pressure). Check main line fuel filter(s), especially the fuel screen in the fuel tank, actually the screen is attached to the fuel outlet fitting on the tank.

Phil

Posted by: mskala Apr 7 2004, 07:09 PM

QUOTE(djm914-6 @ Apr 7 2004, 09:32 AM)
I reattached the caps over the middle two exhaust exits for a quite(er) ride this morning. What do you know... no problems! The car pulled strong to redline each and every time I tried it.

So, how does this effect the engine? Mixture?

I don't think it's going to be such a huge difference as you were describing,
just from a change in backpressure. I think you have an intermittent.

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