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engine surge

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tahoe healey

tahoe healey

Yoda
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engine surge

I got a constant little engine surge that has been bothering me. Engine runs cool (180 to 190) and strong. Carbs are linked well and right on as far as richness. Dampers have oil. Plugs look fine and even in color. Time is advance for altitude (6500 ft) and runs fine. Fuel pump is strong. Am I missing something? Worn needles? Float chamber needle valves? In line fuel filter? I am running all original or original replacement equipment on a BJ8.
Has anyone any thoughts?
 
Re: engine surge

My first thought would be a vacuum (air) leak, perhaps around the carb gaskets.
 
Re: engine surge

HI TH,What is your Idle speed ?,what engine speed does the surge occur at?.---Keoke
 
Re: engine surge

Keoke, it idles at 700+. I think it is about 2500 or sothat I feel it. It's only slight but enough to feel.
Greg, that is a good thought. Could there be a leak in the vacuum advance that might cause that? The rubber conector to the carb seems kind of easy to remove. I've been suspicious when I use the timing light that there is a variable movement on the pully mark at engine speeds above idle.
 
Re: engine surge

Greg, are you referring to the gasket between the manifold and the carbs? Is a sealer used there or just tighten the nuts. They seem tight and I could not detect any leak on the sides I could see. any way to test? I used mist of water then wd40 then watched for changes at the carb/manifold junction.
Anyone know off hand the inside diameter of the rubber hose for the vaccum advance tube? Moss wants big bucks plus shipping for 1 1/4 replacement.
 
Re: engine surge

Hi TH:

That simple rubber hose is fabric re-enforced, so extra cost is "justified". Inside diameter is about 1/16 to 3/32 just large enough to tightly pressure fit on the rear carb outlet. Run a thin wire through the carb outlet opening to clear out any debris. You may also consider checking fuel pressure. Does your's pressurize higher that what's specified for a stock Healey low pressure system (3 to 5 lbs.)? GONZO
 
Re: engine surge

OK TH, forget the reinforced vacuum hose just get some from the local autoparts store.I think maybe your problem may be in the Dizzy if the timing mark is jumping around. To check the Vacuum advance just suck it up like Jeff said. You still got POINTS!!. If you have a dwell meter you can hook it up and see what the dizzy is doing at engine speeds above idle.--Keoke- /ubbthreads/images/graemlins/laugh.gif
 
Re: engine surge

Oh, yea, Keoke. I forgot about my dwell meter. I haven't used it in years. The vaccum advane works well at the dizzy. I'm just not shure about the "suc" at the carb. And there is something quaint and nostalgic about points. Afterall, isn't that what LBC's are all about.
Thanks, Gonzo. I bought the smallest fuel hose Napa had that I will use on the carb over flow also. They are close enough in size to give a thight fit in the over flow and an OK fit on the vaccum.
 
Re: engine surge

Hey TH,carb overflow pipes and the Vacuum pipe fitting should be significantly different in size.--Keoke-- /ubbthreads/images/graemlins/confused.gif
 
Re: engine surge

-- /ubbthreads/images/graemlins/savewave.gif

OK TH, but keep an eye on the carb overflow lines if the hose is stretched to fit because they may split out after a bit.---Keoke- /ubbthreads/images/graemlins/yesnod.gif
 
Re: engine surge

[ QUOTE ]
I got a constant little engine surge that has been bothering me. Time is advance for altitude (6500 ft) and runs fine.

[/ QUOTE ]
Hi TH,
What does it do at lower altitude? Surge more, less, or the same?
D
 
Re: engine surge

Dave, I'm not sure. It hasn't been off the mountain this summer. I'm babying the trans until fall. (third gear scream. I'll be bringing the trans to Bill Boulton to rebuild or repair but until then I avoid third which is needed to climb back up here)I remember a little surge last summer but I cannot recall if is was more or less.
 
Re: engine surge

I had something similar on mine and it turned out to be a 'stretched' spring in the distributor. At lowish engine speeds the car was not smooth at all. Seem to remember bending the last coil of the spring so it fitted over the location peg.

worth checking anyway.

Richard
 
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