Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: TurboFource on Saturday,November 14, 2020, 04:11:38 PM
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Based on pictures of other Stromberg heads it appears that the intake ports at the carb mounts on the spare head I got with my car, have been opened up a little over an 1/8" towards the front of the head on both inlets. Is this helpful mod that helps with flow bias in the siamesed intakes? Not sure if anything else has been done to this head as I currently have nothing to compare it to.
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Photos?
The TC Weber, TC Stromberg and Renault crossflow heads all flow pretty well. Can you make improvements? Absolutely! You need a flow bench and lots of experience though. By all means smooth things out, match ports, etc. Major porting? Only if you know what you're doing.
One example is the port drop to the valve. In as much as possible, you want the mix to flow straight at the valve head. That way it flows around the valve head using the whole open area. A classic mistake is to remove the port floor so the mix goes straight at the valve... sideways. It "looks" more open but really you are now blowing the mix across the valve head and only utilizing half the available area.
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My computer died so I am currently using an old iPad 2...... Not sure how to get photos from my iPhone to this thing.....or if it's even possible.
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My computer died so I am currently using an old iPad 2...... Not sure how to get photos from my iPhone to this thing.....or if it's even possible.
Can’t you email them at least?
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Does the iPad have a camera?
If not, email them to me and I'll post 'em.
j b c o l l i e r (at) s h a w (dot) c a
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The iPad does have a camera..... :huh:
Will try it later.....didn't even think of that.... :confused:
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Test pic.....
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I assume the entrances to the head were modified to match the manifold that attaches to the head. You definitely don't want it to be smaller. Ideally, they should match ( as well as the gaskets) perfectly.
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Are the gaskets egg shaped?
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So, is the secondary throttle housing, the part that bolts to the head also modified to be egg shaped? Perhaps the previous owner was experimenting with porting.
From my limited understanding of porting, the opening to the head is cleaned up so that the edges matches the gasket on the carb outlet perfectly and the rest of the intake tract is ground and smoothed out to optimize air flow per the engine builders experience.
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Can't see any reason for that.
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I don't have a spare intake that bolts to this head so I am not sure why this was done, unless it was done to try to overcome the flow bias that occurs in the siamesed port due to the firing order of the cylinders (and the resulting cam opening events)..... :confused:
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I guess I am confused. Is you car turbocharged? I assumed it was.
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Pfreen,
It is turbocharged, this is on a spare head I got with the car.
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I never noticed that while the head was in my possession.
That head was not from a Europa (no groove for cam oil seal) and its history is unknown to me.
Is it possible that the flat surfaces were milled thinner for some reason? ...Or, did "core shift" occur when the head was cast?
Since the flat surface is at an angle to the port, wouldn't that make the opening oval, as opposed to round?
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I would have thought you should be able to see if it's 'as cast' or been subsequently ground/modified by the surface finish??
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CW, wouldn't it appear that way in both directions?
I will look closer when I get a chance to see if they are as "cast".
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I have a spare for my Elan - a quick measurement was a hair under 47mm both vertically and horizontally, and the gasket ID is round.
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I would guess they were correcting for a casting flaw. Note how the stud holes are offset also compared to the outer part of the flange but centered on the modified holes. Not uncommon, my buddy had a Stromberg head that the front part, ahead of the timing gears, was bent inward significantly but they drilled the front, small bolt heads in it and it worked, just barely. Must have been a 1/4 inch offset.
Jerry Rude
4005R