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Notching the DS fuel rail cover

 
Old 02-08-2019, 04:37 PM
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Kevin in Atlanta
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Default Notching the DS fuel rail cover

Am I the only one that does this to get the rail cover to sit flat?

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Old 02-09-2019, 02:41 AM
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worf928
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I’ve never had to notch them.
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Old 02-09-2019, 04:01 AM
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Michael Benno
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Mine has no interference either.
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Old 02-10-2019, 06:59 PM
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something doesnt look right.
We need better pictures of the whole rail cover,
and of the rail with the cover and quadrant off.
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Old 02-10-2019, 07:40 PM
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Geo55
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This is what my 87 looks like Kevin. Close but it doesn't touch.

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Old 02-10-2019, 08:00 PM
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It's entirely possible you have the wrong covers for the wrong year. They are the same part #s but are different between the early and late S4s.

Here's early S4 ....




28 is insulation. Here is the later one. Note NO insultation....




Hope that helps!
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Old 02-11-2019, 04:18 PM
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dr bob
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Fuel rails changed during 1987 run, with different mountings. IIRC. The rail covers may be particular to the year and mounting heights of the rails. But this is a guess at best.
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Old 02-11-2019, 04:30 PM
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Kevin in Atlanta
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Originally Posted by dr bob View Post
Fuel rails changed during 1987 run, with different mountings. IIRC. The rail covers may be particular to the year and mounting heights of the rails. But this is a guess at best.
That has to be the issue.

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Old 02-11-2019, 04:42 PM
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worf928
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Originally Posted by jej3 View Post
It's entirely possible you have the wrong covers for the wrong year. They are the same part #s but are different between the early and late S4s.
Originally Posted by dr bob View Post
Fuel rails changed during 1987 run, with different mountings. IIRC. The rail covers may be particular to the year and mounting heights of the rails. But this is a guess at best.
Originally Posted by Kevin in Atlanta View Post
That has to be the issue.
There are at least two different fuel rail versions: early-'87 and post-early-'87 with the former needing rubber stand-offs to mate with the early-'87 intake.

There are at least three different fuel rail covers: early 'hollow' covers and two late 'insulated' covers. I don't recall in which MY they changed, but definitely by '91. All replacement covers are now of the second 'insulated' type and require excess insulation to be trimmed away.

I don't have an early-'87 on hand to look at right now, but it may have been the case that those covers were notched OE.

One thing is for sure: if you mix early and late fuel rails with early and late intakes you will be in a 'fuel' situation since the lower injector o-ring won't be correctly seated in the intake bore.

It may be possible to use late rails on an early intake if the rubber buffers are removed and replaced with studs. Note the use of "may". It's not going to be possible to use an early rail on a late intake unless you can make a rubber buffer with a negative height.

Edit: the hollow covers with the separate insulation were still used through mid-'89. I think '90s had the insulated covers.
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Old 02-11-2019, 05:30 PM
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Kevin in Atlanta
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I am only aware of two revisions of the fuel rail. One needs the aluminum spacer and one does not. Regardless of that, the elevation of the rail has to be the same to connect to rest of the fuel plumbing.

So given that early or late rails play no role in the interference, I say this because the rail covers bolt to the rail and rail elevation is always the same. That assumes the injector rail mounts are the same.

Given that either the rail cover is different or more likely my rail cover is warped down.

I have compared the relationship of the injector position in the manifold to a couple of other cars (87 and 90) and the injector is correctly placed.

Sometimes I find weirdness where it isn't really there.

Car runs fine with no leaks. It just was a strange observation.
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Old 02-12-2019, 09:24 AM
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Originally Posted by Kevin in Atlanta View Post
... One needs the aluminum spacer ...
Since Porsche went to a metal-to-metal interface with the later rail and intake, it doesn’t really matter, but the original spacers were ‘bonded rubber buffers’ identical - same part number - to the ones used for the airbox supports.
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Old 02-12-2019, 01:14 PM
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My December '88 built '89 had insulation on the rail, and the cover fit over that. No insulation in the cover itself. Insulation is there to help with heat transfer into the rails, and maybe to help with muffling a little of the noise passed from the injectors. Seems that addressing the noise issue more started in the 1990+ covers, from memory. Although there was a parade of clinic cars while we were in SoCal, only a few have cycled through the workshop here. None newer than mine. The area has a high per-capita Porsche population, but a pretty low capita number.

I can't remember even half of the stuff I've forgotten. That may be a good thing under certain circumstances, IIRC.
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Old 02-12-2019, 05:54 PM
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Kevin will you please post pictures of the parts your working with
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Old 02-12-2019, 06:22 PM
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Kevin in Atlanta
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Originally Posted by Mrmerlin View Post
Kevin will you please post pictures of the parts your working with
another vantage point

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