Down pipe flange hitting the frame rail

I am in the final stages of a 2-year bare-metal restoration. Car feels solid. I am getting an intermittent knocking sound on the drivers side in the front when turning left or hitting a bump. I notice the exhaust flange is very close to the frame rail on the drivers side: 3/8" versus 1 1/2" on the passenger side. The indicates that either the engine in tilted on the mounts or the down pipe geometry is incorrect. Has anyone seen this before? The engine mounts are new. Is there enough play in the mounts to allow the engine to rest tilted?

Yes, and one also needs to be aware of clearance twixt the front SU bowl (on the triples) and the frame rail.

It can take some jiggering, with the mounts, stabilizer, and exhaust down pipes…

Thanks Paul. Let the jiggering begin! Any particular approach? The is a Series 3 and does not have a stabilizer.

Whoops…!!! I’m not an expert in S3s: many here are, and can offer relevant advice.

You can fit a spacer under one (or both) of the engine mounts to change the geometry. Check out my posts on the UK forum on this topic if you have mix and matched new and old exhaust manifolds.

kind regards

Is this the kinda thing where you can just loosen the mount bolts, jack up the engine a bit, wiggle it around, and set it back down and retighten the bolts? Or will shims/spacers be required?

Shimming the mounts will lift the engine. That will be counter-productive on the side that has the tight clearance at the flange. Shimming the opposite side might help, but I will have to give it a try.

You should have almost 1cm between the bottom of the airbox and the frame rail.

Consider also that the gearbox mount affects how the engine sits.

kind regards

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Joe, is the engine sitting level in the frames? Also is the transmission standard, not a non OEM gearbox with a one off gearbox mount?

The original gearbox is in the cat with the standard mount. I have measured the distance from the base of the carb bowls to the top of the frame rail: driver side is 1 1/4”, passenger side is 1 1/8”. So it’s not perfectly level.