This is driving me nuts. ‘74 Beetle 1600 twin port and will have twin Weber 34 ICT’s and J tubes so I need to change the rear tinware over the exhaust for the type with no holes. It has the “wider” breast plate.
Problem is I can’t find anywhere the right shape rear tinware, they all seem to be moulded for the narrow breast plate?
This is the one I bought but it just doesn’t fit:
The breast plate:
And comparison with the one that came off which also wasn’t a sound fit:
Question then, I am wasting my time trying to get the right rear tin? Any issue if I switch the breast plate for the narrower one which should fit the replacement rear tin I already have?
There appears to be a slight mismatch between your 'wide' breastplate and old rear tray as there is a gap on the left side in your picture. Could it have been modified in the past ?
The 'narrow' breast plate will work with that engine and should help with fitting the aftermarket rear tray.
None of the aftermarket tinware is a good fit, so some 'fettling' will probably still be needed.
Yeah, gaps in the tinware is an engine killer.
The wide breastplate and rear tray should close like this, (Pulley cover tin removed for clarity) :
I've also fitted seals along the edge of the tray where it meets the cylinder cowls, (stops squeaks and air leaks), may be overkill, but I remember a test done by John Maher, (of drag racing engine fame), where he noted the oil temp of an engine with properly fitted stock tinware, then sealed all the joints between each tin part and it ran consistently quite a few degrees cooler, (can't remember the exact numbers).
If you want to block up the air hose holes in standard tin - here's a neat and fairly easy way to do it - On ebay you can buy ready cut discs cut from aluminum or stainless, get some slightly larger than the holes (say 70mm) then drill a hole in the centre, put one disc each side of the tin and put a bolt / machine screw in the centre to clamp them up.
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