On the exhaust fume problem, yes of course all the connections have to be leak tight, but also replace the hood seal and the hatch seal at the rear. That's how we solved that issue with my son's car.
When I had my GTV6...I 'discoverd' the following: When I had a non-standard exhaust fitted, I picked up two new problemsStarted doing just that ...driving with both windows partially open. The car is still tappetty but loosening. Still stumbles at an indicated 4000 rpm. and on pushing the throttle. The AFM for the BMW from Cardone arrives....635 csi Ljetronic AFM... and guess what it has 5 pins....God it had to happen did it not.
So another one ordered ...lets hope its the correct one when it comes. Am also in the process of getting a spare one I have refurbished by Vickauto. I WILL WIN THIS.
I have a CSC exhaust system fitted with an ANSA exhaust. Just got a new/ refurbished BMW AFM... will put that on and see .. and if that fails. The exhaust fumes... well sorting out the seals first and then follow your advice if that fails.When I had my GTV6...I 'discoverd' the following: When I had a non-standard exhaust fitted, I picked up two new problems
1) A nasty flat spot/stumble at 3750rpm, and
2) Exhaust fume smells unless the cabin blower was on.
My theory on 1 was the two OEM front stub resonators are tuned exactly to 3750rpm, and if you put a custom system on the injection will get all confused, and over-fuel, as it expects the engine to breath wildly at this RPM.
My theory on 2 is that the tail pipe needs to be centralised, or the exaust gets pulled into the wake vortex and into the rear cabin vents.
My theories held up when I got 3.0 75, I cured a bad flat spot at the magic 3750 by fitting standard front resonators in place of the straight pipes that were fitted. It is not very scientific, but it seemed to hold true on these two occassions. Hope that helps.
I think you should get the correct AFM for the GTV6. You should contact sources in Europe like SAVALI and OKP engineering. There is always some surplus.I am now looking for a L jetronic BMW 633 ECU.
John Kartalamakis mentions in his book that the 635 CSi ecu and AFM work and are plug and play.. well almost ... but these are Motronic and not L Jetronic whereas all GTV6s were L Jetronic so what is he talking about????
Yes I am quite sure the 164 heads will fit on the 75 3L engine. Have not tried that, however the 164 engine is a development of the 75 engine by turning it 90 degrees to fit a front wheel drive engine. The 164 crank is 4mm Shorter than the 75 engine, but I think that does not bear on the heads. With regards to the distributor connection on the 164; the whole sub unit can be removed and the blanking plate from the 75 engine can be installed at that posistion, no problem.pics of heads... will they fit on the 3.0 block form a milano/75 and what mods if any I will have to make...obviously the distrbutor will have to be blanked off...but other things???