I have an issue where my manifolds are glowing red. This is just letting the car idle and then free revving it to about 3,000 rpm for about 20 seconds or so once the engine is up to temp. Also when I switch it off I get a backfire through the exhaust.
Engine is a 711m crossflow 1700 all steel stage 3 244 camshaft twin 40 Weber’s all new and just built compression ratio about 10.5:1
The ignition timing is set at 14deg at idle and about 34deg at full advance so should be Ok. I had a wide-band Lambda checking the AFR and it was fluctuating between 14 and 15: 1 at idle blip the throttle and it goes rich briefly but settles back to around 13 or 14. So not particularly rich and certainly not lean. At this sort of rpm and throttle opening I guess it will not be progressing to mains yet so shouldn’t be an issue with mains chokes etc . Compression test resulted in about 180psi on each give or take a couple of psi (was done cold)
The engine sounds fine throttle response free revving is Ok so I’m pretty stumped.
Any ideas would be great.
I did post this problem a year or so ago and thought I managed to resolve it with help here as I had the wrong Carbs but the project was put on hold and back on it now with New correct carbs and jetting that should be ok as a starting point.
Chris
Bookmarks