MTFCA Forum

I changed my 1915 model t over to a Z head. It began to knock on first start up. I shut her down as this happened on a friends 1925 Roadster on first start up. 2 identical start ups, 1 week apart. The exhaust manifold glowed between 2 and 3 cylinders. I changed her back to the original head and fired her up. No knock but the same glow occurred between 2 and 3 cylinders. I adjusted the mixture between lean and rich and settled on 1/2 way between; the remained. Any suggestions for a fix. Mark J

When you installed the Z head, did you test the head by putting it on without a gasket and with loose bolts to check for interference between the pistons and head? Hand cranking would reveal interference by lifting the head slightly. There could be interference especially if your engine block has been decked and/or if your block has a large overbore. If that is a problem the combustion chambers can be ground for clearance.

I can't help from here with the glowing manifold. Are you certain that it was not glowing before the change? You may have an exhaust gasket leak.

FYI, if you post this question in the general discussion forum will get you many more responses and advice.

Copy and repost on the general forum, this section is for problems with the site not car questions.