Mercruiser 7.4l V8 Exhaust manifold, spacer, and risers

My mechanic told me its was time to replace the exhaust manifolds, (3 inch), spacers, and risers. So trusting him as I always have I purchased all new Sierra parts and gasket/bolt kits. Well the installation went great until I went to close my hatch on my 250 CCR. It would not close all the way. I noticed the top of the risers were about 1/2 to 3/4 inch above the deck of the boat, causing my hatch not to close all the way. Let me start by saying the old manifolds/spacers on the engine were after market (GLM) and the risers were the original stainless steel from Mercruiser. I called the company I ordered the parts from and they verified the parts were the correct parts. I also did the same thing by checking with other comapnies online and got the same part numbers. So.......what is the solution to this problem.

Re: Mercruiser 7.4l V8 Exhaust manifold, spacer, and risers

double check the spacer height, and if the spacers are really required then find a machine shop and cut to rough size and mill to finish size
of 2 inch.

Re: Mercruiser 7.4l V8 Exhaust manifold, spacer, and risers

Oh, I forgot to include I spoke to Mercrusier Reps. who said I better check the clearence of the water in my exhausts before I remove spacers. Those engines did not come with spacers when they were shipped to Crownline. So someone installed them for a reason. Even my mechanic is baffeled

Re: Mercruiser 7.4l V8 Exhaust manifold, spacer, and risers

pages 40-45
http://www.boatfix.com/merc/Install/gas/86419602.pdf

Re: Mercruiser 7.4l V8 Exhaust manifold, spacer, and risers

Ok, well. I brought it back to mechanioc, he said he is also baffeled. His only thought is to buy Mercruiser manifold, spacers, and risers and see if they area any different in height. That alone is over $900. So I did my measurements and got over 15 inch (which is req. by Mercruiser. So I had the spacers milled down almost 3/4 of an inch, cut the exhaust tubes just 1/2 inch (.43 to be exact) and reinstalled everything. It fits. Worst part is I had to buy a new oil filter bracket, $160, new longer hardware, flush brass plugs, and new gasket kits. BUT it worked.