Shah Mat

Anyone with older Checkies have CMI's? I just ordered the headers and I was told the tailpipes would have to be custom made. I thought my boat was just a standard BB/Bravo set up like many other makes of boats. Guess not. I bought the boat with a small block but was told it was a BB originally.
The exhaust holes are 18 1/2 across, center to center and 15 1/4 up from the crank centerline.

A lot of money being spent here, I want to edu-ma-cate myself as much as possible before ordering a set of custom tailpipes.

89 Convincor GTX 25'

Shah Mat

Pic of transom

convincor

you will need to go custom. ran into the same thing with my 90' 251 gtx. I chose a different route. I bought a set of Gil manifold from an OSO member and picked up a set of new 500hp tail pipes from ebay for $299. A couple hundred bucks in materials and I plugged and glassed the factory holes and re-jeled inside and out. you'd never know they where there. I had made some other changes on the transom at the same time. So i worked out great and I didn't shell out $2000+ for tail pipes.
Do a seach in this forum for motor mounts. you being platinum you should be able to see my pics from last winter/spring.
ps. I don't have the factory platforms any more.

Shah Mat

Thanks for the info. I saw the pics, great job!

Those factoy swim platforms were f-ugly huh? That was the first thing I wanted to get rid of when I bought my boat. They did serve their purpose though, and since the rest of the boat looked shabby, I left them on til paint.

I should have done this engine swap while I painted it, then I would have filled the exhaust holes too. Oh well, live and learn. I decided to go with CMI's because of the cam profile I'm running. I don't want to run into reversion problems because I go through no wake zones with long idle peroids sometimes. I also didn't want to go dry. Hopefully with the water entering the exhaust stream 1" from the transom it will be Ok. I'm probably being overly cautious, but I want it right the first time. Nothing worse that down time in the summer, and thousands spent on the wrong things.
The headers polished were $2400 and tailpipes are $675... that is if they aren't custom. I think they quoted me $975 for the custom ones. The thing I'm worried about is the measurements on the transom. He said I have to be within 1/4 inch. That is another thing I want to get right the first time. I'm not sure what kind of return policy CMI has on custom tailpipes, and I sure as hell don't want to find out!

Turbojack

When I had my tail pipes made I went out & bought some 4" pvc pipe & fittings. I then cut, sanded, more cutting & more sanding to get them to fit like I needed them. I then took pictures of my PVC pipes installed. Sent all to CMI with picture of transom & all of the measurements. Their first try was not even close. I sent back with pictures of what they make installed. Got new parts few days latter & they were perfect. CMI worked with me all the way.

Shah Mat

That is good to know, although if I screw up measuring, I'm sure they are mine to keep. I may consider the PCV mock up. Thanks

zzzzzz

Had Gil on mine worked great with powertorque manifolds

Shah Mat

OK, I measured 4 times....

For the crankshaft centerline to the center of the exhaust hole I took two framing squares and layed them flat on the transom, one at the center of the exhaust hole, and one on the pivot pin of the drive. I then measured the distance between the two and came up with 14 1/4".

Then for the distance the holes are apart from one another, I measured from the vertical centerline of the transom out to the center of the each hole and came up with 9 1/4".

The transom thicknes is 2 1/8"

Then I took an angle finder and put it on the flat surface next to the engine hatch where the rear cleat bolts, and then on the transom. Subtracted the two readings and came up with 10 degrees for a transom angle.

Anyone with a Checkmate been there and done this? How does my measurements sound? I'm going to call Fred at Trick Marine Monday morning and order these things.