Trash, I'm wanting to go to the Comp XM-276HR which is 224/230 @.050" but I think its a 110 LSA. But the 4 degrees less LSA combined with 3 degrees more duration means more overlap correct? EMI has some complete manifolds and risers that I can make work, I just don't want to spend that much to get the job done.

I've extended the inner pipe on the riser on a pair of factory style GLM center riser exhaust by welding 2.5" mild steel exhaust pipe into the 2.5" pressed in place pipe. It kept the water and exhaust seperated for another 6"

The only thing I would add is if using it in saltwater you may want to go with stainless tube.

You'd have to look at the intake and exhaust overlap with data off the cam card. I'll try take a look at it later or perhaps SB is motivated to look ;)

I will guess you are close to reversion. When I went to Crower and got my cam Jerry (at Crower) said don't go any bigger.

We use these - Standard height thru transom stainless steel riser pipes fit stock Mercruiser center rise manifolds, as well as Glenwood Magnaflow manifolds. (Sold in pairs $1130.00) All kits include all necessary mounting hardware and gaskets. Weld on or Bolt on brackets available for Shift, ECM or EFI

On my 383s I had some custom ones made from Hardin Marine. I had some pretty nasty cams running in to GLM manifolds then the Hardin Marine risers. Worked very well.

have stainless extensions welded on to your current exhaust portion of your risers. Tack weld extensions with the riser mounted in place to the current angle of your tips. Then pull the riser and fully weld. If done right the extension should not touch your exhaust hose. Bring the extensions to about 1 inch off of your current tips. Nothing else in your setup will have to change. I've done this with great success combating reversion.

I ran the xm276hr on a 355ci. With stock length risers it will revert water. Found small puddles in the center manifold runners. I added 8" extensions to my Hardin stainless risers to fix the problem. Was running GLM alum manifolds. Xm276hr is 224/230 on a 112+2.

GLM sbc setup. Water hoses are covering riser extensions

http://i77.photobucket.com/albums/j7...imagejpg22.jpg

I've done the same thing to my 496 setup.

http://i77.photobucket.com/albums/j7...416_173901.jpg

Ryan, did you like that cam for a small block build? Did you run it straight up or advance it any? Mine will be a 383. Are those risers the Hardin 620-32410 part number that you started with? Thanks for the help.

I ran 1.6 rockers on intake with that cam for more lift/duration. Installed straight up as it has 2* advance ground in. With my AFR 190R heads it pulled very nice to 5600rpms. With it in a 383 it will be all in at 5000-5200 roughly. Mine were the 620-32420. If adding extensions these are what you want. The inner exhaust pipe is extended past the outer water jacket making it easier to weld too vs the 32410.