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I am looking to squeeze some extra mph out of my boat. At it's current setup I am running 65 mph at 5,100 rpm's. I have the Edelbrock RPM cam and intake along with the 750 marine carb. Do you think that a 1" spacer would do anything to help out? I have one sitting on the shelf, and was looking at using it, but if I do, then I will have to modify my hood since there is only about 1/4" clearance now.
Thanks, Dan
the spacer helps a little but if i were you id get rid of that cam and get something with a 108 lobe center.that edelbrock cam is made for a car not a jet boat.
spacer may or may not help, they are a crap shoot. I've seen them make and lose power on dyno so not worth cutting boat to try. 8 mph improvement over last year is pretty good though.
I took my 1" spacer off (it had a liitle crack) & replaced it with a 2" spacer. now my motor idle at 2,000 rpm :rolleyes: I will turn the idle screw down, but at that rpm speed it did make it easy to keep the boat going straight while heading in to put it on the Trailer (just keep working the forward - reverse handle)
I have a 460 with the weiand stealth manifold and the Isky "jetboat" cam. Logs and a holley 750.When I had this motor built I had some hood clearance problems and decided to take the spacer off, I was very dissapointed. I ended up cutting the engine cover so my air cleaner pops through and put the spacer back on. I picked up almost 200 rpms with the carb spacer on.
Carb spacers are tuning devices only. Open hole spacers favor the top-end by slowing down the mixtures velocity. The four-hole spacers extend the carburetor bores, providing for a higher velocity at lower RPMs giving you a strong low-mid range.
Your best bet is to test them out. Buy a sheet of plywood, carbon copy a carburetor gasket to the wood and create you own. Then test them 1/4" at a time to see which works best. Then when you find the correct one buy a fancy billet or phenolic version.
Hope that helps some.
~Ty