Re: more cam or less prop?
 

Not sure. I know zero about those drives.

Re: more cam or less prop?
 

You say you only have 14.5 in of vac at idle. This engine should have more vac than that. The overlap in that cam is not big enough to cause any vacuum loss. Are you sure you that cam was degreed in correctly?

Re: more cam or less prop?
 

I took the time to plastigauge the bearings, file fit the rings and everything but degree the cam cause I lent my wheel and dial indicator to a buddy. Now I feel sick! Does any one make a gage that will fit into the spark plug hole so I don't have to pull a head. This was a comp cam kit I used don't they have good quality control?

Re: more cam or less prop?
 

Andy,
I found this site that lists gear ratios for te king cobra: http://www.sterndrive.info/chart.html
Also, If you can get the model number off one of the drives, I might be able to get to my friend's shop to check the books. There should be a tag on the side of the drive.

Paul

Re: more cam or less prop?
 

I currently have an 89 Formula 311, Bravo drives and almost identical engines. I ran into the same problem as you did, 4400 rpm and 61 mph, using a Bravo One 4 blade 24 inch pitch.I found out by trying different props that I was over propped. I went down to a Bravo One 22 inch prop , now running 4800-4900 rpm and 64 mph.This is what Formula says that this boat should go with this power.I previously had 540 inch 560 horse motors that ran 77-78 mph , those engines could pull a 30 inch Bravo One.

Re: more cam or less prop?
 

Andy,

What spark gap and ignition, I've seen too much gap cause the problem.

Mike

Re: more cam or less prop?
 

Andy, don't start tearing into your engine now. Try the simple things first. Smaller props will make a huge difference. Try calling the prop shops that are advertised here. They have a lot of knowledge and can point you in the right direction.

Re: more cam or less prop?
 

I got the 4barrels working correctly and only gained 150 more rpm and 2 mph max (vacuum pot on carbs loose at carb seal) Have stock coils and Accel distributors mechanical advanced. I'm going to get my prop repitched.