CIG3

Did you try to run with no flame arrestor?

And like Matt said check vaccum with and without. I'm sure there is someone close by that may have a larger flame arrestor to try.

Are your props 25 Mirage or Mirage Plus? I think I have a set or 23's laying around (Mirage)

Full Force

Didn't try no arrestor but you can look through mine and see carbs lol I think air fuels would show lack of flow, like before...

I will try more things but pretty confident it's just where it's is making its power... Almost spot on with old engines with less cam, more CI so kinda washing out...

ICDEDPPL

Full Force

I have 25 mirage plus

5050

just read your thread, sorry to hear all you have gone thru. I think all of us that wanted more out of our boats have had some problems at some point. I personally think there's a lot that really has to go into a build, unless you have a proven combination. There's so many variables and I think the biggest is what u said torque curve which can come dyno and different cam swaps which lobe separation can change whole torque curve not head intake runner size and velocity and compression, so much to a natural aspirated build to get max out of it that I wish I understood how it all works, blowers are the alternative to pure speed on a boat. I don't see why people build 540s when u could 598s for relatively close to same cost. Torque is what pushes these sleds that we love. What cam specs did you run?

SB

It's a twin engine big cube build. Less power in low 5,000 rpms...because of camshafts....Not buying it.

Back in the day , early 80's to mid 90's, many guys only had 454's available. Most builds where near, at 10:1 compression.

Guess how they went faster ? Kept throwing more camshaft at it....yup.....

They'd all start out in mid 220 duration. Go to 230. Go to 235, go to 240...and most would end up between 240-245 at .050".

540+cids are much more of an engine than those...and can take even more camshaft and respond.

Too much cam they where told......but the boats said other wise.

All the above, my IMHO and experiences.

5050

I'm still curious what cam specs are on this 540 build.

Full Force

It's more about WHERE the cam makes power I used someone for cams that is well known for boat cams like him or not, I told him I wanted to peak about 5800-6000 figuring we can still use the 25 plus... That didn't work like expected and I think I was just expecting too much out of my build and in reality it's close to a lateral move and that's fine I at least have rick solid high quality parts in these engines now that before were built out if Chinese no name stuff... If I put small props in I bet the speeds are better if I left them 565ci like before they would have had more grunt but didn't want the rod angles to do that as the old cylinder walls showed lots of wear from it...

If anyone person thinks this was a slap it together no research build you are mistaken it's been everything but that.... Maybe too much thought at times....

Full Force

241/[email protected] 681/663 lift 112 lca

5050

What were cams with procomp heads for comparison