Some carb / intake info
 

This is a copy and paste from a post I made regarding F.Fs intake thread. I felt there was enough information here for it to stand alone for people searching. There are 2 additional pulls here from the old engines that I don't believe I've posted before. So this is a reasonably comprehensive list of popular induction choices for the 540. My 4150s were from Pro Systems actually flowed 986 cfm so they were a decent size. The 4500s were rated at 1050, but I don't know the real word flow. They are Quick Fuel marine. The cams are from Bob. Heads are AFR 305 w/ cnc chamber only. Here's the highlights of the induction changes.

Average cam specs 239/641

Vic Jr 4150 / 4150 no spacer
644 hp 654 tq

Vic Jr 4150 / 4150 2 in. spacer
660 663

New cam, otherwise same parts. Average cam specs 243/ 654

Vic Jr 4150 / 4150 2 in. spacer
674 645

Vic Jr/ 4150 with 2 in. adapter and 4500
686 659

Vic with 4500 plenum (same height as the 4150 version) no spacer 4500 carb
695 664

Same 4500 intake and 4500 carb 1in spacer
699 673

Same with 2 in. spacer
706 666

I ended up going with the 4500 and 1 in spacer. Gave up small amount of peak for overall better hp curve and more torque.

Can you add info to the above post on the cam change, and exactly which carburetors ?

Thanks.

Added the info

Should have put a Super Victor on it. The intakes you used are booth to small for 540 cubic inches. The Victor intake is called the 454-R for good reason. Not many people take notice to that.

I couldn't afford to buy intakes just to test with, so I had to use what parts people would loan me to test with. That was the only intake and carb size that were offered to me for free to try. Courtesy of 88bullet/ jonesyfxr and Blackmer automotive. Edit- in addition to those changes they were also run with different ignitions and lifters. There was no difference from Crane to Daytona. I made 4 hp less with the high end Johnson's than the Morel but that's well within the margin of error with the dyno in my opinion. I did what I could.

Thanks for this information, I am building a 548 with 10:1 and using the same manifold with a demon 850. I was contemplating using a dominator but was talked out of it because this will mainly be a Tahoe boat so high altitude was taken into consideration and for drive ability (family boat). I will be using 088 heads but will be port matched and a little bowl work done and a 252/630 roller. I was hoping for around 600 HP and this looks promising.

What was the RPM range for these? or peak HP RPM
thanks

I'm glad you posted this. I realize your time spent and expense of doing so is difficult for some to share with others however it shows your a stand up guy and can save others time and money to achieve similar goals. I understand slightest little changes can easily change outcome but you did a good job posting in detail and will undoubtedly help others with builds.

I will keep everyone in the loop with my 565 builds as well. I'm getting close on parts needed for engine number one and will be on dyno. The only thing I hope for is to borrow someone's 1250 dominator to see if engine will make more power up top. Currently I just have 1050 doms but really want to try a 1250 when on dyno.

We build 088 headed 540's in the same fashion you are only 9.5:1 compression and they have no problem making 650hp.

Just an FYI cause I know your using a solid lifter cam. The bushing type rollers will nock 25hp right out of the motor.

I was talked into going with the 4150s by the original engine builder because of the improved driveability. In retrospect I should have gone with the 4500s and matching intake from the beginning. Peak horsepower with the first cams and 4150s was 56-5700. The final 4500 and cam combo peaked at 5600 with 1in spacer and 5700 with the 2 in

With that small of a head you really want the largest intake you can get your hands on.

I'd tend to agree, but like I said I couldn't buy just to test with and I wanted to know without a doubt I would gain power before I spent $. I considered going larger with the entire induction setup including heads but it was a huge expense. I wanted a money back guarantee on the power I was promised and I wanted the power under 6k rpm, not over. Of course no one would make a promise like that so I went with what was free and then purchased what I could.

50/50.
Where do you draw the line... with open spring pressures? Good and bad with both needle and bushing.

I don't draw the line as far as spring pressure. I've ran up to 1250# open with titanium valves. Really depends on the entire valve train package...

Now, those original builds with the smaller cams / 4150s walked all over the dominator combo at lower rpms. They were even at 4600 and then the dominator combo pulled away from 4600 to the end at 5800. I really wish someone had the skills or program to overlay all these graphs.

Here's the graph of the 2 4150 pulls. One with spacer and one without. You can see the spacer improved everything. Also this combo with the smaller cam / 4150 easily outperformed the dominator combo up to 4600 then the Dom combo pulled ahead till the end at 5800. Notice this graph has torque on the right on a different scale than hp.

Here is the Dom with 1 in. spacer graph.

That comes at no surprise. Combo/application. Twins vs single... Sacrifices will always be made to achieve maximum hp but not necessarily always ideal for every application. I think you ended up extremely well. Sure more time and more money might have gotten you a few more ponies but give you credit for doing what you did. Going to dyno to jet and look for leaks and go home is not worthy in my opinion.

Nice

The boat tended to like to cruise @ 45-4600. I didn't spend much time below that so it was a decent trade off for the top end. Even with all that low end torque with the original combo the boat just didn't seem to like cruising at 3500

Notice the new cam seemed to kill the torque while it improved hp with the same induction. It was the addition of the Dom that restored the torque considerably and further improved the hp. It was a good learning experience as to how all these parts compliment each other and the combo really has to be on the money and fine tuned with something as simple as a spacer to get the best results