540 BUILD Carb engine
 

Hello All,
I will be starting a brand new engine build from scratch. I would like to purchase a 540 short block and go from there. I dont want to go over budget just make a nice high HP big block. Any suggestion on blocks dart merlin GM . It would be nice to get a completed kit to assm. Any suggestions?
Thanks Jeff

End goal HP? NA build I assume? I’d start with a search right now on any “block” you can get and then revaluate the situation.

You might want to check someone like Blue Print Engines. They make several options for marine applications.

Engine parts can be hard to get right now. I buy a lot of parts through summit and most heads and other higher end parts are months out right now. I am building a 496 and have had to use other brands I normally don't use (like bearings) because of availability. Some good motors and short blocks show up on here and facebook marketplace sometimes if you are in a hurry. Summer comes fast when there is no motor in your boat LOL

OP mentioned KIT however that may or may not be the way to go. More often than not those kit companies leave an open window when coming to parts. Many years ago I’ve heard of people getting what they paid for and the builds last. Everyday use stuff. Not so sure I’d gamble on today. If you could find a local reputable builder and piecemeal it together might be an option. Let him be the general contractor so to speak. Your machining, tolerances, specs, balancing etc will be much more desirable and trusted over a KIT. IMO.

As far as assembly it is fun to build your own engines but assembly is rather inexpensive even with a reputable builder. Just went through that with my 565’s.

All the recipes are on OSO going way back if your looking for cam, induction etc. Not taking away from your thread however do a search here on 540 builds or 540 recipes. Lots of good info.

First question is what do you expect out of your builds? Hp, how are you going to run them? Short burst to top speed or extended pulls 5- 10 minutes at top rpm? Budget? Your comfort level of service intervals? Being honest here can save you much aggravation down the road also lots of $$$
you can build a nice high hp budget engine that will serve you well if you don't operate it like you are in a poker run on every outing. I guess what I'm trying to say is hp cost money but endurance hp is very expensive.
my apologies if this sounded rude just trying to be honest. God knows enough of us have been burnt by trying to cut corners.

Blocks, cranks, rods, pistons, cylinder heads, cams, lifters, intakes for most part are very difficult at moment to come by, its became a get anything you can at any price , not search for good deals any more. So chances of rounding up all the parts you will need before summer are slim. One thing I will say about a "typical" 540, most builds are focused on a 5600 to 6000 rpm peak, do NOT go too big on cylinder heads, IE, dont buy 340, 335, 357 heads for a sub 6000 rpm build, even a 540 or you will be giving up tq and drivability, BIGGER IS NOT ALWAYS BETTER. I recently dynoed a pair of 540s with 340 cc heads, they had very weak torque numbers for the cu inches and poor fuel distribution, I did NOT have any part in the planning or choosing of any parts in these builds, they came to me with all new parts in boxes and I simply did pushrod geometry and assembled top ends, dyno tuned them. Too much cam, too big of heads and fairly big intakes, results were disappointing for the customer, Smitty

305 to 315 plenty big for a 540 at those rpms......I ran AFR 305's on my 540's they made just shy of 660 tq

Yep, I dynoed those 2 540s with 340 heads and they made tq similar to most 502s I build, had a terrible afr delta too, anywhere from 10s to high 14s, lack of signal!

What intake? Just curious. Can you pm me your ph number.
Tks
john

So very true Tahoe on the parts scenario waited 12 weeks on MLS head gaskets, 10 weeks on Alum Rods ,6 months for AFR 385s ,and ordered pistons in October they promised beginning of December then Xmas then New Years now yesterday said there done being coated and in my hands in 7 Days ... Only one that was good was Comp Cam 5 days custom gring and delivered to my door :party-smiley-048:

no waiting on parts, if fits you build spec's

https://www.offshoreonly.com/classif...le-o80988.html

I recently had a 540 carb built from my 502 mag mpi. 712 tq @ 4700 and 711 hp at 5600. It’s in my donzi 22 Classic. I am really happy with it. I am currently ditching the emi exhaust and going to stainless marine.

Very nice! What cnc heads do you have. What a trip your Donzi must be. I remember back in the 80’s-90’s seeing those screaming at 70. You gotta be pushing low mid 90’s I’d think. 🤔

Try a Jomar 1" phenolic tapered spacer, it improves signal and boosts midrange torque. Couldn't believe the difference it made for me. I also added a 1" open and it helped my top end. Both were noticeable improvements you could really feel in the boat.

Very nicely port matched Dart intakes he bought with the heads. I probably pulled #1 of these two motors 80 times on dyno trying different carbs, carb spacers, air bleeds, stagger jetting etc trying to get those hot cylinders cooled down without flooding the cold cylinders. They had Crane 651 cams. a very lazy cam for a NA motor with its short lift vs high duration. We were making about 640 corrected hp and 630 ft lbs of tq using highly modified 4150s my dyno partner norm did ( was hot/humid out, our raw numbers were like 580-590 hp/570-580 ft lbs of torque). The AFRS were worst Ive ever seen though. No carb spacer or staggering of jets could fix it, motor just was lazy and had horrible intake signal/velocity, cylinders in mid 10s and others in mid 15's in certain spots, mid 14's in alot of spots So essentially we had some coal black plugs on verge of fouled and ash white plugs.
We also had Daytona boxes, I found the happiest timing curve vs power right away and it had very little effect on the afrs. Ultimately we took off the modded carbs and put ones on that flowed less, gave up 20 MORE hp and foot lbs of tq and afrs were "only" 3.5 points apart instead of 5. I threw fuel at it until the burn down cylinders were in mid 13's and lost even more power, but a boats got to be able to run at wot and not melt a piston on every outing! Smitty

We did, made zero difference, we tryed every possible spacer, etc to fix the distribution issues. Thes "best" spacers I tried out of all of them on this deal were some un modded chinese speedmasters and it didnt fix the afr problems by any means, would maybe get us to 4.5, 4.2 points apart vs 5 in widest spread area

At least they weren’t your builds. Damm the guy still had near or the same amount of money as builds making a lot more lower with better afr’s to boot. Nice to learn off someone’s mishap also.

I can only imagine the money he had wrapped up in these, DART big ms, good rotatings, ati super dampners, daytona boxes, BUT too low of compression, too much cam, too big of heads, Im not real fond of Dart intakes either, Smitty

I am still getting her dialed in. Just have 20 hours on the new set up. The builder spec’d dart 335 heads with a custom ground cam. The 50 to 70 acceleration is awesome. I really didn’t want or need low end torque with that hull. I don’t think there is any one best generic build. The needs of the hull is probably most important.

I've heard that more often than not regarding dart intakes. They have proven potential however must require some more skill than others. I think years ago when several started to drift away from stock boat engines dart snatched the market. Everybody had to have one. I think they do advertise port to match etc however much more than just a head match.

Just watched an Engine Masters episode where they tested Dart, Profiler, Edelbrock and Brodix intakes on a 598 big block. They saw similar results with the Dart. The AFR’s were all over. The Brodix had the turtle and made the most power with the best AFR’s. Surprisingly it beat out the Profiler.

I’ve got the Brodix and Pofiler. Was going to sell the Brodix as I replaced with the profilers. I’ll have equal amount of work to each and will dyno each back to back on my 565s. For my particular get up Valako was pretty adamant about the csa being to small with the Brodix. If power is close across the board I’ll settle for the best afr’s.

I'm also friends with your head porter, Jimmy V and I consulted on him with these customers dart intakes, he didn't have any great solutions other than what I tried, Surprisingly, I had some very nicely contoured, cncd spacers made by a good friend in Ohio that fit the unusual shape of the Dart intake plenum opening, they did NOT make as much hp as the "normal" ones and didnt helps afrs at all, but thats WHY we dyno. I have yet to find the ideal open plenum intake for a given application. Mainly what I see is TERRIBLE afrs cyl to cyl and lack of tq on small engines like 502s, 454s. When I dyno lets say a 454 and it makes 560 peak tq, 560 hp and has huge tq curve then dyno a peaky one that makes 580 hp 200 rpms higher but 30 to 70 less ft lbs of tq in 80% of power band, id take the one with more average power everywhere. Pleasure boaters who cruise, drive loaded down, etc get best results from motors that arent peaky with broad tq bands. Guys trying to break a big speed number are willing to run light on fuel, spend 10k on various props for every condition, tell their passengers to stay HOME, etc

Id dyno them all BUT knowing what I know about your heads, large ports, high flow numbers Id hate to see you KILL all the gains by restricting it with a intake thats too small. BUT the dyno will tell real story, sometimes results are opposite of what we expect. This is HYPOTHETITCAL for sake of discussion, lets say you got this 450, 480 cfm port flow, ports pretty damn big to get that number, no way around it. On dyno motors lazy and doesnt perk up till top of your power band (IM NOT SAYING THIS IS WHATS GOING TO HAPPEN but, your in prostock head flow territory), you bolt a intake thats Restrictive on, it makes your combination actually work better overall for some reason, ie, creates a restriction thats needed, something. Would be NICE to have those parts on hand to try, Id bring every possible intake you can to dyno and test them all. Maybe one that is ported close to your heads works best, you wont know till you dyno, Smitty