Need help with carb/intake selection

[Real Baja]

I have a pair of 502s with Dart Pro I CNC ported heads. Original head work was done at Lingenfelter for his injected 540 hp 502s. I am not sure if these are the 335 or 355 cc intake runners. Cam is Comp with intake .640 exhaust .623 duration 230/242, @112.0 intake center line.
I am looking for help with carb size and intake.

Thanks

 

[imco offshore]

I have a pair of 502s with Dart Pro I CNC ported heads. Original head work was done at Lingenfelter for his injected 540 hp 502s. I am not sure if these are the 335 or 355 cc intake runners. Cam is Comp with intake .640 exhaust .623 duration 230/242, @112.0 intake center line.
I am looking for help with carb size and intake.

Thanks

your best bet is call a good marine engine man, tylor crocket--cobra---ect,,,, BUT BEWEAR soon a know-it - all is going to come on and tell you all about his, success,,,,,, ask him one question ? have you ever finished a race, ?

 

[MOBILEMERCMAN]

There are some guys here on Serious that can share good info too. Be patient you should hear a few suggestions.

 

[Trim'd Up]

your best bet is call a good marine engine man, tylor crocket--cobra---ect,,,, BUT BEWEAR soon a know-it - all is going to come on and tell you all about his, success,,,,,, ask him one question ? have you ever finished a race, ?

Gee I wonder who your talking about.:leaving:
I'll throw my $.01 in. First off, your heads are a little big for a 502 at 335, and way big at 355 unless your turning big rpm's IMHO. As far as intakes go, I really don't think your gonna see an appreciable difference in any the good single planes Dart, Merlin, Victor etc. If you boat in salt you should get an intake with brass water passages. As far as carbs, a holley 800 should be plenty.

By the way, I am not the know-it-all that was mentioned above, in fact, I know very little about anything,

 

[BGIII]

Unless they made running changes on their engine package, which I doubt, here is a list of the parts used on that engine. This information was gathered directly from Lingenfelter.

Lingenfelter 502CI/540HP
Dart Pro-1 CNC aluminum heads 320cc intake runners, 110cc chambers
2.25"int/1.88"exh one piece Comp Cams stainless valves
Comp Cams 230/242 .634/.624 114LSA hydraulic roller camshaft
Comp Cams stainless roller rockers 1.7 ratio

 

[BGIII]

Cam specs directly from Comp Cams (note that the 230/242 is measured at a different duration than most cam manufacturers)

 

[Real Baja]

Thanks for the information. I have not had time to cc intake runners, I was going by the intake runner size of 1 3/4 inch by 2 1/2 inch. I hope they are smaller than 335 because I do not plan to turn over 5200 or so.

The cam card I got from Comp after getting spec's from Lingenfelter had a little different lobe separation, 112.0. But who knows, it was a long time ago when the 502/540s were developed. The cams were custom grinds back in the day. I could not find this cam on the Comp cams current website.

I assumed the carb should be an 800 or 830 cfm which will likely flow somewhere around 770 or 800 cfm wet, which if I use the standard carb sizing formula is about correct.

I have read and been told that marine engines with max rpm under 5400 make a little better power with smaller heads. I cannot change the heads, but, will these engines work better at lower max RPM (5200) with a large oval port intake that is port matched to the heads or can I use a rectangular port manifold and put a one inch thick four hole carb spacer on the manifold and get better performance?

Thanks for the feedback. I am kind of new at this marine engine stuff. I built a few healthy 289 fords for a 65 mustang, but that was a long time ago. (I purchased my mustang new in 1965.)

 

[BGIII]

Are you going to dyno? I'd love to see the results w/ a single plane rec port intake and an 800-850 carb.


What lifters were in there? Stock GM or Comp?


They may have done my cam special w/ 114 LSA to help with reversion. I have custom made tailpipes with Corsa Captain's Choice for my KE headers. Who knows?

 

[DAREDEVIL]

I would say go with a DOMINATOR,,,i run 510 Ci and it is just @ the max of the Dominator.

So a 540 and those heads can easaly take it ,,,,get the jets right and u have no problems.

 

[Real Baja]

I would say go with a DOMINATOR,,,i run 510 Ci and it is just @ the max of the Dominator.

So a 540 and those heads can easaly take it ,,,,get the jets right and u have no problems.

The engines are 502 cu. in. rated at 540 hp when Lingentfelter originally built. I think a dominator (1050 or bigger) would be more carb than needed.

Any estimates on jetting an 800 or 830 cfm carb? I would think that the carb set up would be close to the Merc HP 500, but not sure and have no experience
with this set up.

Thanks

 

[Chris]

Contact Bob Madara at Marine Kinetics. Tell him we sent you.

585-654-8583. MarineKinetics@rochester.rr.com

He will set you up with exactly what you need, perfectly matched to your boat and existing hardware. You don't mention what exhaust- that will have some bearing. Also, you may need to re-cam to get everything to work properly.

 

[DAREDEVIL]

The engines are 502 cu. in. rated at 540 hp when Lingentfelter originally built. I think a dominator (1050 or bigger) would be more carb than needed.

Any estimates on jetting an 800 or 830 cfm carb? I would think that the carb set up would be close to the Merc HP 500, but not sure and have no experience
with this set up.

Thanks

I'm with Chris,,,and sorry i tought it's a 540CI !

 

[runninhotracing]

I would say go with a DOMINATOR,,,i run 510 Ci and it is just @ the max of the Dominator.

So a 540 and those heads can easaly take it ,,,,get the jets right and u have no problems.

wheres the Dominator BIG Daddy ?????????????????

 

[jeffswav]

Like these guys said, I would call Bob RMbuilder. Sounds like you are a little missmatched. Bob will point you in the right direction. Bore and stroke it to a 540 and the heads would work a lot better. You can easily run 54-5500 RPM with forged parts.