cocktails

Do you have an opinion.?? I always thought my setup wasn't putting out the power that I should. I have had many people over the years tell me how surprised they were that I was only getting 550-600 HP with a 502 and 420 Blower. Even when I dyno'd the engines we just couldn't get the motor to spin more than 5100 rpm on the dyno. That's all she had.
I looked at the Gaffrig arrestors Not cheap. Don't want to spend 1K is it's not going to help a great deal.

Thanks again

Griff

I would think you should be at least 600hp and closer to 650hp. The Merc 600SC used a 420 blower. Maybe try comparing your specs to the 600SC specs.

What are your cam specs???????? flat tappet or roller???

cocktails

The can is a B&M Blower cam made by crane. Flat tappet
283 Int 293 Exh 60overlap
Duration @.050 236 INT. 246 Exh. Overlap 13
Lift @cam .325" Int. .336" Exh.
Lift @valve .553" Int. .571" Exh.
Centerline 114

cocktails

[QUOTE=daredevil;2779231]When I put this project together I sent the carbs to Nickerson with all of the engine specs and that is what he came up with.
The fuel curves look good on the dyno sheets that I remember.

cocktails

Definitely a 420 blower for a 502. I even pulled out all my original paperwork and specs. to double check on the pulley sizes. Although if the 600SC used a 420 blower and put out 600Hp I'm really in the ball park. would still like a little more if I can get it.

cocktails

We ran the engines on the dyno with out the K&N Arrestors so they had no impact. An interesting statemnet in the B&M Brochure it says in the canm description. " B&M's special super charger cams add a substantial amount of power to engine speeds of 4,200 to 6,000 rpm. My boost gauge does not show any Pressure really until I'm at 4000 or so. I know it has to make more power through the midrange because I increased my cruise speed by 5-7 MPH from stock.

Fuel pressure(I do have a gauge right on fuel line before Carbs. ) I think i run consistant 7-8PSI.

Maybe I'm chasing a ghost. This could be all the motor has and tuning more might not get me anything to speak of. Again my original thought was to put the smaller pulley on and gain a bunch of Horse power. But then I thought I might have to reprop. I am only running 23P 4 Blade Hydromotive. for Barvo 1's. I need to send the props out to have Hydro put in the larger Hubs for XR's so if I could gain some I could go to more pitch. I have alot of testing to do I guess. Maybe I splurge and Dyno the motor again with a few different pulley's and see where I end Up. thanks again for all your help and advice.

598Boat

Hi! When you had the engine on the dyno did they check for cfm? How much cfm were you pulling through the carbs? They stick an airflow hat on each carbs. It does sound like to much carb to me also. I haven't run anything smaller then an 8-71 and that would be enough for that. I bought a set of 1050 dominators off a guy who had them on a 509c.i. He was able to rejet the carbs smaller for the air fuel ratio to be good, but was only flowing around 500cfm He had to go with smaller carbs and made more power. I don't know if he was having problems with rpm though. Whomever put the engine on the dyno should have seen a big red flag when it wouldn't go past 5100rpm You're probably leaning on parts pretty hard from this also.

HaxbySpeed

What valve springs are you running, and do you know what they're installed at? It's quite common for springs without enough pressure, or even the wrong style spring to produce bad harmonics causing minor valve float very early in the RPM range. On blown motors as the rpms increase and the float gets worse it starts to bleed cylinder pressure, losing boost and horsepower. Your engine basically hits a wall. Just a thought...

Griff

Thats a pretty good sized flat tappet cam. It should make good power to at least 5500-5700rpms.

Have you tried going down in pitch on the props to try and get it to spin faster???? I really can't see that you should have a problem making enough torque though to get past 5100rpms.

What about the timing?????? Where is it set for full advance and what ignition are you running???

AIR TIME

scoops around the vinly to add air and chillers