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.

Ok,,,just a thought i had ?! Sorry.

But i dont understand why it would not go over 5100 RPM !

5400-5500 sounds better ,,,i think.

Could realy be airflow ?!
Where is the fuelpress ? should be 8.5- 9 PSI at WOT !
maybe mix is wrong ????

Boost should kick in at 2800 up to max.

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.

Let us know the results of the test,,,,,,,intressting.:cool:

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.

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... :drink:

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???

scoops around the vinly to add air and chillers:evilb:

maybe to small of a cam I think they used the old 454 420 cam:grinser010: which I think is close to what is above. being a baja your drives are deep to start with, maybe a 25 mirage plus would loosen up the slip a lil, you could talk to rmbuilder for custom cam, carbs could be tuned up by nickerson if its been a while, props if you get to that brett at bblades has a prop swap you buy 2 props test if you need to go up down or 4 blade you pay for return shipping and handling charge its great then when your on the money you can have them lab it.

His cam is bigger than a 420/525SC cam. I pulled strong to 5400-5500 rpms with a cam very close to the stock 420 cam specs. His cam is bigger and should pull harder up top.

I have to wonder if the cam installed 4* advanced or straight up. If advanced, it would pull the torque curve and peak hp down lower in the rpm range. Also where the timing is at full advance???