ZZ502 w 741 cam issues
#22
Geronimo36
Gold Member
May also need to adjust secondary butterfly if he's not running a PV. I've seen a lot of carbs without PV's load up when using big cams without PV's because the primaries have to be open more to idle at the correct rpms and the carb actually comes off the idle circuit and starts pulling fuel from the boosters.
#23
Geronimo36
Gold Member
Recently ran into a similiar problem with this boat.... It's a 454, 9.6 comp and an 850 holley and 741 cam, which in a 454 makes it hotter then the same cam in a ZZ 502. It didn't have a PV when I started. When I took the carb apart I found that one of the primary jets came loose and fell into the bowl. I then jetted down the primary and installed a 6.5 powervalve. We also went from a #8 NGK race plug to a #7. The engine idles all day long now, no fouled plugs and you can beat the snot out of it.
http://media.putfile.com/Billys-JC-Performance-Motor
http://media.putfile.com/Billys-JC-Performance-Motor
Last edited by Panther; 11-21-2007 at 11:40 AM.
#24
Registered
iTrader: (1)
1BIGJIM, I just noticed you have a Pachanga, is yours a 22 or 27?
If 22, if you had RMBuilder make you a cam that is larger I am going to assume you have more power than I do. ( Actives Dyno was 560 something ).
What is your setup?
I am going to work the bottom of mine, add a 2" shorty and get BBlades on the prop ( he does my drag stuff )
RT
If 22, if you had RMBuilder make you a cam that is larger I am going to assume you have more power than I do. ( Actives Dyno was 560 something ).
What is your setup?
I am going to work the bottom of mine, add a 2" shorty and get BBlades on the prop ( he does my drag stuff )
RT
I never put it on the Dyno.
Brett did my prop last spring. Worked great, 25 Mirage plus. I turn it around 5,000 at 77 GPS
The tail pipes in the picture, are those for swim platforms?
#25
Registered
Thread Starter
Yes, the pipes are for swim platforms, with the bottom turned out to exit the sides rather than back.
I have a stock 26 bravo and turn it 5400 with the 1.50 gears in my Bravo.
What drive do you have?
I have a stock 26 bravo and turn it 5400 with the 1.50 gears in my Bravo.
What drive do you have?
#27
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Vacum Read
I am no expert, but I think a vacum of 4.5 is too low. Even with the cam. Where are you getting the reading from? Check out:
http://sbftech.com/index.php?topic=3020.msg29472
Did you have any backfires? The rich condition could be a blown powervalve.
Personally I don't think a crossover would cause the front two cylinders to run soooo much cooler than the rest. I ran a crossover but went back to circ pump because I could not get the temp over 130. But I loved the look and simplicty of no moving parts, I just wanted my water at 160 and more importantly, my oil above 212.
http://sbftech.com/index.php?topic=3020.msg29472
Did you have any backfires? The rich condition could be a blown powervalve.
Personally I don't think a crossover would cause the front two cylinders to run soooo much cooler than the rest. I ran a crossover but went back to circ pump because I could not get the temp over 130. But I loved the look and simplicty of no moving parts, I just wanted my water at 160 and more importantly, my oil above 212.
#29
Registered
there something going on with only 4.5 vacume, you need to look there, as stated before, if you have a power valve(and you should) and it's anything over 4.0 it's open at idle and will cause a over rich condition....but that vacume seems way to low for that cam and set-up...Rob