Anyone run a 3 circuit Dominator on a BBC with a little 177 or 174 blower?
#1
Anyone run a 3 circuit Dominator on a BBC with a little 177 or 174 blower?
Hi,
Found what appears to be a good deal on a 3 circuit 1150 Dominator, for my set up but I'm not sure if going the 3 circuit route is right for me. List number 9377, so its an older 3 circuit, with no PVs.
My boat is an 89 baja force 235 that runs in the mid 60's at about 4700 rpm with a 24p bravo1 prop at about 6500 ft elevation on Lake Abiquiu in New Mexico
Motor is 8:1 compression 454 with a B&M 174 running 7.5 lbs boost at WOT
Cam specs are,
238 int./248 exh. @ 50
540/540 lift.
114 LSA
Current carb is an 850 boost referenced vacuum secondary with 3.5 PVs. Reason I feel it's far too small is that I ended up having to increase jets from 78 primary/82 secondary all the way up to 97 primary/98 secondary before I got rid of the lean condition at WOT.
Anyhow, I know merc ran a 2 circuit 1050 with 6.5 PVs and some pretty fat jets on the 525SC and it seems to me that I should maybe just copy them....At this point, I've been going back and forth with this guy on the carb and I'm in uncharted territory with the whole 3 circuit no PV thing but I hate to turn down a good deal....
Any advice towards 3 circuit carbs on top of small blowers??
Thanks,
Travis
Found what appears to be a good deal on a 3 circuit 1150 Dominator, for my set up but I'm not sure if going the 3 circuit route is right for me. List number 9377, so its an older 3 circuit, with no PVs.
My boat is an 89 baja force 235 that runs in the mid 60's at about 4700 rpm with a 24p bravo1 prop at about 6500 ft elevation on Lake Abiquiu in New Mexico
Motor is 8:1 compression 454 with a B&M 174 running 7.5 lbs boost at WOT
Cam specs are,
238 int./248 exh. @ 50
540/540 lift.
114 LSA
Current carb is an 850 boost referenced vacuum secondary with 3.5 PVs. Reason I feel it's far too small is that I ended up having to increase jets from 78 primary/82 secondary all the way up to 97 primary/98 secondary before I got rid of the lean condition at WOT.
Anyhow, I know merc ran a 2 circuit 1050 with 6.5 PVs and some pretty fat jets on the 525SC and it seems to me that I should maybe just copy them....At this point, I've been going back and forth with this guy on the carb and I'm in uncharted territory with the whole 3 circuit no PV thing but I hate to turn down a good deal....
Any advice towards 3 circuit carbs on top of small blowers??
Thanks,
Travis
Last edited by 89Force235; 12-31-2016 at 11:19 AM.
#2
Registered
Stay Away from the 3 Circuit , complete pain in the ass to tune. And with out power valves that thing will eat fuel.
You probably had to go richer to cover the heat made by the blower .
You probably had to go richer to cover the heat made by the blower .
#6
Registered
iTrader: (7)
Mike I hear what your saying however I bought a set of pro systems 950 carbs that were built and spec'd for 177 engines. It kinda through me off a bit but I even talked with Patric before purchasing them and his comments were they were perfect for the 177 builds but a little on the small side for my use but would work.
#7
Registered
iTrader: (3)
mercury marine would have used a smaller cheaper carb but they spent the extra money for a reason.on engines like the sc525 fuel distribution is not real good but the dominator 1050 helped.the sc525 came with 7.5-1 compression ratio and a whimpy hyd flat tappet cam,without boost it would not get out of it,s own way.the small 177 blower would not move enough air with a 4150 carb,it made less than 500 hp so the dominator was the answer.
#9
Registered
Pro systems built me two 1150 dom carbs last year. 3 circuit. He had the intermediate circuit very soft. Power valves were the high flow style (I had a ton of PVCR). Clean idle, clean cruise (around 13.5), just a hint of fattening up when the PV's opened. Otherwise they were perfect. I monitored via O2's...I quizzed him on the 2 vs 3 circuit debate in marine. He laughed and responded that it's 2016. Old days are well past us... FWIW they can and do work. [ATTACH=CONFIG]563200[/ATTACH]
#10
Thanks, I've seen this response a fair amount regarding 3 circuit carbs and it seems to make sense to me from what I understand about how the intermediate circuit works.