power valve
07-26-2021, 06:58 PM
#11
Registered
I`ve tried it all, the best fuel curve I got was block off all power valves and tune with jets.
Wanna lean out primary take jet out.
but at the end of the day without a O2 reading he`s pissing in the wind.
Wanna lean out primary take jet out.
but at the end of the day without a O2 reading he`s pissing in the wind.
07-27-2021, 01:17 PM
#13
Registered
I have a Pro Systems 1000CFM 4150 and I have power valves in primary and secondary, although I have restrictors in both. Carb runs great and I get really good fuel economy. Power Valves aren't always bad, if done right. I get 2.5mpg at 60mph all day long.
07-27-2021, 02:33 PM
#14
Registered
Platinum MemberThread Starter
i love like ...love to add o2 sensors,,,but it would be a big job,,,,and sensors would be in wet exhaust extensions,,,heard suggestion put in 90 degree adapter would solve wet problem...maybe..
i think i am going to start dropping jet size..go run boat mid range,,,,then pull a few plugs..
thanks for all advice....boats runs...just seems to fat...
plugs are always black...
thats some good fuel mileage thisisliving..........what rpm u at running 60...4500???
i think i am going to start dropping jet size..go run boat mid range,,,,then pull a few plugs..
thanks for all advice....boats runs...just seems to fat...
plugs are always black...
thats some good fuel mileage thisisliving..........what rpm u at running 60...4500???
07-27-2021, 10:07 PM
#15
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Platinum MemberThread Starter
did u just put on your motors??? i am guessing you had to fine carbs somewhat???
thanks,,,,,,for advice...
07-28-2021, 08:28 AM
#16
Registered
The problem with most carbs out of the box is they are designed for cars that have a multi gear transmission and can rev much quicker than in boats. In addition boats are under constant load. I spent years tuning my carb to get it just right and the proper ignition timing and curve are part of that. I have a big cam and in gear at idle I have 2.5" of vacuum. I had to change power valves, jets, accelerator pumps and squirters to get it to run exactly as I wanted. With a big cam and prop it takes longer to get on plane and build rpm's so I needed to extend the accelerator shot and timing to get me to the point I had some air flow to pull fuel. I ended up going to a 50cc on the primary with a .028 squirter on both primary and secondary. I had to use 2.5" power valve and as I stated earlier I have them on both primary and secondary. I bought an Otoscope to help read the plugs. I started the jets on the rich side and kept dropping them down based on the plug reads. Because I have almost no vacuum at idle it was hard to get the initial timing right. I tried special bushings in my MSD distributor to reduce the total advance so I had more initial timing. Then I ran the distributor locked which helped. I finally switched to a Daytona Sensors system that allowed me to create a custom timing curve with added idle control which made a huge difference. Now even without a choke she starts right up and I only need about 30 seconds of warm up and she's good to go. Once it's been started for the day I just give the key a quick hit and it's running. I know EFI can give you better cylinder to cylinder fuel balance. But when I pull my plugs, they are all identical even looking at them through my 10x Otoscope. I think some of that is due to the improved signal I get when I added a 4 hole tapered spacer. That also made a noticeable difference in performance. With motors as in life, everything matters and effects everything else.
07-29-2021, 09:47 AM
#17
Registered
Platinum MemberThread Starter
The problem with most carbs out of the box is they are designed for cars that have a multi gear transmission and can rev much quicker than in boats. In addition boats are under constant load. I spent years tuning my carb to get it just right and the proper ignition timing and curve are part of that. I have a big cam and in gear at idle I have 2.5" of vacuum. I had to change power valves, jets, accelerator pumps and squirters to get it to run exactly as I wanted. With a big cam and prop it takes longer to get on plane and build rpm's so I needed to extend the accelerator shot and timing to get me to the point I had some air flow to pull fuel. I ended up going to a 50cc on the primary with a .028 squirter on both primary and secondary. I had to use 2.5" power valve and as I stated earlier I have them on both primary and secondary. I bought an Otoscope to help read the plugs. I started the jets on the rich side and kept dropping them down based on the plug reads. Because I have almost no vacuum at idle it was hard to get the initial timing right. I tried special bushings in my MSD distributor to reduce the total advance so I had more initial timing. Then I ran the distributor locked which helped. I finally switched to a Daytona Sensors system that allowed me to create a custom timing curve with added idle control which made a huge difference. Now even without a choke she starts right up and I only need about 30 seconds of warm up and she's good to go. Once it's been started for the day I just give the key a quick hit and it's running. I know EFI can give you better cylinder to cylinder fuel balance. But when I pull my plugs, they are all identical even looking at them through my 10x Otoscope. I think some of that is due to the improved signal I get when I added a 4 hole tapered spacer. That also made a noticeable difference in performance. With motors as in life, everything matters and effects everything else.
wow........alot of info...but i like it...
so do u run the daytona sensor system with your msd distributor????
so u replaced the msd box with the daytona system??
what motor and how big is cam??
thanks for info........
07-29-2021, 10:34 AM
#18
Registered
The problem with most carbs out of the box is they are designed for cars that have a multi gear transmission and can rev much quicker than in boats. In addition boats are under constant load. I spent years tuning my carb to get it just right and the proper ignition timing and curve are part of that. I have a big cam and in gear at idle I have 2.5" of vacuum. I had to change power valves, jets, accelerator pumps and squirters to get it to run exactly as I wanted. With a big cam and prop it takes longer to get on plane and build rpm's so I needed to extend the accelerator shot and timing to get me to the point I had some air flow to pull fuel. I ended up going to a 50cc on the primary with a .028 squirter on both primary and secondary. I had to use 2.5" power valve and as I stated earlier I have them on both primary and secondary. I bought an Otoscope to help read the plugs. I started the jets on the rich side and kept dropping them down based on the plug reads. Because I have almost no vacuum at idle it was hard to get the initial timing right. I tried special bushings in my MSD distributor to reduce the total advance so I had more initial timing. Then I ran the distributor locked which helped. I finally switched to a Daytona Sensors system that allowed me to create a custom timing curve with added idle control which made a huge difference. Now even without a choke she starts right up and I only need about 30 seconds of warm up and she's good to go. Once it's been started for the day I just give the key a quick hit and it's running. I know EFI can give you better cylinder to cylinder fuel balance. But when I pull my plugs, they are all identical even looking at them through my 10x Otoscope. I think some of that is due to the improved signal I get when I added a 4 hole tapered spacer. That also made a noticeable difference in performance. With motors as in life, everything matters and effects everything else.
07-29-2021, 12:45 PM
#19
Registered
Platinum MemberThread Starter
not sure if it was you or someone,,,but it was suggestted to make it a two circuit....
not sure how hard it would be...
but i think a site or two was posted on this..
i did look at one of these sites...wow..
stuff they were talking about changing,,,i didnt even know what it was,,, was over my head..
just did a google,,found a thread on here from 2010...also don terrils speed talk...
thanks info.....
sounds like i should gt new carbs...any suggestions???
Last edited by flashgordon; 07-29-2021 at 01:00 PM. Reason: spelling
