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Have an 89 conbrio. Two years ago swapped out my holley 4010 for a 4060.
Suspect yours is a 4010 model which is the marine version of the 4011.
650 cfm
The 4060 swap has worked great except floats do not have external adjustment.
If at all possible recommend rebuilding your existing carb by a professional carb shop.
Good luck
This kit should have everything you need: http://www.summitracing.com/parts/hly-37-119
That carb is great for a stock 351w. Lucky that you have a carb with externally adjustable floats. Nice to have on a marine engine which typically sits at an angle. If secondaries were dripping your secondary float height was too high or your needle and seat were not sealing. That would absolutely cause a hard start (flooded) condition and other slow speed issues.
600 CFM is finea good match for a stock marine 351w. 650 CFM would be fine as well. More than 700 would be pushing it. 750-800 CFM carbs are fine for big blocks but will result is less than ideal performance and throttle response on a small block. Stumble from low RPM when rapidly opening throttle is insufficient accelerator pump shot. With that 750 you needed a larger accelerator pump shot to eliminate that and/or adjustment of the secondary air valve which enriches the secondary mixture as they open like a choke does.
I would rebuild and run that Holley you have. Be sure to check the base plate and throttle shafts for wear. That will create a vacuum leak and result in low RPM issues such as inconsistent idle and mixture, possibly hard starting.
Great advice CADUNKLE !
Maybe I wasn't clear...the holley parts are interchangable and available over the counter. The carb comes apart in a matter of 5 minutes, and you can take the gaskets to any speed shop to get replacements. Same for the vacuum diaphram, power valve, o-rings, float valves. It's a modular design, and it only had 2 basic variations throughout it's production. I have never had the model number to rebuild a Holley. It's either mechanical secondary double pumper...or like yours, vacuum secondaries.Quote:
Originally Posted by LCYrace
As for the pressure question. At 9.5 psi I would expect the float bowls to overfill, as the pressure is higher than the valve is designed to meter. The vents will dump fuel into the bores, causing starting and low speed problems. 6-7psi is desired. At 8 psi the bowls will fill a bit more than desired, so you may have to set the float levels a bit lower than spec...or you may get fuel dripping out of your jets and have a rich idle and starting issues...like flooding. If the float levels are set the same, but your Holley is not level, then one bowl will overfill and leak, and the other will underfill. At WOT some cylinders will be rich, while others will be lean. You can try to use different settings, but levelling the carb is the better option.
Leveling the carb as much as possible does help. I recommend a phenolic wedge spacer if you don't have a wedge spacer already. Phenolic will help prevent heat soak which can result in vapor lock or dripping after shutdown.
Thanks for all the replies. It is definitely a 4160 of some description. I pulled the carb and measured the bores and all were ~1.56 inches. I went out yesterday with the wife and kids so I didn't get a chance to test WOT but I did pull the tube a few times and a wake-board. I did notice much improved idle over the Eddy and no problems with the boat rocking and dying. I did have some stumble when pulling up the wake-boarder. I couldn't go from idle to full throttle quickly without quite a bit of hesitation. If I was running 1000-1200 rpm it would take full throttle fine. I will get the recommended rebuild kit and try to find a wedge spacer. I am out of room height wise and with the current 1" phenolic spacer I had to create for the PCV vacuum I cannot add a wedge. Unless there is a way to modify the carb itself for the PCV vacuum a wedge is out of the question. I do have the float level set pretty low in the rear bowl so I wouldn't have the drippy secondary syndrome so that may be the stumbling issue. I hope I can get a wedge to work as I think it may have a lot to do with the hole-shot issues. We do ski a lot and the stumbling is annoying when you are the one getting dragged and the boat wont go.
To fix the stumble going from idle to seignificant throttle you need to to try different accelerator pump cams to get more shot earlier on, or a larger discharge nozzle. Check the accelerator pump shot with engine off and working the throttle or pump. It should be a crisp stream down both primary bores. May be a plugged passage or nozzle restricting or delaying the shot, or not allowing a clean stream right on the boosters.
That's a very thick block for your PCV. There is likely an allen plug on the manifold directly under the carb to install a vacuum tap for your PCV. If not, any machine shop can angle mill the plate to be at the angle you need.
The manifold you have is more a short runner design for high RPM, so it may be difficult to get it to hit off idle. These manifolds tend to "come on" like a switch at about 2-2500 rpm. The 2 things you have to adjust it for a better low end hit are the primary side accel pump shot, like Cadunkle mentions, and then you can also tighten the loading on the secondary vacuum servo to come in slower.
Before you rebuild, it is very important to find out what your vacuum is at idle in gear. You have to match the power valve to open just above that vacuum. The wrong power valve opening can frustrate you and cause bogging/hesitation if it is opening early or late.
The beauty of a Holley is that everything is adjustable.