View Full Version : New Holley 4160 Back barrels not opening

08-30-2010, 01:07 AM
I have a 1990 Tristar 190. I recently installed a new Holley 4160. The back barrels are not opening. The boat idles and cruises fine, but with the back barrels not opening I obviously do not have any additional power after about 2800 rpm's.

Any suggestions would be helpful.



08-30-2010, 11:13 AM
Did you install a vacuum actuated secondary 4160? There are multiple models....

Your carb should have a vacuum actuator on the left, like the attached picture. (ignore the manual choke and lack of marine J-tubes, i just grabbed this picture because you can see the secondary vacuum unit clearly)

this is attached directly to the secondary throttle plates and will open up around 2800-3200 RPM on most engines.

If you do have a vac. secondary -- and you're not getting any secondary action... that is based on carb. ported vacuum - either you have a serious vacuum leak somewhere, or the linkage isn't connected...

08-30-2010, 11:37 AM
Could also be a bad secondary diaphragm.

08-30-2010, 11:38 AM
Assuming vacuum secondaries, could also bad secondary diaphragm or spring from the factory, maybe binding linkage from being hit during packaging or installation. Have you tried to open them by hand?

08-30-2010, 11:52 AM
Oh yeah - thanks for putting that there - I got distracted by a phone call at work, and posted before I had finished my thought -- but, secondary diaphragm should be brand new like the rest of the carb... of course that's never a guarantee...

You can pull the secondary actuator off of the carb with 3 screws and a linkage, and test the diaphragm - just put your finger on the vacuum port and gently move the pushrod up and down - you should feel a strong vacuum/gust of air on the port when you push/pull. Of course you can always just take it apart, too, but that little rubber diaphragm in there is a bit of a pain to get back into the housing.

08-30-2010, 10:54 PM
Thanks guys for the suggestions. It is a vacuum secondary. When I move the push rod up and down I can feel the the push of air in the port. My mechanic is baffled as well. I decided to go with the new carb as appossed to a rebuild so I didn't have these problems. Crazy!!

08-30-2010, 11:01 PM
I would get a vacuum gauge hooked up to see what is going on. You could have a bad carb casting ........... pretty unlikely but possible.

08-30-2010, 11:08 PM
I appreciate your help. However a vacuum gauge is beyond me. I wish I was more versed with this stuff. Now if I was fixing a golf swing I could have all the answers. The crazy thing is it idles and cruises perfect.

08-30-2010, 11:18 PM
You can buy a vacuum pump/guage at autozone for about $25. you hook it up to a vacuum port and it tells you how much vaccum there is. It also works in reverse as a pump, to create vacuum.

08-30-2010, 11:20 PM
Thanks for the help. I will buy one tomorrow. I will let you know the result.

08-30-2010, 11:40 PM
one more question. Could it have anything to do with the mixture screws? Just a thought? Maybe not providing enough air flow?

08-30-2010, 11:44 PM
The mixture screws will only have an effect at idle and off idle. How have you verified that the secondaries aren't opening?

08-30-2010, 11:58 PM
Ignore. I posted this twice. Sorry

08-31-2010, 12:00 AM
I verified the secondaries not opening while I was on the water. I took the flame arrestor off an was looking in the carb and saw them not opening. When I opened them manually I had my power back.

08-31-2010, 09:06 AM
I would give the guys at Holley Technical Support a call. You may have a bad casting - I have run into two of those over the years.

Holley Performance Products provides award-winning technical support via phone Monday through Friday from 8AM to 6PM CST, and Saturday from 9AM to 3PM CST @ 270 781-9741.

08-31-2010, 10:06 AM
I verified the secondaries not opening while I was on the water. I took the flame arrestor off an was looking in the carb and saw them not opening. When I opened them manually I had my power back.

How long were you able to look? Was it just a second or two while sitting still?

08-31-2010, 10:20 AM
No I was able to look at it for a half mile or so down the lake. I had the lid open while my wife was driving. I am going to call Holley Tech support. Thanks for all the help.

08-31-2010, 09:12 PM
A couple of things...
1) are you saying it won't go above 2800 rpm? if so this is more than just a secondaries not opening issue. when I bought my 87 Prostar the previous owner had disconnected the secondaries. his contention was that At slalom speed the secondaries were right at the point of opening and he felt it gave an uneven speed as they were opening and closing slightly through the course (I am not a course skier so don't know how true this might or might not be). In any event, we left them disconnected and we still had plenty of power and speed (only knocks a few mph off top end) but improves fuel consumption.
2) the second point is do you know that the diaphragm is connected to the butterfly valve? I assume so but just because the diaphragm seems to work it won't be of value if noT connected (this is probably obvious but sometimes the obvious is overlooked).

back to 1... I am not real familiar with the tristar but I would think it should definitely be able to turn more than 2800 rpm w/o secondaries so if you can't get above that it seems there might be something else going on.

08-31-2010, 09:31 PM
I believe he wrote that he can push the motor beyond 2800 by manually engaging the secondaries at speed

09-03-2010, 07:50 AM

I'm facing exactly the same issue with my new carburetor 4160. I'm curious to know what you have tune/investigate to have this new carb working properly...

Here are some more details about my situation:
WOT I can get 4200rpm without the secondaries open. If I manually open the secondaries it goes easily to 4600 rpm.

In fact, I just need to help the secondaries to open. After that it stays opened, so I guess the diafragm is good. I have also checked the vacuum on the port of the carburetor and I can read 22.

For me, it looks more like a spring issue on the diafrgram.
One last thing: I have noticed that when tightening the carb on the spacer plate it will affect on the butterfly valve. If it's to tightened then the opening is more difficult. Maybe this could be one cause of the problem but having it not tightened may create a vacuum leak...

I also know that holley sells a set of different springs... I might try with a softer one. What do you think ?


09-03-2010, 09:02 AM
I would look at the carb base gasket and see if that is interfering with the secondary throttle blades from opening. If tightening the carb properly is causing a problem, I would look for something that was changed from when the carb was working properly.

09-03-2010, 10:40 AM
Or - Holey Moley - how much torque are you putting on those screws... make sure your base plate is still true (use a straightedge to check for perfect flatness across the corners and cardinal directions)

09-03-2010, 10:43 AM
dchat - that does sound like springs... although as i note in my other post, please check to make sure your baseplate is true (the one on the carb). If it was over-torqued it could have warped/bent. It needs to be perfectly true. Your description of it 'sticking' worries me. I'd check your spacer plate for trueness too.