Holley power valve blow out help help

[Jasoncoronet]

Ok guys car was running great. Shut it down and restarted it and all of a sudden i started to get a very rich idle. Do power valves blow out on newer carbs. I have a 4150 750 cfm. I have checked all vacumn ports for leaks nothing has changed. I took the carb apart cleaned And checked all the floats needles and seat. Cleaned and blew out the meatering blocks. I found nothing weird. O ya the carb is pretty much new also. Any advice will greatly be apprciated.

Thanks,

Jason

 

[bm02tj]

If the seal on the gasket is not good because the metering block is warped you need to straighten it

if you need to I can try to explain how to do it

 

[Jasoncoronet]

Do they blow out. I hear they are blow proof in the newer carbs. I know they are cheap enough to just try but i want to try and check other things also. I pulled the plugs and they are pretty black now. Just seams weird.

 

[WP29440SE]

I read on holleys site that they do not blow out. when they go , they usually leak gas . I have brand new 4160 and the rear bowl has filled up and dumped gas. I lowered the float level and it has been working great ever since.

there is are holley tuning videos on youtube including the power valve shot setting.

 

[Jasoncoronet]

I tried all that. The car was just running perfect. Now at idle i am getting black smoke. Maybe the diaphram tore or something. My fuel preasure is at about 6 psi. Maybe to high. I just replaced the fuel pump that all thats new. My fuel regulated.

 

[WP29440SE]

I tried all that. The car was just running perfect. Now at idle i am getting black smoke. Maybe the diaphram tore or something. My fuel preasure is at about 6 psi. Maybe to high. I just replaced the fuel pump that all thats new. My fuel regulated.

if the shot setting is too tight , It will punch a hole in the diaphragm. I went through that a while back and it was leaking gas on the intake. that's not to say they would always leak if punctured. optimum fuel pressure is 5.5, I don't think 6 would push gas past the needles , but its possible. I had a problem recently with a different holley and regulated fuel at 5.5 , but it kept flooding. I switched to a mechanical fuel pump , the flooding stopped and it ran good. I also had a POS fuel regulator... just a thought

 

[HEMI-ITIS]

You need to look down into the carb while it's running and see if there is raw fuel dripping,if there is,,,,,,,,,readjust the float.If that does not help,lower the fuel pressure 1 LB and see if that helps.

 

[Jasoncoronet]

I think you might be on to something with the fuel preasure. The engine is a 360 stroker 408. I know tha is not much info but what are exceptable fuel preasures for a holley in your opinion. I have it 6 psi.

 

[Meep-Meep]

You can run up to 7 PSI and not have an issue assuming everything is normal. My stock 6 BBL is at 7 PSI and no problems at all. A common problem with externally adjustable needle and seat assemblies is the o-ring around the needle and seat assy can leak and that will give all the symptoms of a float problem. Seems unlikely to have happen on a new carb but it is something to check.

I have always heard about blown power valves but I never had that happen. I have seen bad ones where the diaphragm no longer seals but that's about it. Don't forget the old Autolite 4100 uses the same type of power valve (and a Holley one will screw right in) and you never heard about those carbs being prone to blown power valves.

 

[Jasoncoronet]

Ya i dont know what a blown power valve is either. I bought a new one only because the diaphram looked a little funny on the one that i have. I blew out and cleaned the meatering blocks and dry set the floats low. Tomorrow i will turn the fuel preasure down to about 4.5 and give it a go. I will replace the orings also. When i took off the bowls they are as clean as a whistle. I run a 100 micron pre filter and a 40 micron post.

 

[Jasoncoronet]

OK hears a update to what I think has happend. I did a real bonehead move with my PCV plumbing. I ran the pcv straight to the intake from the valve cover and I am pretty sure it is working like a huge vacumn leak. Also it probaly is sucking oil straight into the intake which will create the richness at idle (oil mxed with gas in the intake). Also my idle circuit in the carb in probably not working correctly because on the low vacumn and the simulated vacumn leak. The weird thing is the car did run great when I initially fires it up. So I am gessing the PCV is my issue and not the carb at all. Any input would be great.

 

[RustyRatRod]

It's not going to make a diffecence whether the pcv is attached to the carburetor base or the intake. They are both the same vacuum source. Oil will not make it run rich anyway, it will simply smoke. Plus, as long as the pcv valve is properly baffled at the valve cover, you'll not get any oil in the pcv system. Let me ask you this. Have you tried running some thin wire down all of the carburetor air bleeds? If they get stopped up that can certainly cause the condition you describe. Look at the picture. That's the air bleeds. There are four in the rear and four in the front. They need to be clean and unobstructed.

 

[Jasoncoronet]

I have not tried that but I will for sure that seams easy enough to do. You dont think that the engine acting like it has a vacumn leak being that the manifold is constantly drawing air from the valve covers. I think you are right on the rich part but what if the PCV is confusing the idle circuit. I think the smoke may be oil though. I dont think the PCV is suposed to have full time manifold vacumn. I cant wait all day at work I want to get home and try this. It just has to be something dumb.

 

[HEMI-ITIS]

Could also double check the power valve rating against a vacume guage to verify a vacume leak:blob1:

 

[Jasoncoronet]

Ya rusty was right on the pcv having no effect. Nothing changed still pig rich at idle. I will have to hook up the vacumn guage again to check. This really sucks i restored the whole car but cant fix the carb issue. I am thinking of upping my insurance and sinking it it the ocean.