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20+ years ago I always used clear sight plugs during new motor startup just to keep fuel from leaking all over the place and causing a fire. So... I put some clear plastic sight plugs on my new 4150 for startup and it was a disaster. After a backfire while setting timing the plug in the front bowl cracked and of course left pices inside the bowl. I had to take the bowl off to remove the chunks before they got into the needle. I ended up with more fuel on the intake than I would have by just leaving the brass sight plugs out to adjust the floats. What a PITA, never again.

Anyone want one clear plastic sight plug ? :noway:
 

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No thanks.Not only do they become milky..they degrade and will actually fall out of the bowls.major fire hazard imo.
Tipped off a fellow at a crusie in with these sight plugs on his tunnel rammed 340 Mopar.They where missing on the passenger side and he thanked me for the observation.:noway:
 

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Ironic that you say that.. I just bought some of those clear plugs to help in adjusting my floats. I took the car for a drive and on the way back home the car was running really really rough.. Once I got back home I noticed that the rear one the was all but fallen out looked the threads melted. So I that junk out and put the brass one back in. They didn't even last one drive. :noway:
 

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Discussion Starter #5
Yep. My intention was to just use them for break in and then put the brass back in, didn't even last that long. Oh well, at least they were as cheap as they were cheaply made and no real harm came from them.
 

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Wow, never had a problem with them myself. My bro broke one once while trying to put one in a fuel bowl, but he breaks everything (bull in a china shop kinda guy). I've used them for years in circle track and never had one fail using 110 octane race fuel. They do get milky looking after awhile, tho. I've always taken a set of small pliers to tightem 'em with, but just enuff where they don't back out on their own.
 

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I've had the same two Holleys with those on my marine motors for 10+ years running a race gas mix and never had a problem. The pounding will make your body feel old (wait I am old now :clonk:)

Maybe its time to change them out next spring :).
 

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If you read the fine print they are supposed to be for tuning only..... I left mine in for a week and one was already seased. I had to pull the bowl off and chip the plastic out. Setting them with the brass screws really isn't that tough.
 

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I know this thread is 2 years old but wanted to remind everyone to stay away from those clear plastic sight plugs for the holley float bowls.

Just like everyone else - my engine was running rough. Took off the air cleaner to find these little plugs (that were less than a year old) were broken and falling out. They got soft and turned milky color about halfway down the threads, the soft plastic broke off in the fuel bowls when I attempted removal. I had to take the primary bowl off to get the plastic out but was able to fish the secondary bowl chunk of plastic out with tweezers.

It must be the ethanol (or another alcohol additive) making the plastic degrade.

also... my sight plugs were from Moroso and did not have any "fine print" on the package stating they were only for tuning etc... I hear the Holley brand plugs fail the same way too.

bottom line - use the orig brass plugs or get new bowls with GLASS sight windows.

Dave
 

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In the event of a carb fire or engine fire, the plastic plugs would melt and a small fire could become a big fire very quickly.

It's the same reason I hate to see rubber fuel hose between the fuel pump and carb. Dangerous as heck.
 

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I know this thread is 2 years old but wanted to remind everyone to stay away from those clear plastic sight plugs for the holley float bowls.

Just like everyone else - my engine was running rough. Took off the air cleaner to find these little plugs (that were less than a year old) were broken and falling out. They got soft and turned milky color about halfway down the threads, the soft plastic broke off in the fuel bowls when I attempted removal. I had to take the primary bowl off to get the plastic out but was able to fish the secondary bowl chunk of plastic out with tweezers.

It must be the ethanol (or another alcohol additive) making the plastic degrade.

also... my sight plugs were from Moroso and did not have any "fine print" on the package stating they were only for tuning etc... I hear the Holley brand plugs fail the same way too.

bottom line - use the orig brass plugs or get new bowls with GLASS sight windows.

Dave
Just a few points being the devils advocate on this...

1. Holley continues to make the clear plugs and sells carbs with them.
2. Some new Holley carbs are now being made with bowl sights that are not threaded and use a clear lens held in with a ring clip.
3. If the float level is adjusted properly the only fuel the plug is exposed to is what splashes onto the very end of the sight plug.
4. In this day and age no company would risk safety and legal issues over a $7 part if their lawyers felt there were any.

All that said, I don't currently use them but have. I don't mind spilling a few drops of fuel onto a rag when adjusting floats and once adjusted I trust my work so brass plugs are fine. I think the potential for issues based on mis-use are enough to stay away from them. By mis-use I mean; anything from over tightening them, cross threading them, over full float bowls, using fuel additives that may cause issues etc.
 

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Just a few points being the devils advocate on this...

1. Holley continues to make the clear plugs and sells carbs with them.
2. Some new Holley carbs are now being made with bowl sights that are not threaded and use a clear lens held in with a ring clip.
3. If the float level is adjusted properly the only fuel the plug is exposed to is what splashes onto the very end of the sight plug.
4. In this day and age no company would risk safety and legal issues over a $7 part if their lawyers felt there were any.

All that said, I don't currently use them but have. I don't mind spilling a few drops of fuel onto a rag when adjusting floats and once adjusted I trust my work so brass plugs are fine. I think the potential for issues based on mis-use are enough to stay away from them. By mis-use I mean; anything from over tightening them, cross threading them, over full float bowls, using fuel additives that may cause issues etc.
Good points Dennis,

followup....

1) Holley does still sell them - But I confirmed there is a "tuning only" warning sheet that comes with the plastic plugs now. Not so sure about complete carbs though - I bet they use the newer glass sight windows / float bowls nowadays.
2)Yep... the new bowls (w/ glass) are avaliable separately too - part #s 34-37 and 34-38
3)With the floats adjusted correctly. Gas stays in contact with those plugs (due to vehicle movement) and if you drive the vehicle every day, as I do, you will eventually have trouble.
4) Holley has the disclaimer now for legal reasons. My Moroso blister pack had none. Maybe it was old stock or something but both plugs definately softened up and failed within a year.

and the parts were hand tightened only with no additives in the gas ever - just premium fuel.

And I trust your work too Dennis :) You're always a huge help in this forum.

Regards,
Dave
 

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I talked with one of Holley's tech guys a short time ago about a 850DP that I was adding an electric choke to on a 572. He strongly recommends AGAINST the plastic sight plugs for all the reasons you guys mentioned. They just aren't worth the risk.
 

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Oh and the scary part is that I drove from DC to CT and back 2 weekends ago. Eleven hours at 5000 rpm (with a hot trafficy NJ turnpike return trip). All the spare tools in the trunk (not needed, yay) would never have put out a carb engine fire!

It was actually an awesome drive. Still have the "top-down" slightly red nose to show for it.
 

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DjD,..we could make list as long as your arm of parts sold today that aren't worth a dang and unsafe. You can still purchase:

Tire plugs
Glass fuel filters
Foam Air Filters
Wheel spacers and adapters
Undersized steering wheels
Brake parts from Asia
Uni-Lug (universal lug) Wheels
Etc, etc,..
 

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I thought I could get away with leaving them in for a couple days while I tuned. One cracked and fell inside the bowl before Day 1 was out! The other separated. I caught it when soon after I warmed the engine up, I just happened to look at one side of the carb and noticed something different. Hmmm... something's not right. The threaded portion was still in the bowl but the head had popped off!
There should be an added line to the 'Tuning Only' disclaimer... to just barely tighten them. Barely. They're cheap brittle plastic. I obviously over-tightened them.
Gotta love the blue gaskets.
;)
I do see cars with Holleys driving around with clear sights on the bowls. Older carbs... not the new generation. And they do get all yellow and cloudy. I'll never use them again.
 
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