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Discussion Starter #1
Just bought and rebuilt by me for a gas mileage experiment on the 327. Idles as smooth as a rock, pulls an unwavering 17" of vacuum, but there is a huge flat spot right in the middle of the primaries' travel that is spiking the A/F ratio up above 20:1, causing a big stumble. Once you open the secondaries(mechanical) it takes off pretty good but that primary side is killing me.

There are 2 primary jets and 2 larger secondary jets and one large jet that I am not sure what it does.

I have almost $60 into this carburetor so I really want to get it sorted. :D

Problem #1, huge flat spot midway through primary travel.
Question #1, are jets for this the same as other holleys? I have nothing to compare to.
Question #2, is that large, centrally located jet a power valve of some sort?

Three things I've thought to try but have not tried yet:
1) disconnect PCV as this could cause a large enough vac leak to have it go lean in the primaries.
2) Adjust pump shot. Not sure if this will help as the take off is fine until I hit the mid-travel of the primaries. Should the acc pump even be needed at mid-travel?
3) Swap secondary jets into primary side to see if just being richer kills the flat spot?

I know the Holley economaster is kind of 'fringe', especially for this forum, and I've read about all I can find on the internet about them(which isn't much) but if anybody with experience with this carb can make suggestions I am willing to try. Thanks.
 

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If a Q-jet worked on the manifold them your Economaster should as well. By mid throttle on the primaries you should have over come any rush of air the squiters would be needed to over come. To go lean like that suggests maybe you are running out of fuel on the primary side. Maybe remove the secondary linkage and see if the issue is actually with the primary side or if the secondary side is opening letting in air before it's fuel is flowing.

I've never worked on one but have never heard any good about this carb. Holley's attempt at a Q-Jet that never gained popularity. If you want a great small cfm Holley, I don't remember the list number but they make a 600cfm single inlet dual bowl spreadbore with vac sec's that is a great match on a 327. I know you don't want to eat the $$ you have in this carb though!
 

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Discussion Starter #5
If a Q-jet worked on the manifold them your Economaster should as well. By mid throttle on the primaries you should have over come any rush of air the squiters would be needed to over come. To go lean like that suggests maybe you are running out of fuel on the primary side. Maybe remove the secondary linkage and see if the issue is actually with the primary side or if the secondary side is opening letting in air before it's fuel is flowing.

I've never worked on one but have never heard any good about this carb. Holley's attempt at a Q-Jet that never gained popularity. If you want a great small cfm Holley, I don't remember the list number but they make a 600cfm single inlet dual bowl spreadbore with vac sec's that is a great match on a 327. I know you don't want to eat the $$ you have in this carb though!
Dennis, I also think the squirter shouldn't be an issue at mid-throttle. I did change the pump rod position for max travel and it didn't seem to make any difference. I haven't heard much good about this carb either but did run one back in the 80s on a buddy's 350 RS LT and it was quite responsive. No doubt the car would have been faster with a larger carb, though.

Trying to disable the secondaries is a good idea for a test. I've looked at it closely and I'm 90% sure the problem is all about the primaries but it's worth at try. What's really stumping me is the larger jet with a spring-loaded valve in the middle that seems to have passages that lead to below both the primary and secondary jets. I am not 100% certain these passages are clean/free flowing. Under what conditions should this jet operate assuming it mimicks a Holley power valve? I think I'll take it apart again and look into that. Thanks.
 

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I used one back in the 80s on the current spread bore performer manifold...
I got it out of the box, had to lean off the primaries a little, thu it ran fine..but liitle rich.
From there was reliable as...could never understand the bad rap this carb got..always put down to people tu tuing with stuff they did not understand..I then used the base plate later on the Impco 465 till wore out the butterfly bushes about 1yr back...unfortunately the body ..everything went to the metal recylers couple months back .
I think you and Dennis are on the right track thu

Get it sorted and it is a very nice carb for your application.
 

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I have been looking for one of my old holley books....in it it has jet powevalve cam etc etc for holley carbs and engine applicantions carbs
Covers several pages , columns etc, fairly fine print and from memory its about 10 pages in....it covers this carb towards the back..just over 2/4 of the way thru... at a guess it would be published about mid to late 80s??? I have not had it out for over 15yrs and cant find it.
Does the description ring a bell in any of your holley books?
 

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Part 34: bottom spring keeps the middle plug in the upper jet.
Part 23: has a spring on the bottom of the upper piston.

As vacuum decreases, as in opening throttle (load), pushes the plug out the jet to add fuel before the main power circuit comes into play.
Spring rate on Part 23 determines the opening point, lighter spring, open sooner, ie, 12 inches of vac, heavy spring, open later, ie, 6 inches of vac.
 

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Discussion Starter #11
Part 34: bottom spring keeps the middle plug in the upper jet.
Part 23: has a spring on the bottom of the upper piston.

As vacuum decreases, as in opening throttle (load), pushes the plug out the jet to add fuel before the main power circuit comes into play.
Spring rate on Part 23 determines the opening point, lighter spring, open sooner, ie, 12 inches of vac, heavy spring, open later, ie, 6 inches of vac.
Thanks Everett, that is exactly the kind of logical explanation I was looking for. This thing is tiny, maybe the size of a standard holley jet, so could be tunable by changing the jet or drilling out. Do you know thread size of typical holley jets? The rebuild kit included all 3 new parts of #34.

Different springs for part #23 are not part of the rebuild kit and there is no trick kit for this carb so I'd have to get creative with the spring tensions but before that I think I will disassemble the whole thing and soak the body because I believe the jet and powervalve passages are somewhat calcified. I sprayed them but did not soak the body of the carb. I know NAPA sells carb cleaner by the gallon...what is the best to use for soaking it... the NAPA brand or some other?
 

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Actually, I have it wrong after reading my statement over and over again.
'Lesser vacuum indicated requires a weaker/lighter spring than a higher vacuum indicated.'

As far as spring rate goes, place two springs end-to-end on a pencil, steel rod, etc.
Then squeeze them together. The most compressed spring is the lighter spring of the two.
 

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Discussion Starter #13 (Edited)
Well, I proved that the jets in this carb are not the same thread as QJet jets and I am told they are not the same as Holley jets either so there's not much chance of rejetting without drilling out. I wonder if Edelbrock jets could work? But that's not really a concern at this point...

Pretty sure now that most of the trouble is coming from aluminum corrosion/calcification build up in the passages below the power valve/fuel bowl/jets. Tried an experiment using CLR on an old, really cruddy Qjet last night and it really cleaned out the calcified passages well after soaking overnight so I'll try that on the Economaster next. I still think I can make a happy little carb out of this 450.:)
 

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Carb bodies ..well most al alloy parts are cleaned up in a citric acid based bath and washed.
In the case of carbs they then get a caduim plating to prevent they alloy corroding in the future...which I believe that notoruios bad batch of corrosion in holly bowels was about.
I learnt the hard way yrs ago rebuilding old zenith carbs for my vintage cars...seemed as perpetually had crap in the bottom of the bowl... These are little single barrel....ends up itsonly 20 bucks more to get these rebuilt (36 hr turn around) than the cost of the kits.
 

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Discussion Starter #15
Carb bodies ..well most al alloy parts are cleaned up in a citric acid based bath and washed.
In the case of carbs they then get a caduim plating to prevent they alloy corroding in the future...which I believe that notoruios bad batch of corrosion in holly bowels was about.
I learnt the hard way yrs ago rebuilding old zenith carbs for my vintage cars...seemed as perpetually had crap in the bottom of the bowl... These are little single barrel....ends up itsonly 20 bucks more to get these rebuilt (36 hr turn around) than the cost of the kits.
If this cleanup doesn't work, I'll just have to keep searching the swap meets for more of these for parts. I inquired with one place yesterday about purchasing a body but they said no parts are available for these aside from the rebuild kits. Will know better if I get the chance to disassemble it tonight after work.
 

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Discussion Starter #16
Took the whole carb apart again tonight and washed it out with CLR. Didn't really see anything idicative of plugged passages but if nothing else I got to study it quite a bit and see which passages go where. I noticed the jets have 3 digit numbers on them. They are 215 on the primaries and 255 on the secondaries. Anybody familiar with 3 digit jets?

Will put it all back together and get it running on the weekend. Then try these three tests:
1) plug of PCV
2) disconnect secondaries
If neither of those helps, 3) leave secondaries disconnected and put secondary (larger) jets on the primary side to see what happens.

Better check the float level again too. Too low could cause leaning out I guess.
 

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Discussion Starter #18
Mine was real sensive to float level.
I will have a look in my box of holley jets on those numbers
Yeah, I am thinking those jet numbers cross to maybe weber carbs or some other mfgr that uses 3 digits. Would be good to know if compatible jets are available.
 

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Nah non in my box of holley bits...this goes back quite a few yrs, BUT
maybe weber carbs or some other mfgr that uses 3 digits.
That rings a bell.. I had a heap of SU stuff around back then.
 

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Discussion Starter #20
Well, it's back together and running again. The two things I improved were 1) made sure the passages below the power valve were clean and the power valve itself had full travel below the jet. There was some sediment in the plunger recess. 2) raised the float level considerably. My suspicion is that the float level made the greatest improvement. I think Steps was right about that. :thumbsup:

So just went for a short drive around the block after warming it up in the driveway. It's dark, 30 degrees F and there's way too many cars on the streets for much horsing around but it is GREATLY improved. It still has a slight flat spot on the primaries but when I boot it from a roll in first gear IT BREAKS LOOSE ALL OVER THE PLACE!!!! I CAN'T BELIEVE IT !!:hurray::cool::hurray: Neither of my Qjets have ever been this responsive. I was giggling when I put it back in the garage.:D

I'll get a drive in tomorrow morning early. Hopefully an economy run if I can keep my foot out of it.

Here's some photos of what the guts of this thing look like. The primary/secondary jets are located lower than the power valve which is the large jet in the photos. So that may have been why the float level adjustment is so important. The thing coming out the front wall is the needle/seat and the hole below it is plugged but looks open in the photos because of the shadow.


This photo shows the plunger attached to the top of the carb that is vac activated to push down and open the power valve.


This is the acc pump. Shaft is plastic. You can still get this part from Holley or Jegs/summit but a new diaphragm (red part) is included in the rebuild kit. I had to email Holley and ask about that and they were helpful.


I think I am going to buy every one of these $5 Economasters I can find at swap meets and horde them. $55 for the rebuild kit. Not a bad deal for the $$ and time spent.:D
 
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