Carburetor?
Thread Starter
|
Laughing Gas
Joined: Dec 2010
Posts: 924
Likes: 1
Carburetor?
Heya guys, So I've been throwing around the idea of changing one more final time. I have a holley 470 truck avenger carb in my garage that I rebuilt and used once on my truck but took off because the secondaries never seemed to open but I did love the snappiness of the throttle it was all there but the issue with the secondaries had me lost. Lately ive been on the search for maybe different metering blocks but no one has replacement ones because the secondary metering block is non adjustable.
Do you guys have any suggestions on what I could check? or maybe buy new metering block and make it so the secondary is non adjustable
Do you guys have any suggestions on what I could check? or maybe buy new metering block and make it so the secondary is non adjustable
More Turbo
Joined: Nov 2015
Posts: 715
Likes: 112
How do you know the secondaries never opened.
They will only open when driving the under load not free revving the engine where you can see them.
See pages 11 and 12 in the manual below.
199r10268-4.pdf (holley.com)
They will only open when driving the under load not free revving the engine where you can see them.
See pages 11 and 12 in the manual below.
199r10268-4.pdf (holley.com)
Thread Starter
|
Laughing Gas
Joined: Dec 2010
Posts: 924
Likes: 1
How do you know the secondaries never opened.
They will only open when driving the under load not free revving the engine where you can see them.
See pages 11 and 12 in the manual below.
199r10268-4.pdf (holley.com)
They will only open when driving the under load not free revving the engine where you can see them.
See pages 11 and 12 in the manual below.
199r10268-4.pdf (holley.com)
Did the whole paperclip test after driving stayed in the same spot that my brother in law and I put it.
Lead Driver
Joined: Mar 2008
Posts: 7,192
Likes: 384
From: Near Los Angeles
Quick Fuel makes an adjustable secondary diaphram for Holley carbs. It costs about $30 on ebay. There is a youtube vid that will show you how to remove the old and install the new. It's really easy-peazy. On the QF unit is a simple screw--turn it one way to slow the secondaries from opening; turn the other way and they will open sooner. Set the screw in the oe position they recommend, and start doing driving tests, opening the screw a quarter of a turn each time, until you're happy with how the secondaries open. DON'T try to open the screw (counter-clockwise) more than a quarter of a turn at a time.
My Holley had no adjustment in the secondary side because it had a plate instead of a metering block. I bought a metering block, new longer filler tube and seals, and longer float bowl bolts, with the re-useable nylon washers/seals, from ... I believe it was Allstate carburetor, but I'm sure Summit has them too. Now I can change the jets in the secondary side as I wish. I opted for the m.block w/o a power valve.
Thread Starter
|
Laughing Gas
Joined: Dec 2010
Posts: 924
Likes: 1
Definitely determine whether the vacuum passage into the diaphram unit is getting vacuum, as Pmuller said.
Quick Fuel makes an adjustable secondary diaphram for Holley carbs. It costs about $30 on ebay. There is a youtube vid that will show you how to remove the old and install the new. It's really easy-peazy. On the QF unit is a simple screw--turn it one way to slow the secondaries from opening; turn the other way and they will open sooner. Set the screw in the oe position they recommend, and start doing driving tests, opening the screw a quarter of a turn each time, until you're happy with how the secondaries open. DON'T try to open the screw (counter-clockwise) more than a quarter of a turn at a time.
My Holley had no adjustment in the secondary side because it had a plate instead of a metering block. I bought a metering block, new longer filler tube and seals, and longer float bowl bolts, with the re-useable nylon washers/seals, from ... I believe it was Allstate carburetor, but I'm sure Summit has them too. Now I can change the jets in the secondary side as I wish. I opted for the m.block w/o a power valve.
Quick Fuel makes an adjustable secondary diaphram for Holley carbs. It costs about $30 on ebay. There is a youtube vid that will show you how to remove the old and install the new. It's really easy-peazy. On the QF unit is a simple screw--turn it one way to slow the secondaries from opening; turn the other way and they will open sooner. Set the screw in the oe position they recommend, and start doing driving tests, opening the screw a quarter of a turn each time, until you're happy with how the secondaries open. DON'T try to open the screw (counter-clockwise) more than a quarter of a turn at a time.
My Holley had no adjustment in the secondary side because it had a plate instead of a metering block. I bought a metering block, new longer filler tube and seals, and longer float bowl bolts, with the re-useable nylon washers/seals, from ... I believe it was Allstate carburetor, but I'm sure Summit has them too. Now I can change the jets in the secondary side as I wish. I opted for the m.block w/o a power valve.
I'm way ahead of you I have that vaccum diaphragm I dont believe I ever used it but it's on the carburetor right now but I think I'm gonna rebuild it again because it's been sitting for a couple years now
Lead Driver
Joined: Mar 2008
Posts: 7,192
Likes: 384
From: Near Los Angeles
With that diaphram, I'd pull it and test it with a vacuum pump. If it works, don't fix it, ha ha. You'll get it working fine. Start the engine with the diaphram off, and put your finger on the vacuum hole, or a v. gauge.
Trending Topics
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
Heya FordBoy.
What RPMs did you get up to? A 470 should definitely be opening up the secondaries if you're getting on it. They'd open up on my 600cfm.
Was it a used or new carb? As others said, it might just have way too strong of spring in it (if used).
Or maybe a blocked vacuum passage. Have you sprayed cleaner through them to be sure the passages are clear?
A secondaries metering block would only allow you to adjust the jetting, but not when they open and close. That's from the diaphragm and spring. And yeah, that QF adjustable housing is pretty nice.
However, I don't think it'll help much if you have a super heavy spring in it as it only adjusts based on the current spring. Maybe get a spring kit for when you rebuild it to be sure it has the right one?
What RPMs did you get up to? A 470 should definitely be opening up the secondaries if you're getting on it. They'd open up on my 600cfm.
Was it a used or new carb? As others said, it might just have way too strong of spring in it (if used).
Or maybe a blocked vacuum passage. Have you sprayed cleaner through them to be sure the passages are clear?
A secondaries metering block would only allow you to adjust the jetting, but not when they open and close. That's from the diaphragm and spring. And yeah, that QF adjustable housing is pretty nice.
However, I don't think it'll help much if you have a super heavy spring in it as it only adjusts based on the current spring. Maybe get a spring kit for when you rebuild it to be sure it has the right one?
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Thread
Thread Starter
Forum
Replies
Last Post
rnelson664
1948 - 1956 F1, F100 & Larger F-Series Trucks
7
Feb 27, 2007 03:06 PM