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Unread 08-16-2011, 09:41 PM   #706
oldtime_ironman
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Quote:
Originally Posted by Dr. Marneaus View Post
Jusr ordered a boat load of carb parts to get the ball rolling on emissions...at least to make sure the CARB isnt the issue. I need to open it up anyway to check what jets its running and figure a rebuild and cleaning will do it some good. Also because my choke sticks open once its warm, so it starts hard the next day.

Ordered:
Complete Rebuilt kit
New accelerator pump
stock size jets and rods (Need the stock ones to have the full range of calibration offered by my calibration kit)
1" Phenolic spacer
Spacer gaskets

Should be a fun weekend project, picked up this book:


I'll try and get good step by step pictures for reference. Should be fairly simple.
FWIW the Edelbrock carbs are nearly identical to the old GM Rochester carbs. I have years of experience with those. At my altitude I had the best luck with about a 20-point spread between the jet size and the metering rod size. EG jets would be #54 and metering rods were the early #74 style.

At your altitude you would want to tighten that up a bit to an 18-point spread. When I lived in Salt Lake UT I used a # 52 jet and the #74 rods. The lower the number, the tighter the jet (leaner) for the same size of rod. The metering rods are opposite: The bigger the number, the bigger the rod diameter (also leaner for the same size of jet.)

You can get a stiffer shot of gas out of the accelerator pump if you stick a washer under the *upper* spring, where it rests against the carb top.

Also, the angled brass floats are better if you can find one. Make sure the level is correct, and use a fresh needle and seat.

Choke: If it sticks open after cooling, my experience is that its usually gummed up or binding in the internal linkage. There's a little rod with a certain kink in it that works the choke and sometimes it can get hung up. If you have the electric/bi-metal choke then its fairly easy to just get a fresh one. The best chokes I ever used were just a little bi-metal "doghouse" bolted to the top of the intake (pre-1974 style)

If you need to know any more, just ask.


Last edited by oldtime_ironman; 08-16-2011 at 09:47 PM.. Reason: choke
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Unread 08-17-2011, 12:05 AM   #707
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I'd suggest switching to a Holley truck avenger 670cfm for some carb fun, but I kinda doubt that would help your emissions. It's a great carb, though! I have one on my Cherokee, and it totally lives up to the rep.
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Unread 08-17-2011, 12:37 AM   #708
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Quote:
Originally Posted by oldtime_ironman

FWIW the Edelbrock carbs are nearly identical to the old GM Rochester carbs. I have years of experience with those. At my altitude I had the best luck with about a 20-point spread between the jet size and the metering rod size. EG jets would be #54 and metering rods were the early #74 style.

At your altitude you would want to tighten that up a bit to an 18-point spread. When I lived in Salt Lake UT I used a # 52 jet and the #74 rods. The lower the number, the tighter the jet (leaner) for the same size of rod. The metering rods are opposite: The bigger the number, the bigger the rod diameter (also leaner for the same size of jet.)

You can get a stiffer shot of gas out of the accelerator pump if you stick a washer under the *upper* spring, where it rests against the carb top.

Also, the angled brass floats are better if you can find one. Make sure the level is correct, and use a fresh needle and seat.

Choke: If it sticks open after cooling, my experience is that its usually gummed up or binding in the internal linkage. There's a little rod with a certain kink in it that works the choke and sometimes it can get hung up. If you have the electric/bi-metal choke then its fairly easy to just get a fresh one. The best chokes I ever used were just a little bi-metal "doghouse" bolted to the top of the intake (pre-1974 style)

If you need to know any more, just ask.
Wow awesome info! At this point im on the quest for emissions, but my first step is to make sure the carbon isn't leaking and is in good shape, hence the rebuild.

Im not sure what the numbers of rods and jets you're referring to mean. Im currently running .083 jets I believe. I don't remember which rods but ill check.
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Unread 08-17-2011, 12:39 AM   #709
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Quote:
Originally Posted by robert_hollis
I'd suggest switching to a Holley truck avenger 670cfm for some carb fun, but I kinda doubt that would help your emissions. It's a great carb, though! I have one on my Cherokee, and it totally lives up to the rep.
Id suggest whatever option is not going to cost 350 bucks..haha.

This carb is a 500 cfm which should be more than adequate for the stock 360 im running. Maybe when I have the cash and time to rebuild my original motor it'll get a new carb that will perform better offroad.
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Unread 08-17-2011, 09:50 AM   #710
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Quote:
Originally Posted by Dr. Marneaus View Post
Wow awesome info! At this point im on the quest for emissions, but my first step is to make sure the carbon isn't leaking and is in good shape, hence the rebuild.

Im not sure what the numbers of rods and jets you're referring to mean. Im currently running .083 jets I believe. I don't remember which rods but ill check.
No problem, here is some info:

When GM stopped making carbs back in 1984, they sold the rights and the design to Edelbrock because the hot-rod guys wanted them. They are rated 750 CFM.

The Rochester carb design uses vacuum-actuated primaries (the small bores in the front) and mechanically operated secondaries (the big bores in the back)

Most of the time is spent on the primaries, below 3000 RPMs because that's how most people drive. Its better for fuel economy, and a Rochester can get within a few percent of fuel injection if you set it up right.

The numbers refer to the relative size of the rods and jets, in thousandths of an inch. A bigger number on a jet means that it has a bigger hole thru it. The rods get fatter with a bigger number, same idea. The rods are shaped like a needle and they hang down inside the jet hole with the pointy end down. It sounds to me like your jets are a bit large, so therefore your rods should be correspondingly large. I prefer the smaller jet sizes because they atomise the fuel better - this means the engine runs cleaner and gets better MPG's -- it also makes better power and throttle respons with the smaller jet and rod sizes.

The rods hang down thru this hole. A high vacuum (idle) pulls the rod further into the hole, closing it off partway. The rods are tapered so they're thin at the point like a needle. Low vacuum (stomping on the gas) lets the rods raise up into the thin pointy end - this opens up the hole in the jet and lets more gas thru.

BTW the jets are threaded 1/4-20. If you can find any good junkyards nearby and get a Rochester Q-jet off an old chevy or cadillac, most of the parts swap with the Edelbrock. The older, the better - try for a 1975 or so caddy or chevy V-8 carb. Be sure to grab all of the choke parts.

As always, if you need to know anything, just ask.

Last edited by oldtime_ironman; 08-17-2011 at 10:04 AM.. Reason: details
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Unread 08-17-2011, 11:29 AM   #711
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If I jet too small wont I create a lean condition?

And I thought the edelbrock performers we're very close to carters?
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Unread 08-17-2011, 12:07 PM   #712
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Quote:
Originally Posted by Dr. Marneaus View Post
Id suggest whatever option is not going to cost 350 bucks..haha.

This carb is a 500 cfm which should be more than adequate for the stock 360 im running. Maybe when I have the cash and time to rebuild my original motor it'll get a new carb that will perform better offroad.
Good point

The 670 can be tuned down a bit to better match the 360, though.

Hope the rebuild goes well. I'm in the process of yanking the remains of my AC system... Always fun to do in the middle of the summer!
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Unread 08-17-2011, 12:51 PM   #713
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Originally Posted by Dr. Marneaus View Post
If I jet too small wont I create a lean condition?
Only if you keep the same rods. If you go smaller jets then you would also go smaller rods. I've never seen anyone run a #82 on something smaller than a school bus. Since your jets are #82 then your rods should be something like # 62 or #64. In either case, the vacuum plunger they hang from needs to work correctly. A good rebuild kit will include the O-rings for it.

Quote:
Originally Posted by Dr. Marneaus View Post
And I thought the edelbrock performers we're very close to carters?
I'll have to check - I'm sure they updated the product line. They also have the "Performer RPM" line. They may have bought Carter at a later date, I dunno. I'll have to check. I have a book here that covers both the Rochester and Edelbrock, but your book covers Carter and Edelbrock.

If your carb is an actual Carter, then take everything I just posted and throw it away.

.
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Unread 08-17-2011, 01:35 PM   #714
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Its an eddy performer AFB which is based on the carter AFB. Its a little different than the AVS but the only real difference is the AFB has a weighted secondary system rather than a spring loaded flap that looks like the choke.

Also the carbon came stock with. 086 jets
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Unread 08-17-2011, 02:00 PM   #715
oldtime_ironman
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Originally Posted by Dr. Marneaus View Post
Its an eddy performer AFB which is based on the carter AFB. Its a little different than the AVS but the only real difference is the AFB has a weighted secondary system rather than a spring loaded flap that looks like the choke.

Also the carbon came stock with. 086 jets
Well, I guess Edelbrock bought Carter then. Unfortunately I know next to nothing about the Carters tho. Maybe somebody else here does?
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Unread 08-17-2011, 04:33 PM   #716
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Ha, thanks anyway.
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Unread 08-17-2011, 08:32 PM   #717
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Hot damn! Summit Racing makes the Acme (think looney tunes) look like a second rate delivery service!

I placed that order last night at 6pm. The parts were on my door at 3:20 today. How the heck?
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Unread 08-18-2011, 03:04 PM   #718
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IIRC there's a distribution center in Reno. I remember on their catalog, they use to show the locations of their warehouses, so you could get an idea of how long a delivery would take (or go pick up from them, if you wanted). Maybe they still do... I haven't had an actual Summit catalog in my hands since my Nova was totalled.
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Unread 08-18-2011, 03:59 PM   #719
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IIRC there's a distribution center in Reno. I remember on their catalog, they use to show the locations of their warehouses, so you could get an idea of how long a delivery would take (or go pick up from them, if you wanted). Maybe they still do... I haven't had an actual Summit catalog in my hands since my Nova was totalled.
Its in Sparks, but still, they must have put it on a truck that night. thats service!
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Unread 08-19-2011, 09:38 PM   #720
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Nothing can go smooth, can it?

Get everything apart, but one of the primary jets was damaged before i even got it it, buy the shop that worked on it last year, apparently.

I tried to go easy with a large screwdriver, but it was JAMMED solid. wouldnt budge.

I tried more downward pressure and it started chipping the jet more than it already was. I let it soak in carb cleaner then tried again. Well, several minutes later the dang thing is damaged past what a screwdriver can do.

Broke off an easy out.

Broke like 5 drill bits, left hands wouldnt work, regulars arent working.

Now i have a super mangled jet stuck in my carb. And I didnt even do the initial damage!
Looks like I'm buying a new carb....
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