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Discussion Starter · #1 ·
This is not related to my previous post; at least not directly I don't think.

Ignorant newbie questions! Please be nice :)

I took the 750cfm Holley DB off my 289 and put on a 600cfm Holley that was rebuilt before I bought it. After a little plumbing I had the thing on and it runs.

Question 1: where the heck does the PCV valve hose go on the carb? The only large diameter nipple on the carb is where I put it (on the base) - hope I'm right!

Question 2: where the heck does the smaller diameter hose go (from the exhaust I believe) on the carb? There is one nipple on the base of the carb and another one on the side of the float. Should one be plugged and ne be used?

Then comes the tuning... I have no clue how to do that :p Is there a website out there that might help?

Thanks,
Aaron

Houston, TX - 67 Fastback in restoration. A-code, C-4, 9" Traction-Loc rear.

"If you wish to make an apple pie from scratch, you must first invent the universe" - Carl Sagan
 
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I don't have much experience with the 4bbl. carburetors, as I'm a 6-cylinder performance modifier type person. But...

Yes, you hooked the PCV up correctly

There should be a vacuum advance and fuel line hooked up to your carburetor. I'm not sure of one hooked up going into your exhaust (manifold?)

As for tuning, there are 3 (or 4) screws that can be manipulated with a flathead screwdriver. Find one, and turn it. See what your engine does... This is how I learned. There will be a screw for fast idle-speed, air-fuel mixture, normal idle-speed and maybe one more. Hope this helps!
 

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Alrite, everybody started as newbie except those that were OF from the beginning. PCV connection sounds right. Should be on the base plate. Number 2: I dont think there is a hose from exh. to carb. Correct me if I am wrong. Probably a vacuum source for distributor.
Better website than this, you must be joking.

Door handle first when cornering
 

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Discussion Starter · #4 ·
Oh I know there is no better site than this, I just thought there might be a Holley tuning specific site :)

Unfortunately, the car is about 10 miles from my computer so I by the time I think of a question, it's usually hours after I've seen the car :p

The carb has no vacuum advance diaphram on it. The 750cfm DB that I took off had the smaller diameter hose going into the base of it. Both the new and old carbs have manual chokes (I think - a little lever on the side of the carb opens and closes the plate to the front two barrels).

Hmmm, wish I could take a look at right now - you guys are still a huge help as it is though.

-Aaron

Houston, TX - 67 Fastback in restoration. A-code, C-4, 9" Traction-Loc rear.

"If you wish to make an apple pie from scratch, you must first invent the universe" - Carl Sagan
 

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Hi Aaron...

First, congratulations for removing that toilet bowl from your engine and replacing it with a more appropriate carb...it has its place but not on a mild street combo...

PCV can hook to carb base plate as long as the port passageways allow access equally to the manifold plenum...on my engines, I use a spacer, usually of phenolic, to isolate the carb and provide PCV hookup..

Hose from exhaust is likely choke stove for the carb choke....small amount of engine vacuum sucks air from exhaust manifold stove through choke coil, expanding it as it heats to open the choke butterfly...that's my guess anyway...

Best way to learn tuning is by experience and by reading a Holley tuning book...do a search on Amazon or here for more info...

I use Dave Emmanuel's book on Holley carbs for tuning my racing engines...

Pat
http://www.jps.net/binay/webdocs/strtmstng002_sml.JPG
 

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Hi, sounds like your car is an automatic and the little hose goes to the vac. modulator on the trans if this is the hose you are looking at this has to be hooked up to vacume the same as PCV if it is the hard line to the manifold it just goes to the choke. John

Opal frost pearl metallic 67 coupe http://www.jps.net/binay/webdocs/febef75b01.JPG
also have a 95 opal frost pearl G/T BOSS edition convertible belongs to swmbo
 
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Sometimes it can be confusing where all of those hoses go, I know because I have been there also.

On your Holley, if you are standing at the grill looking at the carb there will be a large dia nipple on the left hand side of the carb towards the back, there is also a small dia nipple at the front of the carb under the float bowl. These are both full vacuum ports where your PVC or Power brake booster can be used on the large nipple and your vacuum line from your AT (if it is an auto) can go on the little one. The metal line coming from the passenger side of the engine should be the hot air port for the choke and the port for the auto trans usually comes up the back side of the engine. There should be another port on the passenger side of the carb that is located on the metering plate (located between the float bowl and the carb body). This is where the vacuum advance for the distributor should go. The vacuum at this location varies with throttle setting. And of course, all unused vacuum ports should be capped of with a rubber plug. In a pinch you can use a small piece of vacuum hose with a screw driven in on end to get you by for now.

As for adjusting the air mixture there are two screws that are also located on the left and right side of the metering plate, they are very small and the passenger side screw is below the vacuum port for the distributor and the other is directly on the other side.

You also need to check the float setting on this carb. There is a slotted screw/nut combo at the top of each float bowl (front and back). The slotted screw is the "lock screw" where the nut actually adjusts the float setting. There is also a slotted screw (sight plug) on the passenger side of the float bowls. This is your set point for the float. To see if the float level is correct unscrew the sight plug. BE VERY CAREFULL!!! If the float is set too high then gas will rush out of this opening, be prepared to quickly reinsert the screw to stop the flow of gas. It is always good to have some rags within reach and someone on the ignition to turn off the car just in case you get a intake manifold full of gas. Nothing like an engine fire to ruin your weekend. Also, be careful not to lose the gasket for this screw.

A proper float setting is when the gas is just at the bottom of this hole. To adjust the float loosen the "lock screw" (do not remove) and adjust the nut. Clockwise raises the float setting and counter clockwise lowers the setting. When you loosen the "lock screw" gas will spray out so once again be careful. Pack some rags around the bowl to soak up the gas. I have done this by keeping the flat screwdriver always on the lock nut with my right hand while slowly adjusting the float with a 5/8" wrench in the other. That way I can make a small adjustment and then retighten the lock nut to allow myself a chance to see where the adjustment is.

When you are doing this for the first couple of times have someone at the ignition switch so that they can quickly turn off the car if something goes wrong, like dropping the sight plug when the float level is set too high.
 
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