Holley Carb info.

[Chero77]

Since, there are pages of old Holley 4160's for low cost on Ebay, and I have always wanted a car with a Holley carb since I was a kid, I decided to see if any of these could be used in place of the Motorcraft 4350. Turns out there a several list numbers that appear suitable. Here is what I have found out from the Holley website.

All of the following carbs are 4160 type, 600 cfm emissions carbs. They have ports for EGR, PCV, ported and mainfold vaccum. Some obvious advantages of these carbs over something like the carter/edelbrock carbs is that the fuel inlet is in same place as the 4350 inlet and the PCV port is near the rear of the carb. Not in back, like the 4350, but close, and of course you can get these carbs cheap. Also, the above list numbers include the "reverse idle" circuit which all references I have skimmed say is far superior to the standard circuit used in earlier list No. Holleys.

Ok, the list numbers are:

List No. 6989 listed for use with '73-'74 Ford 302s and '73-'77 AMC v8s. I am not sure if this is supposed to have a bowl vent (more on that later).

No. 8005 for 75-79 AMC v8s. Carb has a bowl vent intended for use with a charcoal cannister.

The following list Nos. are for Ford 460's. Presumably these replace Motorcraft 4350s.

No. 7413 for 73-74 Ford 460.

No. 7850 for 75 Ford 460.

No. 8207 for '76 Ford 460.

All of the above list numbers use the same gaskets and the same secondary metering plate. The jets differ slightly, i.e. #62s for the AMC applications and #62-64 for the Ford 460 applications. The power valves and the bowl vents differ in each list number also.

Anyway, I bought a 0-6989 off Ebay for $29. This just happend to be on Ebay when I was checking out the Holley website. I recieved the carb on Friday. A couple of things to note. The carb I got does not have a bowl vent. I don't know if this list number didn't include bowel vents or if someone swapped in a non-vented primary bowl somewhere along the line.

This carb and all of the carbs listed above use two-stage power valves. These are expensive, about $27, compared to a single stage power valve, about $6. So rebuild kits for any of the above list Nos. are expensive (about $60). However, the rebuild kit for list No. 6909 has the same gaskets, needles and seats, and accellerator pump, as the above list Nos. and only costs $17. Of course it has a single stage power valve. I am not sure yet what exactly the two stage power valve does for you, it may originally have been used for emissions reasons.

Anyway, I am going to rebuild the 0-6989, I've got and see how it compares to the 4350. My 4350 is in excellent condition so it should make for a good comparison. I have no timetable for this project, but I will post my impressions after I have run the Holley for awhile.

[jeepbob]

I run Holleys on both my Wa and CJ and have good luck with them, but I suggest you get a Holley tuning book and read it before rebuilding and tuning the carb. I have never had good luck with the 2 stage power valve and only run single stage P.V.'s in both carbs. All Holley bowls are vented, most have a vent tube that comes into the air horn area of the carb. The side hung float, single feed carbs work better offroad than the center hung, dual feed carbs. There is not enough difference in performance between the units with a meetering plate secondary vs the non metering plate version to make paying a premiun for one.
Everyone has an opinion of Holly carbs, whether good or bad, and mine is the reason there are so many cheap Hollys out there is that there are a lot of people will not buy a book and read it and research what they need. After they buy the wrong carb and/or mess it up, they blame the carb. It looks like you done some research into which carb to get, now buy the tuning book.
BTW when you buy a kit for your carb, get one of the Holly Trick Kits so you get the stuff (other than jets)to fine tune your carb.

[Unknown Jeep]

Dave,
A few things to watch out for on those old holleys...

Check endplay on the throttle shafts, lots of play will give you a real lean carb that will never tune right.

check for warped bace plate, main body and fuel bowls.

The holley tune book that BOB spoke of is a killer amount of info, but you must really read it to grasp what they are telling you.

With a holley you must be careful never to backfire through the carb or you will blow the power valve (the new ones have solved that problem.) You will spend lots of time tuning the holley (jets, Acc pump cam, secondary Spring, float level, mix screws...ETC ETC)

Like Bob said, Some love them, others hate them. I will never again own a holley myself, to much of a pain in the butt. To much time spent keeping them running right to make them fun. I have had 5 or so holleys, most in the 600 to 750 range. Single lines have the problems of the little line that feeds the back fuel bowl will leak from time to time. the duel feed ones are ok for the most part, but all holleys hate weather changes. Get the book, mine i gave away years ago, and learn as much as you can. the 50CC acc pumps are great for quick recovery on part throttle uses even if the book says it is great for heavy full throttle launches. Play with the Acc Squirters, acc pump cams, and jets. don't play around with drilling jets to get larger the cheap way. Not drilling the jets perfect will lead to miss matched and sloppy fuel metering. (holleys arn't known for being real good for fuel miles)

A guy I know here just swapped out his 4160 and we made him a carb spacer to bolt a Rochester Qjet to his 302 powered Ranger. We picked up Lots of lowend power, off idle throttle responce, and gas miles. (and would never even think of going back to the 4350) And yes if anyone asks, it was a tight fit, and a blast to drive. (302 HO rollercam out of mustang, 5 speed)

Well have fun, and if you ever get the spare $$ and want to compare more...pick up the Edelbrock and see what it will do right out of the box.

Troy
Elf in Tampa

[Bob Barry]

Those are some interesting possibilities in Holley carbs. Any of them sound like they could be made to work just fine. It would be REALLY interesting if any of them were a square-bore bolt-pattern/spreadbore-venturi to bolt-on directly in place of our 4350's, but I don't think they would be (it would be the first anyone has any heard of such a beast). You'd need a TD-Performance #2199 adapter to make a true squarebore carb work on the stock spreadbore manifold; you may consider putting the $50 that adapter would cost you toward a Performer intake.

[Chero77]

Ok, I picked up a tuning book. Lots of good info and a great description of how these carbs work. You guys are absolutely right, its foolish to just jump right in without reading good technical info.

Just wanted to note, that when I was discussing bowl vents earlier, I was referring to external vents to atmosphere. As JeepBob said, all 4160's have primary and secondary external vents in the airhorn that vent their respective bowls to the air cleaner.

Also with respect to the manifold bolt pattern. The Motorcraft 4350 bolt pattern is identical to the Holley 4160 square bore bolt pattern. Perhaps, I should qualify this and state that the bolt pattern on the #6989 4160 I have is identical to the 4350 pattern and I have been told that all 4160s have the same pattern. I have checked this by placing the base of a 4350 against the base of the 4160. All four mouting holes line up. Also, I checked it with a pair of calipers. The pattern is definitely the same. Thus, an inexpensive 1" open plenum square bore spacer is all you need to put a 4160 on an AMC spreadbore manifold.

I think many people don't realise this because most spreadbore carbs use the Q-jet bolt pattern and they assume that since the 4350 is a spreadbore, it uses the same pattern as the Q-jet. Not true. The 4350, while a spreadbore, uses a standard squarebore bolt pattern, which makes a swap to a Holley simple.

Unknown Jeep, my secondary throttle shaft does have some end play. Sometime in the next week or so I will drop by the local performance shop and see how much play a new 4160 has to get a feel for "how much is too much."

The biggest advantage I can see to a Holley is that it can in fact be "tuned." Want to make the secondaries a little richer, no problem just swap in a different metering plate. Want to change how fast they open, no problem, just change power valves. By contrast, on a 4350, secondary metering is controlled by unchangable passages in the casting. There is no way to change how fast they open either. Its a one-size-fits-all vaccum piston. Even on the primary side, where can you get alternative jets and metering rods for a 4350. This wouldn't be a problem except for the fact that the 4350 is a very lean emissions calibrated carb and our engines can make more power with a richer mixture.

The big drawback I see to the Holley design is that everything needs a gasket. Including the fuel bowl screws. Lots of potential leak points. I expect it pays to get good gaskets.

Anyway, thanks for the tips guys. As they say, either you love Holleys or you hate them. Guess in a few weeks I'll have an opinion.

[ October 15, 2001: Message edited by: Dave _S ]

[JOECOOL]

Dave.
As for the fuel bowl screw gaskets. Mr Gasket makes some teflon ones that pretty much last forever. They are cheap too like less than 10 bucks for a pack of ten. I got mine from PAW. These are worth gold since you will be removing the bowls alot when tuning. Oh yea be carfull not to over tighten the bowl screws as the theards strip real easy on the soft aluminum body.
Also the open spacer might not seal well on the AMC manifold. I had to use a four hole type and that worked fine.

[Bob Barry]

<BLOCKQUOTE>quote:</font><HR>Originally posted by JOECOOL:
Also the open spacer might not seal well on the AMC manifold. I had to use a four hole type and that worked fine.<HR></BLOCKQUOTE>

"Might not seal well" is an understatement; the carb mounting pad is not even a flat machined surface, but rather (if it is anything like my '78) raised rings to which the plastic spacer gasket matched up. An open spacer would have massive leaks.

I can't imagine how people have gotten standard four-hole spacers to work, for a couple reasons:

* The primary bores, while sharing the same centers as the Holley, are much smaller, so the hole for the primaries hits a "step" where the original manifold opening will jut into the bore of the spacer. This also reduces the sealing surface to about 1/8" around that bore.

* The secondary bores are WAY offset, again giving you about 1/8" of overlap between the raised boss for the secondary bore and the outer edge of a spacer (at least on my generic-style spacer). There will also be overlap of the inner edge of the mounting pad and the rear throttle-bores of the spacer.

Maybe people have come across diffferent-sized spacers, and certainly a spacer blank could bored out and shaped to match the dissimilar gasket-surfaces.

To get an idea, though, just lay a four-hole Holley carb-gasket over the mounting-pad for the stock carb; the difficulties should be pretty evident.

Of course, the earlier 4bbl manifolds were true squarebores, so they don't have these oddball problems.

[Unknown Jeep]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Bob Barry:


"Might not seal well" is an understatement; the carb mounting pad is not even a flat machined surface, but rather (if it is anything like my '78) raised rings to which the plastic spacer gasket matched up. An open spacer would have massive leaks. <HR></BLOCKQUOTE>

HOW TRUE... HOW TRUE... For that Ranger motor we MADE our spacer to mount the holley to the Stocker 302 intake (aluminum Ford intake for use with a Motorcrap carb)mounting a Holley to it would not work with out a custom built carb spacer. The guy here (brother-in-law) has a full shop to work with he MADE his spacer to mount the holley to the intake...Then he MADE a spacer to mount a Qjet to the Ford intake...NOw that was a tough one.

Best bet is to Grab that Edelbrock Intake that will mount up that carb right up.....$$$$

Troy
Elf in Tampa
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[Antelope]

Wow that's good stuf!! Can you guys tell me how to verify a blown engine, what ever that means? It's posted.