skinnysteve72
Active Member
Installing a Holley 390 double pumper on my slant 6 but not seeing any ports on the carburetor, thoughts?
390 double pumper vacuum
- Thread starter skinnysteve72
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33IMP
Well-Known Member
I've never heard of a dp that small. Pieced together mixboxel mess?
Any vacuum ports will be off the throttle base, except for a ported vacuum off the non-throttle side of the main body.
With the choke horn milled off, the list number (and all available info from holley) is gone.
Any vacuum ports will be off the throttle base, except for a ported vacuum off the non-throttle side of the main body.
With the choke horn milled off, the list number (and all available info from holley) is gone.
390 cfm holley with vac secondary , 450 cfm vac secondary , both are single pumpers
your 390 cfm holley is very race style carb
harrisonm
Well-Known Member
Well, you learn something new every day. I thought the smallest Holley was a 500 CFM.
That is probably a NAPCAR legal 390cfm HP, older list #is 0-80507-1, many of those HP's have no external vacuum ports on the throttle body.
If you can get in touch with whoever built the carburetor, maybe they can give you more information. I agree with the posts of; it could be a bag of mixed parts, or possibly a NASCAR unit. If it's a cobbled together piece, you'll have a good time trying to tune it and it probably won't have good street manners.
He didn't ask if you've ever heard of it or if they exist, I mean, there it is. Still available new from Summit.
To the OP, have you looked closely all around the base plate? There are usually one or two large manifold vacuum ports there, as well as sometimes some smaller ported ports. The primary metering block appears not to have the timed spark vacuum port on the passenger's side for the distributor. It is more of a race bred carburetor, so it may be lacking some of the vacuum control a more street oriented carburetor would have. You're just going to have to look closely and see.
To the OP, have you looked closely all around the base plate? There are usually one or two large manifold vacuum ports there, as well as sometimes some smaller ported ports. The primary metering block appears not to have the timed spark vacuum port on the passenger's side for the distributor. It is more of a race bred carburetor, so it may be lacking some of the vacuum control a more street oriented carburetor would have. You're just going to have to look closely and see.
33IMP
Well-Known Member
Looking at the pics again in post #1, it looks like a race style main body that never had a choke horn.
Frankly, I would compare your throttle blade size and venturi size with the one pomona missel showed. I wouldnt be surprised to find you have a 600 cfm, or bigger.
Frankly, I would compare your throttle blade size and venturi size with the one pomona missel showed. I wouldnt be surprised to find you have a 600 cfm, or bigger.
This ^^^^ is what it is. He may have to come off the manifold for any vacuum. That would mean manifold vacuum for the distributor so he'll have to adjust the timing accordingly, but no biggie.
Holley 0-80507-1 Holley 4150 Classic HP Carburetors | Summit Racing
That ^^^^ is probably what he has.
That ^^^^ is probably what he has.
33IMP
Well-Known Member
He asked for thoughts. I gave mine. Learning something new every day.
And good ones too. If he will take a picture staring straight down the carburetor throat, we can confirm whether it's a 390. The venturi will be tiny.
33IMP
Well-Known Member
Out of curiosity, where are the list numbers on the carbs with no choke airhorn, like the o.p's?
I've got an old gold claw, a proform and a brawler, all without the choke horn, and the serial numbers are all in a different place.
I've got an old gold claw, a proform and a brawler, all without the choke horn, and the serial numbers are all in a different place.
Stamped "somewhere" on the metering blocks and main bodies. Usually on the top edge of the metering blocks and on the side of the main bodies.
junkyardhero
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the two i have, one is stamped on the main body on the throttle arm side (the other side is similarly cast and just stamped "holley"), the other is stamped on the bottom of the main body. these are both older, so mileage may vary.
33IMP
Well-Known Member
Theoretically.... the o.p. should be able to drill and tap a hole in the throttle body for a hose barb, for manifold vacuum. Ported vacuum, I don't know how.
If there are any numbers on the base flange, I will see if I have one with vacuum ports.
Dave999
Well-Known Member
plug vacuum advance into manifold and use one of these to smooth it
FSE VACUUM ADVANCE ANTI PULSE IGNITION DISTRIBUTOR VALVE APV001 | eBay
allows a barb into manifold vacuum of a size greater than a normal ported vacuum take off to be used.
basically a tube with a bunch of small orifices in it designed to damp any vacuum fluctuations
OEM kit on 2 liter alfa and fiat where it was used to allow vacuum advance to be driven off 1 cylinder when equipped with weber or dellorto dcoe/idf drla/dhla
still available 40 years later due to usefulness, when repurposed for implementing Fuel Injection ECU with MAP sensor
i.e used all over the place for vacuum signal smoothing
got a lathe and some jet drills you could probably make one
only ever seen APV001 i.e Anti pulse valve 1, never seen a 2 so presume they got it right first time
Dave
FSE VACUUM ADVANCE ANTI PULSE IGNITION DISTRIBUTOR VALVE APV001 | eBay
allows a barb into manifold vacuum of a size greater than a normal ported vacuum take off to be used.
basically a tube with a bunch of small orifices in it designed to damp any vacuum fluctuations
OEM kit on 2 liter alfa and fiat where it was used to allow vacuum advance to be driven off 1 cylinder when equipped with weber or dellorto dcoe/idf drla/dhla
still available 40 years later due to usefulness, when repurposed for implementing Fuel Injection ECU with MAP sensor
i.e used all over the place for vacuum signal smoothing
got a lathe and some jet drills you could probably make one
only ever seen APV001 i.e Anti pulse valve 1, never seen a 2 so presume they got it right first time
Dave
skinnysteve72
Active Member
Update: I can get the car running, (after a long while) it wants to idle at 2500 rpm and the idle screw doesn’t back off any more
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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got the PCV installed yet?
skinnysteve72
Active Member
More pics
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
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I see you have 4 air-leaks there; one hole drilled in each throttle blade, commonly done to introduce Bypass Air for a big-cammed engine, something around 300 degrees advertised or more.
That's a lotta lotta Bypass-air, and the engine under it probably did not have any PCV, lol, cuz the baseplate has no provision for it.
If you intend to use that carb on the street, you got some work to do;
1) You'll need to shut up those Bypass holes, and
2) You can't run a street engine without some form of Crankcase ventilation. Well you can but it won't take long to make an oil-leaker and/or oil burner out of it. and
3) You really need some kind of load-controlled timing advance to tame the engine, to maximize fuel-economy, and to provide Part throttle torque.
4) that carb needs a Powervalve
None of these are insurmountable; but Grant's Pass, Oregon is at 904 to 1951 feet, so how are you gonna handle elevation changes?
and, and, you got no choke, but worse is, the carb has no provision for it. Which means you are gonna have to practically pour the gas down the hole to get her started, and then keep pumping during the warm-up period and a good percentage of that gas is gonna end up going past the rings, and into the oil, prematurely wearing out the rings, the bearings, and the cam lobes, etc.
Personally, I wouldn't use that particular carb in Grant's Pass Oregon, in any stop-start/short-hop, street-type application.
That's a lotta lotta Bypass-air, and the engine under it probably did not have any PCV, lol, cuz the baseplate has no provision for it.
If you intend to use that carb on the street, you got some work to do;
1) You'll need to shut up those Bypass holes, and
2) You can't run a street engine without some form of Crankcase ventilation. Well you can but it won't take long to make an oil-leaker and/or oil burner out of it. and
3) You really need some kind of load-controlled timing advance to tame the engine, to maximize fuel-economy, and to provide Part throttle torque.
4) that carb needs a Powervalve
None of these are insurmountable; but Grant's Pass, Oregon is at 904 to 1951 feet, so how are you gonna handle elevation changes?
and, and, you got no choke, but worse is, the carb has no provision for it. Which means you are gonna have to practically pour the gas down the hole to get her started, and then keep pumping during the warm-up period and a good percentage of that gas is gonna end up going past the rings, and into the oil, prematurely wearing out the rings, the bearings, and the cam lobes, etc.
Personally, I wouldn't use that particular carb in Grant's Pass Oregon, in any stop-start/short-hop, street-type application.
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Get rid of that carb. Get a 390 like @pomonamissel posted in post #3 above and be done with it.That 390 is a good one for sixes. The one you have now is not.
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