Holley 600 Vacuum secondary tuning issue.

[eric76]

rgalajda 600 Holley 1850-14.

[rgalajda]

I mean a list of jets , bleeds , restrictors, etc

[eric76]

Holley jet kit 60 through 99 on hand.
Brass allen set screws drill to size if needed. 6-32,8-32,10-32.
Air bleeds 10-32 drill to size from Quick fuel
pump cam kit and shooter size kit .020 to .040
vacuum secondary springs all colors

[eric76]

rgalajda I hope I listed like you requested. Thanks for your time and input and its appreciated.

[GTO Geoff]

Eric,
I disagree that the problem stems from the components, or the combination, of the engine build. None of it is overly radical & 15-17" of vacuum should produce clean plugs. While 16* of idle timing is ok, & not cause your current problem, more would be beneficial. Easiest way is to use a dist with adj vac adv, connected to manifold vacuum. See the link below for more info.

Can you stall the engine by screwing the mixture screws in? If not, then that is a problem & could be THE problem.

I never liked the Holley PV system, it is a real mickey mouse arrangement. A very soft spring balanced against the characteristics of the rubber diaphragm to set vacuum? What happens to the rubber characteristics with heat & immersion/drying out in fuel. Is a 8.5 PV still 8.5 after a few months?

So I would be looking at the PV system &/or porosity.

As far as 600 AFB v 600 Holley. Loooooong before Edel got into re-making Carter AFBs, they compared a 9625 AFB with a Holley 600 6619 carb on a 350 Chev.
The AFB made 17 hp more, 17 more ft/lbs & used less fuel doing it.....PM me if you would like a copy of the test. Also, if you think Edel was biased, a little known fact is that Edel were selling modified Holleys around that time.

MVA benefits, scroll down to post #6.
www.hotrodders.com/forum/vacuum-advance ... 47495.html

[rgalajda]

[eric76]

I coped and used your list and changed to what mine is.
Holley 1850-14

Main jet #65
Primary metering block Stock out of box and current
PVRC .045 to .048 "
IFR .028"
Emulsion .028"
Emulsion .028"

Secondary Metering block upgrade from Holley matched to this carb
IFR .031"
Main jet .073"
Emulsion .028
Emulsion .028

Main Body stock as it came out of box no changes
Prim IAB .078"
Prim HSAB .025"
Sec IAB .048"
Sec HSAB .025"

[80Camaro]

I know I am new here, but I had to reply to this 600 Holley thread as the 1850 gets little respect in the carburetor world. About 5 years ago I had the same problems with my 1850's I used and I remembered one that I build for a 454 I ran in my car in the early 90's. Now even though the 454 was only good until around 5500rpm with it that little 600 1850 would get there much quicker down the track than my 3310's did. After that I decided a few years ago to make a tricked out one. I took the air horn off (not sure if it helped), got rid of the sec metering plate for a new rear block to change jetting there, but the biggest change was when I adapted the 3310 baseplate to the 1850. I did use a die grinder by hand and opened up all the bores to match the bigger baseplate stuck it on the main body and started out the jetting at 69 Pri and 76 Sec. pretty close to what a 4776 600dp was. My 1st runs with it were in the mid to high 11's and I was like WOW this carburetor works. I t was so good that day the smallish 600 was within .003 of my 750 well tuned Mighty Demon and the 60ft. and 1/8 mile times were a few hundredths better. The 600 had such a good signal to the booster that when you cracked the throttle it would literally pull the sec side open so I did need to slow it down a little. All my HSAB and IAB are stock 1850-1 specs with stock metering blocks also. I highly recommend doing the larger 750 baseplate on a 600 like this as it works very well. Guys at the track that day told me, no way is that a 600 Holley running that fast. I told them to measure the throttle openings by the boosters, a lot of, how in the h**l can that work.

You guys have a great fuel site here, I should have joined sooner. Thanks for letting me join.

[eric76]

I have another 600 Holley that I am putting on today and see how it goes. I have done the same thing with another 600 Holley vacuum secondary. I took the main body and grinded the clearance needed for the bigger 1 11/16 base plate. I then popped out the straight leg boosters and installed stepped down leg boosters and then put a set of center hung fuel bowls on and then a Quick fuel adjustable pod to really tune the secondary side of things to get the best opening rate.

That carb is apart for the moment as is a long story on that one. It started with my current problem that went from my previous build over to the current build and I did some investigating on things and the previous Holley 600's I used in the past had the older base plate where the PCV port was on the side and not in the rear like the newer ones have been for at least ten plus years. The old 600 Holley 1850's I used along with the Holley 670 Street avengers were all the newer style base plate and I wondered what is so different that I never had problems with the newer style 600 carb design versus the older ones.

The base plates are not just difference in the design but also the length of the transfer slots changed. On the older side port PCV or brake booster what ever you would want to hook up to that port, base plate design I would have to do 1 and a half turns on the primary idle speed screw to just get just hardly a square transfer slot of about .015 as a .020 feeler gauge would cover it out.

On the newer design base plate with the 3/8 tube in the rear it on all of them takes me only 3/4 of a turn to get a square .020 transfer slot. I got my dial caliber out and measuerd the transfer slots both front and rear comparing on both base plates and the older ones have the transfer slot almost .380 to .400 up from the bottom of the base plate and is way shorter which would cause some problems in theory at least on my build. The newer ones are only about .360 from the bottom at the most and that .020 to .040 difference in transfer slot on the newer and older base plates would effect a lot of thigns in certain situations as that transfer slot is very critical in more ways then one.

I also found out on the older base plates the secondary transfer slot is a lot closer towards the bottom and longer versus the newer ones being further up. I don't have my measurements on that one but the old base plate has been the only thing that has been on the past 1850 models I used and I am putting on a brand new 600 vacuum secondary that has the current base plate design and I am going to find out if the transfer slot difference being the biggest change and difference and me having to open up the old base plate so much to get my idle speed has been part of my problem the whole time.

In the past my old builds were always used with the newer design plates. Its most likely just a shot in the dark but I know a lot of folks who use Quick fuel carbs have problems with there builds at times as there transfer slots are a lot longer and wider and contribute to a lot of issues in certain builds. This might be a case to where the transfer slot on the older base plate is just to short to work with my particular setup and is causing the problems with the idle mixture screws not working. Nice work on your carb by the way and looks good.

[80Camaro]

What I have done with those 750 base plates that have the shorter transfer slots on the sec side is to take my little guitar saw I have and make them the same length as the pri side. Did that on my old 4779 750 and it worked out great with getting both side balanced the same. It ran pretty good last year at the track for a 30 year old carburetor.