The perfect use for holley carbs

Fill them with lead and use them for boat anchors. I have twin 450s for my tunnel ram that are the biggest piece of crap I have ever owned. They pop, crack, puke and the secondaries never come in. Now I know why the guy I got them from got rid of them. I hope if anyone else has them they have better luck than I do with them.

I am going to try a pair of Carter AFBs. If they don't work it's time for an AirGap with a 750 double pumper.

 

450 holleys are picky about the intakes you run them on. they like a lot of plenum area. they usualy work ok on a tunnel ram. carter afb carbs will work good but wont make power like a holley will. you would be better off with holley 600 vacum secondary carburators. the 450 carbs are cheap junk.

 

What I would do, is chuck the tunnel ram too (not designed for the street).

 

Twin 450s on a tunnel ram is a proven combo that works about as well as any tunnel ram ever will. Are they on a motor suitable for a tunnel ram and 900 CFM of carburetor? Honestly sounds more like a tuning issue or parts mismatch issue.

Good luck, it'll undoubtedly run better with the proposed airgap/750

 

First, rebuild the motherfuckers and tune them right before calling them junk. Get some books read a little about them and they are one of the simplest carbs out there to jet and tune. For one, they probably need new power valves if they popped back at all, and as for the secondaries, they probably need a lighter spring or new diaghram or both to deal with the plenum volume of the intake better since it is much larger and changes the vaccuum characteristics under the throttle plates, compared to most smaller intakes. Trust me, unless you are good with AFB, which are a quadrajet styled carb on the inside, you're gonna have fun tuning them to run on a tunnell ram style of intake.

 

The 450s I have are mechnical secondaries so there are no springs or diaframs. They use a metering plate on the secondaries so there are no jets on the back side.The power valves are blocked off. Anything else I should read?

 

Put a ford in it? I have one you can borrow for the drags.

 

If the secondaries never come in then you've either got linkage issues, the floats are set too low, or something else causing them to not flow fuel. All the larger mechanical secondary holley's I've owned had jets in the secondary metering block, always thought the jetless ones were a vac. secondary setup, maybe a holley expert can school us.

I'd be more than glad to buy the whole setup for garbage price.

Good luck.

 

Did they step up the jetting on the main side when the power valves were blocked? I knew they use metering plates on the secondary side, same as all the small non double pumper holleys. I have built many of these carbs from 450 to the 750 double pumps and never had alot of trouble besides getting the jetting right for the application. The secondaries have me stumped though, they should kick no matter what if they are full mechanical.

 

The short block is a ZZ4 with 200cc Dart Pro 1 heads and a ZZ430 roller cam kit. The trans is a 700R4 with a 3000 stahl. The rea is a 3:73 10 bolt posi with a comp engeneering 4 link with 12 way adjustable QA1 Coil overs and 4 wheel disc brakes. I have worked on this car since 2000 and when I had some spare cash. The only reason that I wanted a tunnel ram was to fill up the engine bay. Maybe in a few years I can scrounge up a blower. Keith

 

They open but no fuel. With all of the extra air and no fuel it just falls on its face. A buddy of mine has 2 brand new ones that I am going to use for the weekend. It just gets frustraiting and I am comeing off like an ass hole. I am a nice guy just pissed about the carbs. If your going to the drags I should throw them in a box so you can look at them. Keith

 

900cfm on 350ci with no vacuum signal due to a big cam and 18" runners will spit and fart at all but "insane" RPMs no matter what you do.

Your truck will run better with a modern single 4bbl intake and carb. Hold on to the carbs and put them on your blower when you get it. Good luck.

 

I'm not saying this is THE problem, but having no power valves could be part of the problem. Holley put them there for a reason. I copied the following off another site to explain what power valves do.

"Holley power valves serve to add fuel when engine load is moderate or high. When engine vacuum drops to the rating of the power valve the valve opens and allows fuel through the Power Valve Restriction channel in the metering block. The power valves are stamped on their face with the vacuum rating, in inches.

The best way to select a power valve is to hook a vacuum gauge to your engine and drive around at part throttle. As you gradually step into the accelerator note the lowest point the gauge reaches before vacuum begins to rise again. Select a power valve with a rating 1 or 1.5 greater than this number. Alternatively a rule of thumb is to select a power valve with a rating of half your engine idle vacuum reading.

Many racers choose to block the power valve due to various reasons, including big cams with engine vacuum so low the valve open unpredictably. A power valve block can be installed however jetting must be bumped up several jet sizes to compensate."


I've always ran Holleys with the correct power valve. Don't see any reason a street driven car should have the block off installed.


-Troy

 

I just bought a pair of those for 20 bucks, I had your setup on a 406 sbc and it'd run well about 2800 up but would load the plugs down low.

 

What kind of fuel pressure do you think I should be running? I have a Holley Blue pump and have the regulator set for 7 psi. Keith

 

Of course the full mechanical secondaries probably won't help a whole lot either. Those are kinda like the 660 center squirters. They like to run wiiide open.

-Troy

 

buy a pair of 500 cfm Edelbrocks . they run pisser in pairs. remove the name tag on the front and hit them with some sand paper to eliminate the shine.

 

I don't know if it holds true for 2 carbs, but I was told to keep my Holley fuel pressure around 5 psi (600 vac. sec on a 302). I was running at 6.5, and sure enough backing it down did help some.

Just my two cents.

Jay

ps (it runs great at 4.5 psi)

 

Recardo is right;...those tunnel rams were not designed for the street. Not enough fuel/air atomization.

 

I second the second on ditching the tunnel ram, they look cool, but aren't made for the street.

 

The beauty of the holley is that it is simple to tune, the downside is that the holley HAS to be tuned. It sounds to me that your secondaries are plugged or there is no fuel in the bowl while it is running. Power valve block offs should be considered a "race only" part. A 6.5 power valve will work in most street applications I would start there. I would start with 67 jets in the primaries. Make sure that all of the fuel AND air passages are clear. You would be amazed at what kind of problems you will have if the bowl vent or any of your air bleeds are plugged. My guess is that you got theses carbs from someone that had them all screwed up and that is why they got rid of them. It may be easiest to get HOLLEY brand rebuild kits for both of the carbs and start over. Holley 450s on a tunnel ram can be made to work on the street as long as you accept that it will never be as drivable as a well tuned 650 on a dual plane manifold. I cannot stress strongly enough to use ONLY Holley brand parts when working on Holley carbs.

 

If ya really feel that bad about them junk ass carbs just bring 'em to me at the HAMB Drags and I'll save 'em from a fate worse than death.
Boat anchors indeed,Bah Humbug.

 

Whatever you do, don't waste 10 lbs. of valuable lead, just throw 'em away.

 

The other thing that is helpful when working on Holley carbs is to have the attitude that they will not beat you. Holley carbs are inanimate objects and therefore Will respond to reason...... eventually.

 

Hahaha!!! I understand that sentiment!!

 

Personally I don't think a Holley is worth any more than a door stop, but I have friends that love and make them work, and my Dad could re-build a tune a quader-bog better than I can my AFBs. But I'll stick to my AFBs or Edlebrock's, whatever you want to call them.

As for a tunnel ram not for street use, thats BS. I've ran tunnel rams on 3 different cars, and all 3 where dailys. They launch HARD, and pull just as hard through the curve. The secret I think is not over caming, a Good RV cam, and you'd be surprised. Also don't over think the carbs, just tune and go. I wish I could comment on converters, but all three of mine where adjustable stall, (stick)

 

Pair of 750 cfm NASCAR Carter AFB carbs, (used on '63 410HP 421 Super-Duty engines) sitting on a factory 421SD 'bathtub' tunnel ram. My friend drives this setup on the street all the time, 1963 Tempest with a 428 engine.

Runs a Tremec TKO 500 5-speed and 4.56 gears, solid roller cam is about 240 degrees @.050 on the intake. Any more cam than that and it would tend to 'buck' at lower engine speeds. Pulls off 17 MPG when cruising at 60MPH.



I'm putting together a similar setup, using much cheaper '66 Pontiac 575cfm AFBs on a rare repop of the 'bathtub' intake. I'll be running a 406 with a 231/243-degree hydraulic cam, 3.89 gears/TH400 with a 10" 3500 converter.



Tunnel ram on the street?

Hell yes.

 

you have the "sucker cheapo" mech sec holleys. they were made so summit could sell cheap complete tunnel rams throw them out or like you said use for boat anchors they are designed to work on DRAG cars only with high stall converters 5,000 rpm and low rear end gears 4.88 they are made to launch at full throttle are not streetable!!! junk!!!! replace with a pair of vacuum secondary holley 450's that have power valves or a pair of 400 cfm AFB's the larger edel and afbcarbs also have meck secondaries but have a weighted sec plate also but still all 8 carb plates open together when you floor it plus want a laugh take the carb list number and call for rebuild kit price the 9776 [i think thats the sucker carb part number] kits were 85 each as opposed to reg holeys at 26 each ten yrs ago if you want help pm me john

 

yeh the people who say tunnel rams are not for the street are the people who don't know how or don't want to spend the time to make them work the only real down fall for the street is way overcamming and real cold weather if you're a cold area guy use early ford 1965 water heated carb spacers you can run progressive or straight linkage if you have a sideways carb mount tunnel ram they will need to be re-driled to accept straight inline carbs or buy adopters i would like to see [i always wanted to try - do this] someone use dual large bolt pattern rochester 2 barrel carbs with progressive linkage on a tunnel ram. i think you'll be very pleasantly surprised how well they will perform on the street also when selecting a tunnel ram intake for the street it's best not to use the real tall one's the lower one's seem to be more street freindly john

 

What's to know--5700 RPM, tune for maximum fuel flow, minimum torque.

Unfortunately, that's the case here.

Sounds like you need to go "spend time" with him