Inliners International Forums General Discussion Engines clifford/ holly questions

i bought a clifford intake and holly 4 barrel for my next project. the intake is not the heated kind can one be added to it if so where. i seen the ones on the stovebolt six website, they look like they bolt on the bottom like the stock ex manifold but this intake doesn't have a location for that. also can anyone tell me the location to find out the size of this carb. i think it's whats called a double pumper it has two fuel lines one to each side. need to find out if this will be too big i've read so much different info i don't know what to think and i'm no pro. i got the carb with intake and some other stuff. i was going to buy one of the holly/ weber 2 barrels and still may if this won't work. this will be on a 292 i plan on starting on it in a couple of months.i also have the hedman headers just a waitin too. no groans i don't think i will have to ask as many questions as the 250 i did last year. by the way it's running great so far and has almost 1000 miles on it thanks to all the help i got.

Hoggy I sent you a Private In regaurds to the Hot water Boxes I make and are welded to the clifford Non heated intakes.

On the front of the carb choke housing you will find a number stamped. It will say something like List 3310. Post the number and I'm sure we can tell you what it is.

A fuel inlet to each bowl doesn't make it a double pumper. The double pumpers have 2 accelerator pumps, one under each float bowl.

on the top it has list-4777-3 0160. another location 11166 with 3 under it. 10748 on bottom. lots of pat. #'s. sorry i don't know much about these. can these be rebuilt as easy as the rochester's? in the 63 manual it basicly says they can always be rebuilt and i've done a couple of them with good results. what are these worth? i like the idea of using this if it's not too big.

The 4777 is a 650cfm double-pumper, a tad big for a 292 even but should be ok. Just dont floor it all at once, go about 1/2 way down, then hammer on it at about 3000rpm.

The 4777 is a 650cfm double-pumper, a tad big for a 292 even but should be ok. Just dont floor it all at once, go about 1/2 way down, then hammer on it at about 3000rpm.

Ive got a 500cfm 2bbl im putting on mine and yet undecided on which way to mount it. but I will proably end up making my own adapter and putting the fuel bowl up front and run it front to back.

I'm planning a +.060 292" with 'lump ports' & a mild cam for pulling trailers.

From what I see a 550/600 CFM Holly would be the one, or slightly less than the the 650.

Is there a model (Holly) that has small primaries, as those will be the main use portion. This rig will just need (++ CFM) for going on freeway or keeping up on hills.

John

if your wanting to use a Holley go with what they call a spread Bore. It's like chevys QJet 4b carbs.
all square bore carbs have the same size Primary & secondary.

The Holley Economiser(don't know the list#) is a spreadbore but the CFM might be too big. Then again, it is set up like the Q-jet which (when tuned right) can supposedly be made to run on just about any engine. They have have small primaries with double boosters in each which makes them very responsive. In David Vizard's Book --How to build horsepower vol.2 Carburetors and Intake Manifolds-- He write's:"It is difficult to have too much CFM on any engine of 200cid or more with this carb due to it's air on demand design" he then goes on for several pages explaining how to calibrate, and modify them. Is anyone out there running a Q-jet on a inline six?? Just curious.

I think you'll find the 500 2 bbl not much fun. Other than the gradual opening of the 2 throttle plates there is nothing to maintain vacuum like a 4 bbl 500 would have by only opening the primaries at first. Even with a 50 / 50 split a 500 4 bbl only would allow 250 cfm through the primaries and thus keep the manifold vacuum high enough for proper fuel pull. I know 2 bbl and 4 bbl carbs are flow rated at different vacuums, but what I just mentioned is a non technical way of saying a 500 cfm 2 bbl is not the best choice for street driving on the typical inline 6.

A Qjet while more of a headache to tune up is an excellent street carb. I'd start with one off of a 305 ci mid-70's truck engine. The calibration will most likely be close. Once the QJet is set up it will give excellent part throttle repsonse due to the tapered primary metering rods and triple primary booster venturis. If all round perfromance and economy is your goal then give the Qjet a look see.

I'm running a Edelbrock 500 cfm 4 barrel on my GMC 228 mild build and it runs great. Used to run a holley 390 but had too many tuning problems.

Gentlemen,

What are you guys doing right with this carb that I'm doing wrong? I have that same Edelbrock 500 4 barrel on a mildly built 292, .060 over with stock pistons and a mild (hi-lift Elgin) cam. This is on a WELL heated Offy intake (water heated plus hot tube headers nearby) with a 1-inch spacer. And it's still a bit too much for it. Wonder why it's working better on a 228, which is 64 cubic inches smaller?

My next build will be similar to John Meredith's. I plan on using a set of .040 over LPG pistons I have and (possibly) the lump port head.

-magic mike-

Ah; A Q-Jet, that's a thought & from a 305" that will work, good idea.

Hurry & get that EFI system developed & we all can throw our carbs in the dumpster.

LPG pistons are still 'dished', just not as much. You need flat top or doamed & there $600 (bummer) but necessary. That way you have (exactly) what YOU want.

Remember; The bore, stroke & compression are the engine's "foundation"......

Some v6s also ran the Q jet.

Mike,

Have you tried messing with a calibration kit for the 500? I ran a 292 with a Clifford 264, propane pistons and an Edelbrock 600 on a Clifford manifold with no problem. We have smog checks on 65 and later and it passed without adjustment.

Bruce

I was reading up a little more on the Q-jet and it say's the primary venturi's only come in two sizes 1 3/32" and 1 7/32" also says the factory sells carbs based on application not CFM but they are all "loosely" rated around 750 to 800. Seems awful huge!! The V-6 and the 305 both seem like good cannidates. I think I have seen one on a V-6 before but I can't think of where. Maybe on a older S-10 pick up??

The key to Qjet CFM in the secondary air valve (the flapper on top), by adjusting the limiting tab (either adding or removing material - some folks add an adjustment screw) you can set the amount the air valve opens. So for a V6 (4.3) the air valve will open to say 65%, now on a 454 HP rat motor or a 500 CI caddy the air valve open to 90 degs.

Yes there are 2 size primary bores, for our inlines use the smaller one.

Hurry & get that EFI system developed & we all can throw our carbs in the dumpster.




John... I'm shocked!...

Its coming soon...

A Qjet carb came factory on some of the Pontiac 250 ci inline sixes. HP models, Tempest ,Firebirds, etc.
I think they were smaller like, 625-650 CFM????

well i have decided to try this holley on the new engine but that's some time off. i checked rebuild kits are about 20 bucks. i will prob. do the startup with a stock intake and rochester then switch over. well i'm getting ahead of myself i haven't even started the engine yet. that will give me time to get as much info as i can. i think i saw a holly carb book at barnes and knoble i might look at it. i don't know how much info will be specific for the 292 application. shame i got rid of a q-jet not long ago. hoggyrubber

I agree a 650 CFM is large for a 292. I used to run a Holley 390 CFM, Model R8007. They are a little spendy now. [I paid $89 new in '78]
Currently I run an Edelbrock 500 CFM on my Offy 4Bbl intake. I'm in Tucson AZ so I don't need carb heat.

Carbs are only "better" because the EFI systems to date are way to expensive and require a bunch of test equipment.

You proved it can be done with "mix match" junkyard parts & a little effort.

Something occurs in the transition from AC to DC in the alternator & it makes EFI go 'crazy'. Some type of filter may solve that.

You build 3 prototypes & We'll test them. One in the west, 1 in the 'corn belt' & 1 one back east.

Give it some wacky name & Copyright that.
Or perhaps, a Canadian patient.

Where there's a will there's a way. The rest is history in the making.

90 % of all Info carb & EFI, TBI, cams,So on. Pretty much 90-95% all Books are related to the Vthings. Very FEW books out there have anything to do with L6s of any kind.(Chevy ,GMC,ford Mopar
so on)

Holley used to make a TBI system for 6 cylinders that didn't require programming. They still make a 670 CFM Projection System for V8's that uses several turnpots for tuning, no computer required. It costs under $900.

I installed a 2 injector Holley Projection system on a V8 about 15 years ago. It ran great for a 100,000 miles. Just STP Super Concentrated Fuel Injection Cleaner was required in the gas every 3 to 4 months or the injectors would plug. Straight forward installation. Great starting and drivability. The inputs to the controller were engine rpm, throttle position, and coolant temperature. Later a exhaust gas oxygen sensor input loop was offered as optional. The turnpots tuning adjustments were for low rpm, high rpm, acceleration, and cold running. The larger 4 injector units also had a mid rpm adjustment. With the controller in the passenger cabin, you could tune the system while in the driver's seat with a screw driver, or your finger nail.

Holley has a current system for 6 cylinders, but its more expensive and requires programming. I'm not sure why the Projection 502-20s system (for V8's) can't be use directly or mated with the available 400 CFM throttle body for a straight 6. Engine rpm input to the controller or the shape of the fuel calibration curves maybe? I called Holley tech services once on the matter but they weren't very helpful on the subject.


http://www.holley.com/502-20S.asp 8 Cylinder 650 CFM Turn Pot Tuning
http://www.holley.com/950-20S.asp 6 Cylinder 400/650 CFM Programmable

I answer to the question about Q-jets, I was running a edelbrock 600 on my 250, with comp cams 260 H, 307 flat tops +.030, complete MSD ign including distributor, headwork with stainless proflo valves 1.94&1.60, early 60s 292 exhaust manifold with 38" of 2 1/2 pipe to a dyna max muffler with 2 2 1/4 tail pipes then to back of car. I am running a heated sensor autometer air fuel gage. The mixture was suprising no matter what jets & rods I installed it ran rich unless under full throttle. A friend suggested that I install a Small Q Jet that was used on 1985 Astro vans with a V6 and some small caddies. Installed after a stock rebuild and saw my a/f gage start to read something other than rich. To make this story short after a little adjusting this engine starts and runs like efi and I have increased milage 5- 6 mpg over the edelbrock, I would never have belived this if I hadn't done it myself. I was always an AFB/Eldebrock fan but on my six the Q-jet is much better, I "think" that my power level has also increased (Seat of your pants feel) this engine is also tied to a 700R4 with a 2400 convertor. My friend explained it and it made sense when you think about it "the Q-jet I am talking about was the last carb useb by GM before they switched to efi. NOTE I left the electric fuel sol. unhooked on his advice. Also this carb has an electric choke on it.
Big Bill

Every one that runs a Q-jet seems to love it. I think guys just dont run them cause they just aren't that pretty to look at. I am thinking of hunting one down and trying it on my 250. What intake manifold are you using? Are you heating it? and which way are you pointing the primaries?
Dan

Dan
I am running an intake that I made myself it is designed to take advantage of the exhaust maniflod heat by bolting directly to the manifold , but unlike a stock design that allows the exhaust gases to come up the side of the intake almost to the carb flange, I only heat the flat floor of the intake. I run a 195 thermostat which keeps everything plenty warm. I have the primaries toward the valve cover and I have the carb mounted with the throttle plates about 1 1/2" below the top of the valve cover. I use both cable throttle and throttle pressure linkage. I feed this with a stock fuel pump with 3/8 lines and I have a regulator mounted in front of the carb with a pressure gauge I keep it set at 4 lb. I always set the regulator with the engine running approx. 2000 RPMs this alllows enough pressure and volume to have an accurate setting. I also run a four hole 1 1/2' thick alum spacer right below the carb which then opens into my intake.
Big Bill

I've benn running a 650 holley on my 311 GMC racing engine. This is only my opinion but I converted it back to a vacuum operated secondaries. Still a double feed. I figured the engine was a lot smarter than I was. Played with the vacuun springs a bit and went 157 at El Mirage in a roadster. Keeps the tires from breaking loose. A six cylinder keeps a good vacuum signal especially with a 4 " stroke. I was able to run 155 with a Braswell 2 barrel with annular discharges. It flowed 700 cfm but I needed more atomization.
If you use a Carter/Edelbrock style carb you can lighten up the weights on the rear butterflies for performance and they don't leak..Good Luck