timgman

Is anyone running the holley spread-bore gm replacement carb..
??????????
thanks

lars

A lot of people here run the Holley 4175-series carbs, and I've set up and tested quite a few of them - they run very well once set up correctly.
Lars

timgman

I was just wondering if a 4175 is an easier setup than the q-jet.
My q-jet seems to be running OK with my new 383 but It has a hesitation and I think that a rebuild is over my head in terms of tooling and experience.

I was thinking that a holley might be pretty simple to setup out of the box...
Am I on the right path here?

RunningMan373

I got a one, new last year. No matter what i did with the floats, up, down, etc, the carb made my '73 die on hard brakeing and fast U-turns. Sent it to holley under warrenty, they put it on a flow table, adjusted it, I putr it back on-- same problem. It's now in pieces in it's box. Quadrajet actually incerases RPMs a little on hard braking. Not saying you'll have the same problem, but if you do, start bching to Holley early. Mine was a mech secondary model, I really liked the carb, but was a danger because of the motor cutting off as i was trying to brake

1Fordman

Have one in my sons 69 BB Camaro. It has performed flawlessly since being installed.

timgman

Yeah I must say that my stock l48 quadrajet is doing wuite well.
just a small hesitation when the secondary's kick in .. at leas I think that's the cause.... I plan to drive it to work in the morniong. perhaps I'll re-evaluate a change-out. a rebuild on my q-jet would prob fix it. Maybe It's be less costly than a new holley anyway?
I'll report my performance results in the morning.
timg

Georgia1974

I have the 4175 model, had to lower the rear float due to it was dripping in the secondarys. but after that it has run great with no problems.

Alan 71

I've had the Holley spreadbore on my 71, 350, since 1971. It was the 'thing to do' back then and I still like it. I have the mechanical secondaries, they take a little getting use to but are fun once you figure them out.
Regards,
Alan

PS: The spreadbore looks like a 'shoe box' sitting on the small block.

Patrick73

I have used both and liked both. Like Alan71, I put a 4165 with mechanical secondaries on in 1971 and it performed great for many years. Running Q-Jets now, but both are good carbs if set up correctly.

Alan 71

Hi Patrick,
I realize that carburetors are OLD technology but is that Holley cool looking or what!!!
Regards,
Alan

dennis

Had a holley spreadbore on my 70 L-46. Ran very well. The only problem was I couldn't use the drop base air cleaner. The base would not clear the carb fuel bowls. Used a AC that sat on top of the carb. No problem with the L-88 hood I had, but went back to stock hood and Q-jet

Patrick73

Holley 4165/4175 family ; list 6210, divorced choke, spread bore, double pumper, mech secondaries, 650 cfm on a 1973 corvette. Believe this is a photo from forum member "Kid Vette".

Member Matt Gruber is the forum guru on Holley 4165, List 6210.

71 f/w driver

on my 71 I replace the Q-jet with the holley 4175. glad that I did since I had dumped $200.00 into the Q-jet to have it rebuilt. Couldn't keep it from running rich and had to pump the pedal to get it going. I'm sure the right person could have fixed the problem but I didn't want to let nice weather pass me by... Some guys just have that certain nack on defferent makes of carbs. I got the wrong one...

redwingvette

I have been running the Holley 4175 for about 5 year without any issues once I tuned it to my setup. Out of the box the discharge nozzle, (it came with a size 40 and I am using a size 21) were way to big and I had to change the plastic cam to a very low and slow slop, (I am using the black one). Then I had to change the metering plate for the secondarys to a smaller size.
Out of the box it ran very rich and blew lots of black smoke out the exhaust when I jumped on the throttle.

Avette4me

I've been running this one since 2004 with absolutely no problems

The only difficult part is setting the secondary idle because the adjustment is on the bottom of the carb. Also, buy an assortment of pump cams.

Alan 71

People say that there's a way to be able to use the stock air cleaner base, with crankcase breather, by bending the arm the tube interferes with. Can anyone explain that procedure, please?
Regards,
Alan

Patrick73

"Out of the box it ran very rich and blew lots of black smoke out the exhaust when I jumped on the throttle."

RedWingvette is correct. The 4165's usually run a little too rich at WOT. List 6210 comes with # 60 primary jets and # 83 secondary jets as I recall. I replaced the secondary # 83's with # 76's. Some people run # 78's in the rear.

Lars recommends a 6.5 or 5.5 power valve. ZIP has a step by step installation guide with photos of a Holley 4175/4165 in their C3 Tech Section:

http://www.corvettemagazine.com/2001...carb/carb1.asp

birdsmith

I had one that was given to me by a friend when I rebuilt a Holley 600 for him. After I bought my (stock) '70 I swapped out the (working perfectly) QJet for it because it looked way more cool than the teapot-esque Rochester. From the start it was dripping fuel out of the secondary boosters (re:georgia1974) so I rebuilt it with a made-by-Holley 'TricKit'....same problem. No amount of float adjustment or any other tinkering would stop it (but when the car was running it ran beautifully and it DID look WAY cool) so I finally gave up and went back to the ol' reliable QJet. One thing that I DON'T like about the 4165/4175 as opposed to other Holleys is that the bowls have to be taken off to adjust the floats so you're pretty much guessing at it (especially with this wierd modern gas that we have to deal with nowadays) vs. the tried-and-true externally adjustable sight-plug setup that all their other carbs use. IMHO Holleys are certainly easier to rebuild than any other carbs but for some reason STILL unbveknownst to me this one just couldn't be fixed...I might even try using it again if somebody here (Lars?) could tell me how to get it to quit leaking.....

markdtn

I had one on a 455 Pontiac for many years. Worked like a champ.

Matt Gruber

Lots of info on the 4165 in my sig. link
page down, click on links.
buy carb books.