![]() |
|
![]() |
#1 |
Registered User
Join Date: Oct 2003
Location: San Jose Ca.
Posts: 3,335
|
Carb question
Holley 4175 spreadbore vs a qjet. What are some of the pros and cons? Also vehicle is a daily driver. Stock 350.
Thanks
__________________
RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234 |
![]() |
![]() |
![]() |
#2 |
Registered User
Join Date: May 2003
Location: Shreveport LA
Posts: 3,170
|
Re: Carb question
I put a brand new Holley spread-bore on a brand new stock 350 in 1972 and it never ran too well. I put the Q-jet back on it & it's still there. The Q-jet had much better throttle response, slightly better fuel economy, a much better idle, and seemed to make just as much power, and it didn't sputter and pop (think lighting a small pack of firecrackers) when you floored it from mid-range RPM.
|
![]() |
![]() |
![]() |
#3 |
Semi-Senior Member
Join Date: Feb 2003
Location: Washington, MO
Posts: 390
|
Re: Carb question
Generally speaking, for an everyday driver, Q-Jet EVERY time.
Holleys have power valves that go bad often, idle circuits tend to clog easily. If you like working on your carb, get a Holley. Q-Jets can be hard to overhaul for some. Lot of rods and stuff to keep and get in place. But....once you do have it set up right, it can run good for a long time. Parts are very available form most parts stores. JMHO
__________________
'68 50th Anniversery LWB Custom Fleetside, '77 305 v-8, turbo 350, factory speed alert (still works), '71 drivetrain w/front discs. Some call it ugly yellow, others call it Ochre '83 Jeep CJ-7, <80,000 miles, original owner '04 Chevy Suburban, 4x4, 2500, 6.0 ltr, Predator Diablo programmer '95 GMC K1500 Extended cab |
![]() |
![]() |
![]() |
#4 |
Account Suspended
Join Date: Sep 2005
Location: Monroe, WA
Posts: 3,815
|
Re: Carb question
For a stock engine, it's hard to beat a Q-jet. Small primaries for economy around town, BIG secondaries for the occasional heavy right foot. They're also usually tuned pretty close to the right settings out of the box, and with the vac. secondaries it's kind of self-tuning.
Holleys are great performance carbs, but in my experience they take a ton of tuning to get them right on - my carb was *6 sizes rich* and *3 secondary springs light* out of the box. Additionally, people generally get ones that are just way too big - an 850 double vs. a 600 vac. I don't agree with the observation regarding power valves, etc. - I hear about it all the time but I've never actually seen one blown. I completely agree with the overhaul comment; there are a few tricks (accel pump, etc.) but it's pretty straightforward if you take it slow and careful. |
![]() |
![]() |
![]() |
#5 | |
Semi-Senior Member
Join Date: Feb 2003
Location: Washington, MO
Posts: 390
|
Re: Carb question
Quote:
I didn't say 'blow'. I'm sure if you've been thru a lot of carbs that Holleys are just like Motorcraft 2 bbls, the valve diaphram goes bad. When it does, it will run pig rich fronm fuel running straight from the bottom of the bowl into the manifold. I've ever seen any of them that I thought were 'blown' as well. The ones I see are from being old and attacked by something in the fuel. I agree with all your observations.
__________________
'68 50th Anniversery LWB Custom Fleetside, '77 305 v-8, turbo 350, factory speed alert (still works), '71 drivetrain w/front discs. Some call it ugly yellow, others call it Ochre '83 Jeep CJ-7, <80,000 miles, original owner '04 Chevy Suburban, 4x4, 2500, 6.0 ltr, Predator Diablo programmer '95 GMC K1500 Extended cab Last edited by 68speedalert; 01-05-2006 at 10:15 AM. |
|
![]() |
![]() |
![]() |
Bookmarks |
|
|