4053 Holley carb replacement

[X33RS]

I'm going to run (daily drive) the original DZ carb on mine, it's too expensive to just toss on the shelf and not use it, lol.
I'm an HP carb fan as well.  I run a 950HP on a 454, and that same carb will go into service on the new 502 I'm building.  The 571 my father runs that I had a post about in the garage talk section also uses a 950HP that I setup on the previous 455 he ran.  On the dyno they compared it to Tony's favorite dominator mule carb and that little HP was only down a few HP from the dominator.  Tony was really impressed with it and liked that carb.

   My favorite aspect of them are the replaceable air bleeds.  It's a tuners dream living up here at 5,000 ft and driving down to sea level fairly often.  I can pop the air cleaner lid and make a quick air bleed change and it's ready to rock.  I can go 3 numbers on the high speeds and it knocks it down .5 on the AFR gauge.

[janobyte]

Same: locals finding good dyno numbers out of the box, little less $$ then a custom carb. I think they are actually flowing the advertised numbers. Lets not forget Holley wrote the book on carb mods ( literally, still have a copy from around 20 years ago) Actually my Dad was very pleased with an Edelbrock he had on the 302 when it was on hiatus in a street rod, but I'm just partial to Holley's, and know them pretty well.

lol, APD Racing rebuilt my old 850 double pumper I bought from Super Shops years ago. Alive and well in the race car.

[X33RS]

Yep I have that holley book too, got versed on them at an early age.  Now rebuild/tune/modify them for customers as well as quadrajets.  I get a lot of that being up here at 5,000 ft.  After all the restoration is done, the tuning is always the most fun for me.

[dale_z28]

Anybody use or hear anything about Sean Murphy Induction? I read an article in Hemmings Muscle Machines about their services on Holleys (especially idle circuit revamping). Sounds really interesting to me. I haven't driven my car for 25+ years but when I did, lope-ing around parking lots was difficult because the low idle caused vacuum problems (loss of boosted brakes) and sometimes if you cranked the wheel to hard/fast, the engine would die. I'll run my original Holley for awhile, but I'm also interested in doing an EFI conversion to be able to use a computer-controlled system. It just sounds too appealing. Sorry to the purists out there, but technology has too much to offer, and I won't do anything that can't be reversed.

[X33RS]

Idle circuit mods are pretty simple.  I use a wideband to dial in everything.  In most cases idle feed restrictors don't need attention unless you get into large cams with a lot of overlap.  Then I find I have to enlarge the idle feed restrictors for a little more fuel flow and make the idle mixture screws more responsive.  Very small steps here.

On the DZ carbs, if running the stock DZ cam and intake, I find I don't need any extra idle circuit mods if the correct metering blocks are used.   The cam is actually pretty tame even with it's 254 @ .050 duration, the LSA is spread out to 114, not a lot of overlap and with timing properly set they actually idle pretty smooth and I get about 13-14 inches of manifold vacuum.
   Set up the distributor with 18 initial, and about 18-20 degrees of centrifugal advance. I shoot for 36 to 38 total, that's where they make best power, and with the advance slow enough it will work on pump gas with 11:1 and a real DZ cam, all coming in about 2600-2800.  More aggressive here and you might find yourself running race fuel when it's hot outside.
      I then plug vacuum advance to manifold vacuum (I don't use the original ported location) this gives about an extra 12 degrees or so at idle and increases your manifold vacuum, smooths the idle out a bit and helps with throttle response.    Only after all this is set properly, then I begin on the carb tuning.
   On the dyno with stock carb and intake, I find stagger jetting wakes these little engines up.  I find going 2 sizes up on the driver side of the carb makes a tad more power.   I usually end up with 72-74 front, and 76-78 rear, with the larger jets on the driver side.  Works good when down near sea level.  I tweak that a bit for our 5,000 ft elevation.
   With the carb and timing setup properly, they will idle and drive around in traffic all day long without a hiccup.    I have no problem turning my wife loose in it to daily drive. 

   We have gone the other direction as we get older.  We've had LS powered cars (5 at one time) I've done LS swaps in vintage iron for myself and still do for customers.  Nowadays just kind of sick of it all.  My wife is too, she even sold her newer SS Camaro because she just wants to drive the 69 Z, she likes carbs and points, just the simplicity and low cost of it all is more appealing to use now.  It helps that she has her own tuning guru to keep things tip top.
Hope this helps.

[dale_z28]

Thanks for the info, X33RS! I've got you on speed-dial (here we refer to it as our "buddy list") so when it's time I may get with you on tuning tips.
As an aside, you touched on another aspect that is in the back of my mind: my wife driving my Z... I can't wait!! I remember the look in my moms eyes after the first time she drove my car back in the late '70's... Seems like she warned me less about keeping my foot out of it after she found out SHE couldn't!