Ristow's Holley 4548 vs. My Edelbrock 1405 Shoot-Out

[rreed]

Hi gang, possibly based on conversations revolving around this thread: http://www.ifsja.org/forums/vb/showthread.php?t=154201 Ristow has very graciously volunteered to test the 450 CFM Holley 4548 carb off this '77 work truck against my 600 CFM Edelbrock 1405. Of particular interest in his build would be this page, http://www.ifsja.org/forums/vb/showt...=152113&page=4, which indicates approx. 14 MPG from a 4.10 geared J-20 that is going to pull a bobcat on a trailer. Not too shabby! I suppose the curiosity is mileage and possibly performance vs. my Edelbrock, I'm betting both will be better w/ the Holley. One thing to be clear of please, I'm not an advocate of Edelbrock carbs. I just happened to have this one sitting on a shelf when I bought my J-20 years ago. After spending about 15 min. fiddling w/ its stock MC4350 I threw it in the trash and ordered up the Ford to square bore adapter and dusted off this 1405 I've now been running since around 2005. This isn't a challenge or dare to see if "my" Edelbrock is better than Ristow's Holley, just a comparison to see what happens. While my Edelbrock is fairly well tuned (minus needing to jet up the secondaries) it's likely his Holley is more finely tuned. That is one of the benefits of the Holleys I suppose, is that you actually CAN more finely tune them compared to an Edelbrock, but that's another conversation.
My '76/'79/'81/'85 mutt J-20 is a fairly similar setup to his '77. '76 bone stock motor (360 w/ stock 4V intake, Summit $55 square bore adapter), '79 J-20 chassis, T-18/D20, 4.10 gears. He's running aftermarket full HEI distributor but I'm running HEI/TFI hybrid (stock '79 distrib, AC Delco brand HEI module, Autozone cheap-o TFI coil [haven't gotten around to swapping for MSD 8227 yet], and some wiring), timing chain is stock w/ probably around 43,000 original miles. Our trucks may not be dollar for dollar exact twins but they're close and the only change I'll be making on mine in this shoot-out is that I'll be swapping my Edelbrock for his Holley and redialing my distrib. vacuum advance to match the power stage in the Holley. I'll make sure idle speed is dialed to match mine so it?s not burning extra fuel at stop lights. Driving style and routes will not change; I don't lead a very exciting life these days. This is a comparison of the two carbs, not the two trucks or drivers.

Timing on my rig is advanced until ping then back off just until it doesn't. Vacuum advance will be setup according to another Ristow write-up, http://www.ifsja.org/forums/vb/showt...ht=distributor, which is how I had it on my Edelbrock, matching its 5" enrichment stage. His Holley has either 7.5 or 8.5 power valve so I'll dial my vacuum advance to fully back out at 8.5" that should cover either closely enough.

I've (hopefully) never professed to be an expert at these things, I try to only speak from my own experience and as I understand things I haven?t actually done. I feel w/ an accurate vacuum gauge and a free Saturday afternoon I can reasonably tune my way out of a wet paper bag. Having said that, I'm sure a lot of what I report or describe will be corrected by those who know better than I do. Please feel free if you do, this is an exercise in learning.

At a cursory glance (my first close-up look at a Holley) I can already see this thing is INFINTELY more adjustable than the Edelbrock, which is pretty much only tunable in "stages;" the accelerator pump on the Edelbrock pretty much has three "size" options vs. Holley's changeable squirter and changeable cam (and position thereof) for the accelerator pump. I'm not going to start any religious conversations on "real" mechanical vs. vacuum secondaries but in the most basic sense I would say the Edelbrock is mechanical (twisting the main throttle plate operates some levers that open up the secondary plates [we're not going to discuss the air flapper door cover thing though yes vacuum does come into play] while the Holley appears to be purely vacuum secondary; twisting the main throttle all the way open does not operate the secondary throttle plate, only the vacuum pot on the passenger side appears to operate the secondaries). I'm not going to tear into Ristow's carb to compare internals. His is an electric choke vs. my manual (though I have found at least one manual choke Holley 4548 on the 'bay that I'd like to pick up) so I can't make a whole lot of fair comparisons about choke operation. I'll mooch off something nearby that's hot w/ the key on for the electric choke.

So anyways, w/ a two and a half month old son my time is precious and few to fiddle and tinker w/ the '20. Ristow's carb arrived Friday and I was hoping to at least have it sitting on my truck by Sunday but it hasn't happened yet I'm going to pick up a fresh square bore gasket on the way home today and see if I can either sneak it on before the wife wakes up early tomorrow morning or maybe even drive the '20 to work tomorrow and swap them in the parking lot behind the dumpster tomorrow if I can. I?ll be making every effort to get it bolted on and running on my truck w/in the next couple of days, please bear w/ me and the new youngan.

Stay tuned (no pun intended) and a massive big thanks to Ristow for this opportunity.

[ScottsMojo]

Sweet!

This should make for an interesting read and plenty o' debate, I'm sure!

[serehill]

Like anything else

Usage & preference are the real control factors. This is apples to oranges for me.

[rreed]

I'm a little closer but not quite as close as I wanted to be this morning. Got a fresh base gasket yesterday (sheesh, $6?), was planning on grabbing my tuning stuff and taking the truck to work this morning but forgot the back was still full of camping gear and firewood from a recent trip. Plus I forgot I was still in the middle of flushing my radiator mud (another story) and ran out of time before I could get it filled back up and pull out the camping gear I wouldn't want to walk off during the day. This area of Plano isn't exactly high crime but ya know...

Anyways, should be able to bring the truck to work tomorrow and get my choke wire ran, plus "t" my nice hand-held tuning vacuum gauge into my on-board gauge to make sure I'm getting good accurate readings when I do the swap. Seems like my cheapy on-board might be 1" off but not sure if that's across the board (needing to rotate the dial to correct) or it's on a curve that's way off at either ~20-ish or ~5-ish. We'll see.

[Ristow]

well,hurry up already.

[rreed]

Alright Ristow, I put a tremendous amount of faith in you this morning. In a blinding flash I ran out, ripped my Edelbarf off the truck, slapped down your Holley, slammed the hood, and drove to work. Didn't dial in or adjust a single thing, at all. Made it in just fine.

While cold, it did have a noticeable stumble off idle but nothing that killed it or anything. I could feather it just a little and it was fine. At the moment I attributed it to maybe needing to dial in the vacuum advance to more closely match your Holley but I dunno, you can correct me on that one. For some reason I'm drawing a blank on off-idle stumble causes/fixes this morning. Once good and warm it was perfectly fine, no stumble of idle or anywhere for that matter.

This is just preliminary, as mentioned I haven't adjusted a single thing at this point. I'm not criticizing anything either way, only reporting facts of what I experience and differences b/t. People can take away from this what they wish.

At a glance, I would say my Edelbarf is more "snappier" at lower speeds in lower gears but at part throttle is where the Holley really shines. And a lot of fun at that. From a dead stop I floored it this morning since this tank of gas is about half Edelbrock, half Holley, might as well use it to compare performance and get it dialed in. Anyways, from a dead stop or slow rolling start in lower gears I hate to say my Edelbrock does have a snappier pick up and go. The Holley was able to chirp the tires a bit in first (second on a T-18, I treat granny lows as three-speeds, so please note). and a little grabbing second (again, "third" on the T-18). W/o getting into the secondaries the Edelbrock did a bit better. But once the RPMs got up a bit (2,500 or so) the Holley would suddenly open up and would "pull away" from where the Edelbrock would have been at that point. Then I realized I hadn't looked around for cop cars at that point so I quickly settled down.

At part or even low throttle in higher gears, the Holley really comes out. Ristow mentioned he could mash it at sub-idle RPMs in top gear and the truck would just go, and it does that better w/ the Holley than the Edelbrock on my truck. I could accelerate form low speed/high gear w/ the Edelbrock and it "would" do it, but the Holley does it better. Accelerating from around 40 to 50 mph, 50-60, etc. the Holley does WAY better. It's fun! I dont' know if that has anything to do w/ the vacuum secondaries on the Holley, my guess is maybe.

The truck idles and drives noticeably quieter. Weird. The true dual cheap-o turbo-style(?) mufflers of stock manifolds were a little clappy w/ the Edelbrock but the Holley idles noticeably quieter and cruises quieter. Even getting into it on the Holley is quieter at speed. I dunno? Just an observation.

Got to get to work, more later. But at a glance I like it and enjoy it, it certainly drives much differently than the Edelbrock. Some things better than old man Vic's carb, some things not quite as good as. I'm guessing maybe because the bores are bigger on the Edelbrock than the Holley for some stuff? But as mentioned, I haven't dialed the idle screws in yet (that might more affect MPG than anything) or the idle speed, which could come down just a tad for me, but mostly the vacuum advance needs to be dialed in better. I'll try to do that over lunch today. Ristow also mentioned the secondary spring probably needs to be swapped out for the black one. I'm sure we'll talk about that along the way.

So far, an interesting carb.

[Ristow]

keep in mind that carb was dialed in on a junk motor. feel free to play with the idle speed and mixture screws. the main jetting is factory on both sides.

the choke is out of whack,the pull off is way too much (lean),and the old electric chokes are not so easy to setup so i haven't yet,it's fussy on mine too. the choke can swallow a lot of gas,so i tend to be forgiving of a lean choke and the hassles that come with it.

smaller carb,will surely have less snap for a given throttle apply. my 780 holley is jumpier than the 4180's (580cfm) i like as well.

[rreed]

Duely noted and will do. I'll take it for a spin at lunch to warm it up then find someplace i can throw the vacuum gauge and screwdriver on it.

Agreed on electric chokes, plus the more knobs and levers the more fun a jeep is to drive for me. I may dial it in a bit though, this is north Dallass traffic and hot or cold you'd better get moving or get your butt ran over.

Forgot, it seems to idle at around 22" of vacuum vs. my Edelbarf 21" but cruises at around 16 vs. my 17. The Holley does drop vacuum much quicker when pushing through the trottle vs. the Edelbrock.

[rreed]

I figured of all places, nobody would pay attention to a guy tinkering under the hood of a beat up farm truck in the parking lot behind Autozone (get in the zone).

It's around 75 or so outside and since the cool down from the ride in this morning it fired right up but was still a little stumbly/surgey/finicky heading out of the parking lot. I enriched the choke one "notch" on the black cup thingy once I go to the 'zone, we'll see how that does going home and tomorrow morning. Fast idle is about dead on w/ where I liked it w/ my Edeltoot, around 1,100 or so RPMs. W/ the Edelfart being manual I could also dial how much choke it got as well as the stepped fast idle. This Holley doesn't do a bad job of it w/ its electrical thing. I think I'd still prefer a manual choke overall.

Was going to fiddle w/ the idle speed a little but forecast calls for upper 80s to low 90s this week, think I'll leave it where it is to compensate for the A/C that might get a workout this week. In summer I generally set it so w/ A/C kicked in it's idling at around 500-ish. Seems like it drops a good 100-150 RPM when the compressor is running. I'll keep an eye on it, right now warm idle w/ no A/C is around 600-ish or so according to the tiny Sunpro tach.

Threw the vacuum gauge on it to check the idle screws. Only spent a quick moment but half turn either way to the left or right dropped the vacuum a tiny bit from where it was so put them back where I found them, at maximum vacuum (engine warm, idling). Close enough for me, that's how I set my Edelbarf. Anyone's welcome to argue. I might have a closer look tomorrow, I just wanted to give it the quick once over today.

Tried to get the vacuum advance dialed in a bit but my box of tuning junk seems to be missing some misc. lengths of vacuum hose. At least 3/16, all I could find was 1/4 or 5/16 so wasn't able to splice my good vacuum gauge in along w/ the Harbor Fright hand pump. Checking its built-in vacuum gauge against my handheld showed it was actually accurate b/t 2-10" so I figured close enough, I'll just use it for now. After fiddling w/ the allen wrench and watching the pump gauge not making much sense, I tested it against the good gauge and the pump's gauge was WAY off and inconsistent after several minutes of use. So at this point my vacuum advance is backed out at somewhere b/t...2"...and...12"? Haha, I dunno but it's certainly better than it was, slow town cruising and poking at the throttle is noticeably better than it was. A bit closer to the snappiness of the Edelbrock at the same low speeds/low gears. Hops right up better. I figured for the use of their parking lot I'd go in and pick up some vacuum hose I needed but they were out. I picked up a package of vacuum connection adapters instead, tomorrow morning I'll get my pump and gauge out and try to properly dial in the vacuum advance before heading in to work.

Anyways, it's getting better, definitely a good little carb so far. It's a little weird getting used to the way(s) it behaves differently than the Edelbrock. It runs so quietly now, it's eerie, but when you get into it and those secondaries start to growl at around 2,500+ man it sounds awesome up front. Overall the tail pipes are still so much quieter w/ the Holley. Weird.

[rreed]

Alright play time is over, time to get serious and see how the mileage goes. Filled up this morning on the way to work so we have a starting point to compare MPG. No more flooring it and giggling.

Choke still needs more fiddling but I'm not going to kill myself on it. I am convinced I don't like so-called "automatic" chokes.

Still need to pick up some good vacuum hose, will pick up some 1/4" today and that'll just have to do. It was certainly better on the way home yesterday after haphazardly dialing in the vacuum advance to who-knows-what but this morning after hooking up a conglomeration of adapters, tees, cracked and leaky old hose, I jacked around w/ the vacuum advance a bit and now it's just "different." The right tool for the right job.

Anyways, I'm liking this thing. A lot. It has SOOO much low end grunt it's not even funny. It accelerates so cleanly and refined compared to the Edelbrock. Where the Edelbrock would jump up and pull the front end up and haul a** down the road when going through the gears in a spirited fashion, the Holley just kind of "goes" and you don't notice it. Hard to explain. Like they E was trying to prove it's a bada** and the H just doesn't have to. Similar to when I swapped out the no-name ignition module for an AC Delco a long time ago. Anyways, w/ the Holley you just kind of gracefully and w/o effort get up to speed quickly. It just feels so much more refined in the way it drives. I love it.

I've settled down my jacka**ing around to normal driving now to see how the MPG is going to go. It is a little difficult because this thing brings sooo much low end grunt to the table I find myself leaving it in higher gears at lower speeds and being able to accelerate when traffic picks up w/o down-shifting. The E could do it--but the H does it SOOO much better. I can see why Ristow was leaving it in top gear and grumbling along through intersection turns and what not. I could imagine that having an affect on mileage but that's another experiment on my list to tackle later. This will definitely end up being a before-after-after comparison.

He might not get his carb back at this point.

[Ristow]

the 4180 has a much nicer automatic choke. a bit more sophisticated than the typical holley electric choke. the early chokes like that 450 has are the most difficult to set up.

i put a 4180 (580cfm) on in place of the 450. it is a bit stronger off idle,but overall feels about the same as the 450. it is however getting economy to match that 450,a testament to the annular boosters of the 4180.

[rreed]

Yeah just read up a bit and watched a video on the choke adjustment. I'll fiddle w/ it a little more.

Interesting news on the 4180. I'm paying attention to your findings of the adjustment screw on the bottom of their metering block, even though it has little to do w/ me. I still like to learn and who's to say I won't ever pick one up some day.

Finally got a length of good hose (before I remembered I have a whole box full of misc. hose at the house ) and got the vacuum advance dialed in a little better. I think my cheapy Harbor Fright hand pump is about plum give out on me. My vacuum advance is fully backed out (stops moving) at around 8" of vacuum to cover the either 7.5 or 8.5 PV you indicated might be in this carb. Had to get back to the office real quick but it feels a bit better. Drives fine. I'm focusing on driving decent right now for MPG comparison so I'm driving "normally." Maybe after this tank of gas (and the next?) I'll horse around w/ it a bit more to compare performance. W/ a 52 mile round trip to work plus anywhere I go at lunch it won't take long to run a few tanks of gas through it. If possible I'll hook up to the camper (23' 4,000lb. bumper pull) at some point but no promises. Seat of the pants feel w/ the empty truck indicates it would pull our little camper or a car hauler w/ a Jeep on it just fine.

I was going to pull a couple plugs this morning to get an idea of health and jetting and what not, didn't make it to it. I'll try tomorrow morning.

Still the same though, it's growing on me and I'm liking the more smoothly refined attitude of this Holley over my mouthy punk kid Edelbrock. This Holley is just a darn good carb and I would certainly recommend it over at least an Edelbrock 1405, esp. if it gets good MPG over it in my truck as well. If I had both laying on the shelf I'd continue dialing in this Holley as perfect as I could get it and forget I ever had the Edelbrock. I don't think this Holley would be any more difficult to dial in than the Edelbrock (what, jets, a power valve, and some adjusting vs. Edelbrock's jets, enrichment springs, and some adjusting? oh yeah, the secondary spring, woo-hoo).

[rreed]

Not much to report this morning. Won't through the weekend, my Ma is in town so won't be fiddling w/ the old farm truck until Monday.

Pulled the two front left-hand plugs, they're gray to light gray-ish. Looks like I'm due for a new set pretty soon. Right-hand bank is a little more difficult to get to w/ wires and hoses in the way. Will have a look later.

I know I'm hung up on the vacuum advance thing but man does it make a difference. Hitting the on-ramp and accelerating from around 45 to 60 happens in a second, it has sooo much mid-range throttle response. The Edelbrock does too but the Holley just does it differently, much smoother and you don't notice. More than a few times w/ the Holley I look down and am going over the speed limit in places that muscle memory kept me at the right speed w/ the Edelbrock.

Will be interesting to see what the mileage is at the end of this tank.

[Ristow]

hey,mind the drool....

[addicted]

hey,mind the drool....

What, you don't want it back with rusty throttle linkage?