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

[rreed]

Oh I think it's pulling off too far, not really "choking." I'd have a closer look at it but probably won't bother, I'll just keep complaining. I don't think it's the rich/lean turning of the choke cap, I can dial it all the way rich but all that does is keep the idle speed up longer. I still have to feather the clutch until it smokes w/ the engine rapped up to a zillion RPMs and hope no one's coming when I pull out onto the road when it coughs and sputters and falls on its face and nearly dies. It's just irritating.

I forgot to bring my notepad in w/ me but the fill up on the way home suggests 12.something MPG out of this first tank. Please note I was still adjusting the so-called choke (one day had it turned way up leaving the high-idle on much longer and keep having to work the gas pedal to keep it from dying when taking off) and will admit I did rap this thing up to 5,000 I think for the first time since I've owned it when I got stuck at work until the cleaning crew started running vacuums and emptying trash cans the other day. It got a little abused coming on the way home when I was cranky. Flogging on it just once w/ the Edelbrock will indeed bring the average of an entire tank down a good 1-2 MPG average. I drove like an a-hole pretty much all the way home. Nice to know this Holley can lay a good black mark though, that was impressive! Poor truck, I'm sorry. Anyways, even w/ a little abuse it still got 2+ MPG gallon over driving the Edelbrock like an angel!!

I was also still driving to the Edelbrock which this Holley doesn't really need. This tank I'm driving as miserly as I can and avoid all temptations to be stupid. Shift points are being kept low, unnecessary down-shifting kept to a minimum, I'm keeping one eye glued to the vacuum gauge to keep it above 8-ish inches of vacuum, etc. I'm going to see what kind of mileage I can really get out of it.

Sorry updates aren't timely or exciting at the moment, we're gearing up to put our new youngan in day care tomorrow while his Momma goes back to work so time and attention is a little focused on that right now.

[Ristow]

it's isn't that fussy on mine. just bogs a bit for the first few minutes of running,maybe a buck here and there when letting the clutch out.

that stock intake and adapter aren't helping,kind of a lousy intake tract.

[COLOFIREMAN]

Following this one!

[rreed]

10-4 on that Ristow, one of these days a better intake is on my list of upgrades. One fine day.

189.8 miles to the tune of 15.46 gallons equals 12.28 MPG driving like I was. Not a bad improvement over the Edelbrock's 10.5-ish on a normal day. I'm misering it now and Ristow pointed out some possible timing discrepancies I might have so will do some timing fiddling at the next tank. I expect better numbers to start showing up w/ an adjustment to driving and perhaps timing.

I will also point out this is odometer miles. The speed-o is accurate (according to GPS and those radar signs the cops put up outside neighborhoods to tell you to slow down) so there's that but soon as I can I'll compare the odometer to maps and GPS to test for distance accuracy. I've always gone by the odometer just for point of reference.

I installed my 4" springs and larger secondary jets in the Edelbrock while it's out and on the bench. Hopefully that might give a slightly better performance comparison, regardless once it goes back on I think I'll take the time to get it more finely tuned. It was pretty close as-is but the secondaries needed some work and I didn't feel its 5" power mode was necessary for empty driving.

[rreed]

Some interesting reading regarding annular vs. dog-leg(?, down-leg?) boosters, plus a little appetizer about venturis in general: http://www.carcraft.com/techarticles...n/viewall.html

And pics! To show the difference in the fuel droplets (I kinda figured as much after going through my Edelbrock the other day and noticing its "normal" boosters were just a tube w/ a big hole in the bottom of it. http://forum.grumpysperformance.com/...p=15353#p15353

I found some other graphic cutaway of annular boosters the other day but lost it. In regards to the above, it already did make sense to me how several smaller horizontal holes (Holley annulars) would shear fuel into finer "atoms" as the air rushed by much better than just a big tube w/ a single large hole in the bottom of it (Edelbrock primaries) or just cut off at the end (secondaries) to dribble larger globules of fuel.

I wonder if the annulars being larger and hogging up more of the venturi space is why the larger 4180 still does as well on mileage while improving on power? People keep indicating you can run a larger CFM annular carb than a smaller CFM down leg carb and get away w/ it.

Ah, and another graphic of different booster types: http://www.popularhotrodding.com/tec.../photo_05.html

High of 91 tomorrow, we'll see how it does w/ the A/C on. I could have used it today but was already committed to the windows down once I hit the road and couldn't lean over to roll up the passenger side window in heavy traffic.

[Ristow]

the 850 annular pretty much mirrored the 650 straight leg up to 4000 rpm,then walked away.

http://www.popularhotrodding.com/tech/0511phr_carburetor_boosters_tech/photo_08.html

annulars are king on the street.

[rreed]

So ristow, for my application should i choose a 4548 or 4180? I will say that while this holley does feel more reserved and refined i do actually miss the spry jumpiness of the Edelbrock. Would a 4180 bring that back that quick and snappy resposiveness and keep the low to midrange torque of the smaller 4548?

Working from home today and tomorrow but need to fill up next time on the way to work. Looking forward to mileage numbers.

[Ristow]

maybe. i think the bigger issue is the holley is leaner on the mains than your edelbrock. that would explain why it's fussier when cold. a 1-2 size jump up on the mains would likely liven it up,but there's a cost associated with it obviously.

i have everything i need to put a 4180 together. want to run it?

[rreed]

Maybe, can you have it here tomorrow? There is one of each on the 'Bay right now--both w/ manual choke hahahaha--so I'm really torn and itching to pick one up. The wife is even on board.

That's the funny thing to me about the Edelbrock vs. Holley, is that it seems you can get so much granular and precise about tuning w/ the Holleys. Someone might correct me though. W/ my Edelbrock it was running lean when I first put it on the truck (overheating at highway speed, white/ashen plugs). According to their tuning chart I needed to go one stage richer which was a different set of rods. Did so and it's been fine since. Tan/brown plugs. Done, according to Edelbrock's tuning manual.

Your Holley as-is runs fine at speed and the plugs are gray/tan which I understand to be slightly leaner than my Edelbrock and good and healthy at that. Can you do some horse trading w/ jets and rods w/ the Edelbrock and get the same results? Probably, maybe, but I would think you'd have to be a seasoned Edelbrock guru. If w/ the Holley all you have to do is trade out for some slightly larger jets and try again, that sounds a whole lot quicker and easier for the average joe.

I'd love to try the 4180 but the auction on those two 4548 and 4180 end in a couple days. So um, yeah sure I'll run it! If the 4548 generally gets better mileage than a 4180 then I would gladly run it. As far as I can tell the truck still does what I need it to do just fine and if it can do its job--at a few MPG better--while sacrificing a little enthusiasm at throttle response, fine so be it. I'd still pick an old beat-up Holley over an Edelbrock anyways.

[Ristow]

there is no shortage of 4180's. or 4548's for that matter. no need to jump on either one,there will always be another.

i'll look at what the stock 4548 jetting is when i get home. if i have jets in 1 or 2 sizes richer i'll mail them to you.

there is the possibility it is too lean. i had it on a junk motor,i may not have noticed the problems due to the issues of that motor.


i'll have a 4180 ready here in a week or so.

[ballen0352]

So it looks like the Holley is winning

[Ristow]

i'll send you this one after i dial it in.







new Quick Fuel fully bush'd hi-flow shafts.4 corner idle. converted to 4150 style. idle jets and pvrc's re jetted.

used Eastwoods Carburetor paint. not impressed.

this one will be for sale,but don't feel like you have to buy it. run it against that 450 a while.

[rreed]

What do you want for it?

[rreed]

That's purdy. So for the Holley layman, what does all that stuff mean? I see things about "upgrading" to 4150-style this and that in the Summit catalog while sitting on the throne, sounds important but what does it all mean?

Latest mileage numbers from three tanks through this Holley 4548 so far are:
12.28 (farting around, initial dial-in, and flogging on it a bit)
12.40 (trying to miser a bit)
12.37 (misering didn't go quite as well)

We had new carpet/tile laid in our house last week so was rather busy w/ that and couldn't get to tweaking my timing. Ristow indicates it might be a contributing factor. Going to try to fiddle w/ my timing this week as things settle down. Another factor in my mind is my driving is probably 50% highway, 50% city stop lights, stop signs, etc. plus at least one day a week I spend as much time "driving" to work w/ my foot on the brake as much as the gas when this north Dallass traffic slows to a crawl or stop. I do spend a fair amount of time sitting and idling.

Ristow, don't you drive down two country roads w/ little or now stop lights or traffic?

I'd like to blame the high vacuum 8.5 or 7.5 power valve in it that drives me nuts to try to stay out of but I realize that's probably just excuses and my ignorance. At the end of three tanks so far (just filled up again this morning), I still had to drive the Edelbrock like a saint and hope for NO traffic jams to barely get 11 MPG. I can just drive the Holley whether I miser it or not (trying to stay >10" of vacuum to keep out of the power stage but as indicated could be a complete waste of my time when it comes to misering for mileage) it still gets 2 more MPG better than the Edelbrock. Is it more powerful overall? I dunno, I haven't calibrated my butt dyno in a while. Does it move the torque/power band down lower? Yes but it's also got a much higher power valve and those vacuum secondaries. I presume that makes a difference? Oh, and the boosters are different, it's 450 CFM vs. 600, blahblahblah...

We also consider this Holley might be jetted lean vs. my Edelbrock maybe on the rich side. But I went by Edlebrock's tuning chart to go one stage richer to solve its original lean condition w/ a simple change of rods. Can I dial the Edelbrock back a little lean but not too lean w/ some swapping around of rods and jets? Sure, maybe? But someone might verify that the Holleys are much easier to fine tune. That's my impression, I'd love to find the Ristow of Edelbrocks one day.

I agree w/ Ristow that I'd like a step later spring on the secondaries in this one. They seem to come in at some combination of around 4"-6"-ish of vacuum and around was it 2400-ish RPMs? Seems like that's when I hear it start growling. Give or take. If it were me I'd like for them to come in a little later and/or w/ a little more load on the engine.

Better get to work, more later. On another thread a guy who might know Edelbrocks a bit indicated he went the other way w/ jetting and enrichment springs in his, he went high on his springs and lean in the jets. I've got the spring kit for mine and my original "lean" stock rods so I might try that tack and see what results I get w/ my Edelbrock when we're done experimenting w/ Holleys. That's if I don't just leave a Holley on and sell my Edelbrock. Haha

[Ristow]

did you verify the timing yet?

i run all 2 lane hiways and backroads. handful of stop signs,and speed zones. 50-60 mph on the hiway.

4150 conversion allows using main jets for quick cheap jetting changes,in place of the metering plate with the idle and main orifices that need to be changed out entirely for a jetting change.