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

[rreed]

I expect to get a timing light after it w/in the next day or two. Having carpet done last week killed any Jeep fiddling time i might have had. I didn't bring my tuning stuff w/ me today, will throw it in the truck tonight.

[rreed]

Threw my cheap-o POS timing light on it under the bright TX sun w/o cleaning up and getting a good mark on the balancer or timing mark. And my '76 timing cover doesn't go past 10 degrees, but as best I can tell w/ my POS timing light under the bright noon TX sun I think by eyeballing it might be around 15 degrees? I dunno, pretty close? I'll probably have to put one of those timing tape thingies around the balancer once I figure out what size it is and where to get it.

If my son doesn't wake up early tomorrow morning like he did this morning I'll try to go out and get the balancer cleaned up and mark the timing mark real good. Let the truck warm up and throw the timing light on it again and see what I get. Until I get one of those timing tapes on it I might just be eyeballing it which I doubt will be accurate at all.

[rreed]

Yesterday at lunch I double-checked the vacuum adavance, it was still off a bit from my previously hasty adjustment. Dialed it in better at 8" to split the difference and it smoothed it out a lot, doesn't buck at clumsy take-offs or gear changes, especially since my clutch pedal is getting jerky from one of the bad Napa heim joints I put in the linkage. Need to fix that, got a lot of things I need to fix... Anyways, this morning I double-checked it again, still backed out fully at 8" so that's good. I'm always amazed how much difference that makes in drivability and behavior when your VA is dialed in. Smoothed it way out and behaves much better!

Had a look at my timing mark, yeah on a good night w/ a good light I probably couldn't have found it. After several engine baths and hosings of carb cleaner around it because of my leaking front seal most of the paint was gone off that area leaving the surrounding area nice and dingy black. Cleaned it up a bit and marked either side real good w/ a silver Sharpie and dragged a black one down the actual mark. I'll try to find a good shade tree and throw the light on it if I can, otherwise I'll still need a timing tape to dial it in past 10*

Hahahaha, did something new w/ it this morning on the way to work. So at around 60 MPH I was coming up close to my off-ramp and had to jump up to get to a clear spot to move over a lane. W/o flooring it, I just pushed into the gas a bit to get up and plenty of room in front of a minivan; HOLY CRAP this thing went NUTS!!! The Edelbrock never did that, but I'm sure my secondaries have never been dialed in well. Anyways, the secondaries on this Holley opened up and the truck just kind of shot out from underneath me, in the blink of an eye I was doing 75 and nearly a**-plowed the poor Honda in front of me!! Man that was amazing, the old farm truck has never done that before!!! Hahaha, I was laughing and giggling like an idiot as I shut her down to make my turn, boy was it hard to keep it under 50 on the slower roads the rest of the way to work. I've got to do that again!

At 60 MPH the Sunpro is showing 2500 RPMs, I simply push into it w/o even flooring it and man does that thing go nuts!!! I'm still chuckling. Yeah, I've got to get the secondaries on my Edelbrock dialed in (if it ever goes back on) to see how it compares when you open up the taps. It was awesome, in a split second I was confused at the front of the truck suddenly lifted and took off like a shot. It wasn't a big jolt, it's still smooth in its acceleration, but it still happened so quickly. That was fun.

Ahem, okay so anyways. One other thing about this Holley vs. my Edelbrock is at speed when I let off the gas it won't fall back on compression nearly as hard as it would w/ the Edelbrock. W/ the E I could take my foot out of it and the truck would slow way down real quick. It does a bit w/ the Holley but not quite as much. Nothing good/bad about it, just a curious observation. I do kind of miss that about the Edelbrock but no big deal.

I don't miss the Edelbrock often needing a push on the gas to start after quick run-ins to the store on a hot day. The Holley just fires w/ the bump of the starter under pretty much any circumstance. I've heard other people indicate the same thing about their Edelbrocks. Your motor is good and hot and you duck into the store and out real quick but you have to crank a bit to get going again or give the pedal a good mash and it'll fire right up. It did that on the SBC in my CJ-5 as well. Doesn't seem to affect the Holley. Must be an Edelbrock thing.

I also don't miss how after getting into the secondaries w/ the Edelbrock the idle will be high until you give the pedal a quick jab to bring it back down. I've heard other people complain about the same w/ them and one old veteran race car mechanic once told me "Yeah, those Edelbrocks do that." I don't know why but it sure was annoying. The Holley doesn't do that.

[Tinkerjeep]

I don't miss the Edelbrock often needing a push on the gas to start after quick run-ins to the store on a hot day. The Holley just fires w/ the bump of the starter under pretty much any circumstance. I've heard other people indicate the same thing about their Edelbrocks. Your motor is good and hot and you duck into the store and out real quick but you have to crank a bit to get going again or give the pedal a good mash and it'll fire right up. It did that on the SBC in my CJ-5 as well. Doesn't seem to affect the Holley. Must be an Edelbrock thing.

I did notice that on the Holleys I used to run...but they all had chokes. not sure if that was why, but they would start easy in heat. But in cold...nope. Edelbrocks all have hot-start issues and cold start too. FI is the way to fix that in my climate...100*F in the summer and dry to -20* in the winter and dry...and everything in between.

I also don't miss how after getting into the secondaries w/ the Edelbrock the idle will be high until you give the pedal a quick jab to bring it back down. I've heard other people complain about the same w/ them and one old veteran race car mechanic once told me "Yeah, those Edelbrocks do that." I don't know why but it sure was annoying. The Holley doesn't do that.

Funny you mention this. My cousin and I both had Holley equipped 401-powerd J20s (he still does) and when we would both go on a dual-J20 gravel road run for 40-60 miles, he would often have that problem with his Holley - when it got run at WOT or near it for a while it would idle way high and not kick down. I think mine would too, but not too sure on that...I haven't run a Holley for about 10 years. We haven't run dual-J20 gravel road runs for at least that long, maybe longer. Course, I don't own a J20 anymore and who has the spare gas at 6-8mpg to blow on a 60 mile trip for no reason. all the gravel roads here are pretty overpopulated now and alot have been paved. Sucks.

Anyway - Both our Holleys were 4-barrels, 4150 I think, single accel-pump, secondary metering blocks, etc. BOTH had electric chokes!

My "Edelbarfs"...all 3 of them...do not do this, but they do not have chokes of any kind. Not sure if its related.

Isn't Empirical evidence neat?

[rreed]

I miss dirt roads. AR > TX. Period.

Anyways, filled up yesterday, and after idling in grid locked traffic for half an hour--no kidding, a dirt hauler semi dumped over at the intersection just ahead, I got some good time in tweaking my radio stations, adjusting my mirrors, and playing w/ my phone while they cleaned up the mess--plus at least a couple good pushes into the pedal during that tank (see my last post), 12.71 MPG.

I'd like to think if I could take it on a road trip (back to AR to visit some dirt roads around the Ozark Nation Forest?) perhaps I might see mileage along the lines of Ristow's results. I think all the sitting and idling in traffic and traffic lights really kills the overall mileage.

While messing w/ the vacuum advance lately I noticed my cap and rotor are looking a little crispy, they've been on for no less than a good 15 or so thousand miles (probably more like 20+). Plugs too, I'm pondering the notion of freshening up plugs/cap/rotor. Plug towers are looking a little rounded, that's usually when I replace them. I hosed the inside out a little w/ carb cleaner and it seemed to smooth my idle out a bit, I've probably got some carbon tracking in there somewhere.

Nothing else new at the moment, it's still a good carb, but I'd like to really get my old Edelbrock more precisely tuned in for a more thorough comparison. At first I didn't think I'd like the vacuum secondaries and high vacuum power valve in this thing but both have grown on me. In the end I think being able to quickly get up to speed and settle into cruise is much better than going light on the pedal to try to save a little gas and slowly getting up to speed. The vacuum secondaries make the real power so much more readily available and you don't have to mash your foot into it. If the engine needs it, it delivers it. I think I'm a convert. I'd still like them to come in just a tad bit later though (it's actually around 1800-1900-ish RPMs and low-ish vacuum after a closer look), and that's as easy as swapping a spring.

One thing that's apparent is that this Holley is no where NEAR as affected by long idles or spirited driving as the Edelbrock. IF I had a string of days where I caught every green light, traffic was light, and I would never so much as get into the power stage let alone the secondaries, I might just barely breach 11 MPG. But that is very rare and few and far between. One single traffic jam where I creep my way to work in stop/go traffic and it's more like 10.75-ish at best. If I have to get into it a time or two on top of that it might drop to mid-high 9's. The Holley doesn't seem to care, so far it's going to be a good 12.something.

[Tinkerjeep]

so in a 360, with a manual tranny you were getting 10-11 city mpg with the Ed 1405? What gear in the diffs? 3.73?

[Ristow]

GO READ THE FIRST POST.

[Tinkerjeep]

GO READ THE FIRST POST.

too lazy.

[Tinkerjeep]

yeah, okay...words words words...4.10.
got it. Um I guess I don't feel so bad now...getting 6,7,8 mpg city/10 highway in a slushboxed, moron-machined, warmed up 401 with 31-33" tires, 3.73s and an EDELBROCK 1405 w/ NO CHOKE!!!!!

[Tinkerjeep]

...and driving like I DO! Those secondaries are there to show 2-barrel guys (rare now) what a 4 barrel, 401 V8 can do.

Chest-beating over.

Okjay. I have a stock Carter AFB from a 343 AMC car. its supposed to be like 460 cfm...(anybody else know the CFM for these?) what do you two Holley guys think about maybe just going smaller CFM, regardless of carb builder?

[rreed]

Your engine is going to digest 401 cubic inches of fuel and air per complete cycle regardless of carb or tuning. I can't imagine comparing mileage to a smaller engine. Too many other factors as well. I would try proper tuning and hope for the best w a larger motor.

Anyways, it's possible this holley may be leaner than my edelbrock as well. My plugs were tan/brown w/ the edelbrock but gray/tan w/ the holley. But i have neither an a/f meter nor a dyno.

W/ my timing mark cleaned up i eyeballed it as best i can tell right.at the spot where 15 degrees would be if it existed on the cover. Timing tape is on its way.

Anyways, all taken into consideration i think we've made our point in this excersise. hopefully i've been pretty descriptive of what i've found. I am going to do a little tuning w the Edelbrock to see if i can get a little better mileage out of it but i'm not expect to see an additional 2 mpg. For performance i'll fiddle w/ springs and secondary jets to further compare performance but w/ the vacuum vs. mechanical secondaries it'll be difficult to be fair. Also i'm not sure if this 4548 is annular boosted, they're supposed to be better performers and mileage at lower revs! Haha

Ristow i'll get this 4548 on its way back, massive thanks for the lend! Are you still interested in sending that sweet 4180?

[Ristow]

the 4548 is straight leg boosters. yeah,lemme get the fresh motor in and i'll dial in the 4180 and let you run it.

[Tinkerjeep]

Your engine is going to digest 401 cubic inches of fuel and air per complete cycle regardless of carb or tuning. I can't imagine comparing mileage to a smaller engine. Too many other factors as well. I would try proper tuning and hope for the best w a larger motor.

Yeah. stupid-simple: at any given RPM, a 401 will ingest more fuel/air than a smaller displacement engine, all else being absolutely exactly the same. Duh. You are missing my point. I'm not saying "I'm better"...I'm saying even with your old setup...it was bad...worse than stock. But you are gaining 2mpg from a simple carb change? from maybe not well-tuned 1405/600cfm to a maybe better tuned Holley 450cfm. Wow.

See, I don't expect 15mpg out of MY set-up. 10 city/ 12 hiway would be nice...those are stock 401 numbers. But I'm not stock.
IIRC - 14-15mpg is what the best case scenario mileage figures were for 360 2V w/ manual 4-speed in the mid-late 1970s.

The 401s generally got 12mpg...best case.

Automatic tranny usually drops mileage, street-performance build drops mileage, operating the secondaries alot drops mileage... and then you got higher elevation (so it runs richer unless re-tuned to run leaner (and then you can get pre-ignition)...So I'm saying I guess I'm not too disappointed in my 7-8mpg in cold weather. but the recent 6mpg concerns me...so I'm asking-


"Would a 460cfm carb help mileage a bit or would it be worth it on my truck, with ME driving it?"...Mike?

[Tinkerjeep]

oooooohhhh....

And lets not forget Volumetric Efficiency...so generally a 360 only breathes 306CI at 85% VE and a 401 really only breathes ...get this...340CI at 85%. that decreases as elevation increases.