well, I'm done friggin' around with the stock 2v on my 390.

I've had it rebuilt, changed power valves, and tried to run a phenolic spacer under it... basically, I've spent nearly enough to purchase a new Holley, and it still doesn't act right... so...

I cannot justify time or money to go 4v... even tho I know that is the proper thing to do.

I believe my motor is choked with the stocker, and, I have a part throttle detonation issue that depending on who I talk to, says it's either a jet/lean situation, or, too much mechanical advance...
Regardless, I'm getting rid of this stock carb. I believe it's just plain wore out.

So, as near as I can tell, there is a 350cfm Holley, a 500cfm Holley that is advertised as for off road only... or get ahold of a remanufactured stocker.

So.
The truck is a 2wd long bed 250.
Used primarly for daily driver, but, is about to start hauling gravel/topsoil and trees/shrubs.
In about a year, she'll be a w/e race car hauler... seeing freeway speeds in the 65-70mph range.

The 390 is bore'd 0.060 over.
Fully balanced rotating assembly.
Large port heads, cobra jet valves, crane 268 cam(whatever that is)
It's got deep gears, never checked, but they've got to be 4.10's or deeper. 50mph sounds well over 2500rpm, and 65mph sounds well on the high side of 3000rpm... would not be suprised if it was up over 3500.
It'll have 1-3/4 headers before the end of the month, and has single 3" exhaust out behind the passengers side rear tire.

It's not meant to be a race truck.
It's just meant to make good low end tq to tow the car, and hopefully get better than my current 10.5mpg.

Given all that, what are your fella's thoughts on proper carb?
I'm leaning away from the remanufactured stock carb... based solely on adjustability...

 

Reman. carbs are not high on my list, and others will say so also. They seem to have more GREMLINS than your old one. Not to say you CAN'T get a good one, but seems they are more trouble than worth.

I went thru the same crap you did with getting the std 2 bbl to run properly. I ditched it in favor of a new 750 vacuum secondary Holley I had laying around. I bought one of those 4bbl to 2 bbl adapters and mounted it upside down to put a 4bbl on a 2bbl intake. Bolted it on, runs smooth, idles perfect and this is a stock 352(put some cheap headers on it).

If you want to stay with 2bbl, then get the 500 cfm. The 350 cfm is too small for any power. It may be more responsive due to smaller venturi's, but upper end power will be bad, especially with your gears.

Just a note, I have 3.25's in my '67 and it cruises 3000 rpm at 70 mph. Even with 750 Holley, I can get 11+ mpg if I stay sane with driving. Not that it's a powerhouse, but I tend to want to stay with traffic.

Larry

 

ok, thanks, that is along the lines of what I was thinking, but, nice to hear it from someone with experience.

I remember reading somewhere that the Holley 500cfm 2bbl comes with #72 jets... sounds a little generous... Thoughts?

I'm not sure a 4bbl fits my budget... hmmm... where do you get those spacers?
What are your thoughts on the 500cfm E-Brock 4bbl? I hear E-brock carbs are litterally bolt on and go... virtually no tuning required... an no power vlave to blow out.

My truck is no powerhouse either. I believe the cam is all wrong, and that the cylinders are not getting anywhere near filled.
I let the mechanic select the cam... I'll never do that again. Not that I would know what to look at, but there are are some good cam designers out there, and that would have been a much smarter route. /Grumble Grumble...

Thanks for the info.

 

Go with the Holley 500 2 bbl. I've had two of them on 4 different motors and they both worked on all, without fiddling with either. This includes a stock 302, GT 390 ( as the middle carb of a 3x2 setup), a 400, and the 390 that came with my 68 Merc.

 

The adaptor is made by a company called Transdapt. Go to www.summitracing.com and look for part number trd-2065. It's $15.
You can get a new Holley 500 2 barrel from them for $220, or for 5 bucks more you can get a new 500cfm 4 barrel Edelbrock Performer.
I don't think a Crane 268 is a particularly "hot" cam. I can't find exact specs but a 268 duration cam is usually pretty mild.

 

The E-brock is that cheap eh?
hmmmmm....

From what little I know/theroize... a 4bbl should be easier on gas... ?
And I read someplace on this site, that 500cfm 2bbl, is significantly less cfm than a 500cfm 4bbl... something about hg measured or something...

268, Ya, I was not looking for a wild cam, just something that worked from 1000 thru 3500... instead I got a cam that doesn't make any grunt anywhere. I'd be better off with a stock cam, which I suggested several times, but... too late now I guess...

 

That 268 should be a very good cam for your combo, quite honestly. If you want low rpm power, it sounds about right, although as I said, I can't find exact specs on it.
A 4 barrel of a certain cfm will flow more than the equivalent 2 barrel because as you suspect, they're measured at a different vacuum level.
Mileage? Probably the Holley, but not by much, and you lose more than a few ponies.
Lots of 390's came with 2 bbl's, and they seem to run fine.

A Maritimer, eh? Guess you went on down the road to Toronto and kept on going!

 

If all he's looking for is low rpm pulling power, then the Holley 500 is all he needs. Damn sure cheaper and less hassle than buying an intake and carb, and swapping the intake. Only mod he'll need to make is a minor fuel line re-routing.

 

The 268 cam is dern near a factory replacement type, I think they also offer a 252 which is stock(for the most part). My stocker does not pull anything above 3000 rpm. No way, no how. Useless and only just trying to blow it up when up there.

I'm not big on Carter/Ebok type carbs. Not sure if they are a "bolt-on". It will run, just like my 750 Holley does. I know it's way too much, but it does fine for my daily driving. Performance is not an issue. I was going to put a 500 Holley on it, but I had this carb and got the spacer for $10 at a swap meet last fall. I used what I had.

If looking to buy a carb, I would stick with 500 Holley...but thats ME. It will bolt on and a simple fuel line alteration to hook up. If looking down the road,you want a 4bbl, then get the 600 Holley and find yourself a Performer intake for it later. There again, just my choices.

ALL my vehicles have TWO Holleys on them(except 352). I like them. Guess I'm biased.

Larry

 

ok.
thanks guys, I think I'll go with the 500cfm Holley 2bbl.
thanks to all for the discussion.

Ha!
Naw, 'Torona' was never part of the plan.
Had a firm down here recruit me... made it easy... now it's hard to get back... and no job to get back to... whatever...

 

I bought a reman. Runs worse than the temporary carb I pulled off my old fairlane which had been sitting for 9 years.... Not to impressed, 90 day warranty so I'm taking them back till I get a good one. MInd you they're not all bad I got a reman 4v for my 64 all I did was adjust the choke plate+idle and I haven't touched it in over a year now.

I see what you mean by "no power", with this reman 2v I had to downshift into 2nd gear to make it up mildly steep hills when I'd usually be at light throttle in 3rd.... The last time the truck moved (2days ago) it barely had enough grunt to spin the tires in reverse if the engine was under 2000rpm.

 

This statement is wrong. A 500 cfm Holley 2 bbl flows the same as a 490 cfm ( closest 4 bbl Holley in cfms to the 2 bbl) Holley 4 bbl. If you think otherwise, then you've bought into an incorrect theory going around the internet. If you still believe this, just ask Holley, they'll tell you all Holleys are wet tested for flow ratings the same way.

 

The 490 4bbl has four small holes to equal out to the two bigger holes in a 500 2bbl.

The flow is rated the same, just different number of venturi's.

Larry

 

Ok...
The Holley 2100 500cfm 2bbl is a direct bolt on. Powervalve... do they have blowout protection on these guys?

Both E-Brock and Holley 4bbls are advertised as either no power valve to blow out, or, blowout protection...

Holley 4bbls, have recommended tuning, and jet kits, where the Holley 500 2bbl has no recommended parts...

Does the 2bbl have 'kits' avaible to get it dialed in? Jets metering rods whatever? I really don't want to spend $220 on a new 2bbl only to -not be able to- tune out my part throttle, and tip in issues...

Freightrain,
What do you dislike about the E-brock style carbs? Or, maybe a better question is, what makes Holley's better in your experience?

 

You won't need all the extra "stuff" to tune it. Just bolt it on, set the idle speed and mixture, maybe the accellerator pump cam to arm clearance, and it's ready to go. A new 500 will also have the power valve protection, not that it's needed though, I've never blown one, and been running them for thirty years.