I'd like to put on a 2/4 set up but I'm not sure if I'm going to be able to burn all that fuel. I'll be running a 400(.30 over), 16 heads(ported to flow around 230cfm), cam is a 230/230 dur. w/120deg.LS, around 9.7CR, stock crank, 1.65 roller rockers, Bal and BP'ed, and Long branch HO manifolds. Nothing too fancy but I don't know if it's enough to handle all that fuel that dual quads can deliver. Looking for opinions.
I use a dual 450 CFM set up on my GTO with a 455. My 455 has roughly the same charcteristics as the motor you describe, except I run headers and a little more cam (solid lifter) along with a gear drive and some additional cam advance.
I will run an identical set-up on my 428 which will have a smilar combo, but with long-branch manifolds, hydraulic cam (about like yours) and 4 degreees advance.
I use an Offy 360 dual quad with two holley 9776 450 CFM carbs. These are manual secondary, but with no secondary metering block. So, they are not double-pumpers, but they are also not vacuum secondary. They are almost square-bore. The primaries are slightly smaller than the secondaries. It is an awesome combination. Tuning is a bit tedious, but once you nail it ... wow.
Come by some time and take a ride. I promise you will be happy with the results. Ask Brett ... and Bjorn - but don't ask Bjorn about gas mileage!
Thanks for the advice. I found a dual quad setup in Reno at the swap meet. It was already fitted with carbs but I couldn't tell what size they were. Used, $400. Real nice shape tho. I really like the look of the 2/4 setup. What do you do about the air filter? How's it sound for price?
$400 is not bad for a complete set up, depending on the condition of the carbs. If they are complete and rebuildable, that's a decent price. Did it include linkage?
For air cleaners, there are two or three choices. First is to run two small individual air cleaners. Second would be to use an adjustable-center dual quad unit, which would come from PAW or Summit or someone like that. Third choice would be to try to find an original air cleaner from some stock dual quad application - of which there were many - and hope that the center spacing is right. If you got the Offy 360 Dual Quad manifold, I think the spacing is 9 inches center-to-center. I can measure one of mine to be sure (if it's important).
E-Mail me at: Quenton@celesco.com and I can send you a picture of mine.
Yeah sounds like Q is the guy. The Linkage was on and still hooked up. The only downside that I could see was someone had epoxy'd in the water pump hole in front. Easy enough to fix. The guy said he figured someone wanted to run some other kind of water pump. Curious... I wonder why? :p Oh and my baby went to the body shop this morning to get the rear panel welded in. $300 later it's done. She comes home tomorrow. Body shop guy says I got rust. OH NOOOOOOO....... Robert
You can cut off the water cross-over and use another one from a mangled manifold. Or, you can try to have the epoxy machined out. It's not all that hard to have done. Is it the Offy manifold?
I think it was an offy and the carbs looked like about 450s just from the outside size. I talked to the body shop guy while I was waiting for the tow truck yesterday and he used to have a 2/4 on his goat. He said it ran about the same as his 850 holley until it got to 100+ then you could start to tell the difference. He also said it really sucked the gas( yeah what ever). But they look so cooooooool. Easy enough to drill out the water passage. Not a prob. Brought baby home after surgery. The panel came out SWEET. Looks like it's always been there. I have to replace the little rivets that hold the molding clips. Going to take guts to drill hole into a brand new panel with no holes in it. After all that's why I replaced it in the first place. Thinking about just glueing it on. Robert
The Offy can be identified in two ways: 1) There is a "360*) marking on each side of the exhaust cross-over. 2) The part number 2159 with a casting date in on the underside. (I think that's the right number ... I machined mine off, so I am going from memory.)
As for how it feels compared to an 850, a lot of folks will tell you that a well set-up 4 Bbl runs better, but the 60 to 120 time is about the same as the zero to 60 time! It's a blast to listen to, too. As for mileage, that's not really why you own a firebird, is it?
I thought I was going to be able to pick it up today at the Good guys show but they had the lot tore up at the fairgrounds so they didn't have the swap meet.Bummer. I'm not sure but I might run in to clearance problems with it because the aluminum solid body bushings dropped the body over the frame some and they warned me about possible conflict with the hood closing with the stock air cleaner but I figured they just tell everybody that by way of a disclaimer. Probably worse with 2-4s tho. Really don't want to run without a hood all the time. And no mileage is not really the main object here. Robert
Offy made two versions ... actually, four ... of their dual-quad manifold. One is about 1-1/2 inches taller than the other. I've only seen the taller version. The short version seems to have gone away years ago. I machined off about 1-1/4 inches from mine to make them look better (which they do) and perform better at lower RPM (which they also do). Mine fits under the hood with 2-1/2" tall air cleaners because of this, but the carbs need to have their linkage cut down a little where they interfere. If you get the tall version, and you want it cut down, it's an easy thing to have done.
Thanks Q. I'm going to wait on the set-up awhile. At least until I get the paint on and the car back on the road but it's something that's in the future. Just started a new project and haven't even finished the last one yet. Couldn't find a 68 bird cheap enough to build up with my son so I picked up a T-bucket frame and a Jag rear end yesterday. I may be selling all my excess bird stuff to finance this one.
Yeah it'll be a poncho motor, mostly because I already got one and this'll be kind of a budget build just for kicks. Mostly putting it together with my son so he learns something about cars(my part) and so he can impress the chicks at school(his part). Gotta buy a mig welder to do some fabrication(my part).
Hmmm... how do you "suddenly" have an extra Dual Quad Set-up? Lol... I like the way that sounds, and just want to try to replicate your actions that "caused" this unusual situation...
Then I'll try it with little parts, and work my way up to a whole "extra" Firebird!
My intake is matched to a set of heads I no longer use. The ports on the new heads are slighly smaller than the old ones, so there is a step where they come together. Rather than grind away a set of perfectly good heads, I decided to pick up another complete 2x4 set-up and re-do the ports to match with the new heads. That leaves me with an extra complete set up. If I ever use the heads again, I will need a large plenum single plane maifold, so the 2x4 is extra...
Although ... I am seriously thinking of two face-to face Q-Jets, though ... so if Bob does not want it, I may do a whole lotta work on it.
Q. You're making my blood run a little faster. I really want a 2/4 but I gotta get it back on the road first. It shouldn't take too much longer. It gets some color on the jams tomorrow, then the fenders go back on, then the rest of the color goes on, interior goes back in.....yada yada yada. Couple of weeks hopefully. Maybe you'll still have it when I'm ready.
It's not going anywhere, and at the moment isn't taking up any valuable space, so ... the one caveat is that you'll have to use a set of heads ported to match Ram Air IV intake ports. Darn.
That'll work out because the 16s going on will be ported out to flow about 235 cfm if the numbers work out like Pete McCarthey says they will. What's the port size of the ram4s? I found a gasket set that listed ports as 1.18x2.20. That sound right?
Yes ... that sounds right. I think the stock ports are 2.05 tall. The intake was gasket matched to the ported heads using Ram Air IV gaskets. Should be a straight fit.
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