shiner16

Anyone thought of this yet?

I've always thought the Crossfire TBI manifold (the cross-ram style with the long runners) for the 305's looked sweet, now i find myself wondering what might happen if i tried to put two carbs on in place of the injector units. I'm thinking maybe a 383 or 406 if the intake could be made to flow enough, maybe with (2) 2 brls or ??? I know it would take some extensive re-working of the manifold, but that doesn't scare me. This is just something i have thought about looking into once i get out of school, etc, since i have a 305 TBI laying under a tarp... Feel free to direct me to an old post if there is one archived, i didn't find much myself.

thanks all-
dan

Fast355

iTrader: (2)

The ports in the manifold are way TOO SMALL for even a stock cross-fire 305. It is not a performance intake at all. It would make a good truck intake with its smallish ports. The only cross-fire I have seen that could pull any RPM was put on an old 283.

shiner16

i wondered about that. Any other cross-ram style manifolds that could possibly be had for not so much $$$? tnx-

five7kid

iTrader: (14)

The dual vs. single carb issue has pretty much been settled.

Performance? Single.

Looks? Dual.

Air_Adam

I almost did it about a year ago... I started a few threads on the subject, and there was actually some pretty good info on how to go about doing it.

Concensus was though, that it would look cool, but it'd be more of a 'more-show-than-go' kinda deal.

rx7speed

what about those guys using a IR setup on there cars. they where used in racing applications. seems to be a very common upgrade for older imported cars is to swap out the single and instead put 2 2bbls on the car instead.
and I know I have seen them with 4 2bbls or even sometimes with 6 2bbls

and I swear there are some guys with 2 4bbls on custom made tunnel ram intakes.



or am I Talking about something else here?

1320_Guy

iTrader: (3)

more than one carb isent only for looks, it can be made to produce some nice hp numbers, it is more a matter of weather u need it or not, if your building a mild smallblock and only turning it maby 6500 rpms than there is no way in hell you are goning to need more than one carb, i used to know a guy with an old full body mavric with the 300ci sraight 6 in it, he had 6 single horizontal feed carbs on it, he would launch at 10k and pull the car up on the wheele bars, for a n/a 6 he was in the low 10s

five7kid

iTrader: (14)

Okay, let's step back and look at what's happening here:

First, crossfire manifold. Restrictive, worked okay on the factory set-up, an aftermarket was (may still be) available that helped the crossfire setup work better, especially on larger displacement engines. Converting to a single 600 CFM carb would yield more power (but probably not as clean of exhaust emissions, and probably reduced fuel economy vs. the crossfire).

2nd, dual carbs: On a 305, you've got to be kidding. But, the originator said 383 or 406; okay, get a single 750 CFM carb. Well, assume a track-only car, and just for grins, a big block. Punched out 454; hmmm, a single 850 is still going to be more than adequate. Well, how about a punched and stroked big block, say 540? Okay, get a Dominator.

Well, I really want to go fast, I've got a stripped-down car, running alcohol, over 1000 HP - okay, now you might want dual carbs on a tunnel ram.

In the real world on the street, what I first said still applies.

A crossfire manifold - please...

(Not saying it was a stupid question, I am saying it doesn't make any sense to continue the "debate" about dual or more carbs.)

rx7speed

your buddy was running individual runner setup. that is a whole different ball game then running 2 4bbl carbs

and how the hell is a full body maverick running a straight six going to pull those numbers and those rpms?

rx7speed

speaking of IR setups 57 how much of a difference would a IR setup make on a small block that was already carb equiped?
I know for a lot of the older imports (euro and jap) ppl like to swap to a dual side draft setup. I know I've also seen them on older euro v12's and such.

five7kid

iTrader: (14)

Like the old Weber or Hilborn setups?

Pretty much eclipsed by single 4-bbl technology. Simplicity, primarily. Plenums provide smoother flow through the carb. Injection isn't affected quite as much.

Guss_B

The 4x2 bbls weber IR setups are known to produce huge gains in low speed torque over single shared carbs. They also offer a greater tolerance of long duration cams and tend to give better fuel economy. On the down side top end power tends to be limited to around 450hp with the 48mm carbs cos they just can't flow enough to support more.
Also, if you have the money NOTHING looks better than 4 webers on a IR crossram intake, like this setup from inglese

http://www.inglese.com/pix/IA1245H.jpg

rx7speed

if I had the money i wouldn't mind trying the IR setup on my honda but it's too expensive and requires a head swap so instead it's just a single downdraft weber design that is going on there instead.

never heard of the better gas mileage with a IR setup though.


also out of curiosity why is the crossfire manifold such a crappy design as far as flow goes?
and does anyone have pictures of the crossfire manifold?

F-BIRD'88

The Crossfire manifold has "restricted" ports. it does not flow
well so the high performance potential is limited in stock form.


You would want to use small cfm carbs. 2 2bbls would probabily be best.
U won't make big power with this manifold. The runners are just too small. There is a water passage that runs under the runners across the manifold under side. this water passage restricts the amount of runner porting possible without welding.

Offenhauser makes a dual carbed "Cross Ram" intake simular to the old 1969 302 Z-28 optional cross ram.
You may find one on Ebay.

You may find this link informative. X-RAM

Confuzed1

iTrader: (4)

I dunno. I guess I'll show my age again, but I remember Dodge going with two 4 bbls. - 426 Max Wedge, Hemi....I think Buick even had a Wildcat sporting two carbs....I recall a friend that had one forever ago. They made plenty respectable power...but much better than a single?...? ehhh. dunno

Anyways, I think the idea was better fuel distribution. I've heard somewhere that the cylinder on all 4 corners tend to starve on fuel *run lean) on a single 4 bbl. setup because the runner has to be designed that way, and putting 2 4-bbls. diagonally distributed the fuel more evenly. Then fuel injection came along, which is much more precise of course.

Either way, the cool factor is high....esp. on top of a blower!!

five7kid

iTrader: (14)

The early Z28 302's had a dealer-installed cross ram intake option. It was pretty trick in its day.

Not so trick today.