I'm planning on eventually putting on a 3x2 intake on my 292, so I've been keeping an eye out for them (and carbs). I've done much reading and find alot of bad-mouthing of the Offenhauser tri-power intakes. Anyone have hands on experience with the Offy 3x2?

I understand the Edelbrock 573 and 553 are better, but is the Offy really that bad? Is it only poor for a race set up, but good enough for street use? What's there problem - poor flow at idle, restrictive at the high end, what? I just wonder why there are so many still around if they suck that bad. Are the Fenton or other lesser seen intakes any better?

I guess the real question is:
I'm already asking for trouble tunning 3 carbs, so is getting an Offy going to compound my problems more than what it saves me in effort finding something else?

Don't get me wrong, if I find a decent deal on a Edelbrock, I'll buy it. I just want to know if the warnings about the Offy are really waranted, or if its all garage legend and/or based on racing application.

 

Well, here's my $.02, somewhat based on personal experience.

The current Offy design is designed for the oldest, small port heads. The one I have seen personally was not able to be ported enough to even be close to matching something like an ECZ-G. Depending on what you're doing, this may or may not be an issue for you. I've "heard" (might be some of that garage legend ) that a few people have succeeded in doing this, but I haven't seen it for myself. Maybe this particular design has changed. I seem to recall that there is some other issue...but it escapes me right now. Water passages, or something.

To be kind- most of the Offy multi-carb manifolds, of whatever type, have serious mixture distribution problems. That's being charitable. The newer (relatively speaking, that is) tunnel rams are better. I have worked with 3-4 older non-tunnel ram Offy manifolds over the years, and always ended up welding plenums, adding epoxy, distribution tabs, or whatever to make them work to my satisfaction. That being said- it's quite possible that for a street application, for looks only, on a limited mileage basis, one might be just fine. What generally happens is that one or two cylinders run extremely lean & you have to stagger the jetting excessively to make them live, thereby causing problems with adjoining ones.

Most of their "multi-carb" manifolds were originally designed in the early- mid '60s, before most rodders really cared much about pesky things like mixture distribution. The more carbs, the better, especially considering Strombergs weren't all that big, cfm wise. The later tunnel rams had some thought & theory put into them & many of them work comparatively well.

At any rate, there is an older Offy, no longer in production, that was designed for the later heads. As you mentioned, Fenton & Edmunds intakes are out there as well. Dunno about them specifically, but most of the early ones are bad in the mixture dist. aspect as well (ever seen a Crower U-Fab? A healthy backfire, two "log" plenums fulla vapor, & maybe you get a nice dent or two in your hood for your efforts. ) Still, if you're willing to work at it a bit, I'd bet you can get one of these going just fine for the street, & you can't beat the looks.

 

Thanks Homespun. More like a $1.50 worth of info!

I do have the G heads, was looking or ecz-c heads and wound up with these. So it seems the Offenhausers are out for that fact alone. Although I'd swear I found a post mentioning 2 different size Offy 3x2 intakes, I can't seem to find it again. What I'm getting out of your reply is that the Offenhauser (and other lesser seen intakes) are problematic when it comes to flow. Meaning to me, that getting one of these intakes is asking for alot of frustration and trouble beyond balancing the 3 carbs.

I am assuming your opinion would be to hunt down an Edlebrock 573 or 553 then?

 

Sam,

It may be $1.50 worth, but in Canadian money. Looks pretty, but can ya really use it here??

As to what to get, without knowing you, your carburetion skills, patience level, or masochistic tendencies, I'd say, look for the E-brock. The others will work to a greater or lesser degree, but patience is a necessity, or a willingness to put up with a lot of snottiness (as a friend puts it) from the engine. Myself, I'd use progressive linkage, though others do OK with 1:1, which IMHO is better suited for something a little larger than the average Y.

BTW, I believe the 553 is for the smaller heads from '55-'56, whereas the 573 fits best with the ECZ-Gs. The current Offy is for the tiny '54 heads for the 239 if memory serves. I don't remember the part # for the OOP Offy that fits later heads, & it's been a while since I've seen one. Maybe Carl, Tim, or someone else will chime in here.

 

I have enough patience to wait until I find a 573. Weighing my options, I'm going to go for the Edelbrock and avoid the 'snottiness'. I don't need the extra frustration at this point in my life.

Progressive linkage - definitly. Center main, 2 outer carbs will be secondaries - at least that's my current plan.

I've seen quite a few used Offy intakes on e-bay, but hard to tell the size.

Anyone know if the 553 is alright with the ecz-g heads? I'm not planning on winding this motor up to often, as racing isn't in the plan. Or should I not mess around and just ffocus on the 573?

 

Offenhauser did make a 3x2 for the 272, 292, and 312 engines. Part number 2726 is for the 1954 239 engines. Part number 3199 is for the 1955-1956 Y-blocks. Part number 3199-7 is for 1958-up Y blocks. None of these manifolds are currently in production.

The 3199 with some porting on the inside, specialy around the carb. inlet holes makes it a lot better

 

Hey Arno. Seems you know your parts. Since my last post, I wound up finding a Fenton with 3 good carbs on it (well mostly good) for a bargain price. I'm running it progressive, but still need to iron out some kinks with the motor, but I know it'll do what I want it to.

 

The Offy has at least two problems. First is the fact that it's a 360 degree design; poor performance at low rpms due to plenum volume. Second is the fact that the y-block has stacked ports, not side-by-side ports. Raw fuel gets drawn into the lower ports because of the open plenum design.

From the looks of the manifold, it seems like they had originally attempted to make a 180 degree manifold but later changed the interior port dividers and made a 360. I suspect that they had casting issues that prevented consistent castings.

Your best bet with the Offy is to make sure the exhaust gas crossover is allowed to heat the manifold to help vaporize the fuel.