Offy carb & head Q's

My 68 200 is at the engine builders being cleaned up. I'm planning on zero decking the block, running a 268/274 - 108 cam for some lower end grunt (His recommendation). I already have a 5200 carb but am kicking aound the idea of an offy set up. Here's a loaded question: What carb's would be good to run on this intake (also being relatively easy to find)? I'd need make & model too so that the salvage yard could look them up. Also, is it as important to use a D8 head on a tri-carb set up as it is on a single carb? Would it make that much difference HP & Tq if I stuck with my C8 head and the offy? I have a line on a D8 head but it's a bit of a hike to get and my current head is off a low mileage engine. All of the salvage yards around here are crushing almost anthing that starts with a 19XX...

you can use either head, offy makes adapters for both. however its pretty hard to find the early round-log style, so it may be easier to get a flat top and get the adapter for it. then again making your own is so simple and easy, you could go that route and save a couple hundred bucks. if you want to see mine ill find the link for my old build thread (as long as it wasnt lost).


Weber makes a 34mm 1barrell, the 34ICT/ICH. the ICT has no choke, and they can be bought brand new for $107. the ICH has a choke and is about $150, you dont need a choke on all of them, just the center carb. Parts are everywhere, and jets interchange with other popular weber models (mostly the dgv/dfv iirc) so they will always be available. theyre an extremely simple piece and easy to work with, i have webers on my mustang and my dd toyota and i love it.

http://www.cbperformance.com/catalog.asp?ProductID=502 < source for 34 ICT's

http://www.webercarbsdirect.com < source for ICH's, jets, and everything else.

Thanks '66

I'd like to see your set up. Definately post the link if you can find it. Offy parts lists intakes for both the round and flat top heads. Not much info on their website though.

Anyone else care to chime in? I'm open to learning as much as possible about this before I pull the trigger on which way I'll go...

i think the thread got deleted, theres a link to my cardomain account in my sig, i have pictures of it up there.

http://www.photobucket.com/PatrickL727

The later head has a larger intake track and larger center carb opening along with larger valves. Assuming your D head is in good condition and you have the original valves in your C8 head, the D head will have more power potential as a result. I think the larger valves make the most difference for power, so if you have larger valves already installed in your C head then the difference would be small. If in addition to larger valves, if your C head already has port work done to it, then I'd use that one.

Mounting each type of adapter has it's own issue & needs machining of some type, so from there it's six of 1 half dozen of the other. Just know the log on the C head is not exactly round and the adapter will not fit perfectly (or really even close to it). On mine I had to use epoxy putty to form seats for the adapter to sit on & then a gas resistant sealant to make sure it would seal. The later head requires flat spots to be machined on the log ,as wel as holes, and as a result I think it's easier to get a good seal, but I have no personal experience w/that one.

PM your email to me and I can send some pics as well,
Jay

I have a 66 mustang with a 200 inline 6 with an offy intake. I am running 3 autolite 1100's, but I can not find air cleaners for them.

Thanks for the replies. Keep them coming on what carbs your guys are running! I picked up a D78 head on Friday - now it's time to drop it off at the engine builders and see what he thinks. For carbs, I already have one autolite for a 63. I like the look of Holley's though, especially with the glass bowls. I also have a 5200 that I can direct mount - decisions, decisions...

i run the weber 34 ICH in all three spots. I have not had any problems, they are easy to tune and the jets are readily available.

So when you do the offy tri set up, do you have the change the jets to make it work correctly or is it just an option? if it is a must, what size jets should be used for 3 autolite 1100's and what size for the webers?

that will depend on what else is done to your engine (compression ratio, cam, etc. ), and the environment your going to be running it in. i tried to get a reference chart going a while ago, but it never really got going. i only had a few people send me their specs, and it never got stickied either.

heres the chart though, maybe it will help you:

http://i237.photobucket.com/albums/ff192/patrickL727/jettingchart.jpg