Hello hello...

This is my first posting on this website, but I have been reading in for a while now. It seems to me that there are some solid motorheads around here that could easily handle my questions. I apologize in advance for what must be the longest post(or damn close) that any of you have even seen. But as I have seen many times before with forums, the most helpful suggestions are from people who know as much as possible about the details of the particular situation. This should not present a problem for anyone who is kind enough to read this entire thread. And again...thanks for reading!


I am in the process of building up a 1966 AMC classic convertible to be more of a true muscle car. It will be a ground up job. Everything in the driveline either new or rebuilt/modified. I intend to put together a fast CRUISER here. I have a 69 Firebird with a 12.5:1 comp 383 solid lifter chevy with a turbo 350 and a 8 3/4 mopar rear with 3.91's in a posi for scaring the @#&% out of myself around town. But we all know that combo isn't very handy for much else. So here are my plans to date.

Driveline: I have a cast iron case AMC t-85 3spd(what they used to make the t-10 out of) behind a Lakewood scattershield bellhousing and a HD Borg Warner (.7)overdrive "torque tube" tailhousing. Yes...this car believe it or not has a torque tube driveshaft for those who are not familiar with the car. I intend to KEEP the tube, well sort of. That is I will retain the original basic design. The tube itself will be replaced with a slightly larger(in diameter and thickness) main tube and use only the ends of the original tube to weld it to. This is to house a custom driveshaft that requires the slghtly larger inside diameter of the housing tube. The rear axle is a corporate model 20 that will recieve new custom Moser one piece axles and either 3.15 or 2.87 (did I mention CRUISER) gears in a posi unit. The tranny will recieve all the realistic improvements I can have done to it(basic t-10 stuff) and all parts will be rebuilt completely. With the tranny I have the option of using either a 2.99 or 2.49 1st gear along with the 1.85 2nd and 1:1 3rd. I have both sets currently. The rest of the car will recieve some obviously needed structural improvements, better brakes, sway bars, etc, etc.

My questions regard the motors' induction set up. This is what I have to work with engine wise. I intend to run an AMC 401. I have been collecting them. I may very well have my crank offset ground from the original 2.25 rod journal down to 2.00 and use custom chevy rods with a .8 width at the big end to match the AMC width on the crank. With the then 3.908 stroke and my fresh .040 bore this leaves me at 434 cubic inches. This has all been done before(and much more). Point is that I want to have plenty of torque available to pull reasonably well from a stop with say the 2.87 rear gears with a 2.49 first with 26.5in. tires(BFG Radial TA 255/60/15's) I have no intention of ever running slicks(even though I have a nice set in the garage now) drag radials, etc. Since my tranny should be the weakest link, I'd like not to break it(or anything else if I can help it). I'll assume that I will loose traction before I can really harm my tranny with basic radial street tires...So I hope. Regardless, more than 450 lbs. or so of torque would be unnecessary for my needs with this car. I do though want to be able to run around comfortably at 1500 around town and cruise at 75mph at 1800 or so with decent fuel economy(for a 3500lb. convertible with the aero of a blick!). I plan to run this thing for a lot of highway miles. To that end I am interested on using Keith Black 17.3 cc D-cup dished pistons with seriously ported Stock iron 58cc heads hogged out to 63cc's running a tight quench area and a 10 to 10.2:1 final compression for high test pump gas. I intend to use an MSD 6AL box with the matching Blaster coil and either my NOS 1978 and newer type motorcraft type vacuum advance electronic distributor(same a 80's 5.0 mustangs) or a higher end vacuum advance alternative. I intend to run dual 2 1/2in. exhaust behind ported 70's "free flow" type cast iron manifolds. It will also sport a power steering pump and an air conditioning compressor (cruising comfort) There will be oiling improvement modifications, high flow water pump, 4 core radiator, etc, etc.

NOW FOR THE QUESTIONABLE PART:

There are some good intakes out there for me.
- Stock early 70's holley pattern 4bbl iron manifold(have one)
- Edelbrock basic performer(I have two now)
- Edelbrock SP2P (very small passage dual plane that is supposed to be good for torque and mileage, runs out of gas in the 4500rpm or so range on a stock motor)
- Edelbrock torquer
- Edelbrock RPM Air Gap(most obviously a good choice)
- Offy 360 single
- Offy 360 "high rise" dual quad. (about as "high" as an edelbrock air gap manifold)
- etc, etc

I am interested in possibly using the least likely of the bunch for my needs, the dual quad. It is a single plane "high rise" 360 "equaflow" that is set up to be completely separated from side to side. The center divider runs completely front to back in the plenum and up to the carb mount. Though single plane manifolds are known to handle "larger than necessary" carburetors without too much penalty as long as the booster signal is sufficient and so on, using two carbs would require me to use more cfm that my motor would require at a 5500 or so rpm max. I do though have two holley 450 vacuum secondary carbs that one is from the convertible's original 327 high comp motor and the other is from my 66 rebel parts car with the same motor. I have rebuild both down to the throttle shafts, professionally bead blasted, tanked, Holley trick kits, the whole nine yards. It would be hilarious(if only to me)to be able to say that I am running "correct carbs" on the car. It would sure keep a few people scratching their heads!

So to the smart ones out there.

Are a pair or 450 vacv secondary holleys too much for a 10:1 compression AMC 409 to 434 cubic inch motor that is not intended to spin past 5500 or so? (some recommend up to 600's, some say 390's)
If they'll work OK, how much of a cruising speed gas mileage penalty should I have to suck up for the privelage of running what amounts to an overcomplicated, unnecessary, inefficient, and at least mildly power robbing visual(and humor) statement.
Should the primaries be hooked in tandem or a progressive set up like edelbrocks adjustable progressive linkage.
How much low rpm grunt can this manifold really deal with. Being that it has the shortest runners possible on a v-8 motor...not the main ingredient for low rpm intake velocity for sure.
Obviously the larger displacement of the motor compared to the modest sized small blocks helps make up for some of the manifolds' shortcommings, but is there going to be a HUGE big difference if I stick with the 409 size instead of stroking to 434.
Offenhouser tech department suggested only that I not use a cam with less than a 218 duration, and other that saying that "it'll work just fine", he was not interested in going much beyond that. Any cam suggestions? I'd like not to go much beyond .5 lift and 5500rpm or so in revs. I want to keep the power in the lower rpm ranges.

If any of you are still awake...THANKS!!

ANY thoughts would be greatly appreciated! And I'll try to keep my posts short from now on.

George