Lt me clarify one thing, the above math is correct for calculating your CFM, but where they show engine cubic inches it is misleading because what they show is 720degrees of crank rotation, to figure your CFM you want 360degress (1 rotation) since you feed only 4 cylinders per revolution. I have all of Szabos' books and he is quite clear that you need to base all your calculations on 1 revolution, ie a 350ci motor is 175ci when you do the math. The concept is simple, you calculate cubic feet of air per revolution (then convert to pounds to calculate how much fuel you'll need) and to get CFM multiply it by whatever RPM you'll run at. btw, the numbers will be very small.
I know there is more technical math for sufficient power & fueling @ the level of tunning you are @ , including your leave of tunning over me, we know It can be leaned. The information I posted is just for beginner average person installing a blower /supercharger force induction.. We both know there is more involved. You can explain way better than I can, The average person calls up & purchase a bolt on Kit is not going to get all the Information as you mention, I am not claiming I know all thats in Szabos book's , I know if I need a better under standing or direction Bob is a phone call away
Pruning is primarily done for clearance, but sometime done for a cleaner look. On a flathead, the mounting flange would collide with the radiator hoses. I recently pruned a 4-71 that went on top of a Dodge 270 Red Ram Hemi. That one was for looks. It cleared just fine. In the context of the vehicle that it went on, it just appeared to be too much m*** on top of the engine. It was purely an aesthetic choice. It looked too bulky. I am currently doing up another Dodge 270 Red Ram Hemi, that also has a 4-71. This one is in a full-bodied vehicle, with fenders. In this case, since there is "more vehicle" surrounding the engine, it has a better visual balance.
Cleaner look definitely. Less strong? I doubt it. 6 bolts instead of 4. Intake is Navarro from the Mikes at H&H. On an 8BA (Any 49 and up FH) you could run one not pruned as the T-stat housings are ahead of the blower case. On an earlier FH it can get tight in the center.
Sorry, not my intention to be critical of your post and we really aren't tuning here anyway, just working out the CFM. You are right, Bob or his daughter are very approachable and have the gift of explaining things in a way that we all lack.
@oj No problem , most hear maybe do not know how knowledgeable you are & what you are into / do ,, My self trying to explain things is difficult for most to understand unless you have my personal Cryptid decoder ring
Hey OJ! Great to see u in my thread haha. You just welded my radiator tabs last week! I also got one of your rebuilt 94 carbs… You work on superchargers too? I got this 471 blower and will most likely need a ton of help to set it up! Would love to pick your mind! Here’s my little truck! Just finished ***embling grill and hood thanks to u!
Ah, yes! My mind is similar to the local dump: very well picked over, but I'll be happy to help if I can.
I was pondering that '3456' theorem in the calculations and it occured to me that it is actually 1728 (the amount of cubic inches in a cubic foot) X 2 - so the calculations provided by 19Eddy30 would work fine, the answer would be the same, just a different way of getting there, my bad.
So i got the blower delivered… spins easy but the guy i got it from said its got new rotors new bearings seals and gasketsand that it will need to be timed. Its missing the rear and front plates and I’ll need a top plate for my dual 94s.(I may do 3 holley 94s). Here’s what I’m thinking so far… i found most things available from mooneyham website and the carb adapter from ebay I think these are very standard parts but I’m not very well versed. Anything jumps out or things I’m missing or should think ahead of? I still don’t know about the snout.. also found munro intake available from $800 and my engine won’t require the blower to be pruned so it should be an easy bolt on
Another option on the blower manifold (if you want a trimmed case) is to buy the one from H&H - it has two pop-off valves (which is a good idea). Personally, I like a pruned case - just looks better on a flathead and makes it easier to run center water outlet heads. On the upper carb manifold, you might see what Nystrom Performance is cooking up. He is making a 3-carb cast manifold that looks pretty cool.
I do like that look better but i don’t understand how it attaches. When you prune the blower you get rid of the screw holes no?
You drill and tap the bottom of the blower. The bolts go through the manifold flange, into those new holes. This is one of my manifolds. You can see the socket head cap screws.
@Ed95 Timed ? & spin's freely . Sounds timed now .. If you R& R rotors mark left & right . With end plate on case make also . Timing is done on gears , Some have shims under gears to bearing or you take material off the snout to bearing the faces the rotors. Then you check Rotor to case . Need long feeler gages like 10-16 inch long . Do you know when punned mount you need to pull one of end plates off with rotors to attach or remove from intake . Mounting bolts in side case & care in torque , on outer Flang mount case Bolts are torqued 7/16 to 10-12 ft pounds , on a flat surface. If not flat & even torqued rotors will / can scrub . @gimpyshotrods what's the torque when Punned mounted & bolt size?
I would think they are on the perimeter of the opening - just like the top and you'd bolt through the manifold flange into the drilled/tapped areas of the 6 or so perimeter locations. Essentially, the bottom would be very similar to the top, except for maybe 2 more bolt locations.
But co**** deeper threads. No engineer , just off top of head Wonder if .250 of fine tread equals .125 of co**** thread because of deeper Engagement ? It you tap something when to know use Co**** or fine ? Like .500 of threads in 7/16 to 1/4 hole size . Is there a rule of thumb ?
So i can prune this thing (i like that look better) but need to drill holes to attach studs? Or do i drill thru the blower and do bolts from inside to outside? Doesn’t that mess with boost? Or let air out or anything like that?
Picture of thr bottom side of what I did. I used 6 5/16 studs. They do not go through into the rotors. Manifold has a flange the studs go through.
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