Hey everyone,
Im new to the site.
I built myself a 350...Bored. 30 over and decked,strong bottom end,kb piston,new rods with arp studs,camel hump heads (plained,ported,polished),bigger valves,comp cam valve springs,soild melling .520/.520 cam, jr victor intake , Mallory distributor,headman headers, 4500 stall with 4.11s. What do you think would be a good Carb for my application? Thanks

 

I would use a 650 or 750 double pumper. I also would bet that an Air Gap would run quicker than the victor jr. I have a 350, and the short runner manifold just kills the bottom end. I went quicker with the air gap (compared to a miniram) . Might be worth a try if you can borrow one (and a carb) to experiment with.

 

okay thank you... vac. or mechanical secondaries?

 

Sounds like a pretty serious motor...not a daily driver. I would definitely go mechanical.

 

okay thanks a lot..I am trying to figure out a safe max rpm what do you think is safe ?

 

Carb CFM = (Max RPM x C.I.D.) / 3456

If you wanna get really accurate multiply the CFM you get from that formula by your volumetric efficiency. Usually 85% for a stock street car, 90% for a high performance application, and 100-110% for a power adder.

Bet the math suggests a smaller carb than you thought you needed.

 

Piston speed is the determining factor in safe RPM. For cast rotating assemblies 3500 fpm, for forged your good to 4000.

Piston Speed = (Stroke x RPM) / 6

 

ok thanks everyone!

 

Oh crap...I have been pulling 4100fpm with my cast crank, rods and pistons for years!

 

I'm going to show my idiocy here and ask - what is "fpm"?

 

FPM is feet per minute

 

I do agree with ian1320...better to be safe than sorry. Not every cast bottom end will live. I have been very lucky. My next motor will get a few forged pieces for sure.

 

He asked for safe RPM.

Sure you can exceed the limit but for how long? Is it worth the risk? If you have a couple years on an abused engine then consider yourself lucky imo.

 

I was thinking between 6200-6500 rpm in a safe range ?

 

I think that cam in a 350 is going to definitely want to rev that high. You may shift at 6400 (and actually peak at 6800) to get your best times. I had that cam in a 406 and shifted at 6200 or so to get my best times. The assembly of the short block will play a big roll in safety too. I had Andy Jensen put that 406 together (stock crank, rods and TRW pistons). He thought I was shifting too soon!!

 

it can be a tricky situation! I had a buddy of mine ( drag racer in super pro high 9's and less build it)

 

OK, so what's moving 3500 fpm then? the piston? and that's measured by rpms and the distance a piston is traveling?

 

Piston Speed = (Stroke x RPM) / 6

the stroke of your connect rod/bottom end x your make rpm divided by 6
and as far as i know fpm is the speed of your whole rotating assembly
i hope that answers your question

 

OK - thx. I know basics, trying to know more!

 

sorry i meant to say max not make its 3:30 am where im from lol and i know what you mean i just learning also