I heard that the biggest shot that should be used on a 305 was a 100 shot and the biggest shot a 350 should be a 150. Is this accurate? Please give me some information and personal experiences with nitrous. THANX!

I used a 150 shot on my 305 TBI. Never gave me any problems.

those are the standards based on what the manufacturers feel a "stock" engine with those bore sizes, and cast pistons can handle as far as cylinder pressures. I also recommend no more than 35 hp on 4 cyls smaller than 2.0, 50hp on 2.0 and larger, 75hp on 6 cyls above 2.5 liters. although I have many a customer that through experimentation have grown beyond those recommendations (especially the honda 1.6-1.8 and 50 to 75 hp shots).

So what size shot do you think a 91 tpi 350 with 70,000 miles on it could handle without any problems?

Providing the engine is still in good shape, it should handle up to a 150 shot. Anything over this on a stock motor you would be living on borrowed time.

I agree.

It would also be a good idea to get performance ignition, box, wires, coil, and an AFPR. I changed my plugs to 2 steps colder just to make sure.

"Spray n' pray"

Never spray unless you have the $$ for a rebuild is my motto. And it's a good one to live by.

Please don't call it "NOS" like the import kids.

Heh. My friend is running a 100 shot on his 1.6 liter miata. Of course it has a forged crank and I think forged pistons from the factory. The engine is living fine, but the trannny is about dead.

so a 100shot would work ok on a freshly rebuilt 305? it has about 500 miles on it.

as long as it's properly tuned, with a nice fuel system it can handle a 100 shot all day long.

(proper fuel system == new high flow fuel pump, new injectors, AFPR tuned for about 52psi on 24lb SVOs, high flow filter, etc.)

Not all of that is needed, but I like to be safe.

Also, check into FPSS, Window Switch, etc..
every little bit helps.

the nitrous would be on a different car than my GTA its a carbed 305. thanks for the info though

THANX GUYS!!

Whats safe for a 72 350 with unknown mileage?

YES, 100 TO 150, SORRY