Early 273 intake problems
The specs are:
273 2bbl engine with 2 1/2in dual exhaust
4 spd trans
2:94 rear end
25.4 tall rear tire
Huston; we might have a problem
(273x5000)/3450=396cfm requirement at 100%VE
As a basic engine the 273 might be a 70%er so; 396x.7= 277 cfm,......... which is a 4bbl spec.
As I recall the conversion factor is .67 so for 2bbl this would be; 277/.67=413cfm 2bbl... so a 500-2bbl is plenty/21% plenty
I think the 2bblcarters were maybe 250 or 230s in those early years, so where would a 230 top out?
First you convert the 2bbl spec of 230 into a 4bbl spec and get 230x.67=155 4bbl spec, then
155x3450/273=1959 at 100% VE which is 1959/
[email protected]. So at 2800 the carb might be pulling it's limit, according to the math. That don't mean she hits a brick wall. It just means the engine will start pulling a vacuum in the intake, and drawing the 4bbl spec back to the 2bbl spec
Ok so where does the 230 2bbl spec start choking?
(230x3450/273)/.7=4150 rpm But the engine still doesn't hit a brick wall; that won't happen until the springs lose control or the cam stalls, or I guess the exhaust stalls.. Which with a 2bbl topend might occur maybe, I'm stalling, cuz I'm guessing, possibly 4500, but could be earlier with ancient parts. Could be later too if the PO put something in there. Anyway the carb is still gonna pass the mixture. Of 'course the power is long stalled and gone, and the intake vacuum could be high, but I'll tell ya; see below
In practice, I have installed one of those 230s on a 340 short, with a 318 topend AND 318 cam (1969Sattelite parts,done in 73 or 74) with the onl bolt-on being fenderwell headers (65 Valiant wagon), and because it smoked the 1 tire,lol, it was a pretty sweet ride, for a young 20 year old ,me. These were the parts I had lieing around, and my slanty was burning oil faster than it was burning gas,lol,it had to come out.
OOPs I see I'm a couple of weeks late lol.
Oh well, I had fun.
I always have fun with math.