Hi All...
Please remember I am no expert on this stuff, just an old retired Engineer, that researches alot, then does what seems logical. Most if not all serious racing motors vent to the atmosphere, thats why none of them can pass a emission test, all the PCV valve is, is a part of the emission system, pulling gases out the motor and trying to reburn them, so logically I suppose, the more fuel a modified motor is using, the capacity of the valve has to change with it, I can only address the mid to late 70's, because thats what I own.
Vette79...Yes, use on modified L48's, I did on my 77, after I put in the 350 hp cam and reworked the heads and put a L82 intake on it, and of course, endless carb mods..now that motor is on a stand and a crate stroker is being fitted into the 77....time for some fun!!!
401KVet....2-9246 is the proper number from Echlin, but the quality of it sucks, might work just fine, I dont have to find out because I have a lifetime supply of the Delco's....I hope yours is better quality than Echlins.
Just my observation with one in each hand, just turning them over you notice the Echlin valve opens further, which means a diff in the springs, I know its nit-picking, but all the bucks I have in these cars, they are not going down because of a crappy part if i can help it.
Petes74TTop....774 is the proper one for the stock L48, I dont have a parts book handy, but the number might change at some years earlier, I confirmed mine with my AIM manual and a NCRS book.
Never did that test, only simple tests I ever read about is pull it out with hose attached and cover the valve with your finger and if your rpm drops more than 50, replace it.
The 775 valve is not "better" its just a diff size thats matched to the requirements of a diff engine, my beef was with all the parts stores and even the dealers in my case when asked for a valve for a L82 350, dispensed the L48 valve and swear their books say thats whats required...so I am doing my best to ring the bell and warn people......in my mind, if your motor cannot vent, it must go somewhere, so it would seem the logical places would be into your oil (dirty oil, really fast) and/or out the weakest gasket.
And there is a balance there with the carb, so I doubt it would be beneficial to just throw the biggest flow valve you can find on there then no worries
Hope that helps
Greg
