Thats been a hot topic on this board. Opinions differ. The good news is that its something you can try both ways, and its a free check! I myself run ported on my 350. My 350 is a stocker with a stock distributor so manifold vac will cause a brief timing retard when the throttle is applied. A properly set up high perf distributor will work on manifold vacuum. Hope this answer works and please remember everyone who reads this, my answer is simply what works for me. No need to call me an idiot, my boss will do that tomorrow!ou:
Bad boss? Thanks Dan.!:beer I found it! http://www.v8buick.com/showthread.php?s=&threadid=18686&highlight=VACUUM This helped a lot! Now i understand why "Cyber Buick" wanted me to run manifold vacuum in another tread! I got the Crane kit in my distr. (a MR G kit vent up north.... no god) so i will go for manifold vac. The "how to do the stop plate correctly, different than Crane shows" by the IgnitionMan is way better to restrict the vacuum advance his way. 1.you don't change the preload to the spring in the vacuum canister with every change you make. 2. you don't advance the timing 2* with every 2* you restrict the vacuum advance, so you don't have to reset the timing after making an adjustment. The IgnitionMan wrote "limit to 200/300 rpms over stall speed lockout." please explain, is this where the advance "all in" is supposed to be? (2200 stall speed+200/300= all in at 2400/2500)o No: Lars
The main reason I've found for doing it like that (actually I ditched the crane on, and made something out of sheet metal, but I like that way) is when you do it the crane way you change the phase of the distributer. After running it a while the burn marks on the cap started in the middle of the contacts, and went all the way past the edge of the tab. Doing it this way the burn mark will start near one side of the tab, and end before the other end, so you'll get full spark....
72skylark/ Nick Seems like a nice set up on the 350!:TU: What rear gear do you run? 750 Holley, mec. or vac secondary? Lars
I just got in my Eaton Posi unit, so I'm putting in 3.08's. It currently has 2.56's. Right now it's up on jackstands with the transmission in the garage. I blew apart the planetary gears. I'm replacing them with a new low gear set. First gear is 2.75 (stock is 2.52), and 2nd gear is same as stock. It will be like having 3.36's in first gear. Should roll out alot better. The carb is vacuum secondaries.
Did I get this right? Did I get that right? And by the way, I jumped things to soon.:ball: When I connect the vacuum line I get a little pinging when putting the pedal to the metal!:spank: I am using manifold vacuum (one of the ports on the bottom of my Holley carb.) Is this not a god place to connect the line? No vacuum connected = no pinging!:stmad: There isnt supposed to be any (or very little) vacuum at WOT. is there? uzzled: Lars
Make sure that you have the right port on the bottom of that carb. One is ported and one is full manifold vac.
You got me on to something! :beer The connection i an using is by holley sometimes named vacuum source and sometimes your supposed to connect the choke "opening" vacuum chamber there (if there is one on the carb. its not on mine) If I'm not mistaken its there to open the choke if you floor it. if so this means that it has vacuum at WOT! :error: if this is the case, no wonder it pings! I will try another connection, maybe the one that's connected to toe vacuum modulator to morrow (if its not raining) i have connected the "carbon canister thing" that got something to do with the gas tank breading to the other one, Is this one supposed to have ported or manifold vacuum? o No: Lars
Still raining, soon it will snow Its still raining often enough not to give dry roads where I can do some real lunches :ball: I typed ping in the forum search function, and did I get a lot off more good reading. I switched from the Crane vac. canister to the stock one and restricted the vac. movement to 8* Why, I just could not stand and do nothing. My stock vac. canister needs 12hg to get 8*. I checked this by doing the suck on the line trick. I verified the 8* while at idle suck and watch with the timing light. My Crane vac. canister only needed 10hg (max. adjusted) at 4 notches, they write that each notch is worth 2* =8*, it seems to me that there 8 where more like 10-12.... I got 14,5hg at idle.(800rpm in park) :bglasses: As the org. part got a heavier spring inside, I figured I will loose the vac. advance faster. Did some flicks on the throttle with the vac. gauge connected, its connected to manifold vacuum. Lars
Think I figured out why it did ping with the vacuum connected and flooring it from standing still. At 2200rpm my secondary had not even started to open. This and the fact the prim throttles are small, at 2200 rpm this was enough to get me vacuum in the manifold. I changed the spring, and the ping is gone Lars
