Since most carbs I've seen have the large vacuum port on the base in the rear under the secondaries, is this the preferred place to run the PCV hose? I'm putting my 950hp back on and it has no vacuum ports on it so I'm using a 1" spacer that's tapped for a vacuum fitting. I'd prefer to have my PCV plummed to the front but I'm wondering if this will have any adverse affect on idle quality.

On my Edelbrock carb the PCV goes to the front. I don't have any idea if it would make a difference if you put the spacer with the fitting to the front or the back. I don't think it would matter though.

You should put the PCV as near to the primary barrels as possible. The PCV acts like a vacumm leak and if it is too far from the "idle" barrels, it will lean out cylinders at idle and make for headaches with the low speed and idle.

Greybeard, I've never heard that. However, I've got my PCV hooked up to the back of my Holley 3310. Think it might be worth trying to hook it up near the front of the carb?

The only problem I've had with the carb is that it has a very small "flutter" at low speeds (like a 10-15 mph cruise). Kind of like it's not real "clean". I wonder if it might be due to the relatively big cam for a 355?

I may try to run the PCV up near the front one day to see if I notice any difference in the car.

Justin

Holley chose to put the PCV into the back of the carb where it enters under the back butterflies. Not ideal, but we live with it by running the idle just a touch richer than if it was under the front. It shouldn't give you the "flutter" you mentioned. Had you said "surge", I'd say you were running manifold vacumm to the distributor and that you might try changing to the "ported" source. Your "flutter" could be power valve coming in and it's running fat. Ever put a vacumm gauge on it and see what kind of vacumm you've got when this condition occurs?

Well, my "flutter" might be your "surge". smile.gif Yes, I'm running manifold vacuum and it seems to like it better that way. However, going back to port is a thought to see if it changes.

I like your idea of using a vacuum gauge when this occurs. I think I'll try it. Currently I'm using a 6.5 power valve. I originally used a 3.5 or 4.5 (I can't remember), as I was only pulling like 8" of vacuum at idle in gear. However, as the tuning process went along, I've been able to get it up to about 10".

Sorry to intrude on the thread, but I appreciate your help Greybeard. BTW, what did you ever do with the "survivor" car you had?

I put a vacuum gauge on the car last night while I was driving around. First time I ever tried that and It was interesting. I have a 950 HP with 6.5 PV's and it's running pig rich everywhere except idle and WOT. Part throttle cruising around 3000 rpms is the worst. So, I was concerned about the PV's opening during part throttle. But after watching the vacuum gauge, I don't think that's happening. I have 9-10" of vacuum at idle. I have a manual trans and when I start off from a dead stop the vacuum drops maybe 2" or so and then rises rapidly to 15". The ONLY time it ever dipped to 5" was in 4th gear while accelerating normally. Even lugging it down in 6th didn't pull the vacuum down far enough. So I need to look elsewhere for the cause of my over rich condition. I guess main jetting is a good place to start. I'm a novice when it comes to tuning carbs. :(

Justin,

I sent a few pics to your e-mail. They've been scanned and are clean.

Greybeard