Holley pump cam help

[Bonnewagon]

I thank you all for the great input. As I said in the beginning, I know dick about Holleys. But I am learning, slowly. What I do adhere to, is 'do one thing at a time'. If not, you have no idea which thing worked. So when he gets the cam kit, we start there.

Quick question: I set the fuel level, running, it was in the middle of the sight glass. Two days later, the level was down so low you could not see it. I had to raise it back up. My cousin says that it should be 'set and forget'. But it moved. The only thing done was to wire the electric fuel pump to a switch on the dash. Prior to that we were jamming the wire into the battery clamp. Different current flow affected fuel pump volume? That makes no sense. Idle uses very little fuel.

 

[stew86MCSS396]

Everything that needed to be said has probably been mentioned...watching the youtube video, within the first few minutes "too little timing, too much timing, too much fuel and too little fuel" was mentioned.

Just to place it in a different perspective, I had a Holly 650 on the 396 and I never had to resort to any mystical carb tuning tricks and had not experienced any tip in issues. As for timing, I set the timing with the vacuum can disconnected, set it for max 34-36 and reconnected to ported vacuum source. Can't tell you where that put my initial but purdy certain it was more than 6 degrees.

 

[Bonnewagon]

Anyone ever set the base timing with a vacuum gauge? I once had a problematic Pontiac 400 that would not idle for shiznit. So I read about using a vacuum gauge and I hooked it up to manifold vacuum. I turned the distributor around until I got the most vacuum at idle. Then I noted what the timing light said the base timing was at, and added enough centrifugal and vacuum timing so it did not go past 36° total. It ran pretty good that way.

 

[spidereyes455]

Mark, that is a very old school way of doing it., and yes it does work or at least gets you damn close to where you want to be. I remember when I was a teenager and just learning about cars that was one trick my dad taught me. He explained it was a good way to at least get you in the ballpark if you either didn't have a timing light and especially for an engine that wasn't stock and the factory specs no longer applied. I imagine it was a very common practice way back in the day either before timing lights or even when they were still an expensive luxury that most home mechanics couldn't afford.

 

[Bonnewagon]

an expensive luxury

Jim, you aren't kidding. I bought my Dad his first real timing light for Christmas with my paper route money. A Sears Craftsman with the spring that went over the spark plug. He futzed with old VW beetles, and things like metric tools were not in the budget. We take a lot for granted these days.

 

[Ernest]

Unfortunately, old school ways are a dying breed now, no thanks to EFI systems.

But i've decided to go that way with the Edelbrock Pro-Flo 4(#35760) system only because there comes a time in one's life you want to start enjoying the car and not keep messing around with the engine before you get fed up, and getting older doesnt help.

So its time to sit back, relax, whomp the go pedal into submission and enjoy the fruits of edelbrock's labor!

 

[78Delta88]

There's another post on here where I talked about how to do this. Also yes, my first light was a Craftsman. About $25 in 1980, used it for many years.

Basic baseline process.

Back off curb idle screw all the way so primaries are closed. If it won't stay running then adjust to just keep it running.

Unloosen the distributor hold down bolt/nut to just where it is snug. Rotate the distributor both directions to get your best vacuum reading. Rotate the distributor back about an 1/8 inch the opposite direction. Lock it down. You will lose a little vacuum but that's ok.

Adjust curb idle to specified setting +/- 10%.

Go drive it.

Now work out any other issues.

 

[Bonnewagon]

Well now, I left the guys with instructions on swapping the blue cam in. Then I hid down my basement working on the 48SPL. No phone calls. No news is good news. I had to swing past today so I went to see what happened. I saw a lot of rubber in the parking area. Sure enough, they did the blue cam, and that hesitation is GONE! But I noticed a very rough idle. I checked that the accelerator linkage was right, and I had to loosen it. It smoothed out a lot. But WOWSERS does it take off now! Lights the tires right up. I will have to play with the idle again, but for now it is running great. Thanks for all the replies, I learned a LOT.

 

[Ernest]

Sounds good.... just remember, whenever you replace the accelerator pump cam(s), this applys to the rear one as well if its a double pumper, you have to readjust the pump cam lever as well to make sure it doesnt bottom out the accelerator pump lever after taking any slack out.

 

[Bonnewagon]

Does anyone know at what rpm you are out of the idle circuit? I first had it at 650rpm and that is where I got the smoothest idle with the best vacuum [20"]. They raised the idle thinking that would cover up the lag, but then it idled very rough. I know if the throttle plates are open too much you get the off-idle ports starting to drool gas, causing rough erratic idle. Now that the right cam is in place I can go back and play around with the idle. I am so used to a gentle Q-jet idle that this is annoying to me.