What carb do you have? Sounds like the butterflies are not set correctly.
setting up idle on fresh engine
Just got done burning in my cam with a fresh rebuild on my 460( includes new cam, scja heads, edelbrock rpm int, 3500 stall, and all new bearings and what not). While breaking in cam I had the idle @ 2500 and the timing was around 30 deg w/ vacuum disconnected from dizzy. Then I tried to back down the idle to around 1k or 800 and the thing would not stay running. The new cam specs are 224 @ .050 int & 234 @ .050 exh, .540 lift int & .560 exh. It is a howards cam part # 240041. They told me it is pretty much the biggest cam I can run and still have vacuum for the brakes( so hopefully that is true). When I get the engine down to around 1300-1500 rpms it will stay there and run but anything lower it will die. When I am at that rpm I have around 15 deg advance. I am using a MSD 8477 dizzy (with the red bushing installed 28 deg and one heavy silver spring and one light silver spring) and a 6a box to power it. The carb is a holley double pumper 750 p/n 4779-6. I have around 7 psi of fuel running to the carb, and both the idle mixture screws in the front metering block are 1.5 turns out. The front main jets are 74 and the rears are 84, even thought that shouldn't have anything to do with the idle. Also there is a 3500 stall behind the eng. So the question is what is the correct procedure to set up idle, and what rpms should I be expecting @ idle with that cam?
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its a holley 750 double pumper 4770 p/n
15 at that rpm sounds like not enough initial.
Put the black bushing in, with the red 28 degree bushing in and your total timing set at 30 your timing at idle is only 2 degrees. The black bushing is 18 so set your total timing to 30 and you'll have 12 at idle.
Yeah nuclear that sounds like a plan, I was actually thinking installing the blue one to have 21 cetrifical advance, but I can try the blk one also. What you think about installing both light silver springs? The eng is in a mud truck with 40" tires and that 3500 stall so I would think the sooner the better with the advance or am I wrong? I am also kind a wondering on the transistion slots on the carb, maybe with that new cam they might be set up wrong.
The black bushing and light silver springs have always done me right!
My sugestion would be to sneak up on the timing and idle mixture a little at a time until you get around 1,100 in drive. At the idle you're at it's not even in the idle circuit in the carb yet (throttle plates are too far open). Try richening the screws to 2 1/2 turns and start adjusting the initial timing and mixture from there. Alot of times I tune non-stock motors by ear anyway......They'll tell ya what they need 
.
Rob
.Rob
Yes your right the light silver springs would be good for that combo.Yeah nuclear that sounds like a plan, I was actually thinking installing the blue one to have 21 cetrifical advance, but I can try the blk one also. What you think about installing both light silver springs? The eng is in a mud truck with 40" tires and that 3500 stall so I would think the sooner the better with the advance or am I wrong? I am also kind a wondering on the transistion slots on the carb, maybe with that new cam they might be set up wrong.
Are you sure that you don't have a vacuum leak somewhere?
Yeah that was exactly what I found last night, I pulled the carb off to throw in a carb kit into it quick and found the rear vaccuum port cap blew off-probably due to a back fire I encountered setting up the timing. I installed the kit and ensured all the vacuum ports were plugged with zip ties on them. Adjusted all the idle mixture screws to 2 turns out. Also I put the blk bushing (18 deg cent. adv.) and both light silver springs. The engine does idle a lot better, but can only get it down to around 1k now. Today I am going to go ahead and install the inner valve springs back in on the heads ( took them off to burn the cam in). Then turn the idle mixture screws out another half turn so it will be 2.5 full turns out. With the timing should I just get as much timing @ idle possible and still not cause starter load? Or should I fire it up and run the eng around 2k (due to the set up it looks like it should be all in then) and adjust the timing to 34 or so.
Alright got the truck fired up again tonight and went to go set up the idle and base idle timing. All idle mixture screws are at 2.5 turns out now. With the vacuum disconnected from dizzy I set it at around 10-12 deg, then the idle was around 1k. So i adjusted the idle down to around 800, then checked timing and it was around 8-so upped the timing to 10-12 and then the idle went back up to 1k again. Did this about 4 times with the same results. I did check my vacuum in gear at idle and I had around 4-5 (checking off the front port of carb at the base). So I do know my power valve is way to big being at 7.5, so tomorrow for sure I will get a 2.5 and install. I am guessing that is having a lot to do with my goofy idle. Something else that was goofy is when we got the idle down to 800, you hit the throttle then the idle would stick at 1k again with nothing binding in the butterfly's or cable. So not to sure about that either, but I will install the power valve tomorrow night and see from there.
Power valve is probably blown, I don't think that the carb is enough for your combination. Stock 460's came with that size or slightly larger.
That cam should make more vacuum than that.
I have to agree with him that cam should pull~12-14 inches of vacuum. Are your valves set correctly? Did you replace the carb gasket when you pulled it? I would check the gasket first before installing a new pv.That cam should make more vacuum than that.
Yeah I agree that the carb is pretty small, but trying to get by with it for awhile. The mains are jetted up to 74 and 84, called holley and asked them and he took my specs and said the carb is to its limit-he is the one who said jet it up 4. As far as the vacuum leaks go, I will double check them tonight, all new gaskets were installed but who knows. I did just install a 3.5 power valve, then I am going to hook up a gauge and set the idle mixture screws to achieve the highest vacuum. I do have the screws out 2.5 turns, but might need more due to the fact it is such a small carb. But if the power valve is to big it would be messing with me this whole time while I try to set the idle. At least w/ a 3.5 it for sure should not be letting any gas in, since the lowest I got last night with vacuum in gear was 4 in.
Alright just got done running it again and the thing has a huge vacuum leak at the intake mani to head gasket. I was kind a wondering about this because my gasket kit came with a fel pro intake gasket which is just the two seperate gaskets then there was also a pan gasket that was metal made by victor reinz.
The only one I used before was a pan gasket so I went with that one, well and now it leaks. I did just reset the rocker clearance, with the engine warm I went to zero lash then 1/4 turn ( that is about right correct with ford racing 1.73 roller rockers and hyd lifters or should I go 1/2 turn?).
The only one I used before was a pan gasket so I went with that one, well and now it leaks. I did just reset the rocker clearance, with the engine warm I went to zero lash then 1/4 turn ( that is about right correct with ford racing 1.73 roller rockers and hyd lifters or should I go 1/2 turn?).
So pulled the Int tonight and you could definately see were the int runners were leaking were they met the heads. So I cleaned everything off and installed the new 2 piece fel pro set and hooked everything back up and now the dang thing won't even fire and idle, sometimes you can get it to run for a bit giving it gas but then it just starts to back fire. So I checked the timing 4 times and the dampner is at 0 deg, the pointer is at number one, all wires are hooked up properly, and I even removed the valve cover just to verify that I was on number one. So the only thing that has changed is the new int gasket set, I looked at the new gasket and yeah that one is leaking as well. Even though it is leaking, it still shouldn't cause the engine not to run- it did before. So any ideas on what to look for about this running problem, could a big enough leak cause insane back finring. Also what in the heck is going on with my heads to int seal. Any one run aluminum scja heads with a edelbrock rpm manifold and not have it leak?
Which intake bolts are you tightening first?
Are the bolts bottoming out before they pull the intake down?
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