My car is having a high idle problem, it has a 305 with a holley 600cfm (vacuum advance distributor). I thought replacing the cap,rotor,plugs, and wires would help since around 3 of the old wires had some rust on them. Before I replaced those things, the car would start right up but the idle was a bit high around 1000-1500.

Now after I replaced the cap&rotor(msd), plugs(acdelco) and wires(cheap autozone autolite) the car takes a while to start and I have to push the pedal to get it to start. When I first started it after replacing those, It backfired through the carb and blew the air cleaner off and stalled. If I don't give it gas , it'll stall or sometimes If I give it gas it will stall also. Also when I put it in drive or R it'll also sometimes stall.

I gapped the plugs to .035 and I made sure the plugs were in correct order, I even marked the dizzy cap. The timing is around 8* btdc. I took off the new cap&rotor and put in the old ones to see if that helped, which they didn't. Could the problem be the wires? the plugs are the same ones I used before so I doubt those are the problem

 

You mixed up the plug wires, probably on the dist end.

1-8-4-3-6-5-7-2

 

nope, Thats the order that I put them.

 

I don't know what kind of ignition you have but standing in the front of the engine and looking at the dizzy, #1 is either at 5:30 or 6:30

live and learn, mark #1 next time before pulling the wires or replace them one at a time. And, hopefully you understand that firing order is based on going clockwise??

 

I know where #1 is, Like I said I marked the cap in the firing order. The wires are in the correct order

 

Holley carb. The backfire blew the power valve so it's dumping fuel. Why did the engine backfire? Are you sure you have the cap and rotor indexed correctly. You swear everything is right but if it were, it wouldn't have backfired. You probably have a vaccum leak as well, causing the high idle. May have also caused the backfire. If the engine backfires again, it will blow the power valve again. Just about everytime.

 

Well before it backfired, it didn't want to start so I kept pressing the pedal to get it When it did start, it kept dying so I revved it and that's when it backfired. When I put the distributor cap on, I didn't check to see if it was lined up with the notch on the distributor, I'm not sure if that had something to do with the backfire. It's in the proper place now.

I have a spectre adapter on the intake since its a spread bore intake. I sprayed some starter fluid at the base of the carb and adapter and I didn't hear a change. Should I just buy an edelbrock 2101 square/spread bore intake instead of using the adapter?

 

If installed right, the adapters generally work fine. However, I have seen several installed incorrectly. Im confused though. Are you saying that after rechecking the cap, the engine is running more like it used to? How is your choke adjusted? Have you set up idle mixture? What are you doing for a fuel pump?

 

No, adjusting the cap did nothing. I haven't hooked up the choke wire , its a holley 0-80457s btw. It started up fine and stayed running without the choke so I don't think that has anything to do with the problem. I set the idle mixture as best as I could. I'm pretty sure the fuel pump is stock, I know it needs a carb fuel pump but, it works for now. Before replacing the plugs,wires, cap & rotor, the car ran ok, The idle was just high. Before taking off the old cap and replacing the wires, I taped on the firing order on the cap to make sure I didn't mix up the wires

I'll replace the power valve soon and see if that does the trick.

 

Is this a large cap HEI(internal coil)? Do you have the coil installed correctly in the new cap? How about the button that goes under the coil?

 

yeah its an HEI. I put it the same way as it was. I put the little button along with the rubber washer. I also put the ground where its supposed to go

The wires are pretty butchered though, who ever did the carb swap cut corners. I'll post some pics in a bit so can see what I mean

 

Here's the pics




the black wire is just taped to the red cable you see taped on the dist cap connection



What kind of part should I be looking for to replace the wires, I've checked on summit and they have HEI power pigtails, those seem to be it but Shouldn't they connect with the tach wires connector or what is the proper way of fixing them

 

#1 plug typically goes where you have #8 marked. I would wager that this is you problem. Timing is way off, causing your engine to run rough.

 

I'll move them over and see if that helps. They've been in the current order since I got the car

 

It is possible that's where they were, but typically the #1 wire is on the front right post of the cap. #1 could be on any post as long as the firing order is correct. Best thing to do would be to set motor at TDC and pull the cap to see where to rotor is pointing. This will be the location of your #1 wire.

 

earlier in this thread someone mentioned as you stand in the front, #1 is either at 5:30 or 6:30 (using a clock) and that rotation is clockwise.

Mine is at 5:30

yup, per the photo, he is off as many posters have suggested

i suggest that the OP go to the auto store and buy a manual and he'll see the diagram.

 

Hope this helps.

 

I set the motor at tdc and the rotor pointed between 8 and 1. I moved the plugs over and it wouldn't even start, so I had the wires in the right spot the whole time. I haven't replaced the power valve yet, I have it though. I think I may have left a plug wire disconnected from the #8 spark plug, could that have caused the back fire? I remember having to reconnect it after is started back firing

 

its time for an update. I finally replaced the power valve and its much better. It stays running and starts right up, well sometimes. When I first go to start it, it sometimes takes 2 tries and will start really slow( batteries fine), like it stays around 300 rpm for a second almost as if wants to die. But after the initial start, it starts fine. There's a burnt plug wire , not that badly burn but still, it might be grounding out on the exhaust manifold.