Easy? What is FP for a manual pump and carb?

jerry beach · Jan 25, 2004

This is not a stang, but it has a 600cfm edelbrock carb. and a manual pump. I have measured the FP, but I want to see what some of you think it should be. The motor is pinging, I am thinking low FP may be the cause. It has gotten gradually worse, and no work was done to the car. The car is not down on power and not running hot. The plugs are bosch platinum+4 and they are red in color, WTF is that? They looked normal 2 wks ago, but he has been running octane boost. Its in an 86 monte, mild 305 combo. Nice car, I drove it today. It needs some gears.

89MustangGX · Jan 25, 2004

Should be about 7 psi. Also, those plugs are worthless, I'd just run regular Delco plugs in there.

jerry beach · Jan 25, 2004

Thats exactly what I thought it should be. I have 5 psi, prolly the cause of the lean condition. I played with the timing and got most of the pinging out of it. It has no timing indicator, but the cam is a bit lumpy. Vacuum is at 15 in hg at idle,pretty steady. As I said, mild build-up. I am working on it free for a friend. He doesnt have much cash, so I wanted some opinions as to I am going in the right direction. He's gonna get a FP tommorrow.

I told him the same thing on the plugs. Get autolites or delcos. He swears by his $8 spark plugs. I keep telling him to let it go, they are crap. I dont think this will stop the pinging though. Weak spark is not the cause.

hllon4whls · Jan 25, 2004

jerry beach said:
I have 5 psi, prolly the cause of the lean condition. I played with the timing and got most of the pinging out of it.

Fuel pressure has nothing to do with the fuel mix on a carb. You could turn the fuel pump off and as long as the bowls dont empty, the car will have all the fuel it needs. If you lean out at WOT, then FP could have something to do with it. With fuel pressure being too low, it may have trouble filling the bowls fast enough.

If the motor is lean, put a bigger metering rod in there. Other issues, could be a vacuum leak, or improperly tuned secondaries. Besides A/F issues, there could be a lot of heat in the heads due to hot plug range or a lot of carbon built up on the pistons due to a lot of short trips.

hllon4whls · Jan 25, 2004

jerry beach said:
Thats exactly what I thought it should be. I have 5 psi, prolly the cause of the lean condition. I played with the timing and got most of the pinging out of it. It has no timing indicator, but the cam is a bit lumpy. Vacuum is at 15 in hg at idle,pretty steady. As I said, mild build-up. I am working on it free for a friend. He doesnt have much cash, so I wanted some opinions as to I am going in the right direction. He's gonna get a FP tommorrow.

I told him the same thing on the plugs. Get autolites or delcos. He swears by his $8 spark plugs. I keep telling him to let it go, they are crap. I dont think this will stop the pinging though. Weak spark is not the cause.

BTW, if it is a stock fuel pump, the FP is probably going to be around 5psi.

jerry beach · Jan 25, 2004

Right on, thats what I was thinking too. Its not metering rods, the car has been 12,000 mi without any of this. Its not leaning out at WOT, its load sensitive. It will ping at 20 mph if you are in 3rd and give it a little gas. It has a 700R4, 4speed auto. Since nothing led up to the problem. I will try the seafoam on it next. It really seemed to help the Zephyr. I am running 87 in it and detected no pinging. 1/3 of a can of Seafoam is all I used, so figure $2 to try it. Thanks for all the help. Oh and he does do a lot of short trips too. He is an older guy and was building this thing into a show car, then he hurt his back and hasnt got any income. His wife works, but they dont have cash to throw at it.

Easy? What is FP for a manual pump and carb?

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