460 Ford

[grand dad]

I have a freshly rebuilt 460 and just started it for the first time. I varied the idle between 1000 and 2500 for about 20-30 minutes. I get intermitten pops through the exhaust. It has headers and about 3 feet of straight pipe right now. The popping seems to come and go and from time to time it will pop through the carb if I snap the throttle too sharply. When it pops thru the carb it smells like stale gas. The gas has been in it for a while but I added sta-bil since I knew it would be a while until I got the engine back. The distributor was purchased from Jeff's Bronco Graveyard and it's the HEI conversion type. I advanced the timing and disconnected the vacuum advance and it seemed make the popping stop at both ends but it returns after a while. Any Ideas?

 

[Broncobill78]

I have a freshly rebuilt 460 and just started it for the first time. I varied the idle between 1000 and 2500 for about 20-30 minutes. I get intermitten pops through the exhaust. It has headers and about 3 feet of straight pipe right now. The popping seems to come and go and from time to time it will pop through the carb if I snap the throttle too sharply. When it pops thru the carb it smells like stale gas. The gas has been in it for a while but I added sta-bil since I knew it would be a while until I got the engine back. The distributor was purchased from Jeff's Bronco Graveyard and it's the HEI conversion type. I advanced the timing and disconnected the vacuum advance and it seemed make the popping stop at both ends but it returns after a while. Any Ideas?

Hmmm, I believe you have what is commonly known as a carburetor conundrum /emoticons/[email protected] 2x" width="20" height="20" /> or at least that what it sounds like to me. It's a little funny though because I've always had it pop thru *either* the exhaust *or* the carb but never both at once. When it pops thru the carb what's always worked for me has been to open up the mixture ****** jump to bigger jets or use one of those kits that bumps up the accelerator pump because it's usually running lean when it pops thru the carb. Unfortunately when it pops thru the EXHAUST the fix is to pretty much do the opposete, smaller jets & taking the accel pump down a notch because pops in the exhaust are usually caused by unburnt fuel lighting off which is usually because you're running rich. You might try readjusting the butterflys (primary & secondary) or checking to see it they're out of phase. I'm guessing your carb is either right out of the box (meaning it will need tweaking) or it's the one that was on there before (meaning it will need some tweaking). However you slice it I'd say you've got some carb tuning to do.

 

[grand dad]

Hmmm, I believe you have what is commonly known as a carburetor conundrum /emoticons/[email protected] 2x" width="20" height="20" /> or at least that what it sounds like to me. It's a little funny though because I've always had it pop thru *either* the exhaust *or* the carb but never both at once. When it pops thru the carb what's always worked for me has been to open up the mixture ****** jump to bigger jets or use one of those kits that bumps up the accelerator pump because it's usually running lean when it pops thru the carb. Unfortunately when it pops thru the EXHAUST the fix is to pretty much do the opposete, smaller jets & taking the accel pump down a notch because pops in the exhaust are usually caused by unburnt fuel lighting off which is usually because you're running rich. You might try readjusting the butterflys (primary & secondary) or checking to see it they're out of phase. I'm guessing your carb is either right out of the box (meaning it will need tweaking) or it's the one that was on there before (meaning it will need some tweaking). However you slice it I'd say you've got some carb tuning to do.

Funny you should mention that Broncobill. I had the carb out of the box - holly 750- installed it but the motor never ran properly because the lift on the cam i put in was too much for the stock springs even though the guy at the parts store said it would be fine. After scrubbing the lobes off of the cam and dishing the bottoms of the lifters out, a rebuild was in order. I was in such a way that I forgot all about draining the carb when I tore the motor down. I had a Ford tech do the assembly (Ford engines are new territory to me - always dealt with s/b chevy). When I first tried to start the engine, the rear needle valve was stuck open and fuel pumped out of the overflow. I split the float bowl and noticed that the old fuel had crystalized in the bowl. My best bet would be to clean that carb real well and start from scratch with it. Any suggestions on jet changes? It's .030 over, .490 lift on the cam (I can't recall the manufacturer or duration right now without going into the shop but it's an RV/towing cam. It has headers and a Performer manifold.

 

[Broncobill78]

Funny you should mention that Broncobill. I had the carb out of the box - holly 750- installed it but the motor never ran properly because the lift on the cam i put in was too much for the stock springs even though the guy at the parts store said it would be fine. After scrubbing the lobes off of the cam and dishing the bottoms of the lifters out, a rebuild was in order. I was in such a way that I forgot all about draining the carb when I tore the motor down. I had a Ford tech do the assembly (Ford engines are new territory to me - always dealt with s/b chevy). When I first tried to start the engine, the rear needle valve was stuck open and fuel pumped out of the overflow. I split the float bowl and noticed that the old fuel had crystalized in the bowl. My best bet would be to clean that carb real well and start from scratch with it. Any suggestions on jet changes? It's .030 over, .490 lift on the cam (I can't recall the manufacturer or duration right now without going into the shop but it's an RV/towing cam. It has headers and a Performer manifold.

Man, it's been a long time since I goofed with one. 750, huh ? That's what a 4150/4160 ? Without knowking what size jet you're working with now it's hard to guess but changing jets is something you should always do in steps. I'd spring for the $40 or so a jet kit will cost and that will give you a few jet sizes from something like #60 to #99. Just bump them one size at a time until it stops popping on you. Also, the jet kits come with a gasket kit (or they did back when *I* bought them) and you might want to consider the plastic see-thru float plugs so you can see the fuel in the bowl. Sounds like a reasonable rebuilt & good parts choices. I built one of my 460's to very similar specs and was pleased as could be with it, you should be pretty happy with it once you get the kinks ironed out.