i have a 73 f250 4x4 with a 72 460 the timing is set at 12 degrees it has points ignition and an edlebrock 750 the motor is pretty much stock and it spark knocks like a mother i have tried everything i can think of and it wont fully go away even if i run hi test , i have had a few friends look at it and all we can come up with is that it is doing it to annoy, me has anyone got any ideas ? thanx

 

Im running a 1969 429 in a 79f250. I have the timing bumped back around 8-10 degrees and always run premium it still pings a little with the low grade 92 octane premium. If I run regular its real bad. One thing to consider is how many miles are on the engine. These pistons have a very large surface area and if theres alot of carbon it only makes it worse. Andy

 

Put a timing light on it that shows advance at what RPM. It should be no more than 36-degrees (for a test) on a gradual basis, all in by around 3000rpm or less. If it's all there at idle or more than 36 degrees total, I'd take a look at the following:

If you're running a vacuum advance you might want to check that out. They're prone to throwing way to much advance in way to quick. I'm not real familiar with the procedure to check that and make repairs/adjustments, but there used to be an Allen head screw in the end of the vacuum canister that served as an adjustment.

The second thing I'd check would be the distributor. Most of them have various springs you can use to adjust the advance.

 

I have a 72' 460 nothing to hoped up. Mine pinged like crazy also. I got my distributor (MSD Ready-to-run) professionally curved. Wow, now not a ping is heard. I still time it at 12 degrees and low octane gas. What a difference, power all the way through the rpm range. Point distributors can be done the same way. The only thing they need is your distributor and some details about your ride. It cost me $40, parts included, and an hour of my time. Greg

Greg
71' F250,4X4 460ci-NP435
43 ****** MB204109 289ci

 

I want to ask what is probably a dumb question. What does the spark knock sound like? Being a beginner, I am clueless. I was told if the timing is set too high and you are getting spark knock, then this will lead to detonation??? Then all you need to do is back off the timing a little. O.K., But I couldn't tell you what or when or if she is spark knocking, my motor is really, really noisy. Could you tell by performance? Thanks, Blair

 

I'm not good at describing sounds, maybe someone else can provide you with that. Spark knock is a sure sign that detonation is taking place. In many cases just retarding the distributor won't eliminate the knock as its normally caused by too much vacuum or mechanical distributor advance.

Say you set your intital timing at 12 degrees before TDC at idle by retarding or advancing (turning) the distributor with a timing light on the pointer. Upon increasing the rpms, the distributor's mechanical advance (normally a combination of springs in the distributor and vacuum but nothing to do with turning the distributor) should gradually add another say 22 degrees of advance to where you have 34 degrees of advance by 3000rpms.

Timing is controlled by the relationship of the position of the piston to when the spark occurs. If the ignition spark occurs too soon it can actually push against a piston traveling up the cylinder as it is compressing the fuel/air mixture. This causes detonation and means you have way too much advance.

Older engines with worn distributor springs and faulty vacuum advance cannisters are prone to excessive advance. Even if your engine is noisy, an advance timing light can tell you exactly how much advance you have and at what rpms it takes place.

 

What do you mean "my motor is really, really noisy"? Is it noisy because that is the way you built it (performance, load pipes) or is it noisy when you stick your foot into the carb to pass someone or climb a grade? Does it sound like a hundered little people under your hood beating aluminum pans with hammers (so to speak)? The noise is very much like if you have a hi-performance engine, running low octane and you stomp on it. Suddenly a mess of noise starts (piston ping or octane ping), that is your piston skirts rattling on the cylinder walls. Yes, you loose lots of performance and increase engine ware.

Time your 460 at 12 degrees if your engine starts the rattling noise when you stomp the gas, back the timing off 2 degrees. If the noise is still there back it off 2 degrees agian. If the noise is still there and you are at 8 degrees take the distributor in to get curved. You will be amazed at the increase in performance.

Greg
71' F250,4X4 460ci-NP435
43 ****** MB204109 289ci

 

[updated:LAST EDITED ON 01-11-03 AT 07:50 PM (EST)]I dunno how to explain just what I mean. I assume the noise I hear out of my motor (completely stock, exhaust is stock also), that it is "worn out". Its a 74 Linclon motor, I assumed with its age that some of the noise was the valves or something internal that was starting to wear. When I pulled the intake off, it had carbon buildup like a mother. I assume that there is buildup everywhere inside. It sounds no different to me when passing or running flat out at 65mph, all I hear is a kind of lope at idle, and as I pick up speed she just gets noisy. Kinda winds up. I know some is road noise, but there is a good amount of "clickety-clack" from the motor. In other posts I mentioned some of my troubles, as of right now I got some leaky valves. I wouldn't now what a "healthy" stock 460 would sound like. My water pump makes a slight noise also, my bud says it's about to burn up, that's where I hear most of that stupid "clickety-clack" noise. I know this all sucks as a description, however with all my blown gaskets and vaccum leaks and crapped up fuel system over the last 6 months, I just want to make sure now that she runs half-way decent, that I don't go and screw up something because I don't know what spark knock is. Inexperience is a bad thing to have when trying to fix a truck that sat for 4+ years. Thanks for the heads-up George, I need to get another timing light with the advance feature. I give her a try at 12 degrees, it is set rough right now, I was trying to tune my new carb and haven't really set the timing good and proper. Thanks again, Blair

 

 

Take a LONG shank screwdriver, start yer engine, let it warm up to normal operating temp and listen for the noise...

if ya have to block the wheels, set the parking brakes, put in gear and very very very gently increase rpms till ya hear the noise yer talking about...

then take the screwdriver and place the working end on the various spots you suspect the nosie is coming from and place yer ear on the handle...

works kinda like a stethescope...sometimes ya can isolate the noise and troubleshoot this way...

SAFETY FIRST: remove all loose clothing, jewelry, hair etc etc
Triple check the wheel blocks/brake
triple check the wheel blocks/brake
triple check the wheel blocks/brake

dont mean to be **** but Ive been there and done that...all the hard way....
just my $.02....good luck...