Timing on my 460

effienut2 · Post by **effienut2** » February 28, 2010, 12:17 pm

I have a relatively stock 460 in my '66 slick with headers, electronic ignition and 750 Edelbrock. My elevation here is 5ooo feet. What would be a good timing number? I had been setting it at 8 BTDC degrees but I'm getting dieseling and an occasional backfire. Oh, and I have a leaky exhaust header collector pipe gasket.

Thanks for your help.

64 f100 · Post by **64 f100** » February 28, 2010, 12:37 pm

You haven't supplied engough information. What year engine early or later? Just a used engine or high performance build. High compression early heads with early block also I believe causing higher compression because of deck height. Are you running high octane fuel? Lead substitute? Cheap low quality gas? I remmember the old mans Cadilac would not run on higher octane gas there if it came from one of the cheaper gas stations. Rattle and ping like crazy. Had to use good premium gas. Retarding the timing is about all I can think to do. You don't mention what it's set out now, but 8% before tdc sounds good. If it still rattles and pings or diesels, I'm wondering if it may have a carbon buildup, if the motor has higher miles. You've left a lot to conjecture and most of those on the site haven't dealt with an engine at 5,000 feet altitude. Have you fiddled with air mixture on the carb? Two barrel four barrle intake? For those of you that do not know this is the approximate height of Denver, thus the mile high city name. Also wondering if you need to rejet the carb.

Rich

Tech · Post by **Tech** » February 28, 2010, 6:30 pm

I'm a sea level guy but I see a few possibilities.
High elevation = rich. It could be carboned up and therefore knocking from high compression and hot spots.
Old carbs get dirty and go lean raising combustion temperatures causing the engine to knock.
What color are the plugs?
What plugs are you running?
Have you run some SeaFoam through the tank for a quick engine cleanup.
Does it burn oil?
Tech

effienut2 · Post by **effienut2** » February 28, 2010, 10:40 pm

My 460 is a
73 block with '76 heads which are low compression 8.5:1. The carb is a 750 cfm and the engine was rebuilt to oem specs. It has about 12,000 miles on it since the rebuild. I have replaced the metering rods to lean out the carb and up until a year ago it ran great with 85 octane fuel. Then I shut it down to do a restoration and ever since I put it back on the road I've had these problems. I didn't do anything to the engine at all. It just sat.

effienut2 · Post by **effienut2** » February 28, 2010, 10:49 pm

The engine does not burn oil and the plugs have less than 500 miles on them but Ill check them out. I bought a can of Seafoam last year and forgot about it. So I'll try it out after I clean the plugs. I haven't checked the timing in years so I should do that to see if changed from when I last set it at 8 degrees tdc.

64 f100 · Post by **64 f100** » March 1, 2010, 12:21 am

Quality of the fuel may have droped since you ran it last. Also, if the fuel you had in it when it was parked and not ran, had ethanol or methanol this could also be causing some problems. This stuff will cause any number of things to happen in the carb, tank and fuel lines. Stabil will help when storing, but I don't think it will prevent all the problems that these fuels cause. Especially in older vehicles. Slightly possible, that you may be experiencing a combination of several things. As to carbon , you might try the ice water down the carb trick with the engine warmed up. Just rev it up and keep it fairly high as you poor in the water. I do some automatic transmission fluid afterwards the same way to lubricate the valves and other components. It's possible you may need to take the carb down and kit it, as these previous added fuels may have played havock with something in the carb causing it to be to rich.

Rich

oldtrucks · Post by **oldtrucks** » March 1, 2010, 2:24 am

effienut2

I had an engine that sat for a long time and I was getting ready to put it in the truck and it wouldn't turn over. By that I mean it turned part way and stopped turning like it had hit something, it did hit something, carbon deposits in the combustion chamber. This is an unusual situation but it demonstrates what can happen when a running engine sets for a long time. I had to pull the heads and clean it up. The build up was like the carbon had softened and expanded.

The suggestions to run water and or whatever through the intake is a good one that I do once and a while myself. Wont hurt a thing.

Ford blue blood · Post by **Ford blue blood** » March 1, 2010, 10:19 am

That carb is too big for the engine. A stock 460 will run fine and make adequate power with a 600 CFM. The stock cam/valve train runs out of everything about 4500 RPM. Look for a smaller carb and do the water thing or just take it on a 100 mile run with several hard acceleration runs after the first fifty miles.

Tech · Post by **Tech** » March 1, 2010, 11:38 am

I assume that the old tank of gas is long gone and that you have tried premium gas.
The accelerator pump shaft can stick on those carbs if they sit for a while. Is the backfire during acceleration?
Sitting for a year can definitely cause issues. The carbon gets flaky and breaks loose. this can get trapped in the valve seats causing them to leak. Sometimes enough to backfire. The remaining carbon now has sharp edges where the flaking occurred. This can make hundreds of little hot spots to cause pinging.
Seafoam and water!
Tech

effienut2 · Post by **effienut2** » March 1, 2010, 12:07 pm

I had suspicions that the carb was to big. I have a 670 cfm on my 429 and it works great. Thanks for all of the advice. The more the better.

effienut2 · Post by **effienut2** » March 1, 2010, 12:09 pm

The backfire occurs after I shut the engine off. And I have not tried premium gas but I will on the next fillup.

oldtrucks · Post by **oldtrucks** » March 1, 2010, 12:55 pm

What is happening is called "run on" if the throttle plates aren't closing completely and there are carbon deposits as tech described that will cause the condition you are describing. Does the carb have a curb idle selonoid on it? If it does it is designed to allow the throttle plates to completely close. otherwise the seafoam down the carb and in the tank and a good run to warm the engine completely up will help a lot.

blackagatha · Post by **blackagatha** » March 1, 2010, 6:33 pm

I've had similar problems with my 390....

It has never sat for extended periods, but has had a reputation for pinging like crap when driving through Phoenix, I sometimes have to turn the dizzy way back. It was pretty bad when I showed up for the get together at Teakwoods.

Runs-on pretty bad sometimes. Last time it was bad was in the summer, it was so bad it ended up smacking a valve in the process.... Had to go through the freaking top end again....

Every time the heads come off, there is a pretty heavy carbon ring around the top of the cylinders, and yet the spark plugs are always CLEAN- like white.... sometimes a little red, I've heard that has something to do with something in cheap gas.

Pops a blast up the carb once in a while too....

64 f100 · Post by **64 f100** » March 1, 2010, 6:51 pm

dIf it was running OK before it sat , then it should run OK with the 750 now. If, you think it is the carb, switch carbs and see what happens. I don't think the carb is to much but you may need to downsize the jets. I woud switch and see before just buying a carb.

Rich

oldtrucks · Post by **oldtrucks** » March 1, 2010, 9:23 pm

I use a 750 CFM 3310 on my 429 in my work truck and have never had a problem. I screwed up a while back and changed to a smaller jet size and leaned it out, I got an off idle backfire but it went away when I upped the jets by one size.

I know its expensive but if you continue to experence detonation a set of aluminum heads fixes that. I'm saving for a pair now.

William-in-St George · Post by **William-in-St George** » March 2, 2010, 12:14 am

Go here 460ford.com! I have a warmed up 460 D1VE, zero decked, flat tops, ported D3's, Edelbrock 750 cfm on a performer manifold and set my initial at 12 BTDC and then connect it to manifold vacuum. Timing is 22 degrees mechanical with a total 34 degrees mechanical all in at 3000 RPM. I am at 3000 ft in Utah and run 91 octane without any issues whatsoever. You should not have these problems with a 8.5 compression engine. Like I said, check out the big ford site. I also have a 66 F100 466/c6. Great combination.

blackagatha · Post by **blackagatha** » March 2, 2010, 1:52 am

oldtrucks wrote: I know its expensive but if you continue to experence detonation a set of aluminum heads fixes that. I'm saving for a pair now.

I've spent enough on repeatedly fixing my old crap heads to have bought the edelbrock heads in the first place.... 428 sized stainless valves, and double springs.... I think that would solve many of the probs I have had.

effienut2 · Post by **effienut2** » March 4, 2010, 6:52 pm

OK. I think I got it. I put in Seafoam and then checked the timing. It was at TDC

How the heck could that be? Then my good friend reminded me that I pulled the distributor to prime the engine just before putting it back on the road. So I set it at 8 - 10 btdc and boy did it perk up. I'll be driving it around tomorrow to see how it goes but early indications look good. Thanks for all of the advice.

cool57 · Post by **cool57** » March 6, 2010, 8:44 am

I have a 460 in my truck. It likes 10 to 12 degrees of timing. book tells me 14 degrees. Carl

banjopicker66 · Post by **banjopicker66** » March 6, 2010, 10:15 am

That backfire may be caused by something not engine related - a bad ignition switch.
My truck developed running problems. It would hard start, acting as though it was too advanced, then spit back when I let off the key from Start to Run.
Once I got it running, it would occasionally backfire or spit back when I turned it to Off.
Turns out it was a bad ignition switch.
The temporary fixes were as follows:
For starting, instead of letting the spring return the key from Start to Run, firmly and quickly move it to Run. Fixed the spitting right away.
For stopping, same thing. Turn the key all the way to Off, even to Acc to ensure it kills juice to the coil.

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