Ford Truck Enthusiasts Forums - Recurve on 460

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Recurve on 460 - starting point?

First, let me say I have read some of the better write ups about changing the advance curve and the vacuum advance on the Ford distributors. (Lots of good information and very fascinating - in my opinion.) At this point, I am comfortable taking a crack at it.

I have a mild built 460 (bored .030 over, ported exhaust on D3VE heads, performer intake, 1411 carb, mild Summit cam, about 9.0:1 C/R) with a remanufactured Ford distributor from Napa. I also purchased the Crane vacuum advance kit.

Upon removing the breaker plate from the dist, I found the two clips - 10L and 16L. The clip currently being used is the 10L and my initial timing is set at 12* BTDC. Giving me a total advance of 32*.

I would like my total advance timing to be all in by 2500-2800 rpms.

I use the truck for a variety of situations - running with no cargo, hauling 4-5K lbs in the bed, towing a 2500 lb boat. Most of my driving is around town - maybe 20% of the time is spent on the freeway. I would like to tune the distributor with the ideal setting for my application while offering a decent amount of power from a dig.

I realize every motor will be different and there is no generic setting that will provide the best performance' however I would like to know what others have done (advance curve, vacuum advance setting, lighter/heavier springs on the dist, 89 octane, 92 octane, etc) with a similar set up.

Thanks.

Well, I wanted all my advance in by 2500, I ended up pulling 1 spring out of the dist and that put it right on the $!!!!!!!!!

Quote:

Originally Posted by Beechkid (Post 11609645)

Well, I wanted all my advance in by 2500, I ended up pulling 1 spring out of the dist and that put it right on the $!!!!!!!!!

You mean replacing that one spring with a lighter one or completely removing it??

Usually just running the one light spring & tossing out the heavy spring will result in a ping. I run 2 of the stock light springs in mine.

Quote:

Originally Posted by Myfreeford (Post 11609649)

You mean replacing that one spring with a lighter one or completely removing it??

I completely removed one spring...on the older 60's units, both springs were the same....later on, one was typically heavier than the other...I would remove the light one first...try it.....if no ping and not quite enough, then reinstall the light one & remove the heavy.....if it pings, then you can buy a a spring (or set of springs- whichever you like) that will have the "medium" setting.

I just finished (1000 mi. ago) rebuilding the 460 in my 1977 Ford F250 4X4, manual transmission, 4.10 gears. The 460 is from a 72 Lincoln with D2VE-AA heads (yes I know they are no good for performance applications but, they work fine in my application. It is built for 4500 rpm. max. The engine is bored .020 over and the heads had been milled (not much according to the machine shop.)I expect the compression ration is just over the stock 8.5 to 1. I am running a Holley 1850 on an Edelbrock Performer intake manifold. Exhaust manifolds are stock with 2 1/4 in. pipes and Flowmaster mufflers.

It has a Comp Cam: 210/218 duration @ .050 "lift with .514/.514 gross valve lift.

The distributor is for a 72 Lincoln supposedly but, from what I know, when you buy one from a parts house you never know exactly what you are going to get. The one I bought came with a dual diaphragm vacuum so I bought a single diaphragm vacuum unit. The centrifugal advance choices are 13 and 18 degrees. There is one spring on the 13 degree tab.

I was advised by the machine shop people that the cam I used "likes" some advance over stock. I aimed for no more than 40 degrees total advance. I tried several combinations and settled on 15 degrees BTDC initial, 12 degrees advance @ 18" vacuum and 12 degrees mechanical advance @ 2000 rpm. I live at 4700 ft. and use 88 octane fuel. It isn't hot here yet so I will have to see how things work when it is.

Quote:

Originally Posted by Harley48 (Post 11640966)

Good info - thank you.

I am curious how you got 12 degrees mechanical advance if you have the spring on the 13 tab in the dist? I thought using the 13 tab would equate to 26 degrees mechanical advance and 15 initial would give you 41 degrees of total advance.

Good question. I am with you-I thought the 13 would equate to 26 on the crank. I ran it up to 2800 and 12 mechanical was all I got. I admit I was confuded.

MyFreeFord, how much vacuum advance are getting from the Crane unit?

I have not yet installed it. Hopefully tonight.

After your post, Myfreeford, I went out to the shop and rechecked my work.
I disconnected the vacuum line from the carb to the distributor and read the inital timing-it was 15 degrees BTDC.

Leaving the vaccum line disconnected and plugged, I set the display on the timing light back to 0 at idle and then ran the engine speed to 2800 rpm. Mechanical advance increased to 12 degrees @ 2500 rpm and did not increase between 2500 rpm and 2800 rpm.

With the engine at idle and using a vacuum pump to apply vacuum to the diaphragm at the distributor, I increased the vacuum to 18" and got 12 degrees which is what I had set the diaphragm to previously.

Maybe, somewhere along the line someone put a really stiff spring on the mechanical advance which is limiting the mechanical advance to the 12 degrees even though the tab is clearly marked 13L. It would be interesting to know.