Yes I am well aware of that. I was just trying glean experience from those who have actually done the work on the 460 with the available 3 keyway chain gear sets as to if they "Seat of the pants" got any benefit from altering of theirs when installing a cam. To many variables for sure but a general overall was questioned.

I am tempted to install the new chain gear set as far advanced which is +4° to get that torque curve down low in the rpm zone. Previously, a few decades ago I was playing with high rpm SBC. The BBF is a different critter in a different chassis with radically different behaviours.

 

Moving the cam forward will make a big difference in the low speed torque and performance of the engine, any engine, Ford 460, small block Chevy etc. Why this is so is simply because it closes the intake valve earlier with the same amount of duration. The problem is that when you move the cam you change all of the events not just the intake closing point. Most importantly you open the exhaust earlier in the power stroke. This event is critical in a low compression engine because the burn happens more slowly and there's more combustion happening later in the power stroke than in an engine with higher compression. Start dumping it too early you generate a lot more exhaust heat and you also dump a lot of your torque right out of the tail pipe. So I'd say that if you could get it to about a 112 ICL that'll probably be about as good as you can do with the stock camshaft which I think is ground on a 115 lobe sep.

 

Hey do you happen to have the link to the thread for an in depth explanation of ICL (Intake Closing Limit?)
once I got a lot of brackets and accessories outta the way it seems the old 87 460 only has about 4 degrees of crank chain slack at 100,000 miles but since I'm in as far as water pump already off I might as well check the cam spec in this block which is s smogger engine for sure. Most likely a 1986 that got sent over to Glendale for completion of the MH chasis and classed as a 1987. Being a one ton chassis hoping it has a decent cam profile for 2500-3000 rpm peak torque powerband. What would you suspect i will find for ICL. Lobe separation angles etc and s suggested method to check. It is being fed with a 750 cfm holley 3310-2 vac secondary true dual 2.5 exhaust thrush 2 chamber mufflers. (Nice rumble) presently nice smooth idle, vac reading not recorded ing timed at 8°BTDC cloyes double roller T Chain set arrived it has -4° 0 +4° keyways. Thoughts and rational please.
Or do I just seal the new water pump back up and letter buck. Summers getting shorter every day.

 

I looked through my library of cams that I've plotted and I've got 3 cams on file. All of them are slightly different with very similar durations and lobe seps but differing amounts of lift. All are ground with a lobe sep that's between 112.5 and 113.5 so I'd say that 113 is the spec. As far as the duration is concerned they all have an intake duration that's in the lower 190's, about 193 degrees @ .050 with a valve lift of about .420. This is probably pretty good for the application, it's certainly not out to lunch on the intake duration. The exhaust side has between 204 and 208 degrees at .050 duration with the carbureted 460 cam being the smallest at 204 and one of the EFI cams being the largest at 208 @ .050.

I'd say that the best intake centerline for a cam that's a dual pattern and ground on a 113 lobe sep will be at about 111 ATDC. This will give it some advance but not get the exhaust opening event happening way too early. Best for low speed torque would be a single pattern cam with between 190 and 200 duration @ .050 on about a 108 or tighter lobe sep. A cam ground using the stock intake lobe on both sides on about a 107 and in on 105 would be very interesting.

The cam that's in my 460 now is 200 @ .050 intake and exhaust on a 107 lobe sep in on 104. This cam runs VERY well in a low compression carbureted 460 with an E4OD transmission and a 4.10 gear. It does good for mileage but it does have a noticeable non stock idle. My truck has headers, 2.5 inch pipes to a Magnaflow muffler where it comes out as a single 3 inch.

The rationale behind this strategy when camming low compression is to get the intake valve closed early to build low speed power and to open the exhaust valve later to avoid excessively high EGT and to build more low speed torque. This means that the duration has to be short and the lobe separation angle tight to really make it work well. This also works on engines running on fuels like propane and natural gas.

 

What did your experience find when it came to what Ford put in as stock cam in that carburetor versions. I am really trying to avoid ripping further into what might not be necessary. I got rained out today so I am not working on the MH outside in the rain stuff. Just finishing up an adapter bracket to hold a 130amp 3G alternator in the stock mounting position but using 90° clamping bolts instead of the long 7/16" bolt that won't come out until the radiator us out. Simplified with a 3/8" pipe sleeve and some angle iron.

 

Here's the cam card from the stock carbureted 460 cam that I plotted. I show it here on a 105 intake centerline(7.3 degrees advanced) but that's probably much more advance than what's actually used. With the retarded timing set it is probably back on about a 120 intake centerline and with the non retarded it is probably at 110-112 intake centerline.

I get my information when different engines and cams come through our shop and sometimes I plot them using my test fixture and Cam Analyzer software from Performance Trends. I've plotted a few hundred cams from all sorts of different engines and I've learned a lot. Some of cams have been very interesting.


This is a plot of a stock carbureted Ford 460 camshaft. Very similar to the EFI version except for having a slightly shorter exhaust duration.

 

Stock 460 #2 is probably an aftermarket stock replacement 460 cam.



EFI 460 is a factory cam from a stock Ford 460 EFI engine. As you can see there are some differences but not a whole lot. I'm just not 100% sure about the installed centerlines.

 

I took mine apart today and what it is, is a bone stock retarded gear marked (alignment mark slightly off of keyway). Stock link style chain with the dreaded nylon gear drive, enough slop to be classified as a piccadilly lady of the night. I am still not wanting to dig into the degree wheel dial indicator measurement because what I found is proof enough it was time to repair anyways. Well I might unless I start drinking adult beverages while pulling wrenches. Your knowledge base is greatly vaster than mine and I truly appreciate your replies and feed back. The giant Ford #10 timing pointer secondary bolt broke off in the cover. So I've got a few little things to gobble up my time that I was supposed to already be at the lake. Grand kids have been there since the first of August wondering when we are going to join them. I am so tempted to put it in at +4 Instead of just straight up. Now I just got a call from a friend I need of mechanical assistance on a parking lot sweeper stuck in the lot. It just never stops.

 

So I have already pulled the old worn out chain set. So I either I have to put it back in and do some rotations with dials on number 1 in and ex. Or just install the double roller set where I think it should match up if my stock cam is ground the 7ish degrees advanced your experience led you to discover. Or I am going to start the process at straight up on the Cloyes roller set and hope it was a valid good guess. Just not tonight.

 

If you look at your timing set the timing mark for the zero position should be directly in line with the key slot. If it is that's where I would put the cam timing if you're not going to degree it in it won't end up over advanced and it will be much better than where it currently is at with the factory 8 degrees retarded timing set.

 

The factory gear set has the timing mark keyway almost 1/2 a tooth offset. Since there are 18 teeth that puts me at almost 10° retarded gear set. If the grind was +7.3° but backset almost 10° for an overall effective of 2.7° retarded does it not. If I use the straight up I will be advanced to +7.3° effective overall. Even using the -4° mark I will still be at advanced overall of 3.3° would I not.
It gets a tadd mind twisting why Ford ground in an advance only to take it away with an offset gearset.

 

I don't know what intake center line was actually used on the factory cam but I'd assume that it isn't 105 as shown in my data but probably more like 110 or 112 the 105 center line is arbitrary and just what I used when I plotted the cam. If the stock cam is at 110-112 that would put your cam retarded to about a 118-120 intake centerline. I'd recommend using the straight up position so that you don't get the cam over advanced. It is a big difference and as you've seen it is enough that you can tell just by looking at the gear.

Why Ford used a different bottom gear instead of a different cam grind is a mystery but it was probably just the least expensive way to change the tune up enough to meet emissions requirements. They just had to broach the keyway in a new location.

 

So looking at the gear set regardless of the numbers the new double roller will have to be set at the retarded position which is -4° to not be as retarded as the factory link version which looks to be at least -8°. This will result in my timing being not as retarded as the factory setting. If I use the straight up keyway I will be advancing it almost one full tooth. The cloyes roller gear set which is 16° per tooth. Cloyes gear set has 22 teeth and the Ford link style chain only has 18 teeth, for an effective movement of 20° per tooth. It just seems like straight up might even be more than a person should go. Going to a lot of mental work to prevent physical work... lol
I didn't even want to go in this far into the engine after having several exhaust bolts break off and now one timing pointer bolt. After seeing how stretched the Ford link chain was I am glad I did. I only have 9 days vacation remaining. Saving fuel but getting lots of knuckle skin rash and permanent dirty fingers.

Thanks for tolerating my decision process along the way.

 

Not at all surprised that Ford would experiment with cam time and tuning and not tell anybody
Thanks for all that Dave and the cam specs
I own a degree wheel (one of those cheaper comp cams kits for s sbc)
Why couldn't a guy just use the degree wheel and see where say the intake opens on 1
Then try to set up the new cam and gears to that position and call that zero or whatever the number is for your motor?
I have a gear drive for mine and a crane bumpstick . I assumed I would not have to think too much, but now?
Shouldn't I just use the cam card and do what crane says as to line it up
I plan on experimenting anyway but want to think I am starting at zero
Any suggestions Dave?
Thanks

 

I think that I would go to the zero position( the one with the mark in line with the tooth). Without a degree wheel it is tough to know for sure if the +- positions are 4 crank or 4 cam degrees. I've seen both kinds on a 3 position set. I guess you could measure and figure it out pretty easy. You know the size of the hole, you know how far it is in circumference so then you could measure to see how much it has to move to change X amount of degrees. Most of the time timing sets are made pretty accurately when it comes to the zero position. It'll be interesting to read how it runs with the cam forward and in the position that was originally used for the 429 and 460.