BBF timing sets

[roostwear]

If you've used a Summit timing set, you may want to check this out. (http://www.roostwear.com/forum/viewtopic.php?p=1281#1281)

[LakesOnly]

(Ahem) Is there anyone else you would like to give credit for this "newfound discovery?" :wink:
But seriously, as I stated in my PM, the 72-up chain is zero'd as Summit/Cloyes says, because they are selling you a 72-up chain...and that's exactly where zero was for 72-up: it was located at +4*.
Silly, I know...
LO

[roostwear]

Thanks for the PM to clarify. What surprised me wasn't that the index on the new crank sprocket was correct, but that the CAM sprocket was retarded. Half ass way of doing it.
So, what's your guess on what difference advancing the cam on the Advantage will make?

[dave186]

i think you guys just made me realize what i did wrong on my truck. I swapped to a 5.0 roller cam, and all the lightning boyz told me to put it in 2 degrees advanced to gain back the bottom end for this heavy truck. well i didnt do it right, i think it must be like waaaaaay to far advanced. i simply lined up the dots at zero then slid it on in the 2 degree keyway. i feel so damn stupid now, i was out checking lifter preload and everything. i wish the directions with the timing set said something about how to install it!

[LakesOnly]

What surprised me wasn't that the index on the new crank sprocket was correct, but that the CAM sprocket was retarded. Half ass way of doing it.
So, what's your guess on what difference advancing the cam on the Advantage will make?
Roost, you're right, when one considers the indexing on the factory gearset, the proper way to "interpret" the 1972 change is that the crankshaft was advanced in 1972, not that the cam was retarded. So I guess most of us gearheads that tinker with our engines think of it as retarding the cam...
But it's all relative in the end; is the crank advanced or is the cam retarded? (Is the glass half-empty or half-full? Same kind of deal.) And so I guess it doesn't really matter where the change is made (cam gear or crank gear) as long as we be thinkin' about it. Too bad the aftermarket guys didn't keep it simple...
Difference on the Advantage: By effectively advancing your cam as you did (by way of using the +4* setting on the retarded timing set), you help low-end response. Top end will be hurt somewhat more than usual because--as you observed in your other thread--the 72-up cam is also changed to accomate the revised cam timing of the later engines.
LO
p.s. If all you are doing is swapping chains, then don't forget to correct your your distributor timing.

[roostwear]

The engine that is pictured is going back in the roadster, and performance isn't that big of an issue. The Advantage has the same set, and (I'm afraid) has the cam retarded 4 degrees. As I remember, retarding the cam kills cylinder pressure, so setting the cam straight up (assuming the cam wasn't ground with the index retarded relative to tdc) should give me a little more compression. What effect that will have at 4800 rpm remains to be seen.

[LakesOnly]

The engine that is pictured is going back in the roadster, and performance isn't that big of an issue. The Advantage has the same set, and (I'm afraid) has the cam retarded 4 degrees. As I remember, retarding the cam kills cylinder pressure, so setting the cam straight up (assuming the cam wasn't ground with the index retarded relative to tdc) should give me a little more compression. What effect that will have at 4800 rpm remains to be seen.
Yes, advancing the cam moves valve timing events forward...closes the intake sooner as you pretty much stated.
What I would probably do...leave the chain alone/not hassle, and just "crutch it" by twisting the dizzy over a little more to make up for the lesser cylinder pressure...
But then again, it is off-season...who knows...
LO

[roostwear]

I've been slowly dialing in the ign timing, and if the cam is retarded, that would explain a bit. Right now I'm running 40* all in at 3000 which I felt was a little stout, but no signs of detonation, and I've even run it on 87-89 octane with no problems. It's only at 8.5:1 with D3s, so I probably could have cranked it up a little more (but wouldn't).
I might try pulling the timing cover in the boat (I'm all out of engine stands at the moment) to check it out.

[LakesOnly]

...I'm running 40* all in at 3000 which I felt was a little stout, but no signs of detonation, and I've even run it on 87-89 octane with no problems. It's only at 8.5:1 with D3s...
The low c/r (ie. low cylinder pressure) allows you to start your burn earlier without reaching pressures/temps that are cause for detonation. Still, do plug readings and look for the aluminum on the nose of the plug. Inaudible detonation is common in these engines with the thru-transom exhaust.
Coincidentally, in the jet boat, I'm @ 40BTDC with my D3's too, but I am running straight AvGas with the 10.6:1. Polished combustions chambers, too, for what they're worth.
LO

[Squirtin Thunder]

Lakes,
What did we figure the C/R was with those pop-up pistons and the D3 heads ???
Jim

[LakesOnly]

Lakes,
What did we figure the C/R was with those pop-up pistons and the D3 heads ???
Jim
Funny thing about D3's is that as of late people are cc-ing them and finding uncut D3 chamber volumes all over the place, from about 91cc's to 100+ cc's, depending on the head that is evaluated.
Most often they are 96-97 cc's, and calculating the TRW L2443NF30 piston with a 96cc D3 head on a stock stroke motor, compression ratio is ballparked at 10.66:1
LO

[roostwear]

Thought you'd get a kick out of this. Look closely at photo #3. (http://www.fordmuscle.com/archives/2004/06/460Build/index2.shtml) They set it up "straight up", but this is the same set I have, and we KNOW what that means! Doh!

[Squirtin Thunder]

Thought you'd get a kick out of this. Look closely at photo #3. (http://www.fordmuscle.com/archives/2004/06/460Build/index2.shtml) They set it up "straight up", but this is the same set I have, and we KNOW what that means! Doh!
Mike I ran one of those and it retarded. The power wasn't bad but the exhaust temp was the biggest problem, it screwed a good set of headers. Now that I have an early timing set it is a bit snappier. There is only about 50hp right there, the cheapest 50hp you can get.

[roostwear]

That also explains the paint burning off the exhaust ports the way it has. So with another 25-50 horse, and a set of D0VE heads to get my compression up around 9.5:1, I could crack 75mph....... :idea:

[Squirtin Thunder]

That also explains the paint burning off the exhaust ports the way it has. So with another 25-50 horse, and a set of D0VE heads to get my compression up around 9.5:1, I could crack 75mph....... :idea:
Mike I have seen as high as 65hp on the dyno with the Big Bad Fords with cam timing changes. Now going with a good port job on a set of D0 heads you could pick up about 75hp. The C9 heads may give you a few more hp !!!!
The C9 heads are 73cc - 75cc
The D0 heads are 75cc - 77cc
Jim

[LakesOnly]

That also explains the paint burning off the exhaust ports the way it has. So with another 25-50 horse, and a set of D0VE heads to get my compression up around 9.5:1, I could crack 75mph....... :idea:
I got the D0VE's if you need 'em. Ported or not. PM if interested.
p.s. Don't be surprised if engine paint regularly burns off aound the roofs of the exhaust ports on our sustained high rpm boat motors.
LO