Blowing 3 Gees on my Six

[Luke76]

Here's a photo of my crank with the Mr. Gasket key for comparison. Bubba, I tried your trick of soaking the existing key in PB Blaster and then wailing on it with a punch. All I managed to do was start to flatten the key and I was afraid all my banging might be hurting the crank bearings. So I'm probably just going to leave well enough alone. If I could get it out and if it weren't too much work to fit the new key I might compromise and install the cam 2* advanced. Maybe I'll tap on it again tomorrow after the PB has soaked in a bit more... but if not, I'll probably be fine installed straight up.

(Click for larger versions)




And, if anyone wants to see the 250 timing set, here's another photo. You can see there are zero adjustments as it comes stock, without using an offset key or machining the gears.




On my Clay Smith cam anyway, the cam gear is indexed with a dowel pin.

 

[FalconSedanDelivery]

Keep in mind , Straight up is only that if you degree it and THAT is what it is , lining up the marks IS NOT Knowing ,using a degree wheel a positive stop ( finding true TDC ) a dial indicator along with the knowledge and patience to do is the only way for sure to know the exact timing events

 

[drag-200stang]

FalconSedanDelivery is absolutely correct on the above post. Without degreeing it you're wasting your time trying to figure out what degree key to use. You may be exactly where you want to be or you may be a mile off. It must be checked first.

I've used Key #985, which is for a SB Chevy. It is 1 3/8" long. The one you have, they call short, is under 3/4". Granted, I have not used it on a 250. But the 250 key way is just a touch longer (hardly any). You may have to touch up the key way a little bit on the grinder - no big deal. You may want to split it and use a straight and a offset key. But at least with the long keys you'll have enought material to shape it how you want. No sense worrying about it until you degree it - it is simply pointless.

It looks like your key is damaged now. I've had luck getting the keys out by driving them straight back. They'll ramp out and then you can pry them out. You'll need some kind of hard, square-edged chisel. May have to tap it side-to-side some to loosen it.

Not to add more stress to your build, it looks like you have the late model wider chain - can't tell for sure in the pics but, Ak Miller recommended the early narrow timing chains because the additional weight of the later model, wider ones would cause them to whip. It may not be an issue for what you're doing though.

 

[Luke76]

Sweet mother of Jesus, there is nothing ever simple about this effing build...

Timing Gear
Drag-Stang may have been right about the timing set being the late version. If you look closely at the photo posted above of the timing chain, the Cam Gear is part number S442, which is the late model gear. The Falcon Six Handbook says I need part number S414 which is the '69 "early" gear that is advanced about 7 degrees cam (3.5 crank) from the later gear. The Falcon Six Handbook also says I should have crank gear number S415, which I do have as you can see in the photo. So I've got half of the setup right...

I bought the timing set from Classic Inlines. They specifically say they only sell the "early" timing set because it is more desirable, and if you really must have the later set you must specify it and it will have to be special ordered. However, even without having specified this, it would appear I was sent the late Cam gear anyway. That or the machine shop gave me back my old cam gear, which I will ask them about on Monday.


Degreeing the Cam
Here are the numbers from my first pass at this process, boy is it time-consuming. One thing I noticed is that I consistently measure duration at 0.050" as 218*, whereas the spec card says 214*, but maybe this is not a big deal.

When I got the block back from the shop they told me they had installed the cam "straight up." Here are the numbers I got from their installation on the intake lobe:

Duration at 0.050" Method
Intake 0.050" opening side = 5* after TDC
Intake 0.050" closing side = 223* after TDC
Duration at 0.050" = 218*

Centerline Method
114.25* calculated lobe center

Now you can see the Cam card below, the lobe center is supposed to be 112* which by the Centerline method I am off a tad over 2 degrees. Duration is supposed to be 214*, which I am off by 4 degrees (218*).

As for the degrees BTDC that the intake valve is open at 0.050", I get 5* AfterTDC. The spec card doesn't give opening and closing events at 0.050" lobe lift, only seat-to-seat timing. So that is not very useful for this process, to say the least.

I decided to advance the cam one sprocket (should be roughly 17*) and try again to verify my numbers. Here are the results of the next try, again, intake lobe only:

Duration at 0.050" Method
Intake 0.050" opening side = 12* BTDC
Intake 0.050" closing side = 206* after TDC
Duration at 0.050" = 218*

Centerline Method
96.75* calculated lobe center

You can see that now my intake valve opens 17* sooner, closes 17* sooner, duration at 0.050" is unchanged at 218* of course, and now calculated lobe center dropped by 17 to ~97*.

When I was out at the garage I only measured the intake valve, and I couldn't figure out whether I was advanced or retarded. I realized after I got home that I need to compare the phasing with my exhaust lobe. So I will do that next...

All of this was with the straight crank key, no offset there. If I end up retarded it is because of my cam gear.



Cam Card:

Positive stop used to determine TDC:




Degree wheel:

 

[bubba22349]

Looks like you would be very close to straight up with an early cam gear

 

[Luke76]

Went back out in the blazing heat and made a few more measurements. First, I set the cam and crank gear with the dots pointing toward each other, that the machine shop had indicated was "straight up." All readings at 0.050" lift -

Intake Lobe
Open 5* ATDC
Close 223* ATDC (43 ABDC)

Exhaust Lobe
Open 141* ATDC
Close 1* BTDC

According to this website at ISKY, using what they call "Top Timing" (Intake open and exhaust close), it would appear my cam is presently retarded by 2*. Can anyone confirm this? All the tutorials on the CI website tell how to measure events, but they don't say much about determining advance/retard other than to "compare specs with the cam card."

It seems to me that truly straight up would have Intake open at 3* ATDC and Exhaust close at 3* BTDC (at 0.050" lift), which is a difference of two degrees from what is measured above. But if I am reading this wrong, please let me know!

Hopefully I'm seeing this correctly. Assuming the early cam gear gives me 3* advance, that would be just perfect. I went ahead and ordered one from NAPA, should be here later this week. Kind of expensive at $50, but would take way too long to try for an exchange through CI. I'll post back when I get it.


Luke

 

[FalconSedanDelivery]

If your sure of your measurements, than if they don't match the card the cam is advanced or retarded based on it , if it says it should be 5 before and its 3 before its 2 degrees retarded if it says5 and its 7 its 2 advanced always turn the crank in one direction ,if you go past a point , turn way back and sneak up on the spot again , True TDC is a Must have , no its close or your wasting your time , also if indeed is just two degrees off , leave it be , too much work on those series engines , compared to what 2 degrees would effect ( probably not measurable ) its how picky you want to be

 

[Luke76]

If your sure of your measurements, than if they don't match the card

I trust my measurements, and my ability to locate TDC precisely, no problem. It's not that my measurements don't match the card - it's that the card doesn't include the information I'm measuring, unless I just don't know how to read it.

I posted a picture of the cam card above. It does not give opening and closing at 0.050", so there is nothing to compare my numbers to. The only thing it gives at 0.050" is duration, which as it turns out the card is 4* off on measured duration.

The opening and closing events listed on the card appear to be seat-to-seat so far as I can tell, which is really about impossible to measure accurately no matter how careful you are, because the lobe is very gradual when it first starts to move the lifter, so there is no way you can be precise about when the event first occurs.

That is why I have gone to this definition of "Top Timing" from ISKY, which compares the positions of Intake Open to Exhaust Close relative to TDC. It only works for single pattern cams.

I will do some more searching of the forums here... lots of people have used these CI cams, so there must be a way.


Luke

 

[MPGmustang]

just a refresher
http://www.youtube.com/watch?v=zj-GA494SJQ

locating TDC is easy... making sure the cam shaft does what it says is the main issue...

if your lobe centers are 112 then you want your cam to be max lift @ 112, find max lift, then measure highest lift .050 before and after, then avg the two numbers, if it's more or less than 112 then it's either retarded or advanced. double check the exhaust lobe also.

 

[Luke76]

Thanks Richard, I've watched that video many times. My biggest problem right now is that Clay Smith does not list events at 0.050", they only list advertised duration which is not of much use for checking with a degree wheel (Bill states this in your earlier thread, here.)

I think I might call Clay Smith on Monday to see if they can give me events at 0.050"...

Until then - the '69 cam timing gear cam in from NAPA. The Falcon Handbook says it is roughly 7* cam degrees advanced from the '72 gear I had previously. In my measurements it is more like 9-10 cam degrees advanced.

Previously, I was getting these numbers at 0.050" lift:
Intake Lobe
Open 5* ATDC
Close 223* ATDC (43 ABDC)

Exhaust Lobe
Open 141* ATDC
Close 1* BTDC

Intake Centerline
114*

With the new cam gear, I get these numbers at 0.050" lift:
Intake Lobe
Open 4* BTDC
Close 213* ATDC (33 ABDC)

Exhaust Lobe
Open 131* ATDC
Close 11* BTDC

Intake Centerline
104*

You can see everything has shifted 9-10*.

I have also tried doing what you suggest Richard, and what is discussed on the CI website, called the "centerline method" where you take a reading 50 thou before and after max lobe lift, add, and divide by two.

With the previous gear, I was getting roughly 113-114* centerline on the intake lobe. Now with this new gear I am getting ~103-104*, once again, a difference of about 10*.

Does this mean that before my cam was retarded 1-2* (it's supposed to be 112* centerline), and now it is advanced 7*?? That would be way too much advance.

Supposedly the centerline method is not as accurate which is why I would prefer to use the "Duration at 0.050 Method." However, this method is not of much use to me because Clay Smith does not provide events at 0.050.

I swear if the odometer were hooked up to my engine, I've put a hundred miles on it by hand doing all this cam degreeing. I really want to get it right but it has been very frustrating.

Again, I think I'm just going to try calling Clay Smith on Monday morning....



Luke

 

[MPGmustang]

FOUND IT!!!

http://www.wallaceracing.com/Calculators.htm

I've been looking for this place for a while, but there are some great free cam calc's on here, some that take your 'card' info and put them to 'cam timing events'

don't have much time as I gotta run, but I figured I didn't want to loose it... have fun play'n

 

[Luke76]

Ok guys, I'm sure everyone here is about to shoot themselves in the head, so hopefully this will be the last post on degreeing the cam.

I called Clay Smith on Monday and the guy they had me talk to seemed to be knowledgeable and friendly. He said that Clay Smith recommends the Centerline Method for degreeing the cam (he called it the "Lobe Center" method but the way he described it is exactly what Classic Inlines calls the "Centerline" method). In his opinion he thought this was the better approach.

To recap, to find the lobe center, you zero your dial indicator at max lobe lift on the #1 intake lobe. Then you back off about to about 100 thou before (so you can be moving in the clockwise direction to remove any chain slack). Then move forward. Check the degree wheel at 50 thou before max lift, then continue turning up to max lift, past it, and record the degree wheel again 50 thou after max lift. Add the two numbers from the degree wheel together, divide by two, this is your lobe center.

The Clay Smith cam cards indicate what the lobe center should be straight up. My cam is a 112* lobe center cam, so if by the method above I got 112*, I would know my cam was installed straight up. If the number is less it would be advanced, more would be retarded.

Here's an interesting aside - as we know, the Clay Smith cam cards do not include timing events at 50 thou lift. However, he said you could deduce it from the info they do provide. Namely, if you know the duration at 50 thou (which is on the cam card), and you know the lobe center, you can calculate the opening and closing events at 50 thou.

Take the duration at 50 thou and divide it by 2. My cam has an advertised duration of 214* at 50 thou. Divided by two is 107*. Subtract 107* from the lobe center to get intake opening at 50 thou. So for me, 112*-107* = 5* ATDC should be the intake opening event at 50 thousandths lift.

Add the other 107* to lobe center to get the intake closing event. 112* + 107* = 219* ATDC should be the intake closing event at 50 thousandths lift.

Now on my cam, measured duration at 50 thousands lift is actually 218* degrees, even though the cam card says 214*. But if I used 218* I was always able to precisely confirm my lift at 50 thousandths figures that I saw on the degree wheel.

- - - - - - - - - - -

Anyway... all this to say that you can see from my prior post that the S414 timing gear gave me a lobe center of 104*, which is way too advanced. Skipping a tooth would put it up to ~120*, way too retarded. So ironically, the early cam gear (S414) did not work out for me.

The "late" timing gear (S442) had gotten me a lobe center of 114* which is only 2 degrees retarded. So I ended up keeping this gear and using a Mr. Gasket 988G 4* offset key to advance my lobe center to 110*, which is now 2 degrees advanced. The Clay Smith guy thought I would be happy with about 3* advance given the specs of my car, so I think this should be pretty good.

I had to do a lot of grinding, filing, and cursing to get the offset key to fit just right. The 988G is a very short key, but it's plenty long enough to contact the crank gear, which only "sees" about 1/2" of keyway. For the remainder of the keyway, I used the original straight key from my crankshaft, cut to size. This will mean my harmonic balancer will be installed straight on the crank, not advanced. I'll try to take a picture although by now I already have the crank gear installed.

- - - - - - - - - - -

Now I just need to get the head back from having the spring seats machined, and I can button this engine up, paint it, and get it reinstalled (I also still need to finish painting the engine bay, what a helluva job that is...)



Luke

 

[chad]

Thanks 4 the update, really appreciate it
AND the build thread!

U go man! Not long now!

(no envy here on the "paint the engine bay" task.)