SBF timing set installed on Kelly's 250!

[Does10s]

Well it looks like this is going to work! Kelly's shortblock is reassembled! It's not running yet, but will be in a few weeks. She races again Labor Day Weekend.

I've been at this for awhile waiting patiently for my machine shop to finish up the required machine work.
Anyway here's what I did to get this to work. This is NOT a bolt in!
1. Turned the cam snout down to match that of a SBF.
2. Drilled dowel pin hole into first bearing race journal just like a SBF.
Clay Smith should be able to do the above two items if you special order a cam from Mike. (I just used our cam)
3. To get the sprocket-to-sprocket alignment correct, we removed .050" from the crank. This allowed the crank sprocket to move further aft.
4. Installed the crank sprocket backwards. Yes backwards. Again for alignment. (makes for real fun degreeing! )
5. Fabricated my own thrust plate. The SBF cam sprocket needs a thrust plate that is .250" thick. I Just copied the 250 one and increased the hole size to clearance the dowel. I have a radius of .118" worth of thrust plate holding the cam in the block. This is probably sufficient, but I'm going to fab up a "cam button" out of SBC version. Just for insurance.
6. Shortened the chain by 1 link.

Note the counter sunk thrust plate bolts. This was to clear the roller bearing billet sprocket. Also note the very long crank woodruff key.

Now we have a double roller, billet cam sprocket, multi-indexed crank sprocket with 9 keyways, and we no longer have that stupid little dowel pin!!!

Bigger pics athttp://www.cardomain.com/ride/686815
I'll let you know how it goes!
Later,
Will

 

[80broncoman]

looks good, also looks like the cover is a tight fit.

 

[rbohm]

8) if your mods work will, you might contact clay smith and see if they will make timing chain sets to your specs.

 

[Anlushac11]

LOL Will you never cease to amaze me.

I think you should get the innovator of the month award, if not for the year.

 

[Does10s]

looks good, also looks like the cover is a tight fit.

The cover fits just fine. No clearancing or anything required.

Although I did have an idea about a modification to the cover so I could have a "inspection cover".

I think you should get the innovator of the month award, if not for the year.

LOL! What's the phrase? "Neccessity breeds invention" (or something like that!)

Well, the stock timing set is a very weak point. I hated the fact that I knew that no matter how precise I was when I degreed the cam, that the cam sprocket/dowel interface was gonig to "lean over" and instantly retard the cam, just drove me nuts! We've sheared that dowel completly off. We've bent it over so bad the cam was unuable. And then the last one was the chain broke.
That stupid design was my nemisis!
We'll see how things go. Assuming that it's going to work, I might see if a vendor can make up a timing set with the shorter chain and give it a part number. The sprockets are off the shelf items for any vendor who makes stuff for the SBF.
The thrust plate is easy to make, so I can get a local shop to make a bunch of them fairly cheap.
Mike seems to have all of the connections, I'll give him a call.

Now that I think about it....the only item in or on Kelly's engine that is a pure, unmodified Ford part (or a equivilant replacement) is the timing cover.
Nope, that's not true! I haven't had the need to modify the oil pump drive shaft!
Later,
Will

 

[john-dickjr]

why? is there no good timing sets for a 250 ?

 

[Mustang_Geezer]

Will,

Glad to see that you guys got it fixed!! :mrgreen:

What exactly is the problem why the pin gets hammered all to pieces or bent? Is it because of the cam lift or the turbo boost? RPM's?

Just curious.

Later,

 

[rbohm]

why? is there no good timing sets for a 250 ?

8) nope. only stock timing gears and chain, and for what will and kelly do to their engines, the stock set up wont work for very long.

mg, i suspect that the stock pin is too small for a performance application.

 

[Broncitis]

Will I just love the doers and you get small six doer of the year, very very impressive, you da small six man.

 

[Does10s]

Doug,
I don't know exactly why we keep losing the timing set. It's happened with every motor we've put together. Maybe I'm doing something wrong, but I don't think so.
Our valve spring pressures are just a little more that stock do the increased lift. We're only spinning the motor to around 6200, so I don't think anything is amiss with that.

But I also did this so I can easily advance the cam and go to ANY parts dealers to get a SBF timing set. Just like rbohm stated above there is no one that make a good timing set for the US 250....NOT A SINGLE ONE! You can either get the early "straight up" version, or the "retarded" later one. Both are junk.

Later,
Will

 

[80broncoman]

Will I think it is both the RPM and the added pressure of the aftermarket springs thats killing your timing sets.
in a stock form in a falcon, maverick,.... whatever these engines see what 4000 max??
The ford people who designed the 200 figured with a 1bbl most folks would turn it 3500 or less.
its not just the lift but the duration as well that contributes to the force needed to turn the camshaft. add the higher rpm which it like hitting the chain at a much faster rate and you will eat up oem style chains and gears.
The weakness of the small six timing set is most likely why the 240-300 got the gear set that it has.
I think you have a very good fix for the problem you encountered.

 

[drag-200stang]

Will,

You're not doing anything wrong. When I was working with Ak Miller on my turbo set up, he asked me why don't I try a larger 250? and I asked him which engine had the least amount of vibration problems. He said the 250 had problems with timing chains and the early narrow one was better. That was almost 35 years ago and they still have problems.

Broncoman,

It's the longer stroke that causes the chain's problems. When the engine is under heavy load and high rpm the crank tends to whip back and forth. It's the nature of the long crank shaft and the long stroke with the 120 deg. firing cycles.

Like I mentioned in another post, the 200 uses the same cam. I use a high volume 250 oil pump (custom made) and have run stiff springs and pretty wild solid lifter cams with no chain issues at all. The chain is, of course, shorter. But the 302 doesn't seem to have issues and they are a link longer.

Will, your set up looks nice, good luck with it.

 

[Crosley]

This timing set SBF on the inline is eggciting stuff. I hope this mod works well. I would like to run a higher cubic inch motor.

With the computer tech on hand now , machining a few parts is slightly easier in 2009 than 1969

I have 30 full passes on my 200 cid engine with the timing set from Mike. I only spin the motor to 5500

 

[Does10s]

Kelly and I installed her motor yesterday. So it's almost ready to run again.

I did finally come up with a "cam button" design that I think will work just fine. We'll find out. I took a pic of it, but haven't downloaded it yet.
For those that might not know....a cam button is a device to help limit the amount of cam walking in the forward direction. The only off the shelf ones that you can buy are for a SBC. It might be the only design the might require one....I'm not sure! I'm not a Chevy guy!

The normal thrust plate usually performs this task just fine, but I made my own thrust plate for the SBF timing set, so I added my own cam button as a little sercurity.
I'll let you know how it goes!
Will

 

[russk]

Great job on the timing chain migration and I'll be interested to see what you've come up with for a "button". Sure hope this works well for you since I understand the timing unit is a weak link in the 250 small six.

I'm certainly no expert but I remember reading something about the SBC cam buttons, that they were only required for roller cam applications (I am presuming they mean solid roller cam and not hydralic rollers but perhaps it applies to both). As I recall, the text indicated that the cam lobes on typical SBC hydralic and flat tappet cams were ground with a taper in such a way as to interact with the lifter to put a slight rearward load on the cam that kept it from "walking" back and forth. In any event, I don't think (but I may be wrong) that cam buttons were ever a stock Chevy item and only came as an aftermarket (racing) piece.

 

[powerband]

Could the 250 SBF timing chain setup be made available ? , how much interest is there?.

 

[Does10s]

Could the 250 SBF timing chain setup be made available ? , how much interest is there?.

Powerband,
Do you want to see if it'll work first?

But as I said in the first post this is not a bolt in setup. So the interest would probably be minimal. If someone happens to be rebuilding a 250, then it wouldn't cost much more to do this vs. a standard version.

But if this works I'll check into the possibility of making a few.
Will

 

[Does10s]

Well, for those who care.....
We started Kelly's engine on Friday. So far it's running just fine.
So this is probably the first time a double-roller timing set has been run on a US 250 motor!
We're driving it out to dinner tonight so we'll see how it does under some load.

While I was at it, I fab'd up a larger exhaust system. It now has a 3.5" diameter single exhaust that exits at the rear bumper. Muffler in the stock location.
Sounds pretty good! A bit lower in pitch and it doesn't sound like it's pushing the air out. Maybe we'll pick up a mile or two in the 1/4!

We also had the seats recovered and installed new carpeting. So we were thrashing all weekend!

We race in Las Vegas this coming weekend with the PSCA. Wish us luck!
Later,
Will

 

[rocklord]

Luck!

 

[Anonymous]

Hey Will,
How did the SBF Timing chain mod workout?
Ken