Timing Chain Set (250) - Help
- Thread starter dayman
- Start date
Thanks rbolm
I have read everything I can find on the forum and came to the same conclusion. I don't have the means to make the 289 chain work, although it would be interesting to do. My car is a good weather driver - mid cam, headers, OZ head. Stock chain set will work fine.
I have read everything I can find on the forum and came to the same conclusion. I don't have the means to make the 289 chain work, although it would be interesting to do. My car is a good weather driver - mid cam, headers, OZ head. Stock chain set will work fine.
I used a new standard 250 timing set. I degreed the cam with that found it was 8* retarded from where I wanted it to be. Then I had my local machine shop cut a couple of extra keyways into the cam sprocket to give me some adjustment.
Using this method I advanced my cam from 116* to 109*
If you want any further info just ask
Nathan
Using this method I advanced my cam from 116* to 109*
If you want any further info just ask
Nathan
Hi Steve,
I will try and answer all you questions and proviode some more info for you.
Did you consider cutting the crank gear? - Mine was already pressed on to the crank so it was easier to modify the cam sprocket. I see no reason you couldn't modify the crank sprocket to get the desired effect.
Did you do anything to the gear other than have the keyways cut? - No I just had to two keyways cut.
How did you determine where to make the cuts?
First I installed the timing set straight up (with the marks lined up) and then degreed the cam to determine a starting point. I determined I was 8 deg retarded from where I wanted to be. There are 42 teeth on the sprocket - that is approx 8.57 deg per tooth. But remember that 1 deg at the cam = 2 deg at the crank.
So i decided I wanted new keyways at 2 and 4 degs (at cam). The original key was half way between two teeth (top) so I had one keyway cut inline with a tooth to get approx 4deg (left bottom) and then one keyway cut at 2 deg off the centre line between two teeth (right bottom). I had them cut at 1/3 around the sprocket to maximise the strength in the sprocket. You could cut them closer together or have more keyways cut to suit your application, but be very careful not to weaken the sprocket. I hope this all makes sense?
Using this method I was able to get the cam degreed to roughly where I wanted (109*). I was aiming for 108*, but the decrepancy could be inaccuracies in the machining, my cam degreeing technique or a combination of the two.
Have you had any problems with the gear? - I haven't had the engine running yet so I can't say
I hope that this is useful to you; i'm writing all this from memory so apologise if I've missed anything If there is any info you want that I've missed please ask away
Cheers
Nathan
I will try and answer all you questions and proviode some more info for you.
Did you consider cutting the crank gear? - Mine was already pressed on to the crank so it was easier to modify the cam sprocket. I see no reason you couldn't modify the crank sprocket to get the desired effect.
Did you do anything to the gear other than have the keyways cut? - No I just had to two keyways cut.
How did you determine where to make the cuts?
First I installed the timing set straight up (with the marks lined up) and then degreed the cam to determine a starting point. I determined I was 8 deg retarded from where I wanted to be. There are 42 teeth on the sprocket - that is approx 8.57 deg per tooth. But remember that 1 deg at the cam = 2 deg at the crank.
So i decided I wanted new keyways at 2 and 4 degs (at cam). The original key was half way between two teeth (top) so I had one keyway cut inline with a tooth to get approx 4deg (left bottom) and then one keyway cut at 2 deg off the centre line between two teeth (right bottom). I had them cut at 1/3 around the sprocket to maximise the strength in the sprocket. You could cut them closer together or have more keyways cut to suit your application, but be very careful not to weaken the sprocket. I hope this all makes sense?
Using this method I was able to get the cam degreed to roughly where I wanted (109*). I was aiming for 108*, but the decrepancy could be inaccuracies in the machining, my cam degreeing technique or a combination of the two.
Have you had any problems with the gear? - I haven't had the engine running yet so I can't say
I hope that this is useful to you; i'm writing all this from memory so apologise if I've missed anything
If there is any info you want that I've missed please ask away Cheers
Nathan
Hi Steve,
I started building my engine a couple of years ago, but its keeps getting delayed due to rust issues on my 68 Mustang. I want to fix these before I put the engine in.
I've got quite a few mods. Rather than list them you can look here for details.
viewtopic.php?f=32&t=49449
Cheers
Nathan
I started building my engine a couple of years ago, but its keeps getting delayed due to rust issues on my 68 Mustang. I want to fix these before I put the engine in.
I've got quite a few mods. Rather than list them you can look here for details.
viewtopic.php?f=32&t=49449
Cheers
Nathan
Cutting a new keyway in the crank or cam sprockets is about the only way to go.
Another method that I've used is to use the retarded timing set, and advancing it by jumping the chain one tooth. In our case this netted us 2 degrees adv. timing.
My 5.0 double roller timing set-up is not a bolt on. It does require some crank and cam machining.
But so far it's working very well! I should've did this years ago!
Later,
Will
Another method that I've used is to use the retarded timing set, and advancing it by jumping the chain one tooth. In our case this netted us 2 degrees adv. timing.
My 5.0 double roller timing set-up is not a bolt on. It does require some crank and cam machining.
But so far it's working very well! I should've did this years ago!
Later,
Will
Will
Moving the chain a tooth may work for me. Just depends on the cam and how it degrees. It is a Clay Smith from Mike's shop. I uderstand CS cams are ground straight up.
I really like what you have done with the 289 stuff to make it fit. If I had the resources, I would certainly give it a try. I have a 14 year old daughter who is helping me with this project. We are planning to start running at the local 1/8 mile track later in the summer. Just low $$ fun stuff.
I ran NHRA H/modified production class with a chevy 292 six in a 65 Chevy II back in the 70's. Anyone can build a V-8.
Later
Steve
Moving the chain a tooth may work for me. Just depends on the cam and how it degrees. It is a Clay Smith from Mike's shop. I uderstand CS cams are ground straight up.
I really like what you have done with the 289 stuff to make it fit. If I had the resources, I would certainly give it a try. I have a 14 year old daughter who is helping me with this project. We are planning to start running at the local 1/8 mile track later in the summer. Just low $$ fun stuff.
I ran NHRA H/modified production class with a chevy 292 six in a 65 Chevy II back in the 70's. Anyone can build a V-8.
Later
Steve
Bayrunner
Well-known member
Does10s":1zk9njuq said:Cutting a new keyway in the crank or cam sprockets is about the only way to go.
Another method that I've used is to use the retarded timing set, and advancing it by jumping the chain one tooth. In our case this netted us 2 degrees adv. timing.
My 5.0 double roller timing set-up is not a bolt on. It does require some crank and cam machining.
But so far it's working very well! I should've did this years ago!
Later,
Will
Hey Will, can you share your thoughts on the double roller? White the engine is being machined, I thought this might be the way for me.
Thanks in Advance!
Bayrunner,
Here's the thread where I discuss this.
http://fordsix.com/forum/viewtopic.php?f=5&t=58314&p=447439&hilit=SBF+Timing#p447439
My thoughts on it.....it's working great!
The bad part is that it's not a bolt in deal. You have to machine the crank and cam, and you have to fabricate a new camshaft thrust plate.
So once you start the machine work....you're committed to the design. No block machining has to be done, so you're not totally committed I guess!
Will
Here's the thread where I discuss this.
http://fordsix.com/forum/viewtopic.php?f=5&t=58314&p=447439&hilit=SBF+Timing#p447439
My thoughts on it.....it's working great!
The bad part is that it's not a bolt in deal. You have to machine the crank and cam, and you have to fabricate a new camshaft thrust plate.
So once you start the machine work....you're committed to the design. No block machining has to be done, so you're not totally committed I guess!
Will
Bayrunner
Well-known member
Will, this is awesome. Committed? need to be commited...so people tell me anyways?
Question for you though, once you machine the crank, what do you do about the darn damper?
I do not mind doing the mod, just making sure I have everything covered.
Cheers and thanks for your insight!
Question for you though, once you machine the crank, what do you do about the darn damper?
I do not mind doing the mod, just making sure I have everything covered.
Cheers and thanks for your insight!
Oops! Forgot to mention that part! 
I did make a .050" spacer to fit between the crank sprocket and the dampener. All I did was to cut up an old SBF crank sprocket. An old dampener would work too. The only reason for this is to keep the crank sprocket from walking around.
Another method would be do take at least .050" off of the snout of the balancer so it'll slide into the timing cover a little more. You'll have to mock this up to make sure that'll work. I haven't done that yet. This method will make pulley alighnment an issue though. So you'll have to do some work there too.
Will
I did make a .050" spacer to fit between the crank sprocket and the dampener. All I did was to cut up an old SBF crank sprocket. An old dampener would work too. The only reason for this is to keep the crank sprocket from walking around.
Another method would be do take at least .050" off of the snout of the balancer so it'll slide into the timing cover a little more. You'll have to mock this up to make sure that'll work. I haven't done that yet. This method will make pulley alighnment an issue though. So you'll have to do some work there too.
Will
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