250 double roller timing chain kit supply and demand

hotrodguy":55usgm39 said:
With all these listings is there 1 that will work and hold up in a race 250?

Does10s is running one on a turbo 250 drag Falcon pulling 450HP.
Mike1157 has one in a US250Xflow with a turbo.

This mod will hold up to a race 250.
 
"...turning down the crank to match SBF…"
I missed the detail on how to prevent an oil leak from the back of the component when narrowing this diameter. Would the cutter on the lath stop in a position that would leave the back of the snout 'fat enuff" ? I understood a second piece was machined and placed at the back?

Not clear on this detail of the machining/mod…

Thanks for any clarity provided! May B the 'site saviors' have a "sticky" set aside for those seeking info like myself on this &/or other topics?
 
seal O.D WILL MATCH 250 timming cover, seal I.D. will be same as sbf. I ,am also going to look into machining the crank sprocket I.D. out to 250 crank snout spec,s and rebraoching the keyway. I,d rather do this as opposed to cutting on the crank if possible
 
chad":1d5vjwnf said:
where's xr wagon when u need'em?

On Facebook!

/viewtopic.php?f=1&t=74355&p=571726#p571726
rocklord":1d5vjwnf said:
The 200 is the maximum displacement possible with the original designed block, and keeping the rod/stroke ratio above 1.5.
The 200 is a very compact block allowing for a lower hoodline.

When Ford designed the 250, they wanted to keep as many common parts with the 200 as possible (head, pistons, distributor, cam). They couldn't increase the bore, so they had to increase the stroke. Increasing the stroke meant the deck height had to be 0.392" taller than the 200 to accommodate the additional crank throw. Ford wanted to keep the rod/stroke ratio above 1.5, so the rod length went from 4.715" to 5.88" (1.165" difference). Since Ford wanted to use the same pistons and head as the 200 the decision was made to increase the deck height an additional 0.104" to keep the CR down. So adding up all of these numbers (0.392+1.165+0.104) to the original 7.808 deck height of the 200 gives a 9.469"deck height to the 250. Increasing the stroke also caused the relocation of the cam in the 250.

Look at all Ford had to do to the 200 block just to get 50 additional cubes.

Ford of Australia took a different approach by designing the 250, then destroking it to get their 200.
The downside of doing this is the loss of the compactness of the US 200.

In addition to the above, the reason the Aussie timing gear parts don't fit the US 250 is that the Aussie crank has the US 200 size snout for the 250 as well. They didn't see fit to upgrade it. The US 250 desgner's probably had a good reason, probably engine smootness or durability, and they upsized the "shank for the crank".

Like my rhyme?

Oz stuff is 1.247", nearly the same as the SBC'S 1.25", not the often quoted 1.1247 that is wrong in the Romac and other trade literature. And its still being made that way, that size today in 4.0 DOHC engines making up wards of 362 hp, and often more, like 1800 hp turbo's.

The US 250 has a SBF/BBF sized snout of 1.375".


Put simply, it would take a nuclear blast to kill a 3dr62 timing chain and the SBF timing gear on the US 250 with a SBF timing set. And although the chain is designed for just 1808/1858/1968/1972/2189 and pre revision 2,366 cc engines, it was also used in 135 to 288 hp 253/304/308 and 350 SB V8 Holdens with the Toyota timing set with a different dot index, but the same chain.

That chain has raced at Monza and Spa 24 hrs, taken World Rally champoinships and survived 6 hour races in the antipodes. Same basic twin roller part from 1974 to 1984 in the Tojo, and from 1971-1974 and 1987 to 1999 in the V8 Holden. When GM down graded it to single roller for non L31 or L34 versions for 13 years it failed during endurance race conditions, like 1985 at Bathurst in the Mobil VK Commodore.


Pretty good for a 17 buck part...just don't tell anyone its orginally a Rootes Group and AMC V8 part with 30 years of proven history.
 
I have a replacement chain for my double roller 200.
It looks like this:
s-l300.jpg

http://www.ebay.com/itm/Morris-Minor-Si ... 0880113373
A few extra links and bob's your uncle.
It is for a Morris Minor.
If you google "morris minor timing chain" and view images you'll get the picture.
 
my uncle's 'Joe', Joe Fuller.
Bob who?
 
Bob's your uncle
It's a catch phrase dating back to 1887, when, in a blatant case of favoritism, British Prime Minister Robert Cecil (a.k.a. Lord Salisbury) decided to appoint his nephew Arthur Balfour to the prestigious and sensitive post of Chief Secretary for Ireland.

So "Bob's your uncle" is another way of saying "your success is guaranteed."
You just put these parts together like this, and Bob's your uncle - you have a working model!

You want to go to the stadium? Go straight on until you reach the park, take the first left, and Bob’s your uncle - you're there!
 
chad":sf9qbrwy said:

oh, Bob Cecil, then.
"Ynuck, ynuck, ynuck,ynuck, ynuck.
Wo, wo!"
(must be after midnite, sorry, over tired here).
 
chad":26oq21tz said:
"...turning down the crank to match SBF…"
I missed the detail on how to prevent an oil leak from the back of the component when narrowing this diameter. Would the cutter on the lath stop in a position that would leave the back of the snout 'fat enuff" ? I understood a second piece was machined and placed at the back?

Not clear on this detail of the machining/mod…

Chad,
You don't need to machine the crank "down to match a SBF". The crank snout on a 250 is already the same diameter as a SBF. What I did was to machine the crank so that the SBF crank sprocket would slide aft about .050" to better align with the cam sprocket. I did it that way so I could easily swap out an unmodified timing set if I needed to at the track.

It would be easier to just machine the crank sprocket so it'll slide further aft on the crank.

Later,
Will
 
"...easier to just machine the crank sprocket…"
nice!

1) There's enuff meat there (302's crank sprocket) to do that?
2) Then use a 302 (other sbf) double roller (no mod +/- of links),
3) AND the 302 (other sbf) cam sprocket (that fits on the 250's?).

Thanks Will ~
 
80Stang":2i7y334s said:
chad":2i7y334s said:
3) AND the 302 (other sbf) cam sprocket (that fits on the 250's?).

Thanks Will ~

The sbf cam sprocket does not fit a 200/250 cam


/viewtopic.php?f=5&t=58314&p=447439

Does10s":2i7y334s said:
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! :unsure: )
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.
http://memimage.cardomain.com/ride_imag ... medium.jpg
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!!!
http://memimage.cardomain.com/ride_imag ... medium.jpg
Bigger pics at http://www.cardomain.com/ride/686815
I'll let you know how it goes!
Later,
Will


/viewtopic.php?f=95&t=71986&p=553117#p553117

mike1157":2i7y334s said:
...........

Does10's has already done this swap, and he chose to modify the SBF chain by removing one link and using a master link to put it back together. Originally, I tried the same path, but had a real problem trying to find a link to match the Dido brand chain that came in my Summit brand kit.

After about three days and a bazillion phone calls however, I found a source for the right chain that actually came as a complete piece. Turns out that a 69-78 Toyota Corrolla w/ a certain engine uses this chain. The source told me to just go to autozone, and ask the guy at the counter for a Melling 3Dr56 double roller chain.

Or he could just sell me one for 15 bucks.

I chose "B".

Additional modifications are required to the crank, and the crank gear after that. The SBF gear has a shoulder that is about .300. This shoulder makes the gear stand way off installed conventionally for that reason. Does10s just flipped the gear backwards. I chose to mill off the shoulder.
Either way, whether you flip the gear does10s style, or machine it off like I did, The crank still has t be turned an additional .050 to allow the gear to sit far enough back to line up properly.

f17063ac-5cfb-415d-ac30-d0ca8ff59686_zps76e86e22.jpg


87b7179e-75ab-4f42-b418-8df20375b9ff_zps3318837e.jpg


It fits like stock after you go through all of the above. The chain is perfect, just loose enough to allow you to install it.

Now, about the crank gear. I'm also using a SBF harmonic balancer. Conveniently enough, it's about .300 longer than the 250 balancer, so machining the .300 off of the crank gear would've had to happen one way or the other in order for the balancer to fit anyway.
One last "required" modification is the keyway on the crank. It's way too short and does not extend rearward enough to safely secure the gear given that you have to move it back even further. I had my machinist extend the keyway the full length of the crank snout to be safe.
 
alright, saved as a 2 page wrd.doc to desk top (I know I've seen that thread B4). more 4 my 'archive'

Does this site have "stickie"s (This might be one to save if so.) or is it all on 'search' only?
 
Excellent!
Saw it under "Board Index" → "General Tech" → "Engine Tech".
Now we don't hafta rehash the good stuff all the time.
All this time & never knew we had a 'stickie' .
Great - now there's two! The whole CI site & this.
U wanna a third - hard copy? See "the Handbook"!
 
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