250 LeMons Engine: Endless Rear Main Leaks

mad_science

Well-known member
Hey Everyone

I've got a C9__ block 250 that I run in a '62 Ranchero in the 24 Hours of Lemons. It's a Craigslist special that "came from a running car", so it hasn't been apart (aside from 2 or 3 rear main changes at this point).

It's a great motor that makes good power (by Lemons Class C standards, at least), but for the life of me I can't seem to keep the rear main from leaking.

Of course, we're not really helping it, in that we're reving up to 5.5 or even 6k on occasion and running it for 14 hours of racing, frequently at really high temps (like 220-230).

Just wondering if anyone has any recommendations for install tips or parts/brands to look for or avoid (Mahl, FelPro, National, Timken, etc).

We'll be racing Memorial Day Weekend at Thunderhill in northern California, in case anyone cares.


ranchero leads.jpg
 
we're reving up to 5.5 or even 6k on occasion and running it for 14 hours of racing, frequently at really high temps (like 220-230).

... I'm impressed, wondering if you're running shimmed oil pump, synth oil, what's pressure at those RPM ?, do you read oil and exh temps?. .. The long rod/stroked 200 alias 250 isn't as free spinning as the boxy stroked 200, frequent 5-6K fun is typically just short of 'parts on the road'.

simplest ? : .. 250 doesn't have aV8 157T FW (weighted) ?.

' think I'd leak a little after 14 hrs ...

have fun
 
Stock oil pump, 20-50 valvoline VR1, oil cooler.

Oil pressure is like 30-40psi with everything hot. I'd love to upgrade the oil pump, but no one makes anything for the 250 (that I can find, at least).

It's got a stock 0-balance flywheel.

When we ran a 200, it spent some time over 6k...no consequences. It didn't make any more power up there, though.
 
"never opened" means still the rope seal.
Pull the lill pin there that holds it & use the modern Fel-pro (so they don't kick U out the field). Too much oil on track, not good. :nono:

We have another fella running there (in the past) & he posted lots here. Use the search function 2C his posts on how to win. It only took 1 blown motor.
2X on the 200 ci / 3.3 (250's more a lill tqer)

Sell me the body when ur done?
Thnx 4 da pic, let us know how U do !
:eek:
 
Welcome mad_science.


We've done LeMonz Consultancy Services before.

Mr Wood (parkwood60) and I have the same love for

JB Weld,
200's
Foxes,
Home made multi barrel carb alloy adaptors
and Ford C autos.

parkwood60's 2bbl LeMonz 200
Parkwood60LeMonz2-bbl33racerTop.jpg

Parkwood60LeMonz2-bbl33racerBottom.jpg




viewtopic.php?f=1&t=72474&p=557090#p557090
viewtopic.php?f=76&t=68566&p=525798#p525798
viewtopic.php?f=1&t=67612&p=517746#p517746


The Aussies tried Nuclear attacking this engine from 1960 to 1969, then came up with the 250 2V.

The first issues were making

1. pistons that don't come out of the block,

2. sumps that don't eject oil

3. Not using any recipricating parts that were downgraded during the E&F Engineer William H Gay's "less iron" down grade edict of 1969-1974. (As result of paying the rent for the LeMans wins, Fords foundaries then had to payout by reducing its iron content and curtaling its production cost related items by something like 30%)
That created huge problems for every Cleveland, Windsor and Big and Small Six in line engine builder ever since. Those parts downgrades make each of the engines harder to rework FE/FT and Lima 385'S, which had heaps of iron in them.

Ak Miller said it best.

-Block bulkheads and wall and head castings went down to 187 thou from about 243,
-Cylinder bores got egg shell mouldings to 130 or to less from the previous 180 thou or greater at the trust faces,
-Forged con rods got downgraded to cast iron (1976-1980 on the 250, so your okay).
-Forged cranks disapeared from 300 sixes and FE/FT's. Bill Gay was destined to be Cast Iron Charlie Sorenson in reverse, but he got FoMoCo through an exceptionally bad finacial wrap.


:unsure:
Now to answer your question, follow the factory manual first, you can re-rope seal it, and thats the best option. It will be high drag initally because in Bill Gays day, the factory rope seal was designed to be a high drag solution to stopping engine leaks.
 
not sure Y the oil pump treasure hunt:
the big box stores local 2U (Melling?)

https://www.autozone.com/external-engin ... el=mavrick

"Our man" Matt at vintage inlines dot com (specilizes in these 'falcon' engines, member here)

rock auto, summitt on line

the 'stang specialists (1969 250 motor)

Melling itself

Lottsa tricks for more pwr on these babies. Stick wid us'n C.
DSII & 2v carb upgrade R 1st, then
discs up frnt, sway br, 'shelby drop' to match that. Don't know all da Lemons rules but these R all OEM...
 
Guess I failed to point out: we've already replaced the RMS twice with non-rope style seals. Cut the spike out of the seal race already.

One we killed nearly instantly b/c we overheated the car like 1hr into the day. The replacement to that still leaks after 1 race.

I can find a replacement oil pump (Melling M82), but not an upgraded unit for the 250.

I know Brian and his motors...part of my inspiration to head down this road. We used to run a 200, but that Ranchero is no more. When we built the second one I opted for a 250 for a broader torque curve and easier bellhousing compatibility.

Current 250 has:
  • 2V conversion
  • 264/264 cam + 302 valve springs
  • ~9.3:1 static CR
  • Long tube headers
  • HEI ignition
  • and is backed up by a toploader

For this race we're upgrading from a 1.21 (~350CFM) 2100 to a Holley 500CFM 2bbl carb. The bigger carb is partially about more top end and partially about getting away from a grimy 50 year old casting with a bunch of half-stripped holes.
 
Looks like my reply got deleted...maybe filters didn't like the links.

Guess I wasn't clear enough: we've already replaced the RMS twice with non-rope seals (cut the spike out of the seal journal). We killed one when we overheated the motor and the replacement for that is leaking again after one race.

Other stuff:
Replacement oil pumps are easy to get (Melling M82), but I don't see any high-volume versions that work with the 250.

The motor already has the following:
2V conversion
Milled head for ~9.3:1 CR
264/264 cam + 302 valvesprings
HEI ignition
6:2 Headers
Toploader backing it up

For this race we're switching from an old 1.21 Autolite (~350cfm) to a 500 CFM Holley. Hopefully a little more top end, plus not dealing with 50 year old warped castings with stripped holes.
 
What kind of breather are you running on the valve cover??
Are you installing the RMO seal with parting lines @ 10:00 & 4:00???
Are you putting sealant on the flywheel or flexplate bolts where they hold them to the crankshaft flange.??
Are you sealing the rear main bearing cap & putting sealer on the areas specified in a Ford shop manual??
 
If you can find one that's OEM (Genuie Ford NOS) neoprene rear main seal that is your best bet, don't have the part number handy. It seems that the aftermarket seals aren't being made to Fords specs anymore. If you can't find the OEM seal than you should go back to the rope seal at least it will work, you can make a new pin out of a finish nail. Good luck (y) :nod:
 
Ms, just repost untill you see it. I often end up double posting.

The old rope seal is your answer. Its asbestos based, but safe and its sticks like mud to s blanket.

BW is awesome. Your on the right track.
 
If your engine was automatic, and then converted to Toploder without a rebuild, then the through bolts are most likely too long and will be cutting the seal. I dont like Poly Etheylene main seals. The crank flange has to have texture to ride up against a chain polymer, and new multigrade oils flow so much better than the old ones.

Noel Tuckey from Wheels Australia said a very tight rope seal is still the best option for high performance engines. No one likes 12 mpg high drag running in, but no one likes oil downs on hotmix asphalt.

Vac pumps do a great job, but the problem must be bolts or too smooth surface texture on the crank flange. Id try a cutting compound to linish it, and then repin and rerope it and look at those bolts...too long and they pierce.
 
I C a coupla 'rope seal' recommendations. I wonder it that would have helped:

viewtopic.php?f=1&t=79370

Don't think we were going in that direction back then. Is this now a 'best practices' tip?
Just in special circumstances? (Unfortunately I'm a bit of an absolutist ina lota ways).
 
Mild crank walk due to thrust bearing wear is an auto to manual problem. There is not as much give in neoprene. Starting with automatic transmissions with the one peice AOD, Ford then quickly went to center hole punch totally enclosed manual Mazda transmissions because of crank weepage and Noise Vibration and Harshness reduction. Many modern cars have leaks, you just don't see them. :p

Simonsalz and S-man had the same issue. M_S, for your info:-

https://fordsix.com/viewtopic.php?f=1&t ... 85#p605685

Simonsalz":4upxjb4h said:
So I'm new to this site, so I apologize for any mistakes I make, but I have a ford 200 online six (in my 1965 mustang with a 3 speed) and it was missing and running rough so I decided I'd rebuild it. I've taken so much time measuring clearances all the way to cleaning and prepping the block. Long story short I've replaced EVERYTHING besides the rods(checked and all by machine shop, block (bored .30 over and checked), and the head (valve job and checked for cracks). I still have a very rough idle and like its missing but all the wires are showing no evidence of a miss (I've tested for it) and I'm not sure what to do because I've dumped a lot of money into rebuilding this engine with no luck, just for it to run the same way as it did before I rebuilt it

Any info/help would be greatly appreciated

If the car was born manual stick shift 2.77 or 3.03, then a new auto needs shorter bolts with a proper sealer. If its still manual, then you must use just the right size bolts. You can use any number of other bolts, but they have to be the right shank depth.

The 144-170-200 has a 3.375" nominal crank flange, the 250 (and 221-255-26-289-302-351K-M-C-400 Fords) about 3.75"

The quality of a seal is based on its trimmed to finish size, and the macrotexture of the crank flange, it has to retain some boundary layer oil to seal. New multigrades can cause problems, but the basic issue is how the neoprene is composed and sized, and a rope seal is far more forgiving of errors than the newer seals.

Rope seals have a host of nasty issues. They make a car idle bad (worse than stock, which means a poor idling vehicle then gets a horriably psychotic athmatic horse cylcic stutter), they consume power, cause poor fuel economy, have a long, long run in time and a log head I6 is a dog for bad idle anyway, especially Load-O-matic and old SCV carb. The reason is that our six cylinders don't get fed the same air fuel, and don't get a sufficently adequate spark. When the timing gear is worn, the idle timing drifts. Other issues are that our crankshafts don't have 12 counterweights, flywheels or flexplates can be out of true, and the crank to trans centers are often out of true from factory.

Bill used to be a Lexus dealer, he's helped me out with sensors, Toyoda service and maintenance, and the modern thread sealer he recommends is fine.

Fords movement to neoprene is a good one, and its based on very sound mass production needs to save gas, reduce emissions and ensure when its 50000 mile tested, its still leak free and making good power. You should go right back to a pinned rope seal anytime your still get a leak after sealing the six flywheel or flexplate bolts, and be very carefull to use the OEM bolts for you flywheel or flexplate.

Asbestos is a bad word in many circles, its cancer free as a substance, but it forms elongated longitudinal shearing serpintine like fibres when it grows in the earth in its natural state, but when oiled and preped and not dried back, its never going to cause a health issue.

My school teacher died of asbestosis, and I've been exposed to it, but have done asbestos removal for many years with safety apperatus.

Its

Soul on a roll, but you treat it like soap on a rope
Cause the beats and the lines are so dope....

It does the job. :nod:
 
my local ford dealer has no rear main seal (rope or neoprene).
Can I usea hunka rope? Need special kind (w/asbestoses?).
 
For this race we're upgrading from a 1.21 (~350CFM) 2100 to a Holley 500CFM 2bbl carb. The bigger carb is partially about more top end and partially about getting away from a grimy 50 year old casting with a bunch of half-stripped holes.

Holley 2300 series 2Bbl , the 4412 500CFM version is widely available and has all kinds of options. Extended jet receivers, bowl-anti slosh vents and wide jetting range. Excellent top-end for modified 250 but too much for most 200 builds. The 350 CFM version 7448 uses same parts with more suitable low end performance . Favorite carb for 'Hangar18" blow thru mods as well..

$.02 ; .. a little surprised the 200 isn't preferred for sustained high RPM durability as peak HP between 200 and 250 isn't too far apart. I run 250's for their low end grunt but a well built 200 is close match at top end. ( see Philson Falcon)

have fun

, .
 
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