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  Mustangsandmore Forum Archive
  '69 to '73 -- The Musclecar Mustang
  351 cleveland made into a boss 351

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Author Topic:   351 cleveland made into a boss 351
machlover
Journeyman

Posts: 39
From: Hedgesville WV America
Registered: May 2006

posted 05-04-2006 01:24 AM     Click Here to See the Profile for machlover        Reply w/Quote
Hi I am new to this website just fount it.I was wondering if there is any way you can take a regular 351 cleveland 4 bolt main block.Make it into a 351 boss motor.I have always wonder if you could do this.Thanks Dave

Hans olsson
Gearhead

Posts: 936
From: Sweden
Registered: Apr 2000

posted 05-04-2006 02:10 PM     Click Here to See the Profile for Hans olsson        Reply w/Quote
It can be done,the Boss 351 uses the same block as the more common 351C. 2 or 4 bolted are the same besides the number of bolts that holds the maincaps and either can be used.
You only need to gather all the right parts that made up a Boss 351.
Or you could use a regular 351C with a few aftermarket parts and have a strong running motor.

P.S.
The Boss 351 should be 4 bolted from the factory.

------------------

  • VIN 1F05M139343
  • 71 Mach 1 Ram-Air
  • 351C 4V 285 HP
  • E-F-G/SA
  • Stockers are way cool!

[This message has been edited by Hans olsson (edited 05-04-2006).]

machlover
Journeyman

Posts: 39
From: Hedgesville WV America
Registered: May 2006

posted 05-05-2006 01:24 AM     Click Here to See the Profile for machlover        Reply w/Quote
Okay thanks hans,I have always wondered if you could do this.I got a extra 4 bolt main block that I have not done nothing with.There is only one problem that I have.The wrist pin came a loose in the engine and the cylinder wall is messed up so it would need to be resleeved.But it would be bad to make it into a boss engine.But then again I heard once something like that has happened with the engine, if it would need resleeved you could never make nothing mean out of it.This is just what I heard,I don't know if it is true or not.Like you said to, I could just get me some aftermarket parts and make it a good engine and it would a lot cheaper to probably.That is if it being resleeved don't hurt it. Thanks Again Dave

------------------
1969 390 mach 1 and 1971 351 cleveland mach 1

Ryan Wilke
Gearhead

Posts: 3237
From: Stanton, Michigan, zip 48888
Registered: Oct 2000

posted 05-05-2006 09:45 AM     Click Here to See the Profile for Ryan Wilke        Reply w/Quote
quote:
Originally posted by machlover:
But it would be bad to make it into a boss engine. But then again I heard once something like that has happened with the engine, if it would need resleeved you could never make nothing mean out of it.

--- not true. Many race engines, including Clevelands run with sleeves in their blocks.


... I could just get me some aftermarket parts and make it a good engine and it would a lot cheaper to probably.

--- I'd recommend that idea. Rather than looking for original FoMoCo parts to build a true BOSS 351, I'd build my own "BOSS 351" with better & cheaper aftermarket parts (better intake, pistons, distributor, etc). It would end up being stronger and likely faster.


I'm no expert, but I'm thinking the biggest HP difference between the BOSS 351 and the vanilla-grade 351C engines were their cylinder heads.... ?

As I recall, the major engine parts specific to the BOSS 351s to make it 'OEM correct' would be:

-- a 4-bolt block
-- '70/'71 closed chamber 4V heads (same casting as BOSS 302)
-- solid lift cam
-- forged pop-up pistons (11/1 CR)
-- Standard flanged, aluminum dual-plane intake
-- Dual piont distributor

Good Luck!
Ryan

Daniel Jones
Gearhead

Posts: 972
From: St. Louis, MO
Registered: Aug 99

posted 05-05-2006 10:43 AM     Click Here to See the Profile for Daniel Jones        Reply w/Quote
> I'm thinking the biggest HP difference between the BOSS 351 and the
> vanilla-grade 351C engines were their cylinder heads.... ?

The horsepower difference came mostly from the compression increase and
solid lifter camshaft. The heads were closed chamber 4V's set up for
adjustable valve train. They flow no differently than other closed chamber
4V's

> '70/'71 closed chamber 4V heads (same casting as BOSS 302)

The Boss 302 castings are unique as they have Windsor coolant routing,
not Cleveland.

Boss 351 features include:

cylinder heads - closed chamber 4V's milled & drilled for studs and guideplates
stiffer valve springs with single groove valves and keepers
solid lifter camshaft
aluminum dual plane spread bore intake with Motorcraft 4300D
forged domed pistons
hardened pushrods
dual point distributor
4 bolt main block
selected connecting rods with 180,000 PSI 3/8" bolts and nuts
selected cast iron crankshaft
cast aluminum finned rocker covers with BOSS 351 stickers
thicker balancer with slightly different balance factor

Dan Jones

Ryan Wilke
Gearhead

Posts: 3237
From: Stanton, Michigan, zip 48888
Registered: Oct 2000

posted 05-05-2006 03:32 PM     Click Here to See the Profile for Ryan Wilke        Reply w/Quote
quote:
Originally posted by Daniel Jones:
The horsepower difference came mostly from the compression increase and
solid lifter camshaft. The heads were closed chamber 4V's set up for
adjustable valve train. They flow no differently than other closed chamber
4V's

--- I agree they didn't FLOW any differently, but my point was that the BOSS 351 heads did come equipped with better valvetrain components than the vanilla closed-chamber 4V heads.


The Boss 302 castings are unique as they have Windsor coolant routing, not Cleveland.

--- Yep, I'm bad. I knew that too. Dang! Thanks for setting me straight, Dan!


aluminum dual plane spread bore intake with Motorcraft 4300D

--- Ok Dan, maybe you'll give me 1/2 credit on this one?
I was thinking the BOSS 351 had the 'Holley' straight bolt pattern intake, and the 351CJ had the spreadbore bolt pattern, but thinking more about it - wasn't the 4300D Autolite/Motorcraft carb the weird one that had a straight (Holley) bolt flange, but spreadbore throttle plate bores, making for an odd-looking intake plenum, but the intake was still tapped for a "standard" or straight Holley-type bolt carb flange?


I try to be helpful most of the time, but sometimes I get it wrong! When I'm wrong, I bow to the Cleveland gods and look for forgiveness!

Ryan

machlover
Journeyman

Posts: 39
From: Hedgesville WV America
Registered: May 2006

posted 05-06-2006 01:53 AM     Click Here to See the Profile for machlover        Reply w/Quote
Ya I got a lot of @#$% uncle and he thinks he knows everything.He isn't blood to me, but still.I need to check out the aftermarket stuff for a 351 cleveland.It would probably cost a fortune to make it a boss.The reason I thought about going that rought was because I knew where I could find a set of original boss 351 heads.I could get right now from somebody.But my uncle told me after something like a wrist, like I was talking about would happened it would not be worth trying to do nothing with.Thanks Again Dave

------------------
1969 390 mach 1 and 1971 351 cleveland mach 1

Daniel Jones
Gearhead

Posts: 972
From: St. Louis, MO
Registered: Aug 99

posted 05-08-2006 11:05 AM     Click Here to See the Profile for Daniel Jones        Reply w/Quote
> I was thinking the BOSS 351 had the 'Holley' straight bolt pattern intake, and
> the 351CJ had the spreadbore bolt pattern, but thinking more about it - wasn't
> the 4300D Autolite/Motorcraft carb the weird one that had a straight (Holley)
> bolt flange, but spreadbore throttle plate bores, making for an odd-looking
> intake plenum, but the intake was still tapped for a "standard" or straight
> Holley-type bolt carb flange?

Ford made two aluminum dual plane intakes for the 351C. The first was used
on the 351 HO and Boss 351. It had a Holley bolt pattern but had a spreadbore
plenum opening meant to mount the Motorcraft 4300D spreadbore carb. The
second was an over-the-counter version of the aluminum dual plane with a
conventional 4150/4160 Holley flange. Earlier 351C-4V's had a cast iron dual
plane with a standard flange the mounted a square bore Motorcraft 4300 carb.
Later 351C-4V/CJ's had a spreadbore version of the cast iron intake. The
porting is pretty much the same on all of these intakes but the aluminum dual
plane over-the-counter intake had two oval plenum openings versus 4 circular
on the other intakes. Note the Ford spread bore pattern is different than
the Qudrajet or ThermoQuad patterns, both in bolt pattern and in bore location.

Dan Jones

Ryan Wilke
Gearhead

Posts: 3237
From: Stanton, Michigan, zip 48888
Registered: Oct 2000

posted 05-08-2006 02:32 PM     Click Here to See the Profile for Ryan Wilke        Reply w/Quote

U DA MAN! Thanks for setting me straight, Dan!

kid vishus
Gearhead

Posts: 7251
From: middle of NC
Registered: Oct 2000

posted 05-09-2006 07:17 AM     Click Here to See the Profile for kid vishus        Reply w/Quote
If it is sleaved properly, there will be nothing wrong with it. The last cleveland I had in my racecar had 2 sleeves in it, and it ran high 9's in the qrtr.

machlover
Journeyman

Posts: 39
From: Hedgesville WV America
Registered: May 2006

posted 05-09-2006 10:51 PM     Click Here to See the Profile for machlover        Reply w/Quote
It will probably hold up pretty good then for me.If yours did not have a problem with a 9 second car.I probably would'nt have a problem for sure.That's a lot a power to be 9 second's, man.Thanks Dave

------------------
1969 390 mach 1 and 1971 351 cleveland mach 1

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