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Differences 351C 1970 to 74

Printed From: The Ford Torino Page
Category: Powertrain Specific Forum
Forum Name: 335 Series Engine Forum
Forum Description: 351C, 351M and 400 engines
URL: http://forum.grantorinosport.org/forum_posts.asp?TID=19012
Printed Date: 30-September-2020 at 8:36AM
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com


Topic: Differences 351C 1970 to 74
Posted By: Rivercrest
Subject: Differences 351C 1970 to 74
Date Posted: 29-July-2020 at 3:05PM
Quick question, besides emission controls, would a 1970 casted 351C be the same as a 351C casted in 1974 ? Both have Cleveland foundry stamps. Thanks



Replies:
Posted By: 72FordGTS
Date Posted: 30-July-2020 at 3:20PM
The blocks are all basically the same, regardless of casting number.  Heads from 1970 to 1974 are different though.

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Vince

1972 Ford GTS Sportsroof - Survivor, One Family car

GTS.org Admin


Posted By: Rockatansky
Date Posted: 30-July-2020 at 4:29PM
a very nice chart compiled by George Pence, only 4V specific though




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72 GT Ute
   


Posted By: Rivercrest
Date Posted: 31-July-2020 at 5:54PM
Thanks, I am looking for the correct manifold from Summit to install a Edelbrock 4V carb # 1406 that I already have on the shelf. Summmit says a Edelbrock 2665 manifold will work. Currently a 1970 353 2V engine, I've been told by my mechanic that this is not the right choice as the ports don't properly match. Any suggestions or experiences would be appreciated.


Posted By: Rivercrest
Date Posted: 31-July-2020 at 5:58PM
Is the Edelbrock 2750 the correct choice ?


Posted By: 72FordGTS
Date Posted: 01-August-2020 at 2:17AM
What heads do you have?  4v or 2V heads?

Edelbrock 2750 is for 2V heads (small port)
Edlebrock 2665 is for 4V heads (large port)


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Vince

1972 Ford GTS Sportsroof - Survivor, One Family car

GTS.org Admin


Posted By: Rockatansky
Date Posted: 01-August-2020 at 4:31AM
the Edelbrock Performer intake runners are smaller than the port openings in the heads in an effort to improve intake charge velocity. the 2665 4V manifold more closely matches the size of the 2V cylinder head but the intake runner is not positioned correctly for the 2V port. yes it will work and possibly make more power than the 2750 2V manifold with some mismatch. or you could port match the 2665 to correct the areas that need work and add epoxy where material is missing if you like, or not. if you decide to work with the 2665 use 4V gaskets

use 2V gaskets with the 2750 for a no messing around direct install.

Edelbrock recommends not to alter the manifold runners in an effort to enlarge them to cylinder runner size. they designed the intake as it is with smaller runners to avoid falling into the '351C ports are too big' myth. it's not impossible to do a nice job and improve upon what Edelbrock puts in the box but what some guys do to the last 1" of the runner is criminal. to do it correctly the blending work should extend all the way from the end of the runner to the plenum and that is not easy to do such a great job with basic tools. personally i would uniform the runner openings coming out of the manifold and remove any casting flash and boogers, very minimal and smack it on

this pic shows Edelbrock F351 2V and 4V manifolds, the predecessor of the Performer series









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72 GT Ute
   


Posted By: 72FordGTS
Date Posted: 01-August-2020 at 6:36AM
There you go, Rock always has the skinny on these engines.  So Rock, answer me this.  Would there be a significant difference in the 2750 vs a 2665 on a mild 351-2V?  Or do you have to reach a certain power/RPM level before the bigger intake ports come into play.

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Vince

1972 Ford GTS Sportsroof - Survivor, One Family car

GTS.org Admin


Posted By: Rockatansky
Date Posted: 01-August-2020 at 8:29AM
a dyno might find a couple hp's / tq's on either end of the spectrum  but the Seat Of The Pants realization would be negligible IMO. certainly at some point the larger ports of the 2665 would show some gain over the 2750 but how much really? or would mismatch turbulence negate any gains from the larger volume runners? IDK but using the 4V gaskets on the 2V heads invites fuel puddling in the gasket that would lead to premature gasket failure, not good for the 'i want to do this once' kind of guy.

i thought about the Airgap but Rivercrest is up dere by you eh and carb heat might be a good thing. then i thought about a cast iron manifold and it's heat retaining atomization qualities, the Aussie cast iron 4bbl manifold came to mind. AusFord Parts is only showing the Carter spreadbore style carb pad intakes available. they made square bore carb pad manifolds too but IIRC they use a choke stove that is hard to find unless you get it with the intake. not impossible and not a deal breaker if you don't mind making a block off plate and using a manual or electric choke.

another option is the Offy Dual Port intake if you're up for that, it optimizes low end operation at some cost in the top end but only if your combo is built to the level that it would reach being compromised. again the Offy's are slightly smaller than head port sized but more interchange friendly than the Eddy's

ride with Paul Dilley in his iron headed 2V





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72 GT Ute
   


Posted By: Rivercrest
Date Posted: 01-August-2020 at 10:20AM
Thanks to all for a wealth of information.........


Posted By: Rivercrest
Date Posted: 03-August-2020 at 2:55PM
BTW, does a 1970 Cleveland need a Robert Shaw Thermostat style thermostat, I've yet to pull the thermostat housing to look for the restrictor.


Posted By: Rockatansky
Date Posted: 03-August-2020 at 3:25PM
Robertshaw is a brand. the style is technically a 333 Series which has the hat on the temp sensor bulb,
many different mfgr's produce a 333 Series thermostat and they can be found at Rockauto for under $5


Yes the 1970 351C uses the special 33 Series thermostat in conjunction with the pressed in brass restrictor Wink

Windsor and generic chevy 330 Series on the left, 333 Series on the right



and the restrictor








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72 GT Ute
   


Posted By: hogfiddles
Date Posted: 04-August-2020 at 5:43AM
Originally posted by Rockatansky Rockatansky wrote:


ride with Paul Dilley in his iron headed 2V

I like the soda bottle in the bracket on the left


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1973 Gran Torino Sport - Q code
1969 Torino GT - M code
numerous mid-80's Yamaha XJ-Series (10 trophies and counting)


Posted By: Rockatansky
Date Posted: 04-August-2020 at 10:39AM
i wonder what it's for? i can't think of a lighter weight container though

so getting back to the original question, 2V specific,

Originally posted by 72FordGTS 72FordGTS wrote:

The blocks are all basically the same, regardless of casting number.  Heads from 1970 to 1974 are different though.


yes all the H code (351C-2V) blocks from the beginning to the end are functionally interchangeable, there are some inconsequential features that changed like the D0AE-J block has oil returns in the rear corners of the valley that no other cast code blocks have, the earlier D0xx blocks are believed to have thicker cast cylinder walls and the unused coolant port boss on the timing case changed from a D shape to a square shape at some point

i think Vince is referring to 4V heads, the 2V heads are basically unchanged from 1970-74, some may have A.I.R. / Thermactor passages machined and functional, some have the provisions unmachined and some do not. all have the same 2.04" / 1.65" valves and 'open' 76cc chambers. i'll mention the 1975 2V D5xxcasting heads because they interchange and you'll find them swapped onto 351C's. these heads came on 351M's and 400's from 1975 on, they have a revised water jacket that looks like it causes the exhaust port to be significantly compromised but surprisingly it has no detrimental effect up to and over 400hp builds.

crankshafts and connecting rods are functionally interchangeable or unchanged.

pistons are flat top with small valve reliefs from 1970-72 then for 1973-74 they went to an 8cc dish.

H code motors use the early flat oil pick-up screen with a metal strap covering an emergency debris sucking hole in the mesh.1971.5 CJ motors got a convex screen with no debris sucker hole that can be fitted, the oil pumps are the same std volume or high volume

Hmmm, what else?



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72 GT Ute
   


Posted By: hogfiddles
Date Posted: 04-August-2020 at 3:49PM
Originally posted by Rockatansky Rockatansky wrote:

i wonder what it's for?

Maybe it’s just for a little extra POP


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1973 Gran Torino Sport - Q code
1969 Torino GT - M code
numerous mid-80's Yamaha XJ-Series (10 trophies and counting)



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