351 C 2v upgrade quick & dirty

[Mister 4x4]

All,

I have read a lot on the 351C engines. While researching some of the questions on this thread ran across this web site with all kinds of 351c 2v and 4v information.

PANTERA INTERNATIONAL - A DE TOMASO CAR CLUB

351 CLEVELAND BASICS AND PERFORMANCE TUNING

FOR HIGH PERFORMANCE-STREET CARS AND SPORTS CARS

http://pantera.infopop.cc/eve/forums/a/tpc/f/5650045562/m/319104265

mustang7173

That's a very interesting thread that I also discovered a few weeks ago. According to that thread the cam to buy is grind 523801 from Crane.

http://www.summitracing.com/parts/crn-523801

I wonder if anyone here is using this cam.

He also likes bigger CFM carbs, but with annular discharge.

It's got just a tiny bit more duration than mine, but just a tiny bit less overall lift than mine. Which, if I'm understanding the principles of cams any little bit at all, the Crane cam does pretty much the same thing my CompCams 32-421-8 roller cam does, with less lift and more duration - which translates to a slightly more efficient valve train, yet the roller cam has less friction - making the trade-off negligible, IMHO.

So according to my feeble understanding, I'm thinking it's pretty close to the same as what I've got.

 

[tony-muscle]

All,

I have read a lot on the 351C engines. While researching some of the questions on this thread ran across this web site with all kinds of 351c 2v and 4v information.

PANTERA INTERNATIONAL - A DE TOMASO CAR CLUB

351 CLEVELAND BASICS AND PERFORMANCE TUNING

FOR HIGH PERFORMANCE-STREET CARS AND SPORTS CARS

http://pantera.infopop.cc/eve/forums/a/tpc/f/5650045562/m/319104265

mustang7173

That's a very interesting thread that I also discovered a few weeks ago. According to that thread the cam to buy is grind 523801 from Crane.

http://www.summitracing.com/parts/crn-523801

I wonder if anyone here is using this cam.

He also likes bigger CFM carbs, but with annular discharge.

It's got just a tiny bit more duration than mine, but just a tiny bit less overall lift than mine. Which, if I'm understanding the principles of cams any little bit at all, the Crane cam does pretty much the same thing my CompCams 32-421-8 roller cam does, with less lift and more duration - which translates to a slightly more efficient valve train, yet the roller cam has less friction - making the trade-off negligible, IMHO.

So according to my feeble understanding, I'm thinking it's pretty close to the same as what I've got.

By no means I am an expert at this. This is extremely interesting science. Paraphrasing what Mr. George writes in the Pantera post, the 351c likes the asymmetric profile (longer duration on exhaust) and the larger lobe separation. He suggests that the 351C suffers with large overlaps and when the exhaust valves opens too late, less that 80 deg below BDC. In the case of my cam, the exhaust valve opens at 67 BBDC, which it's too late according to his theory. A late exhaust valve opening affects the high end torque and thus the high RPM horsepower.

Edit: as mentioned below the information i wrote above is for the 4V not the 2V.

 

[Wyostang]

Wyostang,

Plus 1 with 4Vforever with checking the condition of your engine. According to your requirements, you do not want to change the heads and cam shaft. You could do this, depending on your budget.

1: Edelbrock Performer Intake Manifolds 2750 --- Intake Manifold, Performer, Dual Plane, Aluminum, Natural, Square Bore, Ford, 351C, 2V engines

http://www.summitracing.com/parts/edl-2750/overview/make/ford

2: A good 600 cfm style carburetor

3: Pertronix Style electronic ignition

4: 1971 FORD MUSTANG Patriot Full-Length Headers H8412-B

http://www.summitracing.com/parts/pte-h8412-b/overview/year/1971/make/ford/model/mustang

Patriot Exhaust H8412-B 1 3/4" Full Length Header Ford Mustang 351C 71-73 2v Heads only Hi-Temp Black Coating

5: Summit Racing® Balance Tube Kits SUM-642025

Crossover Pipe, H-Style Balance Tube, Steel, Aluminized, 2.5 in. Diameter, Universal, Kit

http://www.summitracing.com/parts/sum-642025/overview/

The headers and cross over will definitely open up the 351C -2V engine while the 600 CFM carb/intake manifold will boost the fuel/air intake flow.

mustang7173

This sounds doable, and I appreciate the parts list. I am trying to do less with more budget wise thus the reluctance to change the heads and cam.

What is your rear gear ratio? What transmission are you running? What do you want to do with the car?

Without this info, determining a course of action is less effective.

Headers, improved exhaust, a 4 barrel of 600-750 CFM properly jetted and tuned to your car, properly curved and reliable ignition system are all great basics to work with-but if you have a 2.75 rear gear, you'll get a lot more out of a gear change than all of the above.

From what I can determine its the standard set up on a base coupe, I simply want to beef it up a little bit, no racing, no drag strip stuff, just a little more zip on the highway.

351 c.i. V-8 2V Carburetor, FMX Transmission

C.R. 8.6:1

Horsepower

177@4000

Torque

284 @2000

FMX Transmission

Number of gears:3

Gear ratios (overall):

I

2.4 (6.6)

II

1.467 (4.03)

III

1 (2.75)

Reference http://www.automobile-catalog.com/auta_details1.php

I am having a hell of time trying to get set and decided on a system for a little power boost. I want to go from 2bbl to 4bbl I am up for trying a new carb and intake I don't want to change heads or cam. How can you do it? What components?

I realize I should have added the following initially, from what I can determine its the standard set up on a base coupe, I want to simply "beef it up" al little bit, no racing, no drag strip stuff just a little more zip on the highway.

351 c.i. V-8 2V Carburetor, FMX Transmission

C.R. 8.6:1

Horsepower

177@4000

Torque

284 @2000

FMX Transmission

Number of gears:3

Gear ratios (overall):

I

2.4 (6.6)

II

1.467 (4.03)

III

1 (2.75)

Reference http://www.automobile-catalog.com/auta_details1.php

 

[4Vforever]

As I said previously, get your engine checked for overall condition before anything. Next decide exactly what you want to do with your car, as you've said a bit more get up and go on the highway and I'd say your looking for a bit more in general driving, with good drive ability and reliability also, so things like single plain intakes, big carbs and gear ratios such as 4.11:1 are definitely out. So then you need to work out your budget, then with that budget, plan which parts will give the best outcome for your requirements and if you can do it yourself, even better as that's more dollars in your pocket to play around with to give you the best package overall to what your really looking for.

As for people on the net like George Pence, he seems very knowledgeable when it comes to Clevelands, but it's like everything, ask 10 different engine builders each for a suitable combination and guaranteed you'll receive 10 different answers. As I've found out over the years, what one part (take camshaft) works well in one engine, might not be optimum on an engine that's slightly different in specification. To say this camshaft or these headers or this carby works well on all engines that are close to each other in specs is very misleading or somebody is just trying to sell you a certain part or have minimal ideas on what it takes to maximise a certain combination.

 

[TommyK]

That's a very interesting thread that I also discovered a few weeks ago. According to that thread the cam to buy is grind 523801 from Crane.

http://www.summitracing.com/parts/crn-523801

I wonder if anyone here is using this cam.

He also likes bigger CFM carbs, but with annular discharge.

It's got just a tiny bit more duration than mine, but just a tiny bit less overall lift than mine. Which, if I'm understanding the principles of cams any little bit at all, the Crane cam does pretty much the same thing my CompCams 32-421-8 roller cam does, with less lift and more duration - which translates to a slightly more efficient valve train, yet the roller cam has less friction - making the trade-off negligible, IMHO.

So according to my feeble understanding, I'm thinking it's pretty close to the same as what I've got.

By no means I am an expert at this. This is extremely interesting science. Paraphrasing what Mr. George writes in the Pantera post, the 351c likes the asymmetric profile (longer duration on exhaust) and the larger lobe separation. He suggests that the 351C suffers with large overlaps and when the exhaust valves opens too late, less that 80 deg below BDC. In the case of my cam, the exhaust valve opens at 67 BBDC, which it's too late according to his theory. A late exhaust valve opening affects the high end torque and thus the high RPM horsepower.

The intake to exhaust flow bias is much less on a 2V head than on a 4V head. On a 2V head a symmetrical cam or one with very little split works fine and will generally make more torque. Different story on a 4V head.

If you are running headers and a good free flowing dual exhaust I would not be afraid of a symmetrical cam with a 2V head. If you are running manifolds I would consider 4-6 additional degrees of exhaust duration. The best bet is to find a cam grinder who is experienced with 2V clevelands heads and see what they recommend.

Perhaps it has been mentioned in this thread and I missed it but the OP should be made aware of the stock 2 piece valve's propensity to self destruct without warning.

 

[mustang7173]

Hello Wyostang,

Thank You for providing us with your Mustangs configuration. There is one piece of information we need. The rear end gear ratio. This information is on the blue sticker on the inside of the drivers door, if is still there. If not, then, hopefully, the buck tag is located on the pinion gear housing stud. Considering your configuration, it may be a 2.75 or a 3:00 open gear.

4Vforever is correct in his response. Check out the cylinder psi per the web site that I referenced below. If they are all within a few psi of each other, then your engine should be OK.

http://troubleshootmyvehicle.com/ford/4.9L-5.0L-5.8L/how-to-test-engine-compression-1

IMO, I still believe by by updating the exhaust system to a dual system with a cross over, install the Pertronix electronic module, distributor ,adjust the carburetor and timing with a good vacuum gauge, maybe the one of the best cost effective solutions. The engines are just one big air pump.

As stated in the earlier parts of the thread, installing a 3.25 to 3.50 rear end gear ratio would also add some zip.

Let us know which way you proceed.

mustang7173