Well I pulled the trigger and bought a 79 today. Has a 351 C (non original of course). Sounds good, needs some new valve cover gaskets and belts, but I'm pleased. Came with a aluminum intake and holley carb, accel coil, flowmaster duel exhaust.

Question: I have read that they have their power band at higher RPM's. What can be done to improve low end torque? Also despite the upgrades, the previous owner did not put headers on. How much will this improve performance over stock?

thanks

 

Does the enigne have 2v or 4V heads? And which brand and model intake does it have?

 

edolbrock intake and I'm guessing 2v heads since I have not pulled numbers off the engine yet.

 

You don’t need to get the casting numbers of the engine. In the 335 family the heads can be Id easily by a number on top of them in one of the corners right beside the valve cover, looking from the top of the engine down to the intake manifold.

2v = 2 or M
4v= 4
The next link has some photos of the heads and some literature of the 351C. This site is one of the first sites I came a cross when I was doing the conversion for my mustang if one of the members is the author of the site TANK YOU for your inspiration.
http://home.comcast.net/~jelerath/mustang/main/master-fr.html



Good luck drof46 in your project!

 

I lost power by removing my stock exhaust manifolds and installing headers.

 

you will loose power to low cr, stock 2v carb and stock camshaft with headers, other wise the better exausht the more torque (faster the gases come out of the cylinder the faster it fills agian making the rtoating mas more unstopable (torque)) well my theory....

 

Both head have the letter M. So based on the website I was referred to I have a 351M instead of a C. How do I figure out if its an M or a C block and does it really matter as far as power or design?

later

 

a Cleveland block has the thermostat housing sitting flush on top of the block, an M/400 block has the thermo housing raised up about an inch or so. most M/400 blocks also have a raised ridge to the right of the distributor.

raised M/400,



Cleveland,



anything's possible, "M" heads could've been put on a Cleveland block...

 

Thanks for the pics. Mine looks like the second pic. I have have a 351C with 2v heads. So back to the original question. With a Edelbrock intake, holley carb, some upgraged cam, would a set of headers improve anything?

Figured out tonight that the reason it sounds good but has zero take off is probably the 2.75 rear end. You guys have any opinions about what would give me a little more takeoff but still cruise down the highway at 65-70 without running the rpms up too high?

Thanks for the responses.

 

HEaders are worth a try, if you find that, after switching to headers, you do loose some feeling of performance, you could always throw a set of mufflers on that are a little more restrictive, so you can build the exhaust gas back pressure back up, thats what i ended up having to do to get the 3/10th's of a second i lost after going to headers back.

Just FYI my truck is a 79 f-250 4x4 with a 400. The 400 is .060 over with edelbrock intake, .484/.510 cam, and holley 650dp carb.

Switching to a little steeper rear gear ratio might help alot. I have 4.10's (too low for highway if you want to keep it at lower rpm's) and i know that in my truck, when i am at 85-90 MPH the tach reads about 4600-4700 RPM

Is it an f-150 or 250? I just ask because i believe that most after market ring and pinon gears (3.54 - 4.10 {series 3 carrier})for the dana 60 must be installed on a 3.07 and numerically higher carrier. 4.56 and numerically higher must be installed on a 4.56 and higher (series 4)carrier.

I could be wrong...anyone?

 

G'day Drof46
In OZ we only had "factory F100's" with Clevelands.
As you will hear over and over again "What heads have you got". My Factory '79 F100 4X2 SWB came with a 351C C6 3.5:1 9" LSD. The heads were the 2V open chamber type which I believe is what you got in the US. The closed chamber ones are what I'm running now along with a Eddy performer manifold and a Holley in my "fill in motor" These have made a marked inprovement (compression ratio related I'm sure) My yet to be installed "New motor" is a stroked 393 with CHI 2V heads an Eddy RPM Airgap manifold and a roller cam. Whilst the bottom end is capable of big HP/RPM numbers, I'm aiming for about 430HP and 500FT/Lbs at less than 5000 RPM. So with a carefull choice of cam and heads a Cleveland can be made to work at lower RPM.
I think your diff ratio is fine for a light sedan but is too tall for the vehicle you are running.
We Had 3.5:1 as factory here.

If the Clevelands over there are anything like the ones here you will eventually finish up with an oil leak from the front/rear of the inlet manifold (nothing new gaskets and silicone can't fix) and a weep from the rear main seal (silicone won't fix this one)

If you ever have a Cleveland block at an engine machinist have the rear main machined to suit a Windsor one piece rear seal.
One day somebody will thank me for this piece of advice but it should take years before they realise its worth.

Hope this helps

Mike

 

Thanks for the info. I guess I'll save a couple of hundred bucks and stick with the stock manifolds. I have a 66 I'll be putting on top of the 79 frame/engine combo. I have a couple of extra axles I'll have to break open an see which gears I have in them. May not have to buy any additional parts just yet.

Thanks

 

Its always nice when you can use parts you have laying around.. and usually alot cheaper too.

 

Hey colo why is back preasure so important? don t really understand why, and its good to know..thanx

 

"the reason that exhaust valves burn is because the engine is burning lean. Normal engines will tolerate lean burning for a little bit, but not for sustained periods of time. The reason why the engine is burning lean to begin with is that the reduction in backpressure is causing more air to be drawn into the combustion chamber than before."

The increase in back pressure / increase in performance for my truck could be just because the fact i have a 650 CFM carb on it.

When exhaust is opened up it allows more air to come into the cylinders easier, the increased air being allowed in may be more than i could tune the 650 carb for, causing the A/F to be overly lean, and result in a lean out condition, which hurts performance. I am by no means saying that EVERY engine needs exhaust back pressure to function, as a matter of fact, i have noticed that the bigger CFM carb an engine has, the less back pressure they will need.

My guess as to my engine / exhaust setup is that the back pressure in my exhaust system "meters" the amount of air being drawn in.

One thing i never did try was running richer jets with open exhaust, that probally wouldnt have slowed the truck down as much because thew A/F would match then.