351 C advice

[83slimer]

Hi guys,

Its time for my motor, Before I plug it in I'm replacing the oil pan and timing chain cover.

I need some advice on my set up,

351 c 72 block 4v heads All rebuilt about 3000km on it,

Harland sharp rockers

Vintage edelbrock 351F intake

Edelbrock double roller chain

Performer RPM cam.

High volume oil pump and Thicker Distributor drive shaft.

I cant remember wether or not my heads were open or closed chamber, the heads have the DOT next to the 4, I dont want to take the intake off again to chech the numbers lol

I used to run a mallory dual point but think I lost some HP when I swapped it in , Id like to go with a HEI since they work so well on Chevs,

I also ran a 600cfm edelbrock, It came with a 750 holly that I traded for the edelbrock, but I think i should of kept the holly, the 600cfm edelbrock seems small for the motor now.

Any suggestions? Any idea what HP I can make with this setup?

Thanks!!

 

[83slimer]

not a single reply hummm ok then

 

[Duncan Mach72]

I think that's because nobody can even guess without knowing the approx. CR i.e. if it's open or closed chamber heads.

You need to provide more information & then ask specific questions, which might be better on the 351C forum.

 

[vozaday]

Yes need a lot more specs including cam. Could be anywhere between 400 to 450hp. If you want an idea there is a program called desktop dyno, you will need to find bench flows of the stock heads and input all your info in. It isn't the most accurate but it will give you a rough idea anyways. I used it when I built my engine and it popped out 375hp and 425tq, so I usually tell people it is around 350hp as I never dyno'd it, but it is a very believable number for what all has been done to it.

 

[Stanglover]

4* heads?? The date codes are in between the rockers and can easily be read. If I'm right, they should be earlier than 1-E-31, 1971-May-31st to be closed chamber. After that the heads are likely open as I believe June is when the change to the so called CJ was made. ( I could be a month off without double checking and I'm also not sure if the 4* was still used on the CJ heads!)

Nice looking engine and bay.

 

[Jeff73Mach1]

accurate compression numbers and cam specs are necessary- but a fair approximation of compression ratio can be made from a warm cranking compression test

140 is around 9 to 1

155 is about 10-1

170 is about 11 to 1

Keep in mind that gauge variances will occur and this is just a ballpark way to get to compression numbers

 

[will e]

Could be anywhere between 400 to 450hp.

I think 300 to 450 is a more realistic range. Like folks have pointed out, with no cam specs it's hard to know. I looked on Edelbrocks web site and didn't see specs for 351C

I do have a few thoughts:

Yes, ditch the dual points they are a pain to tune and will drop out of tune. I don't like the HEI on Clevelands only because they are big and ugly. I run one on my AMC so I am not a hater.

The 600cfm should be fine. Probably provide snappier performance than an larger carb. How many RPM's will you be spinning the motor?

Have you used your vintage F351 manifold before? Did you install it with a 'turkey pan' gasket? My f351 2v would actually hit the pan and pull it down just slightly when installing. It caused leaks.

 

[Jeff73Mach1]

I think a larger carb would result in more horsepower. I have no experience with 2V heads, but horsepower is made by the efficient burning of fuel, compression increases efficiency, but gasoline has a specific amount of energy available and to maximize power, there must be enough. A 670, 700 or 750 CFM carb will allow more power to be built if the engine is otherwise capable of making the power.

 

[vozaday]

Could be anywhere between 400 to 450hp.

I think 300 to 450 is a more realistic range. Like folks have pointed out, with no cam specs it's hard to know. I looked on Edelbrocks web site and didn't see specs for 351C

I was originally going to put 350 as the low end, but I made an assumption that it will have a cam for good to 5500 to 6000 rpm for a 4v. You are right.

 

[Don C]

Here's a couple of spreadsheets that will help you with some engine calculations, including compression ratio:

http://www.7173mustangs.com/thread-engine-and-compression-calculations

http://www.7173mustangs.com/thread-compression-altitude-calculations

 

[83slimer]

Open Chamber heads, edelbrock performer plus cam, Thanks for the input , i'll try the HEI they are cheap enough,