'73 351c 4V Performance rebuild advice

Hi,

The goal of the rebuild is a mild street engine for occasional pedal flooring.

I have a '73 351c 4v engine with a stock compression of 8:1. The camshaft kit I bought (comp cams 280h) calls for 9:1 compression.

The '73 351c had lower compression due to dished pistons. If I used flat top pistons my compression ratio should be in the neighborhood of 9.5:1 based on my attempts to use the online compression ratio calculator:

http://www.csgnetwork.com/compcalc.html

1. Can someone please confirm that flat top pistons will be sufficient to bump up my compression to around 9:1

2. Do I need to bump up my compression to 9:1 in order to make use of this camshaft? How would the compression ratio affect this cams performance/driveability?

Sorry, I'm still learning. I haven't looked at pistons much because I'm yet to take the engine apart to determine exactly what is inside as it has been rebuilt once in the past. Also, I will be doing this rebuild with the help of an experienced mechanic.

The engine itself will have the following modifications thus far:

1. Full length headers

2. Edelbrock RPM Air-gap intake

3. Holley Street Avenger 670cfm

4. 2400 stall converter

5. Mallory Hyfire 6A electronic ignition, Promaster coil, and Comp S/S magnetic distributor w/ 8.5mm wires

6. Comp cams 280h camshaft kit (includes lifters, springs, dual chain timing gear, retainers, etc...)

7. Comp cams Magnum push rods

8. Comp cam roller rockers

9. Melling high volume oil pump

10. Spectre 761r cold air intake. Which should line up exactly with the ram air vents on the hood.

11. 3 core Aluminum rad with electric fans

I appreciate everyone's help.

Thanks!

Very similar to my to my engine build. The flat top pistons should get you there as far as compression goes. I would increase the cfm to a 750. I used a stock oil pump. I've been told the high volume units can empty the oil pan so quick as the pump can starve of oil and drop pressure just when you need it most. I love my Air-gap manifold! I'm running a crane 278 split duration cam, headers and stock rockers. Rear axle ratio will have the greatest effect of "The Fun Factor". I want a trac-lock 3:91 but am getting by with a peg-leg 3:25 for now. Good luck with the build up!!

For a nice streetable but fun motor, I would do a little differently: First of all I would ditch that RPM air gap( single plane) and instead get a "Performer" dual-plane manofold ( or some other brand of dual-plane). Instead of the "Magnum 280", I would a "Hi-Energy 273" from the same company (Comp-Cams). Your stock pistons will work well unless you really intend on doing some serious street racing. These will also give you no worrirs using crappy pump gas. I wohld stick wjth the smaller carb you have, which will give you awesome off-the-line performance and great 0-60 street performance with gobs of low end torque. Unless you tsking it to a drag strip regularly, I think you wkuld be happier this way. Nice smooth idle, accetable fuel economy and grest throttle response.

You will definjtely want to replace your stock timing set with a "0" degree performance set, and a limited-slip rear of 3.25 or 3.55 would

be perfect for street use ( if automotic trans), 3.73 or 3.91 if a manual trans.

The RPM air gap is a dual plane manifold. (Performer works fine also, it's what I have)

My car has flat top pistons and runs all day on 87 octane.

As for the oil pump, for a steet motor like this, a regular pump is probably a better choice.

All,

At one time,I thought that the high volume oil, along with the chromoly oil shaft, was the way to go. Another option was to purchase standard oil pump and change the pressure spring. This also seems to be not necessary. So, I did a Google search and came across this article. It references that the early Ford V8 cam gears were not as bulky and strong as the Chevy engines.

Excerpt: Ford gears tend to get eaten-up because they just aren't big or strong enough to take the load that a high volume pump puts on it.

Are high volume oil pumps OK to run on the street?

http://www.badasscars.com/index.cfm/page/ptype=product/product_id=91/prd91.htm

So, to do it over again, a good oil pump with an oil pan that has the baffle, Chromoly oil pump shaft, should work fine for a performance street motor!

Comments?

mustang7173

My mistake, I thought the air- gap was single-plane.

Sure,flat-tops can run 87 pump-swill, but you have to watch that total dynamic timing under WOT.

His recipe is a good one, I just think its a little more aggresive than what he said his intentions are for it. In almost every situation, most daily-drivers would be much happier with a little less of an agressive build for street use.

But either way, that wkuld be a great performer!

Hello Machlovin,

Since your engine is the 1973 vintage, then your cylinder heads should have the 4V (Open) 74-77 cc

CJ D1ZE-DA

D3ZE-AA

HO D2ZE-A

A good set of TRW SpeedPro forged pistons should yield 9.5:1 to 9.89:1 compression.

Sealed Power L2379F30 - Speed-Pro Power forged Ford Pistons

Sealed Power#844-L2379F30

351C Stock-Type Piston, .030'' Overbore

• Piston Dia.: 4.030''

• Piston Top: Flat Top, 2-Valve Reliefs

• Pressed Pin

• Comp Ratio: 10.76:1 w/58.6cc Heads, 8.90:1 w/76.2cc Heads

• Ring Grooves: 5/64'', 5/64'', 3/16''

• Sold as Each

Source: http://www.csgnetwork.com/compcalc.html.

Recommend to Read:

Ford Performance by Pat Ganahl

http://www.amazon.com/Ford-Performance-Pat-Ganahl/dp/1884089275

Ford 351 Cleveland Engines: How to Build for Max Performance (SA Design) Paperback by George Reid

http://www.amazon.com/Ford-351-Cleveland-Engines-Performance/dp/1613250487/ref=pd_sim_b_6

Sounds like the flat top pistons would be a winning Hand here! Comments?

Mustang7173

I have around a 290 gross duration cam in mine. It's a soggy turd below 3K. Bump the compression no matter what cam you run. It will make it a much more efficient engine.

So, to do it over again, a good oil pump with an oil pan that has the baffle, Chromoly oil pump shaft, should work fine for a performance street motor!

Click to expand...

Just to note, I did get the ARP oil pump shaft as recommended in the book

"Ford 351 Cleveland Engines: How to Build for Max Performance" by George Reid.

Hello Machlovin,

Since your engine is the 1973 vintage, then your cylinder heads should have the 4V (Open) 74-77 cc

CJ D1ZE-DA

D3ZE-AA

HO D2ZE-A

A good set of TRW SpeedPro forged pistons should yield 9.5:1 to 9.89:1 compression.

Sealed Power L2379F30 - Speed-Pro Power forged Ford Pistons

Sealed Power#844-L2379F30

351C Stock-Type Piston, .030'' Overbore

• Piston Dia.: 4.030''

• Piston Top: Flat Top, 2-Valve Reliefs

• Pressed Pin

• Comp Ratio: 10.76:1 w/58.6cc Heads, 8.90:1 w/76.2cc Heads

• Ring Grooves: 5/64'', 5/64'', 3/16''

• Sold as Each

Source: http://www.csgnetwork.com/compcalc.html.

Recommend to Read:

Ford Performance by Pat Ganahl

http://www.amazon.com/Ford-Performance-Pat-Ganahl/dp/1884089275

Ford 351 Cleveland Engines: How to Build for Max Performance (SA Design) Paperback by George Reid

http://www.amazon.com/Ford-351-Cleveland-Engines-Performance/dp/1613250487/ref=pd_sim_b_6

Sounds like the flat top pistons would be a winning Hand here! Comments?

Mustang7173

Click to expand...

Thank you for your insights. I did get the book by George Reid. I will look into those pistons as well.

Your on the right track. Flat tops will get the compression you want. Not a huge street avenger fan. if i was doing a vacum secondary carb on my motor, i would do a holley 750 vac PN 3310. they are fairly cheap and work and perform great! I do have a brand new set of speed pro hyperutectic pistons for sale, they are flat tops with valve relifs. They would work great of you aren't planning on a supercharger or nitrous. as well as an almost new 2500 stall for a c6 ill let both go for cheap.

I do have a brand new set of speed pro hyperutectic pistons for sale, they are flat tops with valve relifs. They would work great of you aren't planning on a supercharger or nitrous. as well as an almost new 2500 stall for a c6 ill let both go for cheap.

Click to expand...

What size are the pistons and what is your asking price?

Thanks.

They are for a standard bore. They sell for about 210.00 new but I will take 150.00

Here's a very good, but older reference book I recommend:

"How to Rebuild Ford Engines" by Tom Monroe

It covers 351C-460.

I also agree to use a standard volume oil pump.

Here's a very good, but older reference book I recommend:

"How to Rebuild Ford Engines" by Tom Monroe

It covers 351C-460.

I also agree to use a standard volume oil pump.

Click to expand...

I already went with a high volume pump because that is what George Reid recommended in his book "Ford 351 Cleveland Engines: How to Build for Max Performance."

Do you guys think I will be okay with the stock oil pan for now? I won't be doing any kind of racing, except the occasional pedal flooring.

Machlovin,

Does your oil pan have the baffle in it?

mustang7173


Machlovin,

nosdelacruz does have a good price for the pistons. Do you know what the cylinder wall specs. are? Will they need to be bored out? Definitely would found out before buying pistons.

mustang7173

If the pump isn't installed then dont use it. I've used both high volume and stock volume and stock is correct for any street engine.

Use flat tops. Try to go for a minimum overbore. Usually .020 can be done and that is a standard piston size.

I like the 3310 but only the first version 3310-1 with downleg boosters. Ebay would have to be the source for that.

The baseplate will have to be swapped out for one with a PVC hookup. And change the front bowl to a dominator/ ford style for the stock stealth look.

A new off the shelf carb and I'd go with the Barry Grant thermoquad. I'll ultimately use one on my daily driver once I can get a EGR plate from an Australian 351C

Recurve the distributor and order a 400 truck damper from damper doctor

Replace your valves and rod nuts.

I'm not a fan of changing the fan during a rebuild. What if you have an overheating problem. What do you troubleshoot first?