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72 351C new heads stock exhaust
#1
Work in progress!  Love the Mach! I thought I was going to be OK with my stock 1972 351C but it's just not cutting it.   I am not looking for street races but right now there is just not much under the foot!  Undecided  

Here is the latest engine sort of dress up:
[Image: image1_zps0iqzwpuv.jpeg]

What I would really like is a set of heads that can increase my compression and low end torque, work on pump gas fit my stock exhaust manifolds!!    I have had various header experiences and just not a big fan. 

Anyone know of such a thing?

Really appreciate it!

[Image: image4_zps0cylnzgr.jpeg]

Back in the day we used to ride around in jacked up cars and poke fun at people that lowered. Lessen: keep your mind open.  
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#2
What heads are currently on the engine? What cam etc?

351C heads are honestly some of the best factory heads ever made. A properly designed cam does wonders.


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#3
Most people feel that the best combination of head, valve and combustion chamber are the Australian 302 heads that bolt right on a 351 C. You have runner size of a 2-V head with bigger valves and I believe a little smaller chamber.
I have a 351 C that the PO had bored .050" installed flat top pistons, Eldebrock Performer intake. 2-V runner size to a 4-V carb. The heads are the 2-V heads. The exhaust ports are also smaller on the 2-V head and that makes the headers different also. He also installed long tube headers and dual exhaust. The car seems to have great low end and mid range never had it over probably 80 mph, too many cops here, lol.
With that combination I run on 90 octane pump gas but no ethanol.
He also put in a cam which I have no idea what it is, lol. I should have checked lift when I had the heads off but I did not.
He had also installed MSD ignition.
I do not know what you expect but the Cleveland will never keep up with a new Mustang with Mod or Coyote engine. They are way ahead in HP and technology.
Some pics of the engine.

[Image: 100_3509.jpg]

[Image: 100_3510.jpg]

[Image: 100_3539.jpg]

[Image: 100_3549.jpg]

[Image: 100_3550.jpg]


When a man is in the woods and talks and no women are there is he still wrong??
Tongue
David
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#4
You'll just be able to go so far, without headers. An engine is a big air pump, the more air it pumps (along with fuel) the more power it will make. If the air can't get out of the engine the pump efficiency is reduced. Cleveland exhaust manifolds flow fairly well, but not as good as headers, which also reduce reversion as well as back pressure.

A better cam will definitely help. A lower geared rear end will give you a big improvement in acceleration, just don't plan on cruising down the highway and getting good gas mileage.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#5
I can speak to first hand experience on headers hurting gas mileage and no gain in performance. I have a 1987 Ford Van with a 351 HO engine. Came with 4-V. I ordered a new Eldebrock carb and headers and lost about a mile to the gallon and could not tell any difference in performance. The reason I change was the cast iron manifolds kept breaking and HO 351 vans are not too common. Could not find cast iron.
The length of the header tubes needs to vary with the expected rpm range you are going to run. They calculate the length using same formula that is use to pipe organs. The exhaust pulse should be at the end of the tube right when the next one hits to "Tune" the headers.
My old boss use to make his own since the over the counter were just an average mid range thing. If he knew it would be in 5,000 rpm it would be one length if 4,000 rpm would be longer.
If you have ever kart raced it shows up big time with the small engines if your exhaust is not tuned to your rpm.
So when you put on tube headers it may or may not help performance. All the parts have to work together. That is where tuning on a dyno really helps, no guessing no seat of the pants real numbers.


When a man is in the woods and talks and no women are there is he still wrong??
Tongue
David
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#6
I've run or have installed headers on just about every brand of American car there is. I have two favorites, the reproduction Tri-Y's for the 289/302 and the Hooker Comp headers for the 351C in the 71-73 Mustangs. 6915 for 4V heads, 6921 for 2V. The headers are wasy to install and the only "clearance" issue is that the pitman arm may just hit one tube at full lock.

As far as heads, if you have 4V open chamber heads, then a simple swap would be a set of closed chamber heads. If they are 2V, then you could go Aussie closed chamber.


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#7
I went with Trickflow. Awesome power! Stroked to 408. Factory manifolds will work, but I went full length headers and they fit perfect.
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#8
Update:

We pulled the engine apart.  It sort of hurt because it was hitting on all 8 and started right up every time.   But we needed to bore 30 over because too many scars.   I guess now i have a 356 Cleveland (I think that is right).   CHI 2V heads 190CC and 60CC chambers.   A Comp Camps conservative hydraulic roller and some rolling out rockers.  Everything is pretty conservative i had may share of barely street drivable in the past!  Should top out at about 5500 but should be pretty strong getting there I hope. 

Maybe now I can take a Prius off the line for at least the first 100 feet?   Haha


[Image: 57481172980-A126734-C-70-DB-446-D-A995-E...E1-DFD.jpg]

Back in the day we used to ride around in jacked up cars and poke fun at people that lowered. Lessen: keep your mind open.  
  Reply
#9
+1 to 408 stroker. It can get you in the 500 hp club with good heads and cam combo. At that power level it will be as much as the car can handle without serious mods.

Sent from my SAMSUNG-SM-G930A using Tapatalk

        [Image: 20160929_171923_edit2_small.jpg]

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump
Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes
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#10
Did you use Comp cam hydraulic roller lifters?? If you did, I would pull them out and throw them straight in the garbage. I had multiple failures with mine. They knew of the problem and never fixed it. My engine builder will not even put them in any engine any more.

Kevin

1971 Mach 1
408C Stroker
C4 w/3,000 stall
8.8" Rear w/3.73's
Disc brakes all way around.

[Image: 044.jpg]

https://youtu.be/SoW1fhaFPzY
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