Head/Manifold Choices for 351C-2V?

Cash is King, what's the budget?

you can spend the same $ on 2V's as you will the 4V's, all the same basic concepts just a little different geography that makes quite a difference. I doubt you'll get much of a discount at the machine shop because "they're just 2V's"

2V's will get you to your goal, even the D5xx smog castings (1975+) will make 400 hp if done right... but why?

besides budget, the next factor is time-frame

how soon do you need heads?

you'll find a screamin deal on running take-off heads if you're patient, it's the NOW that costs $

Thanks for the reply. As far as budget, I contacted SCM already & I would pay the money. The toughest pill to swallow is the shipping!!!! I don't want to do the Iron 2V's at all, although in the 2V world, they are good. In my mind, I would rather run fantastic heads/intake & use a stock Boss cam.

Hey Tim,

How come you don't like Corvettes?!
Seriously, I love the older Vettes. When I was shopping for my first car I found a silver 1968 L88 4-speed car at a good price, but I was a about $2K short and dad said he wouldn't help me buy something I'm gonna kill myself in. Man I wish I had that car now!

So, back to your question...
It's not hard to build the kind of power you're looking for with a Cleveland. So first of all, determine how you're going to use the car and what kind of driveability you're looking for; everything else will follow from this decision. Next, what does your engine builder recommend? Often, it's best to go with your builder's recommendations if you expect him to stand by his work if you don't get the results you're after.

And don't waste time or money R&Ring the iron 2V heads. Determine what a decent set of 4V closed chamber heads would cost (shipped to you) as well as the cost to R&R those heads and set them up for your application. Then compare that to the cost of a set of CHI 3V or 4V heads (if your bent on 4V heads); I think you can get a quality aluminum head for nearly the same money (maybe more) as you'd spend on old cast iron heads. There are other aluminum heads which are capable of meeting your power goals as well, but they're all 2V heads - hence the importance of talking to your engine builder. And avoid ProComp heads like the plague - they're cheap Chinese knockoff's of CHI heads that tend to need more $$$ in machine work to make them half-way decent than you'd spend buying quality parts. Anyway, your cam needs to work in conjunction with your heads as a system.

FWIW, I'm running Edelbrock aluminum heads on my 383 Cleveland stroker that have been ported and have larger valves than what they come with from Edelbrock.

When I got my CHI 4V heads the CHI website price included shipping within Australia. When all said and done the additional ship cost to the US wasn't that much. At that time it was a choice between CHI and AFD, but now there seems to be significantly more options. Give the Trickflow heads a look before deciding, they are very competent heads with lots of reviews online. A good price and free ship from Summit Racing.

Julian

Joules, How did you use your heads? Are they preforming up to your expectations????

Thank Garth, Apparantly, I must be pretty transparent! I agree with you about the 2V's. I kinda think that if you get the best head you can & cam it to your power level & not expect too much, that you'll end up with a nice street car.

quote:

Originally posted by garth66:


So, back to your question...
It's not hard to build the kind of power you're looking for with a Cleveland. So first of all, determine how you're going to use the car and what kind of driveability you're looking for; everything else will follow from this decision.


Next, what does your engine builder recommend? Often, it's best to go with your builder's recommendations if you expect him to stand by his work if you don't get the results you're after.

Make sure you have a engine builder that understands the 351C ! Many don't !!

The engine is 40 years old now and not all that common in the U.S. compared to other engines, that puts it outside the experience of many builders and they can tend to treat it like it is a 350 Chev. That will be a mistake.


Unless you can get some super deals on alloy heads where you are i can't imagine rebuilding a set of used cast iron 4V heads would be more expensive even with new valves, hardened valve seats, valve guides, springs ect

Be sure to check exactly what you get when comparing head packages, eg: do the alloy heads come with valves ,springs ,retainers ? ect and what type are they ?

Do the alloy heads require special manifolds ? Does that limit your manifold choice ?

Do they require a specific set of headers ? Does that limit your your header/ exhaust choice ?

Compare apples to apples not apples to oranges.

quote:

Originally posted by alnukem:
Thanks for the reply. As far as budget, I contacted SCM already & I would pay the money. The toughest pill to swallow is the shipping!!!! ... In my mind, I would rather run fantastic heads/intake & use a stock Boss cam.

I guess that answers the budget question

and I like the concept of the good top end / basic bottom end, Keep It Simple

I've been close to snapping off on a set of Scott's Masterpieces myself, did you get a shipping quote?

is there an option more economical than next day air?

He told me about $600 US.

so prices from Scott's web page converted / shipped right at $4K

heads $2k each & we'll send you the matching intake Free!

actually not bad at all considering what's hidden in the design / engineering, the stock factory appearance & hopefully the quality

2V ported Trickflow's list as high as $1400 each & they don't have a dual plane intake that I saw?

I thought they did, what happened wit dat?

Your rear wheel horsepower goals equate to 470 to 500 crank horsepower. My advice is to not set a horsepower goal, rather build the engine for a certain type of power characteristic, and let the numbers fall where they may. I'm of course infamous for my appreciation of the 4V cylinder heads. If you build the engine right you can rely on it to accelerate the car like nobody's business, by virtue of the kind of power delivery it will have equipped with 4V heads.

Keep in mind that 500+ bhp was the horsepower output of this motor in endurance racing tune 40 years ago. Cleveland race engines normally made peak horsepower at 7000 rpm (or higher). You desire to reach this same output at lower rpm, in street tune. This is possible due to progress made in camshaft/valve train technology. You cannot achieve 470 to 500 bhp with a 40 year old Boss cam (as you mentioned above). Those 40 year old 500 horsepower race cams had very long duration lobes, which was a necessity to open the valves 0.600". Long duration cam lobes are always accompanied by lots of overlap, which ruins drivability. It was possible to make 400 horsepower 40 years ago with a hydraulic tappet cam and still have good drivability (about 0.500" lift and 60° overlap). 400 horsepower in a street car was a lot of horsepower! There were 450 horsepower solid tappet street cams, which gave-up quite a bit of low rpm drivability to achieve that extra 50 bhp (about 0.540" net lift and 70° overlap). Utilizing modern lobes will make it easier to achieve your power goals while not having to compromise drivability or low rpm performance. Actuate the valves with a modern cam having about 228° intake duration (at 0.050) and net valve lift of 0.600" or more, BUT less than 2° overlap at 0.050 (less than 62° overlap based on advertised duration). The exhaust valve should open around 80° BBDC and the intake valve should close around 70° ABDC. No less than 112° LSA.

The better the induction and exhaust systems are the easier your power goal will be to achieve. At your power goal the 4V heads would need porting. They don't need much porting, pocket clean-up and 3 angle valve seats are the biggest improvements. The important thing is to avoid screwing-up the performance of the heads as many porters do, so its nice if you can find a head porter who knows what they're doing in regards to those heads. The best "carbureted" induction would be the Aussie Speed manifold and Weber IDF carbs. If your preference is a single 4 barrel carb, then choose the Blue Thunder manifold and a 750 or 850 carb with annular booster venturis. You can achieve a higher peak number with a single plain manifold, but the Blue Thunder manifold will make more bhp across the rpm range where the engine shall operate 99% of the time. On the exhaust side choose headers with 1-7/8" or 2" primaries, and a proper collector. Set-up the engine for 91 octane fuel with 7.7:1 or 7.8:1 dynamic compression. Complement the engine with 3.89:1 gears (assuming a 26" rear tire), traction lock, and Shelby/Traction Master traction bars.

In terms of aftermarket heads, there are several choices in high port racing heads which will make big power numbers if you want to go that route. They are limited in intake manifold compatibility, and in most instances the carb will sit so high it may not fit beneath the engine compartment hood. Race heads would probably require custom headers for the Cougar as well. The first aluminum Ford race head, the A3 head, had a dedicated intake manifold based on the Edelbrock Torker, that would probably fit under the hood. The SCM dual plane manifold will probably mate with those heads too, it mounts the carb even lower than the Torker.

Moving on to street heads with standard height intake ports the SCM heads are a great choice, they are modern iterations of the iron 4V heads in many ways. The intake ports are about the same cross-sectional area (tuned for the same rpm as the 4V heads) but they lack the big inlet and ramp that the 4V intake ports have, therefore the intake port "shape" is much more consistent. The valve pockets are very modern (generous in size). The CNC intake ports flow "out of the box" about as well as professionally hand ported 4V ports. That's quite an achievement considering the SCM ports do not have the ramp built into them. Darin Morgan is also very proud of the exhaust port he designed for those heads. Replacing unported 4V heads with a set of SCM heads will net a 70 bhp increase in horsepower. Some of that is due to the fact the SCM heads are CNC ported out of the box, some of that is due to the improved exhaust port, and some of that is due to the Westlake/Yates style (high swirl) combustion chamber. Manifold choices are limited for heads with "stuffed" 4V ports, so that is something to consider, depending upon what your induction preference is. In terms of a dual plane manifold, the SCM manifold is the only choice ... but its a well designed choice. All aftermarket heads have smaller exhaust valves than the 4V heads, and work better with headers having 1-3/4" primaries.

I'll tell you why I like recommending these heads. First, they are designed by a gentleman who is at the top in his profession, Darin Morgan. Second, they are cast and manufactured in Australia, not China. Third, I have confidence you'll have no regrets doing business with Scott Cook. He's a good guy.

In terms of 2V heads, or domestically manufactured heads, the CNC ported Trick Flow heads are the way to go. There's lots of good feedback regarding their performance.

George, thank you very much for your insight, I was hoping you were going to post.

So, going the SCM heads/ dual plane intake seems like the easiest & best way of making a powerful street engine?

Do you think the 3.85" stroke is where I should start or would the 3.5" get me where I want to go? I know as far as strokers, there comes a point of diminishing returns, where friction starts eating up power. Also, I've heard that the longer stroke & leverage of the longer stroke starts getting tougher on main bearings. And that the shorter pistons start to induce piston rock. Is this the case on the 3.85" or 4" stroke stuff?

As far as the cam goes, isn't a 228 duration @.050 just a wee bit more than your typical street 268 type cam? Sweet! Is your choice of lifter, flat solid or hydraulic roller?

And I know the devil is in the details. I know that starting with the right parts is key & tuning is where you get your streetability. I would pony up the money to have it dynoed.

To me, having a powerful & optimized setup is priceless & rewarding....a car that does what it should.

I would carefully consider piston(dish) availability & even possibilty in the choice for how much stroke

adding stroke puts a real Whack on the static CR & Scott's largest chambers are 59.5cc

depending upon piston CH it may not even be possible to create a dish large enough to manage DCR ?

as far as stroke in general, the stock block may not have long enough bores toward the bottoms IMO

it's a delicate dance to get a piston short enough(ring pack & dish) to use a long enough rod to keep the piston from coming out the bottom of the bore at BDC

I have heard about a serious custom piston that incorporated a 'trough' around a clearance bump in the piston dome for the top of the rod, probably not made from a 'stock piston blank' but from billet block

I have Scott Cook heads and dual plane intake on my 393cuin in my Pantera. I wanted ~550hp at 6,700rpm and got 626hp @ 6,700rpm and 556 lb-ft @ 4,900rpm, so maybe my engine builder / cam tech underestimated the potential of this package. :-)
11.2:1 comp ratio with 93 octane and no ping, custom Comp Cams solid roller cam, 250 & 258 duration @050. It idles pretty nice and I still run vacuum brakes. This engine for me worked out great, not a stump puller but then my Pantera is not a truck, it is easy to drive at low revs, 18mpg and comes alive when you stomp on it, just how I wanted it.
My heads had 58.5cc and Kuntz & co used Mahle 275030F03 pistons and I think he machined them slightly to get to his target cr.
I used Yella Terra YT6321 roller rocker arms so no pushrod guide plates.
The Scott Cook heads and intake certainly look and worked out great. I can even run a 4" tall filter under the stock Pantera engine cover.
I did have some CHI heads which rubbed against the pushrods even after cutting the guide plates, the "pushrod holes" needed grinding, not impressed.

Just goes to show you don't need a blown Chevy. to make over 600HP. There are many other Clevelands out there that do that and more.

quote:

Originally posted by alnukem:

... Do you think the 3.85" stroke is where I should start or would the 3.5" get me where I want to go ...

3.5" stroke. The '67 cougar is not heavy enough to warrant more stroke. The 351 will light up the tires at will. All other things being equal, increasing stroke does not increase horsepower, it lowers the rpm of peak horsepower but the horsepower remains the same. Peak torque increases however.

quote:

Originally posted by alnukem:


... As far as the cam goes, isn't a 228 duration @.050 just a wee bit more than your typical street 268 type cam ...

228° at 0.050", but about 282° advertised duration. Just another ubiquitous 280° street cam. Horsepower peak will be 6000 rpm.

quote:

Originally posted by alnukem:

... Is your choice of lifter, flat solid or hydraulic roller ...

This is a street engine, isn't it? In that case hydraulic roller.

quote:

Originally posted by alnukem:

... And I know the devil is in the details. I know that starting with the right parts is key & tuning is where you get your streetability ...

The low overlap high lift camshaft is the key. Yes the carb & ignition must be tuned appropriately. The SCM heads can take at least a 1/2 point higher compression ratio (10.5:1), this will help reach the power goal AND give the engine even more snap.

When the time comes to order a cam I'd recommend an off the shelf cam from Crane or, if you wish, I can put together a spec for a custom ground cam from Bullet Cams.

Thank you gentleman for your help. You were all very kind & informative to me. I will go ahead & SCM Heads & Manifold coming. I am sure I'll have more questions in the future. Thanks again. Happy New Years to everyone! Tim