Cylinder head work and valves

Sounds to me like a stock guide/valve combo to me Paul. I checked some old valves that were laying about, and they had similar letters I do know that this set was sodium. As far as I have heard, there is no way to tell if they are sodium or not, at least visually. Put one in a vise, held by the head n tap it with a small hammer (appropriate safety lecture inserted here), it will not bend if it is Sodium. At all. They snap. IMO ou best courseof action is to get intoch with SI valves, as they are good quality, and the prices seem to beat the others. I use them exclusively.
As to the porting, it is doubtful that you are going to harm anything, other than if you "strike water". Port matching is a good way to go, and I wouldn't worry about hurting performance by the exhaust work. With street muffler systems, you wont be able to out flow,so there is no harm done there. I would suggest taking an old exhaust gasket that is in good shape, place it o the studs, pulling downward, as the gravity would do. Then scribe around the opening,and blend that in a well. Repeat on the header while itis off, as the can be as much as 1/8" off. To best avoid problems in torque curves and a welding job to boot. leave the port pretty much as is, just polish it after any odd bumps are taken flush. You will be happy that you did.
Kermit

 

After you strike water use your heads to hold your door open.

 

On the piston below topic, I would think that it may be necessary to leave some clearance for piston/rood stretch at higher RPM's I do not know what is the minimum on the 308 motor, as stroke length, rod and pisto design play a large part in it. I've measured some that were .030" down, and heard of .050" down. Anybody have some input on this one? In past non Ferrari motor building, often there were different tolerances called for by the different MFG's, and not a set standard which is to be expected.
On the head topic the only other thing that comes to mind is POLISH. Piston tops,and combustion chambers as well as exhaust ports. unless you plan on some of the new coatings for thermal barrier (I personally haven't gotten comfortable with any yet), this is the best way to put the heat to work and not get absorbed by coolant or oil. It may sound a bit odd at first, but in reality, a square inch of area that is polished offers a lot less "real" surface area. a good illustration is cut a 1" square of plain old corregated cardboard. Peel of the top layer. It measures 1" but if you pull the corregated part out flat, it is often a full 1/3rd longer. Simple, but an excellent illustration.
I prefer to polish th intakes as well as the exhaust ports for the same reasonn. The intakes, to keep heat fro transfering into the incoming charge, and the exhaust to hold the hea back from the coolant.
HTH,
Kermit
AAAHHH, after a sip of Java, I remembered NO SHARP Corners. Round them slightly, as they are potntial hot spots that can cause detonation.

 

For those that read this little exchange between Krowbar and Kermit please refer to this older thread where you can learn what happens when an "expert" strikes water

http://ferrarichat.com/forum/showthread.php?t=50989&page=1&pp=20

This referral has been approved by the moderators.

 

paul,

if i remeber correctly you have the holy grail p6 cams so there is no doubt in my mind that your engine has been massaged by someone or something that knows what it is doing. Cant help you on the valves but wish I had your cams!!!

Rob

 

On the guide issue, from what I gather you are refering to practice common on American heads where the guide is integral with the head. On Ferrari, it is simpler to replace the separate guide. Removing them is a trick endeavor if done the wrong way.
As to the valves, I have not found any referance material to post. Perhps if in doubt, clamp the head of one in a vice and see if it bends. that way you will know if they are or are not. if it does, only one needs to be relaced. if it snaps off and it isnt hollow, you will have to replace all 8 anyway.

 

Paul
On two of your points above:
(i) The most informed view (to my judgement) on the 2v heads has come from Bill Pound/Michelotto. Tate Casey and James Patterson indicate the same when questioned (by me). All point to the exhaust ports being too large on the 308, even with the bigger cams (P6 and other profiles). Thus work to flow the ex ports tends to involve welding and filling (or starting with the 208 heads as Michelotto used to do).
(ii) The exhaust manifold on US cars (308, Daytona) was offset to reduce emissions. This was confirmed to be by Tate and Brian Keegan (now of T Rutlands). Euros and comp headers were different. I port matched the header to the manifold. Took several hours with a die grinder before sending the headers out to be coated. Tate tells me that one modification is worth 5 BHP on their dyno.

The 4v are very different.
HTH
Philip

 

Very interesting link you posted there Paul but on the bottom of page 5 Kermit posted a waiver given to your lawyer that is signed by you which releases Kermit from any wrong doing with your heads.

 

It does not release him of wrong doing, Read it carefully
It is a waiver releasing him of liabilty in his unsucessful "attempt" to repair the damage he caused when he cut into the water jackets, I DID NOT release him from doing the damage he did when he ported into the water jackets in several different places. I sent him two perfect heads from a car I was driving until the week before I sent the heads and $5000 what I got back was two destroyed heads and 32 brand new unused Ferrara racing valves that were garbage.

Kermit was playing lawyer and wrote that waiver himself and I must say it is as bad as his machine work.

By the way he had my stuff for almost 1 year.


Moderators: I was just responding to a post that was directed at me.

 

Krowbar, I am a bit "dumbstruck at the statement :"you were suprised to find them in there". I'm certainly not saying that there was no truth to the statement, it is just my experiences with cams and their drivability, etc. In all fairness, my current comparison is a 4 valve with Capo 934 a Cams @260 degrees or so. It is runing a superlight Quartermaster twin 7" disc clutch that is supposed to be track only, and it has virtually no inertia to speak of, so that has a dramatic effect on drivability. The idle is under 2000RPM, and you had better have it aimed when it "comes on the Cam" as it turns into a rocket. Yet I see others running the famed P-6 on the street, with seemingly no problems. What of mixture problems caused by low RPM reversion with the intake closing that late? The 943closes the intake at close to what a stock 348 does, and it can still be a handfull. Any enlightenment?
And BTW Pillip, I concur with the exhaust issue. Personally, I just remove that which causes undue turbulance, and do not open other than the headers . port opening, providing there is an overlap (there usualy is in US cars) Joe Theiler (RIP) and I spoke at great length on the topic and he was of the very same opinion.
Kermit

 

krobar, the engine is an air pump and anything that you can do to get the flow in and out will create more efficiency. Go for it

 

I appreciate the input Krowbar, glad your'e back.
I am not suprised on the reversion, I guess what I have a bit of trouble understanding is: I have studied the valve events on every model Ferrari that I can find, and with a vast background in cam design in how it relates to engine size, rod/stroke ratio et al. I'm suprized to find them on the street. Everything I have studied indicates it should be a handfull. Must be some power in the upper ranges if ported right though, but how drivable is it on the lower end?
Kermit

 

Gary... the exhaust does need to be made turbulant for better drivability.

There's no use having 300BHP at 9000rpm if you only have 150 at 7000.

The engine is a "variable speed" air pump. And it's efficency must be managed to make it flexible and drivable.

 

The two 308 core engines I am working on for Nick had the pistons .050" down the hole at TDC. Rather strange since the stock piston also has a dome. One would think Ferrari would have used a flat top piston at zero deck to arrive at the 8.5:1 compression ratio.

In any case, the aluminum Corvette engine has the pistons .007" out of the hole. Stock gaskets are .050" thick. That leaves .043" piston to head. Note that the Vette engine has a 3.622" stroke vs. the 308 stroke of 2.795". There is a lot less "stretch" with the shorter stroke and lighter piston, rod than on the Vette engine.

The hot piston to head is actually slightly more because the aluminum block expands roughly .012" from cold to running temperature. The Ferrari block has about 87% of the deck height of the Corvette block so I would expect it to expand roughly .010" from cold to running.

Both 3.5 and 4 liter engine will have zero deck with .044" MLS gaskets. You can run tigher but you need to leave clearance for carbon buildup on a street engine.

Regarding the 2 valve heads. The exhaust ports are large because the US cars had an air injector (rather large) sticking in the port. The intake port is actually smaller in cross section than the exhaust port on these heads. Hard to imagine a flow bench was used in the original development.

Not sure if my flow data sheet was uploaded but in any event, the exhaust port flows more than enough as is. When "matching" make sure to leave the exhaust port smaller in diameter than the exhaust manifold or header. This helps to reduce exhaust back flow into the head.

The intake side needs a lot of work to get flow up to contemporary standards. I recommend you install a slightly larger intake valve (1mm) - a flatter back side on the valve will help as well considering the low valve lift. If the guides are loose, replace them with new bronze guides. Most of the bronze guide material today requires about .0015" - .002" clearance on the intake and .0025" - .003" on the exhaust. If you run them much tighter you run the risk of sticking a valve in the guide. The thin wall liners are made by K-Line. You would probably end up damaging the top of the original valve guide if you tried to install the liners. Be less expensive and better to just replace the guides as Kermit recommended.
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Steve:
Can you identify (and comment) on what is measured data and what is modeled in the table you supplied?

Starts to explain why Pound and others have found 80 - 100 horses from (the heads of) 2V carb'd cars.
Philip

 

purposely missmatching ports from the factory creates turbulance right at the point where they would inject air for emissions control, thats why such big gains can be had after a port match and removal of all the emissions junk.
I even belled out the headers on my 246, you cant believe how much of the header stuck into the port

 

The measured data is in the rows labled "corrected flow."
My flow bench is the best one SuperFlow makes - 1020 Pro Bench. It is very accurate and repeatable - it has to be for my R&D work.

A good rule of thumb, on a V-8 engine 1 cfm per intake runner in flow equals approximately 2 horsepower at the crank. So 143 cfm per cylinder @ .300" lift can yield about 286 HP. That's pretty close to what these engines were rated in US trim. One can get more in a highly tuned race engine (well designed headers, better intake, long duration cams), but it wouldn't be very streetable.

My goal is to achieve 400 hp out of the 4 liter engine. With a little work and larger reshaped valves, I have been able to get the intake flow up to 177 cfm @ .485" lift. The remaining 23 cfm will not come easily.

Note that the stock intake port tapers off in flow at a bit over .300" lift. No matter what you do to these heads the flow at or below .300" lift is not going to increase enough to make a great difference in power output. One must get cams with higher lift and ports to flow at those higher lifts. I've got Web working on cams for Nick's 3.5 liter based on some of their motorcycle profiles.

I attached a flow chart which should be easier to see than the chart I posted last night. Session #1 is the stock port and valve flow data. Session #2 is where I am at now with reworked valve bowl and larger valve. The potential flow is illustrated by "P" in the chart. That potential is based on the theoretical flow of the size valve I am testing in a well designed port. Unfortunately the Ferrari intake port is far from a good design.

What you are doing on the exhaust side is good. Get the manifold ports centered over the head ports. Do make the manifold ports larger in diameter than the head ports. There should be about an eight of an inch step at the head manifold interface. Make sure there is enough metal in the manifold before you start grinding away. You don't want to ruin your manifolds.

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Very helpful, Steve, thanks. Sound like 13mm lift cams are the ticket if you can get the ports to flow!
Philip

 

Steve, thanks for posting the graph! What it does is show how flow of air through an engine is the path to more power, you have to remove barriers to flow or reconfigure the shape or size of the flow path. Whenever the path is modified intelligently with respect for the particular application, you will see gains throughout the rpm range and not loose anything down low. Your chart shows how a little massaging can have dramatic effects on total cfm's. A case in point is a project P-car where the only thing done was to give it a less restrictive induction tube and a less restrictive exhaust that was port matched. Big gains were realized throughout with the bottom end power and drivability increased substancially. There will claims to the contrary but they will not be based on fact.