Porting and polishing - $1500

ditto

 

INTRESTING. Fchats longest running sponsor does head work. Look at pics below
http://www.nicksforzaferrari.com/forzaferrariwebsite1_006.htm
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Can anyon explain what a "good multi-angle valve job" entails and why it is effective?
Thanks,
Ron

 

Nick, can you post some details of what you can do for a QV head? Any before-after dyno #s

 

The valve seats on what is normaly a 45 degree cut inot the seat. It wants to be about 1/32" wide. On brand new seats, you can just cut in the 45 degree angle, so the air flows acroos the seat and sees 0, 45, 90 degrees...it's a pretty sharp corner and the air doesn't really like it. I'm pretty sure 308s came this way, at least my QV had a 3 angle valve job when I opened it up.

On a 3 angle valve job, you add about 60 and 30 degree cuts, so the air sees 0, 30, 45, 60, 90. The air likes that alot better. The original purpose was that when you re-work the heads and re-cut the 45 degree, it gets too wide, so the 30 and 60 degree cuts are added to get it back to size. Alot the way they realized it flows better. My XR harley came with a 5 angle valve job which is better yet. State of the art today is a radius vavle job where there is a true radius cut before and afer the 45 degree seat that blend nearly tangent to the seat, often with a diffent radius used on both sides of the seat to optimize flow on the partipular port and combustion chamber design.

 

I would like to know this too, especially dyno #'s

 

i was going thru the pics i took of the motor and i'm trying to figure out what difference would be made on porting the 2v head. from what i can see on mine unless you go hog out the track and chamber it's pretty smooth and direct. i have no missmatch to the intake ports either. unless the PO had a port job done, i dunno.

comments? if these are how the factory puts them out then they look good to me. ofcourse i'm comapring this to the horrible job done on factory detroit iron. so take it for whats it's worth.
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I've reworked the heads on two cars in my life time, with excellent and good results. There are some changes that will improve flow and power gains without a lot of risk. My personal preference is to preserve low end torque and raise power throughout the normal rpm range.

The first head I did, many years ago, was a TR3-A head. This engine produced about 100 bhp stock at the flywheel and was an OHV design with an inverted bath tub type head. When completed and tuned, it put 120 bhp down on a chassis dyno with decent low end torque and a very impressive mid and high rpm response. Obviously there were a lot of opportunities for improvement on a tractor engine of this design. Fortunately, I had the Bob Tulius competition guide to tuning a Triumph, (Bob was factory sponsored way back) and followed his guidelines.

The second head I did, again some years ago, was for a Weber (40DCOE's) equipped Lotus Elan with about 115 bhp (Special Equipment spec.) at the flywheel stock, from 1558 CC's, This lotus head is very similar in design to the 2V 308 hemi head. Although results were never tested on a dyno, seat of the pants suggested about a 10-15% increase in power over the useable rpm range, again preserving low end torque. For this cylinder head I:

1. matched the carbs to the cast-in inlet tracts and blended in the revised opening, well into the port. The ports were not in gerneral increased in diameter except to remove casing defects and ensure a gradual blend. The idea was to gradually increase (via a decrease in flow area) gas velocity to a maximum, to where it peaks at the valve seat sealing area. Suface finish was smooth but not polished.

2. I then fitted the larger Sprint spec inlet valves with appropriate hardend (Stelite) valve seats and new standard size exhaust valves. The inlet valve throats were bored to the appropriate size using a radiused boring tool for a short distance. The boring tool were registered with a pilot shaft seated in newly honed silicone brass valve guides to ensure concentricity of the valve seat. The boring tool used 2-ceramic cutters, with the proper radiused profile, to create a radiused flow/sealing surface with the valve. The radiused seat was then precision ground with a seat grinding stone to establish the desired ID and OD geometry of the sealing surface. The valves were ground to match the seat dimensions, undercut to blend, and lightly lapped, using Dykum red as an indicator, to achieve the desired sealing surface.

3. The port segment between the new limited depth bored throat and the valve guide was blended to remove casting defects and a smooth transition. Special attention was paid to the inside radius to minimize the bend toward the valve seat area. No attempt was made to influence flow swirl into the combution chamber.

4. The combustion chambers were CC'd to achieve equal volumes and therefore equal compression ratios, of about 9.3:1, very modest. A little extra care was spent on creating a decent finish on the combustion chamber to discourage carbon adhesion.

3. The exhaust ports were matched to the tubing headers and blended well into to exhaust ports. The exhaust ports were not in general increased in size, merely smoothed and finished to again discourage carbon build up and adhesion.

Results of this work were never quantified on a dyno, but seat of the pants says I probably gained about 10-20 %, which in a 1500 lb car is noticible. One could expect a similar response in a 3000 lb car of 2900 CC using these guidelines.

What I didn't address was the choke point at the valve guides. The end of the guides could have been tapered or rounded off, or even thinned for additional benefits. The fact is that I didn't want to disturb the new pressed in guides to perform this additional flow stream obstruction reduction. Next time I'll pay a little more attention to them and maybe gain another 2 %.

If anyone else has previous experience in porting and their results, I'd love to hear about it, especially in regards to 2V or 4V 308's. If one can realize a 10-20% increase in torque and/or power over the standard rev range, that is goodness.

Bill

 

smg2,

One of the things I noticed on my tired 308 was extrusion of the gasket between the intake manifold and the head inlet ports and a mismatch between the intake manifolds and the intake ports. When I replaced my carbs with new ones, I also replaced the manifold to head gaskets and delt with the miss-match by blending the intake ports to the intake manifolds. Total mis-match was on the order of 1/16-inch in some areas. I used paper towels in the intake manifold to prevent chips from falling into the combusion chamber and a carbide burr in a die grinder to do the actual material removal.

The key to horse power on a normally aspirated engine is inlet valve size. More specifically, it is the flow area of the inlet valve seat area. Imagine the flow area a defined by a ring extending between the valve seat cantact area and valve contact area and its height. Good geometry is important but this area is key. This is why higher lift and duration work. This window is open wider and longer. To preserve driveablility, just make this window wider.

Bill

Bill

 

right, however the ports between the manifold and the head are spot on to each other and larger than the gasket. i'll had to trim the new gasket open and a little larger as 'squish' occurs to make sure the ports stayed smooth.

the motor is a rebuild be rutlands, so i'm assuming that they just start with a core and go from there. if the PO of the core motor had any port work done it would be in those heads. as it stands i have high compression pistons in this one as that was what was in the core motor.

so fro mwhat i can tell getting a motor from rutlands can be crap shoot as to what you're getting. no offense to rutlands but a blue print or list of parts would be nice.

 

a better pic, stock or not????

if you're wondering i have megs of pics from doing this service and supercharger project. i've gone thru a case of batteries for the digital camera.
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Intake side work is really a crap shoot. There was a similar discussion of this type with someone's 348. He has this really *****in looking hotter than hell intake system and we still have not seen dyno numbers. In fact it is amazingly quite. Regardless one must assume for the sake of being cheap Ferrari would have the system matched from intake to exhaust. So if you really want any gains you really need to start at the intake plumbing before you even consider decking heads and PP. There is much more to disgn than just the flow. Some earlier post illuded to the increase in flow but decrease in velocity so that there was no power increase. Yup I understand that completely so you really need to change pistons then what about stroke etc.... etc... until you get to the shiny tailpipes. It is not cheap and Norwood is definately on the right track going with the turbo. He is a pro and I think he is right. Other prop port and polish etc for racing because of different contraints like turbo illegal or max displacement rules etc... So you build to your rules. Today's turbo lag is nothing like it was in the past and todays engine management systems are very user friendly. I really think this is the way to go and the best have your cake and eat it too compromise.

Finally, there is no way to make power by flowing heads you have never done. It take experience and time and experimentation to make good flow. It is more likely that your heads will be worse than before rather than better. There are more ways to screw up a head on a flow bench and grinder than make it better.

 

Scott,
When it comes to ports, look can be very deceiving. In 1984 I bought a Harley xr1000 (and I still have it), it had the factory racing heads hand ported by Jerry Branch, the best in the bussiness and they looked beautiful. The catch was that to pass EPA, Jerry had to keep the flow under 110, so all the heads went out at 108-109 cfm at 12 inH2O. When you sent them back to him and paid the $1200 if I recall, they came back looking exactly the same, but with a new manifold and now flowed the 148 cfm the engine actually needed. Hp and torque went up 10-20% across the board….but they looked the same.

Ferrari did basically the same kit on a 2Vi engine, not surprising since it was the same time frame. The cam in the 2Vi engine does not have adequate lift to let the valve flow anywhere near what it is capable of….300 lift is just barely enough for the tiny valves in the QV head, it’s something like .100 short of what the big intake valve in a 2V head wants. After that the shape of the back of the valve and the way the seat is blended into the port and combustion chamber can change the flow by 10-15% on some engines. Also, in the 70s, early 80s the standard was that exhaust flow should be about 92% of intake (and part of the reason these engines suffer terrible blow-down under boost)….today the number is 70-80%.

A 2V engine that redlines at 7700 should clear 300 hp naturally aspirated. My 2V pushrod XR engine with basically the same bore, stroke and valve sizes as a 2v 308 makes 125 hp/liter on pump gas…food for thought.

 

so it's a stock port job? i'm not concerned one way or the other just curious. the pic doesn't show it well but there are very definate hone/swirl markings. i assume the factory left it cast in nature right?

 

Increased induction pressure by super charging or turbo charging is the most effective and least expensive route to increased power, except for maybe a nitrous injection system. These systems are probably best used in injected vehicles, not carb ones.

If one insists on remaining normally aspirated, without a nitrious system, some noticeable gains still are achievable with modest risk. My porting philosphy was to match the interfaces then slowly but steadly increase the flow velicity to reach a maximum at the valve seat interface. At this point, flow inertia would drive the flow field through this last restriction. I sought only to improve the overall flow by conservative material removal. In general, the ports were not hogged out for maximum flow potential, only to match the interfaces and straighten out the flow. The flow area was increased only modestly in a very specific area, namely the throat area just upstream of the valve seat, to accomodate the larger inlet valves. Luckily, I had later Sprint valve seat dimensions and David Vizard's book "Tuning twin cam Fords" as a guide. Transition to the valve seat area was carefully crafted with the radiused boring tool, in effect, a multi angle valve job.

Intrusion of the valve guide and valve into the port remain the one area where some gains are still possible without extensive flow bench work. I notice in SMJ2's photo, the end of his valve guide appears quit blunt. This will disrupt flow somewhat. If one were to insert a small obstruction to flow at this point, to perturb the flow, a noticable increase in pressure drop would likely be seen on a flow bench's manometer. Rounding or tapering of the end and maybe slimming of the protruding portion of the guide, relative to the flow direction, would net some limited benefit. It also appears the valve face is cut with a single angle and the face is probably a lot wider that it needs to be.

Breathing is the name of the game. The more air one can force through the system, the more the power and torque potential, whether by normal aspiration or forced induction. Increased breathing works even on engines with modest compression.

Other fruitful areas not discussed are increased compression, yielding increases in torque and power, but with an octane increase penalty. Revised cam timing and increased lift are other avenues where increased overlap helps the high end to the detrement of low end torque, while increased lift helps everwhere, but may cause increased valve train wear and challanges piston clearances.

There's nothing easy about any of this stuff and it is easy to make mistakes. I'm really disappointed that there isn't more specific information freely available to the Ferrari community on this subject. Maybe this thread will flush out some tidbits.



Bill

 

bill, the pic isn't clear enough but it does have a 3 angle seat, and is lapped. i talked with the engine builder when i started to notice odd things about the motor. from what i can tell the heads look to be ported, in some spots there was bad porosity and it had been re-welded then ground again.

in talking with the builder he says rutlands just pays him to put them together as a stock re-build. rutlands motor are built off site according to them. anyway, alot depends on the core they use. so if you P&P your motor and at some point send it in as a core or the car gets wrecked and the motor is pulled as a core, you can guess the rest.

 

Those are stock heads as far as I can see. Ferrari does a hand clean-up on the ports, finishing them with 80 of 120 grit, blends the seats nicely and puts on a 3 angle valve job. That's probably what the guy Russ was talking to though he was going to do for $1500...not knowing the engine comes stock that way. By doing that, they probably increase the flow by as much as 10%.....but it's still low by 30%+ from where the engine would like it to be.

If I recall, there is a good discussion about 2V flow in the 4 liter thread, as Mark was building a 2V engine. I think he's since retrofitted it with 4V heads, making me think that he couldn't make the flow number he thought he was going to with the 2V heads.

I'll say again, a port and valve that size should flow about 140 cfm at 10 inH2O through the intake....my understanding is they only flow about 90 (with the CIS not connected). Also, a valve that size needs about .400" lift to make full flow (if the seat and port are shaped correctly). I run .570" in my XR (similar size valve, port and combustion chamber), but that's an old cam grind, if I were building the engine today I could probably hold it to arond .500" lift and make the same dyno numbers.

 

I can say that my 308 GT4 intake did not line up at all. I did the port matching myself, and the car feels definitely stronger down low.

One thing I didn't do is touch the port in the head near the valve (only the section adjacent to the inlet manifold). The goal for me was to go from a big port area from the carbs to the small port area of the head. I wasn't sure of the flow characteristic of the head, but I still wanted a velocity increase as it got to the head. Spend more time matching the carb to manifold (opening it as big as the carb throat), and it naturally tapers to the valve opening, hence velocity increase.
I also did all this with the head on the car (making sure block the intake near the valve), but the manifolds and carbs off of course.

If you look down the intake, it's a pretty straight flow down to the valve, with hardly any turning of the air flow, so to me, it doesn't need a raising of the floor, as it has no floor (it's almost vertical).

Anyway, those are my observations, and the car now is even more driveable at low engine speeds.

 

I believe it was Mark who commented that the stock 2 valve US head had exhaust ports that are too large. Someone commented that they believed the GT/4 LM car had used 208 heads as they had smaller exhaust ports for that reason.

For those who believe Ferrari did all they could to give you high performance, pay close attention. On both 308 engines I have, the exhaust headers do NOT align properly with the head ports, but are "off" by over 1/8 inch. I would need to either shave off head material to lose the step, making an already to big port even larger, or mill the header flange to move the header back over the ports. Two engines, four heads, two sets of headers, they are both alike. One other course would be to either relocate the studs, or make an insert to fill the port, both reducing its size and off setting it to align correctly with the header. I believe this would be a bad idea as someone pointed out a loss of heat transfer. Thats the exhaust side.

The intake manifolds. Again, two engines, four intake manifolds. Scott, your ports look about the same finish as mine, Ferrari did a good job there as far as the finish. However, all my manifolds are "off" by a minimum of a 1/16" and slightly over 1/8" in every single port. Flow bench or not, getting those steps out of there has to make a vast improvement. However, I do not know if I should open the area up or weld up the manifold and match it to the head. That would keep the port size as it is. Also, again, the manifold is much larger than the bore of the carb, like its actualy made for 44mm carbs. I would believe welding them up and matching the manifold to the carb bore would also be an improvement. I notice that in the area of the manifold gasket, the port is considerably smaller than the intake valve. So the manifold tapers down in size from the carb, passes through and then expands before getting to the valve head. If anyone has advice on what size the port should be be along its path I would be all ears.

I also got looking at the headers. Inside the collectors the pipe runs well inside the cone, causing what would appear to be quite a disturbing restriction. Its almost like they want it to appear high performance, yet place obstacles in our path preventing it from making good power. Like a Pirates treasure map with one corner torn off. This does not at all make me mad or angry, I beleive Ferrari did this for a particular reason, intentionally. The parts and the design are there before our eyes, all we have to do is manipulate it.

Mark, I could make a flow bench. I have several links from online of how to make one, looks really simple. But like you and your patio, I have neither the time to make one nor presently the place to put it and play with it if I did. I also want a distributor machine, and am running out of room for all these toys. I would be more interested in knowing what to do in the meantime just to make the stock ports better. If the manifolds on either side dont even line up correctly, it wasnt ported for crap in the first place. Looks like Luigi just honed some ports freehand, and grabbed some intake manifolds from a box and slapped them on. Done. Surely we can make it work better than that without resorting yet to a flow bench? So the question is what size do we want the intake port in that area? Any suggestions?

 

Personally, I wouldn't touch them without a flow bench....I just been surprised too many time. I think ferrari already did what can be done free hand with any confidence. If you want I could measure my XR heads and give you the cross-sectional areas at a couple points...but the ports aren't really round and it's that slight out of round here and there that make them flow the numbers they do. The other thing is you want all the ports to flow the same. On a CIS car, there is nothing you can do but live with bad mixture cylinder to cylinder, on a carb car you can jet each cylinder individually, with many EFI systems you can trim the cylinders....but it's way easier to just make the port right to begin with.

 

Russ,
I talked to Vic today. He's got 2 engines one going out this week one next week, then he'll have time to start looking at my stuff. He has the scrap head I bought to practice on and I'll ship my headers and intake manifolds (my blower intake plus Paul Sloan was kind enough to lend me a stock QV intake so we can get numbers on the stock set-up, minus the CIS of course) this week. The next rainy weekend (when I can't work on my patio) I'll drive up and go over everything with him.

I'll post numbers as soon I have them, all stock in a couple weeks then ported a couple weeks after that. As a refesher, Kermit got 94 cfm intake, 86 exhaust, both at 10 in H2O. The engine wants more like 135-145 intake, 105-115 exhaust, so the stock head is about 50% low. I expect the ported numbers will hit ideal values pretty closely. I never seen Vic quit without hitting the number....and a stock QV engine with heads that hit the numbers and EFI or carbs should make about 330-340 HP (crank) naturally aspirated.....which is about 800 at 20 psi

 

I may have this all wrong, but isn't port velocity also a factor to consider (as well as flow rates) ?

Maybe in a forced induction application, velocity is irrelevent (outside factor), but for a N/A engine, increasing flow rates doe not necessarily increase port velocity, it may even reduce it.

 

Velocity is extremely important and making the ports oversize to hit the flow numbers in the main cause of poor bottom end performance after an incorrectly done porting job.

The cross-sectional area of the port needs to key off the seat and expand at about a 4 degree angle as you move away from the seat. The flow numbers are just a matter of getting the shape of the port correct as the efficiency stays high. So basically, the cross-sectional area is determined ahead of time to product the designed velocity and flow is improved through port efficiency improvements, not port size.

 

100% agree. I'm not planning any head milling either.