Shortly i will be fitting my new manifold to my heads. I intend to port them to fit the manifold ports. How does one do this ?

Thanks

 

Google turns up tuns of articles when searching for "manifold porting."

Here are a few:
http://racingdownloads.com/racing_software-5.html
http://roadstarclinic.com/content/view/53/96/
http://www.sa-motorsports.com/diyport.aspx

I hope that helps.

 

Typically, the heads and manifold are ported to the gasket.

Select the desired gasket that is slightly larger than the existing ports (e.g., Fel Pro-1256 for a small block Chevy). Position the gasket in the head surface and using engine "dye," color in the area of the head exposed within the gasket opening. Do the same with the intake manifold.

The area that was colored is to be removed by smoothly "blending" it back toward the runners. This is typically performed using carbide tips and/or sanding tips used on a die grinder.

 

Buy an extra set of the gaskets you'll use and coat them with Prussian Blue on both sides (NAPA and others carry this: http://tds.loctite.com/tds5/docs/PRUB-EN.pdf), then bolt one side of the intake to the head with the gasket in-between and remove. It's extremely critical to not to just match to the gasket to the head and intake surface, because this won't identify any potential mismatches.

Now you have the mark of the gasket on both and can look at how to bring them together. You absolutely DO NOT want to blend or radius the entry into the head or intake - just determine what cross-section you can carry all the way into the runners. You also don't need to do this to .001 inch - close (1/16 or less) is good enough - you're looking to eliminate any significant mismatch between the ports, not make them match exactly. Don't get carried away or you'll end up buying new heads and intake.

The SA Motorsports link is a great one, and they sell all the required supplies. A die grinder and air compressor is the only other stuff you need.

 

Ahhh, but the real trick is once the holes in the heads and manifold are the same size, getting them to align exactly when you put it all together.

There is always some "slop" when you put the manifold on, and this works against all of the hard work you did getting the holes the same.

What I do is to assemble the manifold to the heads leaving the bolts loose. Reach down though the carb hole with a stiff wire and "feel" where the port surfaces match. Slide the manifold around (in-place) until you get the smoothest feel.

Mark the manifold relative to the heads so that when you later drop it on, you can get back to this same spot.

Remove the manifold and apply the sealent at the front and back of the block mating surfaces and let it "set-up." Also put the gaskets on the heads making sure that they are properly aligned. A touch of sealent will ensure that they don't move when you do the final assembly.

Now drop the manifold on using the marks you made to get it back in the proper position. You don't want to be sliding the manifold around once you have your sealent on.

 

Have you ever actually done this? IMHO, it's not possible. The position of the manifold is determined by how it bolts together when it's torqued down...you have VERY little (if any) play. This is why some professional builders pin (drill a hole through the manifold into the head and drive a dowel pin) manifolds to heads during trial assembly.

I'm going to call on this unless you have a picture

 

Yes I did this and no it is not ! And if you put a manifold on, you will find that there is plenty of slop due to the area around the bolt holes. And if you think about it..., if there was no slop, there would be no need for dowel pins because the manifold couldn't move at all.

My combination is extremely mild but such attention to small details (like this) pays off in big dividends. Lots of people with engines that are far larger and more radical (lots of ZZ4s) would kill to make the power than my mild, simple, and extremely streetable combination makes.

My combination:

331 CI, pump-friendly 9.5:1 CR
K&N 14"x4" air filter, Corvette drop base and lid
Holley 600 dp, choke horn milled, polished
1/2" Aluminum open spacer port matched to manifold, exterior polished
Edelbrock Performer RPM, port matched, exterior polished with all extraneous castings and lettering removed
Homemade lifter valley splash shield to keep hot oil off manifold bottom
Camel hump 1.94/1.50 heads hogged out to 2.02/1.60, pocket ported, port matched, pump-friendly hardened seats, 3-angle valve job
Cylinder bores clearanced to unshroud the valves
Comp Cams 1.52:1 roller-tip rockers
Crane Cam Vintage Muscle 327/350 hp cam, 222 degrees @ 0.05, 0.447" lift (with 1.50 rockers)
Doug Thorley headers, dechromed and ceramic-coated
2.5" mandral-bent exhaust (including tips), 2" cross-over just before rear axle
DynoMax stainless Ultra Flow mufflers
Mallory Hyfire IV CD ignition box triggered off Accel points
Mallory high voltage chrome coil
Mallory spiral-wound coil wire
Mallory solid copper plug wires, ends soldered to wires
Champion plugs
37 degrees total ignition advance (now 34 degrees per Lars tune-up)
Carter high volume fuel pump
Melling high volume oil pump
Open breathers
Polished aluminum high flow water pump
Flex fan with polished aluminum spacer
Polished aluminum one-wire 100 amp alternator
Muncie M-20 CR 4-speed (now Keisler TKO600 5-Speed)
Hurst shifter (Now Keisler With Hurst Tower)
3.70:1 positraction
225/60/15 Firestone Firehawk SZ50s on 7”-wide Western 30-spoke Turbine Wheels

At the time of the dyno pull the engine had never been professionally tuned up. The car did 293 ft-lb and 293 hp @ 5,500 rpm on the chassis dyno. The engine pulls to 6,200 rpm and does over 200 ft-lb from 1,900 rpm. This was prior to some clean-up work around the junction of the carburetor and base of the air cleaner that smooths the flow through this area and a Lars tune-up and should be good for a few ponies. The car has run 107 mph in the high 13's (old, bad tires) at the quarter. The car is extremely streetable and could probably even run 87 octane if it had to. (I can't get the engine to ping no matter how far I advance the ignition.)

The secret to power is in the attention to the small details!

 

Huh. And this is the same guy that's suggesting that people NOT do this on another thread?

http://forums.corvetteforum.com/show...post1562480717

My point is that if you're NOT pinning the manifold you have virtually no means to firmly control the alignment.

And dyno sheets don't lie...but I sure can't see 375HP from this combination. Not trying to go OT, so I'll drop out completely

 

did i miss the part about 375hp? I'm pretty sure it says 290hp, which seems reasonable with the parts combo listed.

 

It's a chassis dyno; 293 HP + 20% drivetrain losses = ~375HP at the flywheel. I really don't want to (or mean to) take shots or take this thread OT, so let's drop it

 

No..., again you misinterpret..., probably intentionally.

All I said in the other thread was that because he port matched the manifold doesn't necessarily mean he's making more power. I also said that each case was different and some times it does and some times it doesn't. But if you really bothered to read it, you knew that.

And I never said the engine makes 375 hp. If it is doing ~375 at the crank, great! It just goes to show that my attention to details paid off because it really is a very mild (but well planned out and assembled) combination. And this is from an engine that was built over 20 years ago!

All I said is that lots of ZZ4 owners would kill to get near 300 hp to the wheels. Read the forum posts over the years and you'll find most don't get beyond about 255 hp at the wheels. But you probably knew that too if you follow the forum.

And like I said, when I feel the manifold interface as smooth as possible, I mark it so I can get it into the same spot. Obviously you can't feel each runner, but if properly port matched, just feeling a couple is sufficient.

Just because you don't seem to be able to control where the manifold is placed doen't mean that some of us others can't get it much closer than just plopping it down and hoping for the best.

And, if you don't believe the dyno sheet, just ask Lars about the time he shifted into second and got the car sideways.

 

No, not at all - I did read, I don't misinterpret and there's no intention. But thanks for playing the home game.

How would you interpret your flywheel HP from the chassis dyno given drivetrain losses?

Having installed 2 ZZ4s, I know quite the opposite and you should go back and look at Bob Onit's ZZ4 post...and dyno results: 282HP...within 2 HP of what I said he would. Do YOU follow the forum, even the ones you post on?

Gee, it's a pretty far cry from saying your method doesn't work to me "just plopping it on". I work with a number of engine builders, and they've all called on your method. We're clearly not going to convince each other, so in the end, we differ and that's fine - the OP has to do his reading on all the information offered and make up his own mind.

Lars is an incredibly smart guy, but I didn't know he had an engine dyno in his butt

If you feel you need to respond, feel free to PM me so we don't clutter the thread - my bad to start it, but let's agree to end it.

 

Then you and your tuner friends may as well call Car Craft Magazine because I got the idea from them and it works for both of us.

And 282 hp out of a ZZ4 (that is a bigger engine and probably more radical than my mild combination) is no big whoop either. Most don't get above about 255 hp.

So of you want to drop this..., then drop it.

 

Hi

Just for my info. How do you pin the manifold ? Do you drill it when it is correctly installed ? Where ?

Thanks & brgds. Günther

 

You can mark "witness lines" at the cylinder head intake bolt centerline and intake manifold flange to align the manifold to the cylinder head when you install it. I don't use the gaskets they give you for the valley area end rails under the intake manifold, I rough up the area with apunch or chisel, clean it very carefully and run a BIG bead of RTV Silicone sealer along the end rails which will make it very easy to adjust the intake manifold. The RTV "trick" has been used for years here in the US with very good service life (no oil leaks!)

 

We Pontiac folk put plastic bushings in the bolt holes of the intake manifold to eliminate any movement upon installation. I've never done it on a Chevy intake, but I don't see any reason why it wouldn't work. One just has to take care to center the gasket around each of the bolt holes when one is marking the intake.

 

cool, just wanted to know where you got your numbers from.