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Topic Review (Newest First)
01-30-2013 10:45 AM
oldbogie
Quote:
Originally Posted by ChevroletSS View Post
Hey F-Bird check out these bits. will these work ok. They are similar to what you have below.

I guess these are made for cast iron??? I have no idea.
GOODSON : Engine Building Tools and Supplies
Check this out >>> GOODSON : Porting & Polishing : Rotary Files <<< it shows the difference between rotary files for iron versus aluminum. Iron uses a finer flute than those for aluminum. This is because aluminum melts into the clearance between flutes plugging and gumming them up till they won't cut. Iron just makes solid chips that fly off the cutting face.

You can use a coarse aluminum bit on iron all that will happen is a rougher surface finish from some chatter the wider flutes create, but they'll cut just fine. Aluminum will gum up the smoother fine iron flute almost instantly. You can kind of get away with the fine flute on aluminum if you frequently run the bit into a piece of bar bath soap. This lubricates the flutes preventing the aluminum from sticking. Same thing if you're cutting aluminum with a rotary stone or drum sander, run the stone or drum sander into piece of bar soap every few cuts and it'll stay pretty clean of imbedded aluminum. This of course leaves your bits and stones smelling clean and refreshing.

Bogie
01-30-2013 09:06 AM
ChevroletSS Hey F-Bird check out these bits. will these work ok. They are similar to what you have below.

I guess these are made for cast iron??? I have no idea.
http://www.goodson.com/5_Pc_Set_of_L..._Rotary_Files/
01-29-2013 09:33 PM
vinniekq2 1gary,do you have any experience with super stock engines? How do you measure cfm flow on stock castings
01-29-2013 09:19 PM
1Gary We all know as casted OEM heads are all the same.Right??. I'm call it BS. So to follow the same pattern reaps the same results without a flow bench to check if your just hacking away at a pc of metal or really doing better or worst. Taking tech back to what amounts to caveman times is illogical.

The first set of heads done right usually the response is OH!!!. That's what I have been missing..........
01-29-2013 02:45 AM
1Gary
Quote:
Originally Posted by F-BIRD'88 View Post
None of this general porting on this stock SBC head requires a flow bench. You got to put some air in a tire first before messing with the tire gauge.
A picture says a 1000 words.
http://www.hotrodders.com/forum/atta...0&d=1347916622

i did not do this head. Buts a really good pic of the desired finished form. Look at the chamber too.
Congratulations,you have just discredited the whole foundation the aftermarket bases it's self on.......................

Now that just doesn't make any sense.
01-28-2013 09:28 PM
ChevroletSS Thanks for the info. Greatly appreciate it. Can you point me in the right direction on some bits to use for porting. All I have is the port and polish kit from jegs which is ok but not efficient. I need something about six inches long id say and one maybe three inches long. A good carbide bit I guess. What do you suggest
01-26-2013 12:15 PM
cdminter59
14101083 Cylinder Head

Quote:
Originally Posted by 1Gary View Post
Yeah,that's the link I posted earlier in this thread.
You must have this thread mixed up with another one. You must have got excited at the chance to argue with F-Bird'88 that you thought you posted a link to the flow bench. I only see the link for a flow bench once in post# 51.
01-25-2013 10:37 PM
ChevroletSS Thanks guys. What is the common wall side
01-23-2013 08:36 PM
hcompton
Quote:
Originally Posted by ChevroletSS View Post
Ok guys when porting these heads can I smooth these round humps down so its nice and smooth or do I need to keep these there???
Yes make them flat they are just casting marks.

Best way is to shave a little off at a time so you can get them dead flat without cutting any metal around the area since you want it as flat as possible.
01-23-2013 07:13 PM
ChevroletSS Ok guys when porting these heads can I smooth these round humps down so its nice and smooth or do I need to keep these there???
01-07-2013 11:04 AM
oldbogie
Quote:
Originally Posted by ChevroletSS View Post
Ill port them myself. Now I have practiced porting on heads for endless hours but what I still dont get is how Im supposed to tell if I made all the runners the same. I mean its very possible that by doing it myself that when Im done none of them will be the same. Does it matter if one flows just a little differently than others and so on?????
First is the needing of a flow bench to tell it your makeing improvements or causing degradation. In a simple sense and especially with older heads (think pre GT40P, Magnum, Vortec) it was pretty easy to improve ports. This was simply streamling the huge guide bosses and blending the rough cut of the upstream lip ahead of the seat into the wall. This make a marked improvement that was felt when you stepped on the throttle. Modern heads are much more refined in this area today so there is less impact by massaging this zone.

When you get away from the port pocket things are much more subtle, therefore, it is easy to degrade the overall flow. What seems logical to the eye is most likely not where the flow will or wants to go. Most people reporting here state that there is little to be gained by working the port between the manifold face and the turn into the pocket. This really isn't factual, but this is an area where it is easy to do more harm than good. To tease this out you really need a flow bench and a decent understanding of how gasses respond in a physics sense. There are plenty of web sites that lead you into building an inexpensive flow bench using little more than a decent shop vac as a power source.

As far as getting all ports to match the old fashion way was to arrive a good test port then make templates of the port at critical points. The uncut port is ground at the same points to fit the templates then the material between the template stations is ground to smooth connection between these points. There are people on the web that sell templates for known port shapes.

Bogie
01-06-2013 10:44 PM
1Gary Yeah,that's the link I posted earlier in this thread.
01-06-2013 09:38 PM
hcompton The 12 v heating element is not regulated so 11 volts and 13 volts will give different temps so the readings that are taken will be different as well. Fine for the car since it adjust every few seconds and the alt provides the voltage once the engine is running.

its really important that you get the same results every day. Regular flow bench corrects for altitude and pressure. Along with temp and maybe a few other factors.

You can build a pro style flow bench. Here is a link for the best home kit i have seen. But may need more options for larger ports. Most vacums wont pull more than 200 cfm. With this kit and a vacum even the powerful one they recommend is 145 cfm at 28" and 210 cfm at 10". So totally useles for car heads that flow well.

Flow Bench | Digital Flow Bench | Flow Bench Kit
01-06-2013 06:44 PM
Project89
Quote:
Originally Posted by hcompton View Post
Using Some plex in a 4 or 5 inch circle. With the head on top and the shop vac under neath. Then you can use strings and smoke to tell how things are flowing. Strings are really important for flow bench testing. And you dont need an expensive meeter and test unit that will not be acurate from day to day.

If you use the maf be sure to use a regulated power supply that can produce the same 12 v everytime. If it delievers more volts when it gets more volts it will screw the readings. Everytime you wife turns on the dryer you port work will be better. One of the main reasons home made flow benchs dont really work cause ypu need lots of tech equipment to support the meeter and reading of the meeter.

String always works if a little low tech. Also works great with smoke.
thanks for pointing that out osmetimes i forget not everyone will know what i know and how to check stuff

with the maf style flow bench ur readings can very well channge from day to day so its important if u dont finish in one day to go back and re measure a port u have done so ur ports u still have to do come out to the same number.

the 12 volt supply isnt as importnant as the 5 volt , the 5 volt is what gives the readings , normally the cars ecm supplys the 5 volts to the maf this way if it reads a lil high or low on the 5 volt line the ecm can compensate


in the case of a flow bbench if u have 5,2 volts one day and then 5.4 volts the next day ur results will read artifically high . so each day of testing or when changing from port to port its just as important to stick the dvom on the 5 volt line to make sure voltage is the same from port to port.

if not u can just see what the difference is and add/sub it from the reading u get when taking the flow measurements.


u can always buy 2 cheap vlt metters as well and ties one into the 5 volt feed line permantly and then the second onto the 0-5v output of the maf so u have constant readinsg of both lines


the 12 volt feed is used for the heating of the maf, the 5volt side is were the actual readings take place
01-06-2013 06:25 PM
hcompton Using Some plex in a 4 or 5 inch circle. With the head on top and the shop vac under neath. Then you can use strings and smoke to tell how things are flowing. Strings are really important for flow bench testing. And you dont need an expensive meeter and test unit that will not be acurate from day to day.

If you use the maf be sure to use a regulated power supply that can produce the same 12 v everytime. If it delievers more volts when it gets more volts it will screw the readings. Everytime you wife turns on the dryer you port work will be better. One of the main reasons home made flow benchs dont really work cause ypu need lots of tech equipment to support the meeter and reading of the meeter.

String always works if a little low tech. Also works great with smoke.
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