Inliners International Forums General Discussion Engines 261 chevy 848 porting

I’m in!

My spare 848 head has an appointment with a CMM on Saturday and a solid model of the “before” condition will be on it’s way to CNC Dude in the next week or 2.

Cool, I cant wait! I'm sure others are anxious as well....

This is a great thread. Ive been waiting for someone to put modern principles to use on these old heads. My own porting efforts have yielded noticeable changes on my cars. Mostly in midrange tourqe. The way I look at it anything helps on the old design ports.

Great! I hope that I have been able to "stir" peoples imagination with my comments and "advice"(if you can call it that). Maybe it will let you take your ride to a higher level....As you said,anything helps these heads,so maybe modern thinking applied to them will help as well, if not, its at least fun bench racing them into the winners circle(ha ha). Don't change that channel,I will soon be posting pics of my progress!

CNC dude, I will be following this as well with great interest. Also, I can furnish you with a 302 GMC head if you want to experiment with it as you go along. I too am in North Ga. and will deliver it if interested.

Keep it up, Eddie

Thanks Eddie,PM sent!

CNC-Dude I can't seem to send PM. Send me an e-mail address or phone number. Thanks, Eddie (littlejeep2) 706-835-5990

Update:

I got the head cleaned up for inspection and my programmer and I gave it a good look. We agree that standing it in a 4 axis horizontal machine should give access to get in from both sides in one setup. A 3 axis vertical could also be used but it would be quite a bit more time consuming. NOT requiring a 5 axis mill reduces the expense greatly at least in my case. Tomorrow we measure it with this:

http://us.romer.com/stinger-iii

Many thanks to littlejeep2(Eddie) for the GMC 302 cylinder head he donated to the cause.Few people would drive an hour and a half to contribute time,gas,and parts these days to help others in this way! Again, many thanks and I enjoyed our "bench racing" at Cracker Barrel this morning....I'm glad to have had the opportunity to meet you!

Thanks for the update Curt!

This is off topic.

But lets say a guy has a hand ported cylinder head that flows like nothing else.

What $$$$ figure would he be looking at to have this head measured and the data saved?

What $$$$ figure might be then expected, to have an untouched (stock) cylinder head duplicated?

Guess I should ask, what are the limitations of the CNC machines, could they duplicate what was originally done by hand?

Kinda like what powerheads has done.

Dont wanna screw up this thread, but this has been on my mind, so if anyone has some input, feel free to PM me. Thanks

Were still talking ported heads, so I think were on track here! And this is a good point that might need to be brought to others attention for explanation purposes! The potential for CNC is unlimited,considering you have the maximum number of axis' needed for head porting. Most companies that specialize in head porting, have equipment that can move the head(or part) in (5) different axis' to reach every concievable spot on all the surfaces of it. There are many neat videos on YouTube that people have posted showing heads and blocks being machined from a solid billet of aluminum. Just type in the words : 5 axis CNC, and you will be amazed at what is possible with this technology. Not all heads will need 5 axis' to be ported or be copied. As Curt mentioned, his 848 head only needed 4 axis' to have its ports scanned and probed. I personally have never had a head scanned or probed, so as far as cost to have that portion of the process done,I couldn't say. Maybe you could PM him, and he could give you some input on the process and whats involved in having it probed. The cost to actually reproduce the head once all the data is gathered is usually based on the machine "run time", plus any fixturing that needs to be made to attach the head into the machine. If it is a different type of head than they have done before, they might not have fixturing and will have to make it. Since aluminum is the most common material, and the fastest and easiest to machine, cast iron is going to be more costly, just from the simple fact that the speeds and feed rates in which your tooling operates will be slower, generating more machine "run time". I see your username, and figured that you are inquiring about a 300 Ford head. My friend Cotton Perry raced against another Comp racer that had an awesome 300 Ford in a roadster, and now that racer(Ambrose) has probably the fastest 300 Ford in NHRA. Those engines have great potential. Hope that answered your questions, and thanks for joining in on our discussion!

This is my friends cylinder head shop.
Click on the little pic of cylinder head & mill to see a video of CNC porting
http://www.proheads.com/services.html

MBHD

Its just amazing what we are capable of making and producing with the technology we have at our disposal today! I couldn't even begin to number the parts i've designed and made with CNC for different engines! If you can think it....you can make it!

I've sent dbane several PM's about his offer for the FREE 235 cylinder head, and have not gotten any response yet! I sent a PM to Curt today to see if he had any updates. Maybe we can soon see some action with all the interest that seems to be happening with this topic....

sorry about that lapse in responses there bud, been super bsuy with midterms and all, i havent even been sleeping really, couple hours a night, took my zoology test today, organic chemistry tomorrow and I have a physics midterm and art next week, super busy. None the less the head is up for grabs, we just got to figure out the shipping and all and we'll make this happen for sure, I have just been super busy this week and will be next week too. I will definetly try my best to get a shipping quote for ya next week if I cant get it tomorrow. So that was a lot of talking, anyway I did send you a response to the PM that you sent me, did you not receive that message? I will do my best to stay in contact with ya, talk to ya soon.

Thanks for the reply! No, I didn't receive any PM's from you. I also had others that had difficulty in sending PM's to me, but then there were several that were able to, leaving me to think that there was just probably work or something that had people busy. No problem or rush, thanks for the update, and good luck with your studies.

Delete.

BTTT....

Sorry for the delay but now the guy is swimming in an ISO audit and may not get to it for another week or two. I see him every day and the equipment is always available so it will get done. In the mean time I have put together a starting point for him to digitize from based on the following dimensions on the intake side which I would like someone to confirm on another 848 head.

Port center to center distance = 8.562”
Alignment ring bore diameter = 1.562”
I.D. of alignment ring installed = 1.414”
Alignment ring bore depth = .188”
Bore diameter @ .188” deep = 1.437”
(45 degree bevel transition from this point to cast bore)
Intake runner diameters:
Min. found = 1.340”
Max. found = 1.395”
Inconsistent all around but no more oval than .03” at any point.
Runner diameter continues in to a depth of 2 ¼” where it widens into bowl.



It would appear one would be able to generate a “hill” with the material available but where is the jacket and what kind of minimum wall thickness should there be?

If opened to 1.5” on the intake side the alignment rings would be eliminated. How to address this? Cut a bigger step in the head and intake for larger rings? Dowel the intake and head as an assembly? Ignore it and try to align by eye? How big is the hole in the gasket?

As far as opening up the area behind the valve what kind of radius into the bowl would be most beneficial? A lollipop cutter could do wonders there to generate a smooth curve from the valve seat into the bowl.

I know im probably beginning to sound like a broken record, But as soon as I can ever get my "test" head, I can begin to address and answer some of these questions. Since there is no alignment dowels for the intake, only the port rings. Then, the counterbore for larger rings will need to be machined into the head or possibly as you said, some dowels placed into the head and intake to locate them at each end! Still its a start,we will just be patient. You have gotten farther than I have so far....Thanks for the info and update!

My 848 head will ship on Mon. the 27th of Oct. so this coming week I should be able to dive into my research, and be able to soon give some details!

I received my 848 cylinder head on Saturday 11/01/08, now I have a 235 Chevy and a 302 GMC cylinder head to begin doing similar porting styles to each, and see how both engine families can benefit from the "lump port" technology that we have been discussing so far. I'll post pics as soon as I can begin to document my steps one by one. Curt told me he would try to have his 3D model completed this week as well. Also, special thanks to 6inarow and Patrick's antiques on the 848 head!

As far as im concerned, everyone here on Inliners is in the "loop". I appreciate everyones interest and support on this project. And will be glad to share my findings with everyone here. If anyone feels that certain issues might be overlooked or skipped over, just let me know, and I will be glad to address them. This project is for all us Inliners to benefit....

Glad to hear it. Looking forward to the results (and details along the way ).

The 848 head has an appointment with the flow bench this coming weekend to see what fixturing or adapters need to be made, if any, to bolt it onto the flowbench(Superflow 600). I know I will need to make a transition tube to bolt to the intake port entry with a radius to help stabilize air entry into the port. I will "bump" the valve seats, and establish a baseline of flow #'s(intake and exhaust) to have a starting point with a head in stock trim and condition. I will then systematically make changes that you would normally make in trying to increase performance and airflow, such as enlarge the bowl area(bowl cut)and radius the short side,step up the valve sizes, enlarge ports and entry,etc...checking each mod of the bench one at a time to see how each item helps or hurts the flow. Then I will move on to the "lump" port style mods that really got this topic "fired up".But not all at once, just preliminary setup this weekend. Also,pics will follow as well.....

YEAH!!!!!!!!

I cant tell you how good that last post is to read!!

It seems a huge waste that a tool with this ability lays around in the case for months on end waiting for an oversize part that requires a CMM report:

http://good-times.webshots.com/photo/2665966070023244788oQVBZl

http://good-times.webshots.com/photo/2160856010023244788yvMWRm

http://good-times.webshots.com/photo/2129548620023244788hVOGgy

http://good-times.webshots.com/photo/2644169740023244788KLmKum

This project has forced myself and a couple co workers to actually climb the steep learning curve on collecting surface data. The point cloud is quite disorganized on our first effort but hopefully enough of a platform to build from. We will make another effort using other more organized approaches soon. If anybody has a ported head that’s cracked don’t throw it away as the ultimate knowledge in all this will be to determine how close yesterday’s masters came to the flow geometry generated by today’s software.

Scott,
pm me a destination and I’ll forward you the data.

Also… Everybody remember or thank a veteran today.

Curt B

Curt, anytime we step into uncharted waters, delays and unexpected learning curves seem to be part of the journey. But, once we get there, it will be well worth it! Thanks for all your help. Its this type of comradery, that will make this project succeed,where others have not....TEAMWORK!

Okay, that's just impressive there. And you say that's your first attempt? You're doing better than I would.

You can tell the "Boss Man" that the head is a new "calibration tool" for the CMM, and must be used frequently to keep the CMM fine tuned for the tasks it needs to perform for the company(LOL),because if it sets idle it is not good for it, and therefore must be kept in ready to use condition at all times....

Wow you guys are making it happen! A digital model is on its way. Very cool, cant wait to see where the limits of the casting are. Keep up the great research.

I would venture to say that nowhere else on the internet will you find such a high tech approach applied to these Stovebolts and GMC's, definately making Inliners the place to be, and the standard for all others to follow! I also think it will rival any V8 websites by far, making them seem insignificant in comparison to our research and achievements. Where else on this planet can you get a 3D model of a 235 intake port....Inliners! Where are all the soon to be fastest and highest tech Stovebolts and GMC's....Inliners! Where are all the coolest Inline enthusiasts....Inliners! Inliners has got it goin' on, you dont need to go to any other website, its all right here! Don't change that dial....you might miss something!

Not to take you off in another direction, but, in 1969 Bud Moore had a port problem with the 351 Cleveland motor. The exhaust port had a terrible path even though it was very large. His solution was to mill a rectangular chunk off the entire length of the head down to the bottom of the port and replace it with an aluminum bar with his own high port design. As I recall it was held in place with head bolts.I dont know if it got into the water jacket but you might be able to furnace braze a steel piece to the CI head.
He got away with it by calling it part of the header.

The exhaust ports on a Cleveland extend outward from the head and do not get into the water jacket, and is a common mod still done today. I have a friend that I have made some port plates for on his race engine, and it does straighten the port out and really increases the flow substantially. A lot cheaper than a set of Yates heads....

Someone was selling 'header plates' (or port tounges) that did essentially the same thing without the machine work (sandwiched between the header and the head).

Don't know where you could apply that to our beloved inlines, but it's a good mental exercise.

Im hoping to have flowbench data this evening for both the 848 Chevy head and the 302 GMC head. I had to make some pieces for the intake ports to form a radiused entry for the air leading into it. This helps simulate a manifold being attached to the head, and gives a smoother,more consistent flow into the port,and is standard procedure for flowing intake ports,as is bolting a short piece of tubing to the exhaust port to simulate the transition from head to header....

CNC,

The results of your tests will be like an early Christmas present. I did some simple calculations for a stock 848 head using the methods we use at work for calculating pressure drop for aircraft engine components; for a valve opened to 0.500", the flow at 28" of H2O was 155 SCFM. This seems low; I've heard that it could be about 170 SCFM.

Your work and wisdom is really welcome here.

How does reversion/ engine pulse effect a siamesed port?

Its not as pronounced in an inline compared to a V-style engine such as a Flathead. Mostly because the cylinder firing is farther apart in degrees of rotation(90 degress for V,120 degrees for inline 6)and scavenging from the shared ports isn't as much of a problem in the inlines as the V engines that are siamesed. Putting exhaust dividers in the ports of a Flathead helps scavenging when real radical cams are used....