Generally Accepted Tolerance, Dart Complaints

[jsup]

Hey guys, I'd like to know if there is a generally accepted tolerance in terms of port size and flow numbers.

Anyway, I'd like to link this thread for your consideration:

http://www.corvette-guru.com/modules/newbb/viewtopic.php?topic_id=6028&post_id=59142#forumpost59142

I would appreciate the "Dart response" as people will be positioning this as a quality issue.

How does Dart address such discrepancies in their advertised product and the actual delivered product?

[Trmnatr]

Hey guys, I'd like to know if there is a generally accepted tolerance in terms of port size and flow numbers.

Anyway, I'd like to link this thread for your consideration:

http://www.corvette-guru.com/modules/newbb/viewtopic.php?topic_id=6028&post_id=59142#forumpost59142

I would appreciate the "Dart response" as people will be positioning this as a quality issue.

How does Dart address such discrepancies in their advertised product and the actual delivered product?

I have alot of thoughts here:

I think any "as cast" head should have extra thick walls etc. for porting and if you break through the maker, Dart, AFR, Brodix ETC, should be able to measure the width of the bad area before they make a decision on if they should replace the casting, if it is opened up .500" more than than the "as cast" design i would say no warranty BUT if it was say .025" larger than as cast and you broke through i would warranty it

Example: We have used 1.625" springs in Dart heads for some time, We never had an idea of how thick the casting was. We came across a damaged Dart head so we cut the spring pocket to 1.635"-1.640" and went down .130" further down than the Dart spring pocket, No water, so we then took a punch and tried to break the spring pocket in the event it was thin going down .130" further -- It did not break and we were hitting it in the corners hard

Any mods you do to any head if its Dart or AFR, YOU MUST KNOW WHAT CASTING YOUR WORKING WITH AND KNOW HOW FAR YOU CAN PUSH THE LIMITS OF THAT CASTING

As far as the runners being larger cc's,
1) your buying an "as cast" head, The design parameters are 200cc (for example) but after cast it could be 205-210cc

2)when dealing with a CNC ported head, they will start with a 180cc head (for example) and port it to 200cc for example , of course the CNC'd head is gonna be more accurate BUT how do you know your engine package will respond to that CNC program? It doesnt run quick because the heads are cnc ported, the cnc'd runner has to match the engine

Have you ever got a crank and had it oversized? Have you ever had a crank where the journals had too much taper? Have you ever had rods where the big/small end is too tight?

I can come up with one thing on every assembled head i dont like and that includes ALL heads

If your serious about your program, Buy the parts such as heads bare and put together so they match your combo

If your using an "as cast" head you want to stay on the small side in the event there are any issues like this

And he said his GM heads are maxxed out at 12.7 ???????????? GM double hump 291 heads will run 10.70's+ in a 3400 pound car with a 332cid BUT there is alot of welding to do as they are an oval type port after cnc'd

The bottom line is this, "You want to play you got to pay !"
What i consider play?
-Porting
-Modifying parts in search for an advantage
-changing parts and comparing hp/et's
-changing fuels
-changing/porting/altering intake manifolds

Go to an IHRA or NHRA event and ask all the racers what heads they have, 99% of the names you will hear are:
-Dart
-Brodix
-BMF
-GM in classes that require them with extensive mods

Bottom line, use what works, above is what works

[jsup]

Sorry, my comments were specifically to the complaint that the guy purchased Dart Pro 180 heads, they were measured at 190 and did not flow as advertised.


I'd like to know how Dart addresses the complaint specific to the DART issue bought up on that link. This is the SECOND time someone said something similar.

There is an argument being made that it should be "dead on" to what was purchased, 180 is 180. Is it unreasonable to expect that, or are there generally accepted tolerances? They also point out the flow wasn't as advertised..

Those are the issues, why I asked.

[Trmnatr]

Sorry, my comments were specifically to the complaint that the guy purchased Dart Pro 180 heads, they were measured at 190 and did not flow as advertised.


I'd like to know how Dart addresses the complaint specific to the DART issue bought up on that link. This is the SECOND time someone said something similar.

There is an argument being made that it should be "dead on" to what was purchased, 180 is 180. Is it unreasonable to expect that, or are there generally accepted tolerances? They also point out the flow wasn't as advertised..

Those are the issues, why I asked.

To get a head design where the cc's measure with in 1cc it would have to be a cnc'd head which is gonna cost $2,100 or more for bare heads

Airflow, If the heads were flowed on a flow bench in Michigan and the flow bench has an honest 240v and they go 250cfm, they advertise it, Now the buyer in Denver buys the heads and flows them on his flowbench that is suppose to be 240v but is hooked up to 208v and its a totally different climate, i think you can see whee im going?

Also, the flowbench will see a steady depression, The depression the heads see on an engine are different every 1° movment in the crank sooooo, how does airflow help?

The thing is, when you get more airflow did you get more fuel flow? This is one reason Dart uses a wet flow bench

Yes the platinum heads flow more air, But its proven they flow more fuel also. Now if the heads flowed the same amount of air as the platinums but didnt flow the increased amount of fuel on the wet flow do you think they would still make more power?

Also, the port cc's, Certain things are beyond control, tooling etc. That poster has posted some fishy stories

Have i had any problems with Dart heads, Yes, ONE HEAD and it was replaced with no questions and it was a 180cc head.

Dart heads make power, Dart is the #1 head in any port shop. Dart has always been know around here as the premier head to work on

It all started with the Dart II, There are probally more Dart II's than any other head out there, Yes they are World now but they are the original Dart design.

Want to know how good Dart is? Dart II's dominated then when the split or what ever went down happened, World called it Sportsman II. Now that was an awesome head and still is but needs some work today to be close to a Dart 200cc or platinum 200cc. Now they dominated in quality etc, Now do a search on World on QC. Thats the kind of work Dart puts into products

[jsup]

To get a head design where the cc's measure with in 1cc it would have to be a cnc'd head which is gonna cost $2,100 or more for bare heads

Airflow, If the heads were flowed on a flow bench in Michigan and the flow bench has an honest 240v and they go 250cfm, they advertise it, Now the buyer in Denver buys the heads and flows them on his flowbench that is suppose to be 240v but is hooked up to 208v and its a totally different climate, i think you can see whee im going?

Also, the flowbench will see a steady depression, The depression the heads see on an engine are different every 1° movment in the crank sooooo, how does airflow help?

The thing is, when you get more airflow did you get more fuel flow? This is one reason Dart uses a wet flow bench

Yes the platinum heads flow more air, But its proven they flow more fuel also. Now if the heads flowed the same amount of air as the platinums but didnt flow the increased amount of fuel on the wet flow do you think they would still make more power?

Also, the port cc's, Certain things are beyond control, tooling etc. That poster has posted some fishy stories

Have i had any problems with Dart heads, Yes, ONE HEAD and it was replaced with no questions and it was a 180cc head.

Dart heads make power, Dart is the #1 head in any port shop. Dart has always been know around here as the premier head to work on

It all started with the Dart II, There are probally more Dart II's than any other head out there, Yes they are World now but they are the original Dart design.

Want to know how good Dart is? Dart II's dominated then when the split or what ever went down happened, World called it Sportsman II. Now that was an awesome head and still is but needs some work today to be close to a Dart 200cc or platinum 200cc. Now they dominated in quality etc, Now do a search on World on QC. Thats the kind of work Dart puts into products

You don't have to convince me, I own Dart heads.

My point is that stuff like this gets out on the internet and all of a sudden Dart has "quality issues".

People will gauge the quality of a head in funny ways, some ways are valid some aren't.

I'm asking if these are valid ways to judge quality. Is it unreasonable for the consumer to expect that port size, chamber size, and flow numbers should be close to as advertised? That is really my bottom line question.

How far off is regarded acceptable?

[Trmnatr]

You don't have to convince me, I own Dart heads.

My point is that stuff like this gets out on the internet and all of a sudden Dart has "quality issues".

People will gauge the quality of a head in funny ways, some ways are valid some aren't.

I'm asking if these are valid ways to judge quality. Is it unreasonable for the consumer to expect that port size, chamber size, and flow numbers should be close to as advertised? That is really my bottom line question.

How far off is regarded acceptable?

Your asking a BLANK question

How far off is an Eagle crank, .0005", .0006", .0007", .001". .002" etc - have seen all of those

An "as cast" product is that "as cast". When the as cast heads are stated @ 180cc they can be larger due to tooling. As to how far, i dont have a clue, im not Dart. They will be larger though

One thing with the platinum heads is they are suppose to be right around what they are rated as, 200cc etc

I have never had to CC one, they work so why mess with them. Maybe Dart Vader will chime in

[jsup]

I get it.

Here's the thing. People fixate on stuff like this, and it is the consumer's opinion that if brand "A" sells a head that is 195, and when checked is 195 that's considered a "quality" piece. If the chamber is supposed to be 64CC and it is, that is considered a "quality" piece. If the flow is XXX and it flows XXX that is considered a "quality" piece.

When they take head "D" and the specs don't line up as advertised, it is considered less "quality"..therefore the conclusion is head "A" is better than head "D"...see how it works?

I am not saying it's right, but I clearly see the point. I was wondering what the industry position is on this kind of stuff. More specifically Dart's position.

Now, I agree to the extent we can measure every single piece that goes into a motor, and many will be off. That doesn't change the perception, and this is about perception.

In some cases, as you point out, this deviation from tolerance may INCREASE performance, who knows. The issue, as you can see by the link, is "getting what you pay for".

Hope to hear from DartVader.

[Dart Vader]

Trmnatr's posts pretty much nail this issue honestly, there isn't really anything more I can add to it.

Chamber volume can vary with different valves and whatnot, and flow numbers can vary based on elevation, temperature, etc...

We are extremely demanding about tolerance as a manufacturer, and we stand behind everything we make.

I encourage anyone who has an issue with tolerances and flow numbers to contact our technical department, as we would be happy to address whatever problems they are having. (And in the case of flow numbers, to read Reher's article "Technically Speaking" on our site, as I believe that flow numbers are vastly over-rated as a cylinder head evaluation tool in the current performance culture)

[Trmnatr]

Trmnatr's posts pretty much nail this issue honestly, there isn't really anything more I can add to it.

Chamber volume can vary with different valves and whatnot, and flow numbers can vary based on elevation, temperature, etc...

We are extremely demanding about tolerance as a manufacturer, and we stand behind everything we make.

I encourage anyone who has an issue with tolerances and flow numbers to contact our technical department, as we would be happy to address whatever problems they are having. (And in the case of flow numbers, to read Reher's article "Technically Speaking" on our site, as I believe that flow numbers are vastly over-rated as a cylinder head evaluation tool in the current performance culture)

To add to that,

A scanner for your new car will give you a code that says "02 upstream lean" etc so you would think to replace the 02 then you may still have a problem

Thats kind of like a flow bench, it points you but you got to have the knowledge to know if the point is correct in your given situation

[wesmigletz]

Also, the port cc's, Certain things are beyond control, tooling etc. That poster has posted some fishy stories

My heads were advertised at 180 CC. They measured 191 CC. The chambers were advertised at 64 CC, and measured at 69 CC.

Since when is tooling beyond control? What else is beyond control? 11 CC difference, on a 180 CC port is a variance of 6% give or take. Do you expect me to believe that is beyond control?

How about linking up the fishy stories.

[Dart Vader]

My heads were advertised at 180 CC. They measured 191 CC. The chambers were advertised at 64 CC, and measured at 69 CC.

Since when is tooling beyond control? What else is beyond control? 11 CC difference, on a 180 CC port is a variance of 6% give or take. Do you expect me to believe that is beyond control?

How about linking up the fishy stories.

Have you called us and spoken to a tech yet? If there is a problem with your heads we will definitely help you out.

What sort of valves are you using?

[wesmigletz]

Dart Vader, I have not called you guys. I'm running the valves that came with the heads. The head volumes were checked and re-checked, FWIW. The 200 CC Pro 1 Platinums we tested were spot-on.

Regarding not calling about the heads, it's just not worth it to me. I'm not happy about the difference between the advertised and measured intake runner volumes, but not bothered enough by it to go through the hassle of dealing with a manufaturer to try to resolve it. Then again, I don't send food back at restaurants either.

The engine is in the car and running. I plan to go back to the track on Saturday, and I'll see how the heads do. My car is pretty well sorted, and the time slip will tell the tale...

[Dart Vader]

I would expect that the heads will perform excellently for you, but if it turns out to be problem for any reason let us know.

Our quality control process is very strict, all our castings are done in the USA and all our machining is done in our own facilities, we don't outsource, so if a problem does show up (and they do occasionally) we take it seriously.

Enjoy the heads!

[wesmigletz]

Dart Vader, I've used Dart heads before, and I expect the new heads will perform... which is pretty much why I didn't call.

I simply posted what I found when we CC'd the heads. I wasn't expecting my thread to be cross-linked.

Thank you for the follow-up and offering to help.

Wes

[rbrduck71]

hey guy its the duck quacking again, speaking of tolerances, i posted a thread in chevy engines tech, DART IRON EAGLE 180/49cc heads, im not typing it all again, but anyways one of the things we found was one head was slightly warped, less than .005 didnt have smaller feeler guage, other head was straight, to my surprise block deck was good too, motor was never over heated, heads ran 10-20 hrs. should i have checked them right out of box? is this acceptable? i cant return them, painted and gasket matched, owned for about two years before i used them, i picked DART because most of the guys i know at the track used one or another set of DART heads, i really want to get it straightened out cuz my buddy is running summit aluminum heads and i wanna beat him, itsa iron versus aluminum thing no brand bashing here, please read my other post/thread before trying to answer my question, THANKS!!!
rubberduck

[Dart Vader]

hey guy its the duck quacking again, speaking of tolerances, i posted a thread in chevy engines tech, DART IRON EAGLE 180/49cc heads, im not typing it all again, but anyways one of the things we found was one head was slightly warped, less than .005 didnt have smaller feeler guage, other head was straight, to my surprise block deck was good too, motor was never over heated, heads ran 10-20 hrs. should i have checked them right out of box? is this acceptable? i cant return them, painted and gasket matched, owned for about two years before i used them, i picked DART because most of the guys i know at the track used one or another set of DART heads, i really want to get it straightened out cuz my buddy is running summit aluminum heads and i wanna beat him, itsa iron versus aluminum thing no brand bashing here, please read my other post/thread before trying to answer my question, THANKS!!!
rubberduck
If you have further questions or concerns regarding that thread please post them there, rather than in this thread.
Also, please try to avoid reviving threads that are very old unless there is a really good reason to do so.

If a bunch of old threads get hijacked and revived with semi-related questions it makes it really hard for people to find information they are searching for on the forums, which is not good for new users! (Or old ones for that matter...)

Thanks -DV

[rbrduck71]

the thread was talking about tolerances! i guess i worded it wrong. what is acceptable warp tolerance, is less than .005 acceptable. or should i have checked the DART IRON EAGLE 180/49cc heads before using them, i asked because i didnt think head warpage after 10-20 hrs was acceptable. i knew there would be history questions so i saved my two index fingers by telling where the history was already typed. im sorry if i broke any rules, im just trying to find out if i did something wrong to my heads to cause these problems after only 10-20 hrs of use.
concerned customer
Buck Morris

[Dart Vader]

the thread was talking about tolerances! i guess i worded it wrong. what is acceptable warp tolerance, is less than .005 acceptable. or should i have checked the DART IRON EAGLE 180/49cc heads before using them, i asked because i didnt think head warpage after 10-20 hrs was acceptable. i knew there would be history questions so i saved my two index fingers by telling where the history was already typed. im sorry if i broke any rules, im just trying to find out if i did something wrong to my heads to cause these problems after only 10-20 hrs of use.
concerned customer
Buck Morris

The warpage question is fine. It should be posted in the thread you created.
This thread is old and the issues discussed herein were resolved.

[Trmnatr]

The warpage question is fine. It should be posted in the thread you created.
This thread is old and the issues discussed herein were resolved.

I kind of agree that his question fits into this thread, this thread is all about QC, he is asking if QC accepts this

IMO, this is a good thread to post QC machining questions on

Just my $.02 which really dont matter

I have seen everything you can think of out of alot of heads, Dart, GM etc. I always buy bare heads ever since sportsman II's were hanging valves in them,,

Bottom line is,, CHECK EVERYTHING

[rbrduck71]

I Wish I Had!!!!!

[Dart Vader]

Your question is perfectly valid, and I suggest you post it in the thread you started for the purpose of discussing your heads.

If a new user were to look at this thread, they would be very confused when the thread suddenly changed to a different discussion directly after the previous resolution post. It makes things difficult to follow and glean useful information from, which is bad for the forums.

I would like to see any issue that you are having resolved to the satisfaction of all parties, and I would like any discussion regarding your concerns to be available for others to read easily, as we like to encourage open, honest discussion here at the Dartboard, even if it involves a potential problem with our products.

Please post your thoughts and concerns in the appropriate place. This thread is now locked.