68 Head Question

[CTMopar]

I have two sets of 68 heads, 906s and 250s. Whats the difference? I can not find much info on the 250s, they do look different from each other.

 

[RustyRatRod]

The ports on the 906s are better by far. Though they may look similar, there are differences that make the 906 better. Although it's not an HP head per say, the 906 flows better than most. If you have a set, use them.

 

[CTMopar]

I am trying to find out what the specific differences are, they do not look similar.

 

[IQ52]

The specific differences? They would be meaningless. The 906 is a better flowing head BECAUSE it looks so much different. The specifics are in the different looks.

 

[RustyRatRod]

I am trying to find out what the specific differences are, they do not look similar.

I was referring to ports and chambers. Those look similar. At least to the naked eye. I said naked. heh heh heh huh huh huh.

 

[CTMopar]

I wasn't asking which one is better, I was asking how are they different?

 

[RustyRatRod]

It sounds to me like you have both sets in front of you, yet you're asking us what the differences are? Have you got a pair if calipers? You can make measurements and tell US what the differences are.

Not trying to be a smartass, but you've had two experienced people....(IQ52 being a *published* professional engine builder) tell you which heads are better. Why the heck does it really matter what the differences are if you know the better head? You have them both. Measure them and let us know.

 

[CTMopar]

They are both on running engines. I wasn't trying to decide which ones to run as they both are doing their jobs. I was just curious as to the differeces if someone knew. I don't care enought to tear down two running engines to find out.

 

[Deleted member 214]

Tactful reply to a less than tactful comment. Good job!

 

[RustyRatRod]

Tactful reply to a less than tactful comment. Good job!

I beg your pardon? "Less than tactful"? I take time to try and help people here. I'm not worried about trying to be warm and fuzzy or trying to be "tactful". I answered the question, as did Jim. Do you know what Jim does for a living? Do you care that he took time out of his day to try to help someone? Really, what honest difference does it make what specific differences there are between the heads? He now knows which ones are the better of the two. What would he do with more specific information? Bench race with it? Mopar Muscle has a very good writeup on big block heads that's been on the internet for a long time now.

Here is the article. Complete with flow numbers. That should more than tell which head is best and why.

http://www.moparmusclemagazine.com/techarticles/5115_cylinder_heads/

I cannot remember if they flowed the 250 casting there, but it is compareable to the 346 or 452. Nobody meant anything personal in this thread. Why you should come here and make it out like that I have no idea why.....unless you're looking for trouble yourself. Rest assured, you won't find it with me. I'll just move onto the next person that appreciates help.

 

[IQ52]

I have two sets of 68 heads, 906s and 250s. Whats the difference? I can not find much info on the 250s, they do look different from each other.

They are both on running engines. I wasn't trying to decide which ones to run as they both are doing their jobs. I was just curious as to the differeces if someone knew. I don't care enought to tear down two running engines to find out.

Now you have me curious. You have them on two RUNNING engines and they look different? Different how?

 

[Meep-Meep]

Some late model heads have features on the ends that look different than 906 or 915's. I can spot a set of 452's from across the swap meet aisle. I'm not familiar with 250 heads, but out of all the typical factory heads I have seen, there are three intake port designs. The early heads, including the Max Wedge, have flat floors with the Max being obviously larger than the rest. Then starting with the 915 and rolling over to the 906 the port got a major redesign that improved flow. The identifier is a nice radiused port floor, which helps with the transition into the pocket. After the 906 came the 346 and the 452 and those went back to the older flat floor port design. I have no idea why they went backwards but it could be emissions related. There may be other differences as well but I don't know for sure.

 

[65 Plymouth Satellite 426]

Both Of The Cylinder Castings Numbers #2843906 And #2951250 Are Identical In Every Way Both Being Chrysler Part #2843904 With 2.08 Intake And 1.74 Exhaust Valves And Open Chambered Heads Combustion Size 79.5 cc! They Fit 383-440 Engines! They Are Identical! If You Want A Good Flowing 383-440 Head, the '67 #2780915 Heads Have 2.08/1.60 73.5CC Heads And Closed Chambered Meaning More Power! The ONLY Difference Is What Meep Said Above About The Flat Floor Ports!

 

[Meep-Meep]

Both Of The Cylinder Castings Numbers #2843906 And #2951250 Are Identical In Every Way Both Being Chrysler Part #2843904 With 2.08 Intake And 1.74 Exhaust Valves And Open Chambered Heads Combustion Size 79.5 cc! They Fit 383-440 Engines! They Are Identical! If You Want A Good Flowing 383-440 Head, the '67 #2780915 Heads Have 2.08/1.60 73.5CC Heads And Closed Chambered Meaning More Power! The ONLY Difference Is What Meep Said Above About The Flat Floor Ports!

Are you sure about the 73.5 CC? My 915 heads CC'd at 79.5 so the open chamber must be larger. If memory serves I believe 86 CC.

915's can be found with 1.60" or 1.74" exhaust vales. The 1.74" valve heads have a large HP or HP 2 stamped on the machined boss where the alternator mounts. The castings are identical otherwise.

So the 250 head may be a service replacement?

 

[court9155]

Are you sure about the 73.5 CC? My 915 heads CC'd at 79.5 so the open chamber must be larger. If memory serves I believe 86 CC.

915's can be found with 1.60" or 1.74" exhaust vales. The 1.74" valve heads have a large HP or HP 2 stamped on the machined boss where the alternator mounts. The castings are identical otherwise.

So the 250 head may be a service replacement?

Dont be fooled, RUSTY knows these 250 heads, his buddy has them on his wagon and it thumps the ground pretty well:

http://www.forbbodiesonly.com/moparforum/showthread.php?t=9093&page=2

 

[Deleted member 214]

I beg your pardon? "Less than tactful"? I take time to try and help people here. I'm not worried about trying to be warm and fuzzy or trying to be "tactful". I answered the question, as did Jim. Do you know what Jim does for a living? Do you care that he took time out of his day to try to help someone? Really, what honest difference does it make what specific differences there are between the heads? He now knows which ones are the better of the two. What would he do with more specific information? Bench race with it? Mopar Muscle has a very good writeup on big block heads that's been on the internet for a long time now.

Here is the article. Complete with flow numbers. That should more than tell which head is best and why.

http://www.moparmusclemagazine.com/techarticles/5115_cylinder_heads/

I cannot remember if they flowed the 250 casting there, but it is compareable to the 346 or 452. Nobody meant anything personal in this thread. Why you should come here and make it out like that I have no idea why.....unless you're looking for trouble yourself. Rest assured, you won't find it with me. I'll just move onto the next person that appreciates help.

Rusty, I could put a caliper on two sets of heads and give you the port dimensions and valve sizes, but that would tell me only some of the differences between the heads. Meep-Meep and 69 Satellite helped by answering the question that was asked, which is what are the differences between the heads, and added some extra info on which is better for performance. Your earlier posts seemed to be answering a question not asked, then questioning the reason CT Mopar asked the question in the first place. How is that helping? I DO appreciate the information I've gotten from this site over the last few years and have taken the time myself to help out others, even gone under the dash and under the car to take pictures to help others out. The last three paragraphs in your latest post are very helpful and do answer CT's question. I have bookmarked the link for future reference. Thanks for that.

 

[CTMopar]

Now you have me curious. You have them on two RUNNING engines and they look different? Different how?

The 906s have freeze plugs and the 250s do not. I know that 902s and 452s have additional water jackets do the 250s have less or a different design? I am just curious because I like to know things not because I want to change either set.

 

[IQ52]

Ah, yes. The 250 appears to be a transition head from the 516, which it resembles in port design, to the 906, which is drastically different in port design. The 250, in my opinion, is the 516 head with a larger combustion chamber like the 906, 346, 902, 452 and also has the larger 1.74" exhaust valve rather than the 1.60" valve of the 516.

As to design of the water jackets, I cannot speak to, other than that which I can visually note. The water passages on the head to block surface are the same as the 906 and 915, but with the addition of the freeze plugs in the ends of the heads on the 906 and 915. Both 250 and 906 head designs have the freeze plugs between the exhaust ports under the exhaust manifolds.

 

[RustyRatRod]

Rusty, I could put a caliper on two sets of heads and give you the port dimensions and valve sizes, but that would tell me only some of the differences between the heads. Meep-Meep and 69 Satellite helped by answering the question that was asked, which is what are the differences between the heads, and added some extra info on which is better for performance. Your earlier posts seemed to be answering a question not asked, then questioning the reason CT Mopar asked the question in the first place. How is that helping? I DO appreciate the information I've gotten from this site over the last few years and have taken the time myself to help out others, even gone under the dash and under the car to take pictures to help others out. The last three paragraphs in your latest post are very helpful and do answer CT's question. I have bookmarked the link for future reference. Thanks for that.

That's cool.....then if nothing else, I stirred the thread up and got some answers.

 

[RustyRatRod]

Dont be fooled, RUSTY knows these 250 heads, his buddy has them on his wagon and it thumps the ground pretty well:

http://www.forbbodiesonly.com/moparforum/showthread.php?t=9093&page=2

Naw, I just know a pair of them are helpin to drag a 5300 pound wagon down the 660 to the tune of 8.40s. That's all I really know. That and one or two useless bits of info.