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  #1  
Old 01-12-2008, 05:32 PM
Mecki Mecki is offline
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Confused BB 915 Head

Just found that my 915 heads are fitted with 1.60" exhaust valves. According to the info I have available, in -67 only the 516 on B and 158 on RB engines were with 1.60" exhaust, and all 915 with 1.74". The heads sat on a junk yard -67 440 and I did not find any signs at all that the engine would have been apart before

Did they run out of 158 castings for the 440, or is this a joke someone made on the 440 HP assembly line? Is this some one-of-the-kind setup?

What would you do?
1. Keep "rare, should not exist" heads unchanged.
2. Fit 1.74" valves.
3. Fit hardened 1.74" seats and valves.
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  #2  
Old 01-12-2008, 06:06 PM
cudabob496 cudabob496 is offline
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I had 915s on my 440 once, and they had 1.60s as well. When I had some port work done, I switched them to 2.14/1.81 valves.
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Old 01-12-2008, 06:21 PM
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23T-Wedge 23T-Wedge is offline
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I had a set like this several years ago, with the 1.60's also, I've never been able to find out for sure what they came on, can't even remember now where I got them. Don't know if all the castings were like these but we were able to port them out to 238cc's on the intakes with just a minimal amount of epoxy in the area above where the ports split at the valve cover bolt hole. According to the sonic tester we could have taken out a little more but I wanted to keep them somewhat durable. Later my head guy tried to duplicate the port on a 906 head and could only get 217cc's with a lot of really thin spots. I suspect but have never been able to substantiate the 915's (with 1.60 ex.)might have been on the 365HP 440 that came out in 66' only in the Plymouth Sport Fury's. I know they existed because my dad had one. Had more torque than I could ever imagine anything having at the time.

As far as your questions, don't really have an answer, guess it depends on what your objectives are. Doubt they are worth anymore untouched, but I've been wrong before. Btw, I went 2.14" X 1.81" on the valves.
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Old 01-12-2008, 06:38 PM
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Thanks Bob and Wedge!

So, they are not the only ones then. Do you think that, going from 1.6 to 1.74, would considerably increase the flow without a port work? The valves and seats are in pretty good condition to restore and I was not planning to have them ported now. For the moment, I don't need to use them either.

The block they came on has casting date 10 14 66 and is stamped C440 and 5 23 (C for -67).
The heads have also a #, 01117, witch I think is the casting date.
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  #5  
Old 01-12-2008, 08:16 PM
cudabob496 cudabob496 is offline
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Quote:
Originally Posted by Mecki View Post
Thanks Bob and Wedge!

So, they are not the only ones then. Do you think that, going from 1.6 to 1.74, would considerably increase the flow without a port work? The valves and seats are in pretty good condition to restore and I was not planning to have them ported now. For the moment, I don't need to use them either.

The block they came on has casting date 10 14 66 and is stamped C440 and 5 23 (C for -67).
The heads have also a #, 01117, witch I think is the casting date.
Won't help much at all if no port work.
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  #6  
Old 01-12-2008, 08:38 PM
valiant64 valiant64 is offline
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Stepping up to the 1.74 ex valve would be a worthwhile improvement. Make sure at the minimum to have the valve job blended into the port when this is done. Depending on what youre planning on doing with the rest of the engine, stepping up to the 2.14 / 1.81 valves may be something to consider, as well as having some good porting work done.
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Old 01-12-2008, 11:11 PM
cudabob496 cudabob496 is offline
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Quote:
Originally Posted by valiant64 View Post
Stepping up to the 1.74 ex valve would be a worthwhile improvement. Make sure at the minimum to have the valve job blended into the port when this is done. Depending on what youre planning on doing with the rest of the engine, stepping up to the 2.14 / 1.81 valves may be something to consider, as well as having some good porting work done.
I'm pretty sure that just going to bigger valves will not be much of an improvement at all, unless the bowls are cleaned up with some at least mild porting, and the cam is improved. No use using larger valves if the heads are the primary restriction to air flow. I researched all this when I found out my 915's had 1.60 exhaust valves. On my 440 I went from a mild eddlebrock cam and dual plane to a M1 single plain intake, 484 purple cam, Holley 750 DP, and then some port work on the heads with 2.14s and 1.81s installed . Picked up about 75 horse at least.
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Old 01-13-2008, 03:04 PM
DartGT66 DartGT66 is offline
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915 heads came in '67 440's. 383's still had the old 516 heads, while all the 440's had the new 915 heads. They came with 2.08/1.60 valves, but the high performance 440's had the bigger 1.74 exhaust valves. So, the majority is with 1.60 exhaust valves.
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  #9  
Old 01-13-2008, 03:25 PM
Mecki Mecki is offline
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OK. But what is then the 158 head with 1.6" exhaust witch is supposed to be on the non HP 440 in -67 ?
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Old 01-14-2008, 10:45 PM
Steve DeTar Steve DeTar is offline
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On imperials....they had the small valve in 67
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  #11  
Old 01-15-2008, 01:52 AM
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If you're going to do the work, go 2.14/1.81 with hardened exhaust seats. Valve job, bowl work and porting are things that you should do, if you want to actually take advantage of the larger valves.
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  #12  
Old 01-15-2008, 02:37 AM
cudabob496 cudabob496 is offline
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Quote:
Originally Posted by Mecki View Post
OK. But what is then the 158 head with 1.6" exhaust witch is supposed to be on the non HP 440 in -67 ?

http://www.cowtownmopars.com/CastingNumbers.html
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  #13  
Old 01-15-2008, 08:07 AM
Mecki Mecki is offline
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That link does not list any 915 head with 1.6" valves either, only the 158 for 440. Obviously, the factory information has an error in this matter, but never mind, going bigger is not a big deal if I have a valve job done.

The advantages of the 915 appears to be quit limited anyway. According to your replies, they will never become any flow monsters and the CR advantage is easily achieved by milling open chambers or piston selection.

As the valves and seats are in restorable condition, I will just keep them for a resto project and put the money in a set with bad valves instead.

Thank you all for your replies.
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  #14  
Old 01-15-2008, 09:51 AM
Charger 69/72 Charger 69/72 is offline
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I don't know if I would say that the advantages of the 915 are quite limited. You may be able to raise your compression by milling a set of open chamber heads but you will not have a good quench. A good quench is necessary to prevent detonation. I have 2.14 / 1.81 valves in my 915s and they were ported to flow 265 cfm without any epoxy and we found no thin spots. By zero decking the block (.005 in the hole), using a Felpro head gasket (.039 compressed thickness), and using closed chambered heads I have a quench of .044". I drive this car on the street regularly using 93 octane and 34* total timing with no detonation.
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  #15  
Old 01-15-2008, 11:11 AM
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23T-Wedge 23T-Wedge is offline
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Charger,
As I mentioned in my above post we were able to get 238cc's of port volume on the 915's with very minimum of epoxy or thin spots, tried to match a set of 906's and couldn't get close. I always regretted never getting them flowed to see what air they were moving. Have you ever actually cc'd the port to see what the volume was. I often wondered if all 915's were as thick of a casting as the set I had. Sold them several years ago, sure wish I had them back.
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  #16  
Old 01-15-2008, 12:01 PM
Charger 69/72 Charger 69/72 is offline
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23T-Wedge,

Let me dig out the paperwork on the heads - I know that they were cc'd - I just don't remember what the figures were.
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  #17  
Old 01-15-2008, 02:37 PM
cudabob496 cudabob496 is offline
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http://www.moparmusclemagazine.com/t...ads/index.html
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  #18  
Old 01-15-2008, 04:56 PM
Paul Precht Paul Precht is offline
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I see no reason to make the ports bigger. If you don't have a flow bench and a lot of experience don't port anything, you may be making it worse. I did a set of Super Stock 440 heads for a guy about 5 years ago and I used epoxy to make the ports smaller, they are already too big. The intakes averaged 296 CFM @ 28" with 2.08 valves and a port that was only 2/3rds the size of the stock port. The 915/906 intakes should be pocket ported only. Unless you're going to raise the port, fill in the floor and take down the short radius which is an expensive time consuming job and requires a custom made intake the port should be left alone. Port matching looks great to customers which is why I always did it but it is almost worthless flow wise with the exception of an extreme mis match. Above all what looks good is not always what flows best, Paul.
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Old 01-15-2008, 05:38 PM
Mecki Mecki is offline
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Quote:
Originally Posted by Charger 69/72 View Post
I don't know if I would say that the advantages of the 915 are quite limited. You may be able to raise your compression by milling a set of open chamber heads but you will not have a good quench. A good quench is necessary to prevent detonation. I have 2.14 / 1.81 valves in my 915s and they were ported to flow 265 cfm without any epoxy and we found no thin spots. By zero decking the block (.005 in the hole), using a Felpro head gasket (.039 compressed thickness), and using closed chambered heads I have a quench of .044". I drive this car on the street regularly using 93 octane and 34* total timing with no detonation.
Good point, did not think about that. It's a major advantage, even if I stick to smaller valves.

Thanks!
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  #20  
Old 01-15-2008, 05:44 PM
Mecki Mecki is offline
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Very good article Bob. Thanks!

Printed it out for bed time reading, need to read it a couple of times.
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  #21  
Old 01-15-2008, 06:32 PM
Mecki Mecki is offline
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Quote:
Originally Posted by Paul Precht View Post
I see no reason to make the ports bigger. If you don't have a flow bench and a lot of experience don't port anything, you may be making it worse. I did a set of Super Stock 440 heads for a guy about 5 years ago and I used epoxy to make the ports smaller, they are already too big. The intakes averaged 296 CFM @ 28" with 2.08 valves and a port that was only 2/3rds the size of the stock port. The 915/906 intakes should be pocket ported only. Unless you're going to raise the port, fill in the floor and take down the short radius which is an expensive time consuming job and requires a custom made intake the port should be left alone. Port matching looks great to customers which is why I always did it but it is almost worthless flow wise with the exception of an extreme mis match. Above all what looks good is not always what flows best, Paul.
Thanks Paul!

I totally agree about home porting. I have no intention to start with that without proper equipment, just cleaning and smoothing sharp edges.

I found an other thread, where the costs for a head reconditioning including porting, was compared to the price of a complete set of much better flowing aftermarket heads ready to bolt on. Makes it a little bit hard to motivate an extensive porting of the 915 heads, when the final cost is about the same. I'll just enjoy the closed chamber without spending my money on porting.

Interesting , that a considerably smaller port would flow so much better. I would have thought, that a reduction of flow area to 2/3 would have inevitably restricted the flow.
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  #22  
Old 01-16-2008, 10:55 PM
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The other head in 67 was the 516. It was 208, 160 also

I've never heard of a 158

The 915 literature has to be taken with a grain of salt.
I've seen 67 440's with 516's.
I've seen 67 383's with 915's.(looked orig, with stamped gaskets etc)
After 40 plus years, it's hard to say what was orig and what wasn't

My own thoughts are that the 915 got put where ever they needed it.(except for the bigger Valve version) The closed head was on it's way out. Chrysler knew it, by the time the 915 was first rolling off the casting line.
Had to reduce nox, so the 906 was already being developed. (just an open chamber version with the same runners)

That said, I think they started making the 915's, and used the 516's to help fill in, when they changed up to the 906.

Chrysler is know for throwwing whatever they had on the pile on the next car that came down the line so who knows. my .02
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Old 01-16-2008, 11:04 PM
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As for the port debate. If you don't clean up the bowl considerably behind the exhaust valve, there is no point in going to the bigger valve. After they cut it for the bigger valve there is shelf of material behind there(just went through this on a set of 516's).

If you don't plan on cleaning up the bowl, then leave in the small valve. IMHO, it will flow worse if you just slap in the bigger valves.

The small valve will still perform. Lot's of chevy small blocks, stroked out to 427 or 454 use a 2.08/1.60 valve combo, so it will run fine.

The same inexperience that makes you not want to port the heads (which I totally understand) is also not alowing you to understand that there is no point in the valve change if the bowl is not cleaned up to match it.

Hope it works out for you.
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Old 01-18-2008, 03:33 AM
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Small ports and valves increase velocity, bringing the low end torque on. Bigger smoother ports and valves increase top end.
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Old 01-18-2008, 07:30 AM
Mecki Mecki is offline
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Thanks Dave and Kruzer!

What you are saying about the smaller valves is backing up the conclusion I made after reading the article in mopar muscle, Paul's post and putting together tips I picked up from other threads.

Is not smooth good for velocity too?

I mean, removing sharp edges and cleaning the rough surface of the port should make flow disturbance and flow resistance smaller. The higher the flow velocity gets, the more sensitive it is to disturbances caused by edges and surface roughness. (At least in pipelines in general.) Paul's observations about increased flow in a smaller port must be a result of this. Or what do you think, Paul and the rest of you?

If this thinking is correct, then a low end torque engine with stock valves and ports should gain a lot, all over the rpm range, from smoothed polished ports without changing the shape and volume?
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Old 01-21-2008, 02:43 AM
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Quote:
Originally Posted by DartGT66 View Post
915 heads came in '67 440's. 383's still had the old 516 heads, while all the 440's had the new 915 heads. They came with 2.08/1.60 valves, but the high performance 440's had the bigger 1.74 exhaust valves. So, the majority is with 1.60 exhaust valves.
Do you know if the shape or volume of the port was different for the HP head? The casting is the same and taking in consideration that this is a factory mass production item, makes me think that not so much was done to the port. Was the bigger valve job originally even blended into the port?
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Old 01-21-2008, 08:59 AM
Paul Precht Paul Precht is offline
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Hi, yes the vale job was properly blended in the big valve head. The ports are identical between both heads and the same as the 906. It's possible they had thousands of 1.60 valves laying around that needed a home, Paul.
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Old 01-21-2008, 04:27 PM
Mecki Mecki is offline
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BTW, does anybody know the compression height of the stock 440 -67 piston?

I did not remember to measure the piston to deck distance when I disassembled the engine.
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Old 01-21-2008, 04:37 PM
hotrod7043 hotrod7043 is offline
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Read the engine Book fellows, Bye the way i gotta aset that are template ported good springs etc. available with a Team G and crane rockers pm with all offers.
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Old 01-21-2008, 04:43 PM
Mecki Mecki is offline
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Don't have the -67 book. All shop manuals from -68 to -80 though, but that's all with open chamber and they don't state the compression height of the piston. The Engine Book I have, gives 2.03" for -68, 2.06" for 70-71 six pack and 1.93" for -72. Nothing for any closed chamber application.
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