difference in heads 906 vs 915 vs 452?

[Stegs]

what are the differences between, which is preferable?


Im having my 440 freshened up, they are going to call me and let me know what iron heads i have. being stock im going to have them port/polish them since new heads are not in the budget.

The car with a unknown history 440 seems to have tons of power, but i think a fresh 440 and some polished heads with a new intake should be a welcome improvement


So fill me in guys, what is good? bad? worse?

[BLK 68 R/T]

All 3 are good heads, you may also end up having casting #s 346 or 516 casting. I don't know to much about the latter 2 that I mentioned so someone else with more knowledge may chime in on them.

From what I have gathered reading about the 3 you mentioned.

915s are a closed chamber design, non hardened seats, good flow #s, should have a little higher compression due to the closed chamber design. I'm sure with some port/polish work they would be just as good or better than 906s. Note-these are a semi-rare head and unless you have an original 67 HP motor is unlikely these are the heads you have.
906s are an open chamber head, non hardened seats, standard head on all 68-70 big block engines, 71s as well??, can be made to flow really good with larger valves and port/polish work and hardened seats added.
452s are basically the same as 906s from my understanding with the exception of hardened seats already being installed.

[Stegs]

All 3 are good heads, you may also end up having casting #s 346 or 516 casting. I don't know to much about the latter 2 that I mentioned so someone else with more knowledge may chime in on them.

From what I have gathered reading about the 3 you mentioned.

915s are a closed chamber design, non hardened seats, good flow #s, should have a little higher compression due to the closed chamber design. I'm sure with some port/polish work they would be just as good or better than 906s. Note-these are a semi-rare head and unless you have an original 67 HP motor is unlikely these are the heads you have.
906s are an open chamber head, non hardened seats, standard head on all 68-70 big block engines, 71s as well??, can be made to flow really good with larger valves and port/polish work and hardened seats added.
452s are basically the same as 906s from my understanding with the exception of hardened seats already being installed.

thank you

I will post what heads are on the car when he calls

Supposedly its a original 70 HP block

[John_Kunkel]

I remember one of the porting services stating they preferred the 452's.

[Challenger340]

516, 1966 and earlier, Flat Port Floor, Closed Chamber, 2.08" Intake / 1.60" Exhaust
915, 1967 only, High Huber Hump Intake Port Floor, Closed Chamber, 2.08" Intake Valve / 1.60" Exhaust (low perf), 1.74" Exhaust on HP Engines
906, '68 to 1970, High Huber Hump Intake Port Floor, Open Chamber, 2.08" Intake Valve / 1.74"Exhaust (All)
902/346/452, 1971 & up, Low Port Floor W/swirl hump on siamesed inner Port wall(acts like a short turn), 2.08" Intake, 1.74" Exhaust(All)

from my studies...
Worst flowing to "Best" in stock 2.08"/ 1.74" Valve configuration to .450" Lift W/30* / 45* @ .039" /  60*@ .080* / 75* Throatcut,  and 30* Backcut on Valve
                                                                                                                   45* @ .065" Exhaust

Worst.... 516.... 902/346/452 series, but VERY close to 906/915 series.

Above .500" Lift with Portwork becomes a different story.
The 906/915 can still exceed the 902/346/452 series, but requires a far higher degree of Port Short Turn "FINESE" to get the curve right, and work to get the Bowl Volume above on the roof, especially with bigger 2.14"/ 1.81" Valves. !
Generally speaking,
above .500" Lift, and with bigger 2.14" / 1.81" Valves, it is far easier with less porting work to get better Flow out of the 902/346/452 series than the 906/915 series, even if it does just go crashing out the backside into the spark plug... Flow is Flow, more than one way to skin a cat.

The thing everyone needs to understand.... ALL THESE HEADS can support 500hp even with stock 2.08" Intake Valves and 1.74" Exhaust Valves, even the 516 Casting.

[Challenger340]

I remember one of the porting services stating they preferred the 452's.

Yep, I agree.....  the 902/346/452 series Heads are the easiest/cheapest/most cost effective to get the Flow.
But,
that is not to say MORE FLOW can't be had with the 906/915 series than the 902/346/452..... just takes ALOT more work to get there, that nobody wants to pay for nowadays ?

[BSB67]

what are the differences between, which is preferable?


Im having my 440 freshened up, they are going to call me and let me know what iron heads i have. being stock im going to have them port/polish them since new heads are not in the budget.

The car with a unknown history 440 seems to have tons of power, but i think a fresh 440 and some polished heads with a new intake should be a welcome improvement


So fill me in guys, what is good? bad? worse?

Interesting.  If I had a running motor, and I wanted to get the most from it with the least $, I would put all of the money into the heads and leave the short block.

You should only port the heads after you have established that the heads are in good shape.  Other wise, It's pretty much a waste.  Not to be Debbie Downer, but it is unlikely they are in good condition.  To make a set of used factory heads good, comp valve grind, and porting, you will be at or over the cost for new aluminum replacements.

Be sure to get a compression distance from your machine shop.  This is critical information for any future head decisions you might make.

[Stegs]

what are the differences between, which is preferable?


Im having my 440 freshened up, they are going to call me and let me know what iron heads i have. being stock im going to have them port/polish them since new heads are not in the budget.

The car with a unknown history 440 seems to have tons of power, but i think a fresh 440 and some polished heads with a new intake should be a welcome improvement


So fill me in guys, what is good? bad? worse?

Interesting.  If I had a running motor, and I wanted to get the most from it with the least $, I would put all of the money into the heads and leave the short block.

You should only port the heads after you have established that the heads are in good shape.  Other wise, It's pretty much a waste.  Not to be Debbie Downer, but it is unlikely they are in good condition.  To make a set of used factory heads good, comp valve grind, and porting, you will be at or over the cost for new aluminum replacements.

Be sure to get a compression distance from your machine shop.  This is critical information for any future head decisions you might make.

the are going to freshen up the motor, basically a stock rebuild but with new rings/gaskets etc

Obviously they are going to degrease it, inspect it, reassemble and paint

while they have the heads off, they are going to harden the seats so i can properly run unleaded fuel

At that point they will give me a idea on port/polish

I figure if its true that factory heads can go up to 500hp, than a mild port/polish should only improve on a stock rebuilt 440 right?

[Stegs]

update for everybody

this is what they found on my car

7 month production

1969 block

906 heads

forged crank

he isnt sure on if its a HP block or not....but maybe you guys could help me out "how to determine that"

[BLK 68 R/T]

If it's an HP block it should be stamped HP in the flat raised pad on the top of the block by the front of the valley pan. Most got a pretty legible stamp but some are pretty faint so take a good look. It will also have other info stamped in the pad such as undersize or oversize bearings from the factory indicated by some sort of a symbol and year code represented by a specific letter, like D440 - which indicates 68 model year engine. Good luck with your build!

[Stegs]

update again

He is going to give the block a better look over for the HP stamp

He just fluxed my heads and they are in great shaep (what a relief) 

something wierd tho he found

It had 4 original pistons, 2 were aftermarket replacement and 2 were "trw" old speed shot parts LOL

They are going to bore 30 over and do 8 matching pistons, do a port/polish on the 906s and bolt up my eddy intake

For the most part is a factory rebuild, but it should move really well now with some head work and eddy intake

[Challenger340]

update again

He is going to give the block a better look over for the HP stamp

He just fluxed my heads and they are in great shaep (what a relief) 

something wierd tho he found

It had 4 original pistons, 2 were aftermarket replacement and 2 were "trw" old speed shot parts LOL

They are going to bore 30 over and do 8 matching pistons, do a port/polish on the 906s and bolt up my eddy intake

For the most part is a factory rebuild, but it should move really well now with some head work and eddy intake

Be very careful with replacement Piston selection, as it relates to the "Compression Distance" of the Pistons.
Do NOT select Pistons by "published" or "advertised" Compression ratio in Catalogs.....
rebuild the Heads FIRST,
then "CC" them for Volume when done, then apply THAT CC number with a known Head gasket like the Fel-Pro # 1009, etc. when selecting a conduscive piston "compression distance" height for your desired Compression Ratio WITH the Cam events to be used.

[Stegs]

update again

He is going to give the block a better look over for the HP stamp

He just fluxed my heads and they are in great shaep (what a relief)  

something wierd tho he found

It had 4 original pistons, 2 were aftermarket replacement and 2 were "trw" old speed shot parts LOL

They are going to bore 30 over and do 8 matching pistons, do a port/polish on the 906s and bolt up my eddy intake

For the most part is a factory rebuild, but it should move really well now with some head work and eddy intake

Be very careful with replacement Piston selection, as it relates to the "Compression Distance" of the Pistons.
Do NOT select Pistons by "published" or "advertised" Compression ratio in Catalogs.....
rebuild the Heads FIRST,
then "CC" them for Volume when done, then apply THAT CC number with a known Head gasket like the Fel-Pro # 1009, etc. when selecting a conduscive piston "compression distance" height for your desired Compression Ratio WITH the Cam events to be used.

This company builds motors everyday. He is ordering the equivalent to oem specs.

he is a ford guy, but his best friend is a Road Runner guy....he said he knows these mopar 440s and 383s better than a 302 ford

he is ordering what he feels will be best, and from his knowledge .....Im not doubting it one bit.

[heyoldguy]

Please don't disregard Challenger340's advice on compression distance. Seems like OEM spec's changed from year to year. At the same time you should be able to trust your machinist. But a Ford guy who has a Mopar buddy sounds a little iffy to me.

His iron head information was exactly what I have experienced.

[BSB67]

update again

He is going to give the block a better look over for the HP stamp

He just fluxed my heads and they are in great shaep (what a relief)  

something wierd tho he found

It had 4 original pistons, 2 were aftermarket replacement and 2 were "trw" old speed shot parts LOL

They are going to bore 30 over and do 8 matching pistons, do a port/polish on the 906s and bolt up my eddy intake

For the most part is a factory rebuild, but it should move really well now with some head work and eddy intake

Be very careful with replacement Piston selection, as it relates to the "Compression Distance" of the Pistons.
Do NOT select Pistons by "published" or "advertised" Compression ratio in Catalogs.....
rebuild the Heads FIRST,
then "CC" them for Volume when done, then apply THAT CC number with a known Head gasket like the Fel-Pro # 1009, etc. when selecting a conduscive piston "compression distance" height for your desired Compression Ratio WITH the Cam events to be used.

This company builds motors everyday. He is ordering the equivalent to oem specs.

he is a ford guy, but his best friend is a Road Runner guy....he said he knows these mopar 440s and 383s better than a 302 ford

he is ordering what he feels will be best, and from his knowledge .....Im not doubting it one bit.

Well, you should.  If you choose to not be informed, you bare the responsibility for what he puts in it and how it runs.  This is the only time to get piston selection right.

Of the OEM equivalent pistons available today, only one is worth using.  Everything else is complete junk and a very poor choice for any performance rebuild.

I'm curious, what is his cost estimate for the rebuild?

[firefighter3931]

Hopefully a Speedpro 2355 piston has been chosen for this build 



Ron

[69wannabe]

Hopefully a Speedpro 2355 piston has been chosen for this build 



Ron

X2!!!! These are a good mid to high 9's in the compression range and a good replacement piston for a HP 440. These are what I had in my last 440 build and they worked very good. You want to see part numbers when he order's your piston's!! You don't want to wind up with the low compression flattop's that are offered too. 2266's is the low compression pistons I think and they are rated at 8.5 to 1 or something like that. It would be good to get him to make you a part's list so you can see what is being put into your engine build!!

[Stegs]

he told me what they are, i forgot.

he is matching pistons to the heads and doing a gasket matching

i think the pistons were something like 4283 (maybe a part number?) he told me but i have a bad memory and didnt right it down since i was driving


I know they are spec to oem pistons

total for the rebuild, using stock cam, crank, heads etc (port/polish heads), new cam bearings, new rings, gaskets, machine crank, bore the cylinders 30 over
new pistons, re-assemble and paint hemi orange was 2300

that also includes stuff like a new timing gear and chain, new oil pump (mellings) and im sure a bunch of other stuff that i forget.

The nice part about everything is this is only going to cost me about 400 out of my own pocket, the rest is taken care off  


edit
piston number is 1276, very close to oem spec. He said there is a tall and a short piston, im getting the tall

compression ratio should be around 9.8 and 10.3 with the heads and gasket

Spec on that motor is 10:1, so we are right there. No it wont be a 8:1 motor, it will be spec'd as close to oem as possible

He just informed me that the valves in the heads are pretty beat up, and probably didnt seat well, so im having those replaced with new.

He said with what he found that car wasnt close to 10:1 when it came in.....but it still moved, so this fresh motor should be a nice improvment

[c00nhunterjoe]

Might want to look up that number. I think thats the low compression keith black piston. I could be wrong though.

[heyoldguy]

http://www.summitracing.com/parts/UEM-1276-030/

Yep, 8:1 compression piston with the 906 head.

[69wannabe]

he told me what they are, i forgot.

he is matching pistons to the heads and doing a gasket matching

i think the pistons were something like 4283 (maybe a part number?) he told me but i have a bad memory and didnt right it down since i was driving


I know they are spec to oem pistons

total for the rebuild, using stock cam, crank, heads etc (port/polish heads), new cam bearings, new rings, gaskets, machine crank, bore the cylinders 30 over
new pistons, re-assemble and paint hemi orange was 2300

that also includes stuff like a new timing gear and chain, new oil pump (mellings) and im sure a bunch of other stuff that i forget.

The nice part about everything is this is only going to cost me about 400 out of my own pocket, the rest is taken care off  


edit
piston number is 1276, very close to oem spec. He said there is a tall and a short piston, im getting the tall

compression ratio should be around 9.8 and 10.3 with the heads and gasket

Spec on that motor is 10:1, so we are right there. No it wont be a 8:1 motor, it will be spec'd as close to oem as possible

He just informed me that the valves in the heads are pretty beat up, and probably didnt seat well, so im having those replaced with new.

He said with what he found that car wasnt close to 10:1 when it came in.....but it still moved, so this fresh motor should be a nice improvment

Them 1276 are slugs and if you are doing this now is the time to stop him and tell him you would rather have the speed pro L2355F pistons!!!!! There is a big difference in a low 8 compression engine and a mid 9 compression engine. The 2355's are a replacement 6 pack piston and not the best for lightweight performance but still better than alot of the other offered pistons out there for the price. $422 at summit racing and they are forged and not cast. A HP 440 would have had forged pistons anyway and not cast pistons. We are trying to help you make the right decision while your engine is apart!!!! Take it from these guys that know mopar's myself included that them 1276's are a huge mistake for your engine!!

[Challenger340]

he told me what they are, i forgot.

he is matching pistons to the heads and doing a gasket matching

i think the pistons were something like 4283 (maybe a part number?) he told me but i have a bad memory and didnt right it down since i was driving


I know they are spec to oem pistons

total for the rebuild, using stock cam, crank, heads etc (port/polish heads), new cam bearings, new rings, gaskets, machine crank, bore the cylinders 30 over
new pistons, re-assemble and paint hemi orange was 2300

that also includes stuff like a new timing gear and chain, new oil pump (mellings) and im sure a bunch of other stuff that i forget.

The nice part about everything is this is only going to cost me about 400 out of my own pocket, the rest is taken care off  


edit
piston number is 1276, very close to oem spec. He said there is a tall and a short piston, im getting the tall

compression ratio should be around 9.8 and 10.3 with the heads and gasket

Spec on that motor is 10:1, so we are right there. No it wont be a 8:1 motor, it will be spec'd as close to oem as possible

He just informed me that the valves in the heads are pretty beat up, and probably didnt seat well, so im having those replaced with new.

He said with what he found that car wasnt close to 10:1 when it came in.....but it still moved, so this fresh motor should be a nice improvment

This has GOTTA be a JOKE Thread right ?
STEGS,
If you allow that NUMBSKULL to stick those 1276 Pistons in a BB Mopar after all the friggín MILLIONS of warnings about THOSE Pistons on this and other forums..... then there is no helping mankind...... we are all doomed !
Just STOP OK ?

My apologies for shouting if indeed this is some kind of prank post ?
I just can't believe anyone would still use a Silvolite #1276 piston for anything but a doorstop.

[firefighter3931]

These are the pistons you want :

http://www.summitracing.com/int/parts/slp-l2355f30



Ron

[Stegs]

he said he is ordering the tall pistons...giving me a compression of 9.5 -10

There are 2 sizes , short and tall....im getting the tall ones for higher compression

im confused now

your telling me this is not going to give me around 10:1?

its a stock rebuild guys, just to get me buy 3-4-5 years before i do a stroker motor....


help!

[Challenger340]

he said he is ordering the tall pistons...giving me a compression of 9.5 -10

There are 2 sizes , short and tall....im getting the tall ones for higher compression

im confused now

your telling me this is not going to give me around 10:1?

its a stock rebuild guys, just to get me buy 3-4-5 years before i do a stroker motor....


help!

I will agree on one thing, you certainly must be confused ?
Myself, and many others on here..... have told you repeatedly NOT to allow your MORON machinist(who obviously knows nothing about Chrysler OEM Specs), NOT to use any of those "advertised" numbers for piston selection.
You will be NO WHERE NEAR 10.0:1 with either the "short" nor the "TALL" version of those Pistons.... NOT even CLOSE !

Before any of this started, I POSTED here a caution here for you.
Remember this;
Be very careful with replacement Piston selection, as it relates to the "Compression Distance" of the Pistons.
Do NOT select Pistons by "published" or "advertised" Compression ratio in Catalogs.....
rebuild the Heads FIRST,
then "CC" them for Volume when done, then apply THAT CC number with a known Head gasket like the Fel-Pro # 1009, etc. when selecting a conduscive piston "compression distance" height for your desired Compression Ratio WITH the Cam events to be used.

And now,
you are making EXACTLY the mistake I was trying to warn you about up front, wherein the "published" data on those Pistons is incorrect regarding it being anything more than an OEM smogger Engine replacement Piston.

Stegs
If you use either of those pistons , the short(#1276) or TALL(#1263), I don't care which, one is just worse than the other....
You will NOT have a "stock" O.E.M. anything other than a 230 hp TERD !
and,
You will be no where even close to 10:1 Compression ratio(maybe mid 8's at best)

You've been told, do as you wish, just like that Gump fella....

Call your idiot machinist and tell him to grow a brain !