new cam selection - your opinion

[Scaregrabber]

Yup: Steel shim head gaskets help a negligible amount but not enough to make much of a difference. There's a whole lot of 7.5 440's out there. I used to be happy when using the Six Pack pistons but they only got you to about 9.2-1 or so as well. This day and age I tell everyone to measure before disassembling and using good quality pistons but they don't listen anyway.

Sheldon

[BSB67]

Yup: Steel shim head gaskets help a negligible amount but not enough to make much of a difference. There's a whole lot of 7.5 440's out there. I used to be happy when using the Six Pack pistons but they only got you to about 9.2-1 or so as well. This day and age I tell everyone to measure before disassembling and using good quality pistons but they don't listen anyway.

Sheldon

I have a set of 915s that I loan out to people that I trust.  Boy do they wake up those .080" to 0.110" in the hole piston - motors.

[Stegs]

wow guys great info

It sucks for buyer such as myself that dont have alot of knowledge and was lead to buying 9.5 pistons and only getting 8.5 


doesnt sound like there is much i can do for this motor other than a 750 carb and enjoy it.


Ill start saving up for a better build, maybe a stroker motor or something like that. 

[BSB67]

So, as an example you probably have 90 cc heads, and a 0.040" head gasket.  If you installed my 915s with a shim head gasket, you would be over 9.7:1 CR (assuming the 8.5:1 number you stated).  Between that, and the quality of the work on my 915s, I would estimate that you would pick up 40 to 50 hp, across the entire rpm range..  Most other hp mods will not do that.

[Stegs]

So, as an example you probably have 90 cc heads, and a 0.040" head gasket.  If you installed my 915s with a shim head gasket, you would be over 9.7:1 CR (assuming the 8.5:1 number you stated).  Between that, and the quality of the work on my 915s, I would estimate that you would pick up 40 to 50 hp, across the entire rpm range..  Most other hp mods will not do that.

Dang ...Seriously? want to sell them?

Can you explain the difference from my 906 heads, and your 915s?

should i look for a pair of 915s to bolt on to my motor? that to me sounds like my best bet to improve performance...even if they are expensive!!!!!

[Challenger340]

So, as an example you probably have 90 cc heads, and a 0.040" head gasket.  If you installed my 915s with a shim head gasket, you would be over 9.7:1 CR (assuming the 8.5:1 number you stated).  Between that, and the quality of the work on my 915s, I would estimate that you would pick up 40 to 50 hp, across the entire rpm range..  Most other hp mods will not do that.

Dang ...Seriously? want to sell them?

Can you explain the difference from my 906 heads, and your 915s?

should i look for a pair of 915s to bolt on to my motor? that to me sounds like my best bet to improve performance...even if they are expensive!!!!!

Given that aftermarket Aluminum Heads do NOT work well at mid 9's Compression ratios due to the greater heat dissipation factor, the BB mopar Closed Chamber Iron Heads have historically in the past, been the best alternative as a correction for bumping compression when those # 1263 low-pop pistons are present.
and,
if the Closed Chamber Irons are used in conjunction with a complimentary Camshaft profile, it is a very noticeable improvement.
915's are the BEST of the closed chamber designs in my experience, also huber humped Intake floor, basically a "closed" chamber version of the 906.

[Stegs]

so basically i should track down a set of 915 casting heads for a 440 mopar....they will bolt right up to my 69 block (my guess is these wont be easy to find)?

I could then match a cam that will fit these new heads....and therefore get a nice little performance boost


following Rons advice, going with a holley/proform 750 carb would help also then id assume....


something to look into for sure to help me out.

i had no idea ...still learning

EDIT: found some...worth it or no? http://racine.craigslist.org/pts/5192410207.html

edit: may be a dumb question, but couldnt i get my heads shaved down, thus bumping compression? or use a thinner head gasket? just asking, again still learning

[cdr]

what about these Bob ? this is what i would use.

http://www.summitracing.com/search/brand/trick-flow-specialties/part-type/cylinder-heads/make/chrysler/engine-size/7-2l-440/engine-family/mopar-big-block-rb/product-line/trick-flow-powerport-240-cylinder-heads-for-big-block-mopar?autoview=SKU&sortby=Default&sortorder=Ascending

[Stegs]

what about these Bob ? this is what i would use.

http://www.summitracing.com/search/brand/trick-flow-specialties/part-type/cylinder-heads/make/chrysler/engine-size/7-2l-440/engine-family/mopar-big-block-rb/product-line/trick-flow-powerport-240-cylinder-heads-for-big-block-mopar?autoview=SKU&sortby=Default&sortorder=Ascending

aluminum wont help me right....low comp motor...these will only make it worse correct?

[cdr]

the heads i posted have smaller chambers, they are new to the market .

[Brass]

Quote: "Aluminum Heads do NOT work well at mid 9's Compression ratios"

To clarify, do they NOT work well at all – or just not AS well as a 10:1 compression engine, which is a given?  I'm sure heat dissipation is a sound theory but also wondering just how much of a real-world difference it makes.  I remember reading one test where the difference was negligible, and am aware of gains made using aluminum heads on a very low-comp motor.  On balance, it seems the dissipation would be mitigated at least a little by the smaller closed chambers, better flow, and weight savings; all good things.  Perhaps improved further with some milling and Cometic gaskets?  After all, I thought the whole concept behind the E-Street aluminum heads were to improve performance on low-compression motors.  Not disagreeing or trying to be argumentative – just hoping to get a sense of the actual tradeoff.  Especially because I too am eyeing the Trick Flow stuff.  : )  

[Challenger340]

If you are going to contemplate a head swap.... don't buy a Cam until you make that decision.

Just me... and I don't wanna get into long winded tech discussions here, but I personally don't like Aluminum Heads on low 9.'s to 1 C/Ratios, especially with 3.23 gears and stock Torque Convertors. I think you will be dis-appointed.

The new 78 CC Trick Flow as a "bolt on" would still only be very high 8's:1... maybe 9.0:1 for C.R., and really, any "flow" advantages to Aluminum Heads performance potential is not utilized until higher rpm's, where Camshafts able to tune for those rpm's and exploit the added flow, are once again cylinder pressure challenged to colder burns at lower rpm as the aluminum dissipates heat of combustion quicker.

"Future" plans are always the intangible here ? as in....
is a guy better to just go buy the Aluminum Head now.... knowing it won't necessarily be the "best" fix on the current low compression engine, but still a stop-gap temporary "mid-way" improvement.... but with the ability to already have the Aluminum Heads for later use, in a future BETTER Engine ?
versus,
spending money on closed chamber iron heads now for the low-pop Engine....  as the "best" current results ?

Good arguments both ways !
I can't comment any further, other than to say, IMO, if you are planning a newer, better engine later.... save your money for that, enjoy this one the way it is.

[Stegs]

If you are going to contemplate a head swap.... don't buy a Cam until you make that decision.

Just me... and I don't wanna get into long winded tech discussions here, but I personally don't like Aluminum Heads on low 9.'s to 1 C/Ratios, especially with 3.23 gears and stock Torque Convertors. I think you will be dis-appointed.

The new 78 CC Trick Flow as a "bolt on" would still only be very high 8's:1... maybe 9.0:1 for C.R., and really, any "flow" advantages to Aluminum Heads performance potential is not utilized until higher rpm's, where Camshafts able to tune for those rpm's and exploit the added flow, are once again cylinder pressure challenged to colder burns at lower rpm as the aluminum dissipates heat of combustion quicker.

"Future" plans are always the intangible here ? as in....
is a guy better to just go buy the Aluminum Head now.... knowing it won't necessarily be the "best" fix on the current low compression engine, but still a stop-gap temporary "mid-way" improvement.... but with the ability to already have the Aluminum Heads for later use, in a future BETTER Engine ?
versus,
spending money on closed chamber iron heads now for the low-pop Engine....  as the "best" current results ?

Good arguments both ways !
I can't comment any further, other than to say, IMO, if you are planning a newer, better engine later.... save your money for that, enjoy this one the way it is.

i agree.....

but challenger340, these heads would cost me roughly 1000 and he would bring them to me as he passes thru here for work

taking advice from a post above, a member stated that those heads with some work would add (guessed) 40 to 50 HP across the entire rpm range

that in my opinion is huge, and if i got that, i would live with this motor for a longer time as im sure i would be very happy with that

But, as you stated i would need to change the cam with these heads? or would my stockish cam do ok with these heads, and maybe do the cam in the later spring of next year?

and is 1000 a good price for those heads? is that what they normally go for....i mean he will bring them thru here so basically free delivery

all in all, great advice.....im going to speak with my engine builder tomorrow hopefully if he is around....i have a few more questions on my motor as it sits

[BSB67]

Slow down

No, I would not buy those heads.

My "good" 915 and those for sale likely have little in common other than the casting number.  Those heads are probably wore out, and with that, not worth $1000. 

To make a wore out set of 915's "good" will take considerably more money than a new set of Stealth heads.

So, you need to decide wehether to spend about the same or more money on a good set of 915s that flow 225 cfm, or aluminum heads that flow 270 cfm?  For your application, I would lean towards the 915, but almost no one else will tell you this.  There is such a huge attraction to "new" and higher flow, but for a motor intended for 500 hp or less, factroy heads will work.

I always recommend buying and using the right parts on the motor you have, verses the motor you hope to have in the future. 

[Stegs]

Slow down

No, I would not buy those heads.

My "good" 915 and those for sale likely have little in common other than the casting number.  Those heads are probably wore out, and with that, not worth $1000. 

To make a wore out set of 915's "good" will take considerably more money than a new set of Stealth heads.

So, you need to decide wehether to spend about the same or more money on a good set of 915s that flow 225 cfm, or aluminum heads that flow 270 cfm?  For your application, I would lean towards the 915, but almost no one else will tell you this.  There is such a huge attraction to "new" and higher flow, but for a motor intended for 500 hp or less, factroy heads will work.

I always recommend buying and using the right parts on the motor you have, verses the motor you hope to have in the future. 

ok. Ill pass on these heads then.....

Ill order a proform carb today or tommorow, start there....and read up on these stealth heads....maybe i bite the bullet after the holidays and just order all new pistons that will work with my 906 heads!

Ill save up all christmas money!


but for now a carb

[Challenger340]

I am sensing there are some various options being thrown around for Stegs to think about ? ... so in no particular order, and hopefully clarify....

1.) try and correct the current low-compression Engine:
IMO, and historically in the past..... people have pursued a Closed Chamber stock cast iron head in conjunction with suitable Camshaft.
It works OK if done correctly, invariably the rebuild of the iron heads and use of a Steel Shim head gasket does bring the C.R. up in the low 9's, which with a suitable Camshaft wakes them up.
I am guessing here, as I don't know prices in your geographical area.... but with "properly" redone closed chamber irons, gaskets & parts... $1,500 ?

2.) Dis-assemble the entire engine, re-do with better pistons, camshaft, etc., etc. ?
Might as well just double again whatever was just spent rebuilding it the first time... PLUS the better parts !

3.) Buy the expensive aftermarket "aluminum" heads now, as a correction for the current low-pop Engine, but with the "futures" to be able to use them on a later and better future Engine build.
As stated, I don't think you will be happy ?, because of the Aluminum heads greater combustion heat dissipation. While it has the potential to bump the C.R. on the current low-pop engine same as option #1 with the cast iron head, unfortunately the heat loss compromises low response, and the extra Flow that the Aluminum head provides can not be then exploited until mid-higher rpm's which conflicts with the "stock" T/Convertor and 3.23 geared application.... IMO.

Stegs,
I'll go out on a limb here.... and this is for EXPLANATION purposes only(I don't wanna get shot on a later tech discussion because YES, far more going on)
and,
I am only just trying to describe this for Stegs understanding on his 3.23 geared stock convertor application.

So,
you have to think of cylinder head "material" (as it relates to engine output, as in cast iron versus aluminum) this way... as it relates to applications.

If you have 2 IDENTICAL sets of cylinder heads, one pair being cast iron, the other set being aluminum....
all things being equal, and rule of thumb...
you need to run the Aluminum Head at approx 1 Point HIGHER Compression.... than the Cast Iron Head ?
So, If you were running a Cast Iron Head at 8.5:1 ?
If you were switching to the identical Aluminum Head... you would want it installed at about 9.5:1 to maintain the cast iron headed 8.5 C.R. output.

Capeche ?

So, on your "current" low-pop Engine, if you are contemplating a Head swap to correct it.... to "closed" chamber heads WITH a Cam upgrade...
and BOTH the Iron and Aluminum Heads would provide you the SAME 9+ C.R.....
BE CAREFUL...
because for running purposes, really you have to think about the Aluminum Head as 8+ C.R. installation as it will feel, because of it's heat loss properties,
as opposed,
to the Iron Head will FEEL like the actual 9+ C.R. Engine.

make any sense ?   
   

[66FBCharger]

 

[myk]

I'm in the same boat as Stegs, and I vote for a proper tear down and rebuild with the correct parts, with a block built to our specs.  No point in buying a set of trick heads or reworking the iron ones if the bottom end can't support it with the proper compression.  I would guess that you would end up with a car that was an under-performer in a different way than now.  Buy the new 'carb, maximize what's there now, while saving up money and parts for a proper build up...

[BSB67]

No point in buying a set of trick heads or reworking the iron ones if the bottom end can't support it with the proper compression.  I would guess that you would end up with a car that was an under-performer in a different way than now. 

Generally, I disagree.   But it depends on the goal. Certainly you should not go through the entire effort and expense of rebuilding a motor only to put the wrong pistons in it.  But it is done.  It is a little unfortunate, but I would not say the only option is a new motor. 

He can get to 9.5:1 CR which is about all he could run anyway with an iron head on pump gas. 

If he wants 425 to 450 hp and run deep into the 13s, maybe into the 12, in his full street trim, spend $2500 on the top of the motor he already has.

I would not do another motor unless the goal was 11s in a docile, full street trim car.  And to do that, You would need 500 in. motor and ported aluminum heads.

He could have gotten to higher hp easier with the right pistons, but when you have lemons, make lemonade.

[ChargerST]

Just to throw in another option:

get aluminum cylinder heads and have the chambers coated! There are coatings which act as a thermal barrier to keep the heat in the chamber. Like here:



You would gain compression without the adverse heat dissipation effect of aluminum heads. There several places that can do the coating for you. One among other coatings is TechLine's CBC2