440 Heads
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440 Heads
I have a 1968 440 i am currently building. The engine originally had 906 heads on it and i am thinking about putting 915's on (aluminums are out of my budget). I was wandering if this is worth my while. I have heard good things about these heads but have also heard that i might bump my compression up too high? This is the first 440 i have ever built as you can tell.
#2
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if you have stock compression for with the 906 heads, the 915 heads will jump compression to 13 to 1, and the tops of the pistons have to be grounded down a little
#3
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13:1 ?! That is a little excessive. I am trying to up my compression a little, but not that high. Would i be better off having these heads shaved or is there another casting number that would work better? Just out of curiosity what kind of compreccion could i make and still run pump?
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I definately don't plan on super charging the engine but it would be really cool! Do you think it is worth swapping the heads out? I plan on having them ported (i know this is expensive, but cheaper than aluminum) but i have heard that the closed chamber design works better than the 906's open chambers.
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Like i said this is the first RB i have ever built so i don't know much about them. I appreciate your input because i haven't had experience with either head design (i bought this motor already pulled). I have already got a few parts for the motor such as an Edelbrock RPM intake, Mopar prurple .509/.509 248in 248ex 108*centerline, and TTI full tube C-body headers. I am pretty sure having the heads ported would help quite a bit and that is next on the agenda if you don't think 915's are worth it.
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I have heard good things about those heads but now i am afraid of what my compression ratio may turn out to be. If these heads wind up giving me 10.2:1 plus i am putting in a cam w/ over .500 lift i don't know if i will be able to run pump gas.
#14
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the bad part about the 915's is just trying to find a set of them; short production span! 906's work good on a street car. BTW, a bigger cam [longer duration] will reduce your cranking pressure and make engine more pump gas friendly. Just keep the cranking pressure less than 150 psi with the iron headed big blocks, should get by with 92 octane with correct timing.
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Is there a way to tell what my cylinder pressure will be without being able to start the motor? I do plan on having hardened valve seats installed on these heads if that makes any difference concerning the allowable cylinder pressure.
#16
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but I think you will be fine with the 509 cam and the 906 heads. also depends on the pistons. [stock pistons;no worries] My friend had a similar combo and was fine, [I'll try and find a calculation to use and post later]. Valve seats wont affect comp. unless severely worn out [sunk].
#17
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Like i said this is the first RB i have ever built so i don't know much about them. I appreciate your input because i haven't had experience with either head design (i bought this motor already pulled). I have already got a few parts for the motor such as an Edelbrock RPM intake, Mopar prurple .509/.509 248in 248ex 108*centerline, and TTI full tube C-body headers. I am pretty sure having the heads ported would help quite a bit and that is next on the agenda if you don't think 915's are worth it.
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If you can afford a few more hundred bucks have bigger valves installed. i run the .509 cam and 906 heads on all my 440`s and never have a prob. I use trw 10.2-1 domed top forged pistons, then they install 2.14 intake and 1.88 exhaust valves in the heads, My machine work I have around 650.00 for all the work. you can do the port work yourself at home with a handdrill, just get the porting templates from a speed source like summit racing or mopar perf. I use the felpro thick head gaskets, like .39 thou thick. and run 93 octane gas no prob. when you port out the heads also port match the intake to them, or there isnt any sense in doing it. you have to have the same amount of space from 1 pc. to the next for it to have the desired effect. just lay a papper intake gasket up against the intake, color the metal with a highlighter around the inside of the gasket , then using an auger bit just start cleaning the inside of the intake ports till the colorings gone. The 915`s are a great head, but like earlier posts. theyre harder to find and more expensive, the cost difference to obtain a sets not worth the time to get them. good luck.
#19
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There is a rough way to calculate it, dont have the info at hand
but I think you will be fine with the 509 cam and the 906 heads. also depends on the pistons. [stock pistons;no worries] My friend had a similar combo and was fine, [I'll try and find a calculation to use and post later]. Valve seats wont affect comp. unless severely worn out [sunk].
but I think you will be fine with the 509 cam and the 906 heads. also depends on the pistons. [stock pistons;no worries] My friend had a similar combo and was fine, [I'll try and find a calculation to use and post later]. Valve seats wont affect comp. unless severely worn out [sunk].
http://www.kb-silvolite.com/calc.php?action=comp
I think you need to stay under 7.5 DYNAMIC COMPRESSION for 92 octane
#20
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I am running stock pistons on this motor. The next thing on my list will definately be having these heads ported and polished (maybe larger valves if the wallet allows it). Thanks for the link, i'll throw my numbers in it and see what i get. Also, i was wondering about my rocker arms, they are the stock stamped pieces. I really don't want to spend the money on roller rockers (running a hydraulic cam), but was thinking about putting new 1.5 or 1.6's in. If i did the math correctly 1.6's would give me somewhere in the neighborhood of .543in. lift. I don't want to lose my low end power or have valve clearance problems and like i said before it needs to run on pump. Just an idea i was throwing around but don't really know the reprocussions...
#21
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the lift of a cam realy doesnt mean you lose bottom end. thats duration more duration less bottom end, more lift and duration ur compresion will suffer slighty.if u want to run a hot cam on the street id suggest a tight centerline of 106 deg or less to help give you that get up and go from light to light. rhoads lifters or the compcams copy will help in bottom end also..
#22
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the lift of a cam realy doesnt mean you lose bottom end. thats duration more duration less bottom end, more lift and duration ur compresion will suffer slighty.if u want to run a hot cam on the street id suggest a tight centerline of 106 deg or less to help give you that get up and go from light to light. rhoads lifters or the compcams copy will help in bottom end also..
mate this thing will hammer with ported heads & 1.6 rockers + 509 cam
#23
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Do you think with that kind of lift and 1.6 rockers i will still be able to run on pump? Running on pump is a must. Also, the intake i got is matchef for this cam's power range (2200-6200) will this have a signifigant change on my power band?
#24
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Well what did you end up doing? I think yhe 915 is the best head. But need to watch the compression. Use the calculator on the keith black pistons site to get an idea of where you will be on static compression. Go .015 deck clearance, .020 gaskets with flat top istons, and it should run great on premium 93 octane.
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