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Thread: 327 build help

  1. #1
    Join Date
    Nov 2007
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    26

    Default 327 build help

    Hey guys last summer i put my 327 i built fresh a few years back finally into my new monte. the engine has less then 100km on it since build. long story short im looking to change up the setup to get a some more juice outta her.


    327, double hump heads they have been decked twice
    block is fully polished all the oil galleys ect..
    fully balanced rotating assembly
    flat top pistons
    edel 650 carb
    edel performer eps intake
    im not sure on the cam? but im assuming close to stock it came with the block when i bought it and never changed it.
    msd distributor


    so im looking to get as much power as a can keeping it on pump gas i would like a nice aggressive cam setup (love the sound) what do you guys recommend as far as cam,lifter,rockers,valve springs ect... to push the limits of this engine... im hoping to keep the heads as im a student trying to save funds.

    sorry for the long read!

    oh, 3.73 posi and 5 speed incase that matters for cam setups!

  2. #2
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    Nov 2007
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    if it helps engine casting number is 3858180 and heads are 3782461

  3. #3
    Join Date
    Jun 2006
    Location
    Katy,TX
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    1,348

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    If the heads have been shaved you surely won't be able to run pump gas with the smaller chambers and flat tops might have to get some dished pistons to keep it 9.5:1 or lower.
    1978 Black Trans Am 455 Edelbrock heads 10.99@124.5 through mufflers on pump gas
    1981 Trans Am 400 stock type motor
    79 Camaro getting a 500" 695 hp IA2 Pontiac motor
    1965 GTO project car
    470ci/Chevy dual quad 409 604 HP 64 Impala SS project
    2004 Pulse Red GTO

  4. #4
    Join Date
    Nov 2007
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    i ran it on pump gas no problems hardened seats 93 octane last summer for aprox 100km. im not sure the gasket thickness. sorry for the dumb question but how would i figure out the comp ratio.. i been reading online and im slightly confused. thanks!

    also i read a few guys had good success with the comp 12-600-8 what do you guys think?

  5. #5
    Join Date
    Jul 2008
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    Ft. Worth, TX
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    415

    Default 327 build help

    A 327 with flat tops and even a 60cc chamber is still only around 9.6 to 1 so you will be alright on compression. The cam you asked about is in the thumper line up which is more about sound than drive ability and power. With the intake, gears, carb and cubes you have I suggest looking into comps 268 xtreme energy it's 224/230 at .050, around .470 lift and 110 lobe with a 106 centerline. The extreme energy series cams make great power with good drive ability. Use the valve springs that comp recommends for the cam. Also use a aftermarket retainer or more retainer to valve seal clearance. Use a good 1.5 ratio roller rocker (comp, crane, scorpion, crower, etc) and you will be ok. Also upgrade you pushrods to at least a hardened pushrods that is .065 or thicker. You can use a cam of this lift with or without pushrod guide plates. If you run a cam over .500 lift your heads will need some work unless they already have been. The valve guides will need to be cut down, spring seats cut, screwin studs and guide plates installed.

  6. #6
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    Nov 2007
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    thank you very much for your advice, would that cam still give me a good lumpy sound? also im thinking about changing my intake also to get a few more hp and port matching the heads. im hoping to get as close to 400hp as possible (maybe im dreaming) do you guys think its possible with these heads?

  7. #7
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    Jul 2008
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    Default 327 build help

    Stepping up to a performer rpm will gain you a few more hp. Port matching the cylinder head and manifold will gain almost nothing without other porting to the heads. I wouldn't bother with it.

    The cam would give a nice rumpled idle but is very drive able. The idle speed can e set around 650-700 rpm with that cam. I believe comp has the cam sound on their website. You could step up one size to 230/236 at .050 .477/.480 on a 110 lobe but you will start to lose drive ability. Another thing to keep in mind is if you use power brakes this would be the largest cam you can run without using a vacuum canister.

    With 9.5 to 1 compression, double hump heads, rpm intake, 650 carb you would be looking at 375-385 hp. With a better cylinder head like an afr 195, tfs 195 or similar you can gain approximately 35-40 hp for a total of 410-410 or so.

  8. #8
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    Nov 2007
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    perfect! thank you very much. also im running a mechanical fuel pump would I be better off to switch that out for an electric or pointless at this hp level. sorry if these questions are stupid im 22 this is my first real build and learning along the way, just trying to squeeze out as much power as possible out of this little engine till i can afford a LS swap

  9. #9
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    Jul 2008
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    Ft. Worth, TX
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    Default 327 build help

    As long as you have a 3/8 fuel line to the pump just use a performance mechanical pump. I would still use a regulator to make sure the pressure is where you want it. With the edelbrock carb set the pressure at 6-6.5 psi. There is no need to switch to an electric pump at this point.

  10. #10
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    Nov 2007
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    okay. now.. i been comparing the magnum 280h which seems to have very similar specs to the xe274h. the magnum seems to have that lumpier sound. but i believe I would get a better torque curve and more power from the xe274h i think im leaning towards that one. as far as rockers should i go with the basic comp roller tip or the aluminum gold comp rockers? they are similar in price.

    i've been reading a bit about wiped cam lobes on the comp xe series.. is this a common problem or just from people not keeping up with maintenance

    also i can get a very good deal on edelbrock 60989 heads (e-tec) and even better price on the new e-streets, and the local speed shop is trying to convince me into a set of procomps for 500 for the set...... are these heads worth the price or should i just save my money and enjoy the cam setup for now until i can afford LS

    sorry for the 1000 questions

  11. #11
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    Ft. Worth, TX
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    Default 327 build help

    The 274xe will make more power. It is more aggressive than the 280h. The 280h grind is about 35 years old or so. As far as flattening cam lobes go every cam manufacture has issues. The oil manufactures were forced to take all the high pressure additives out of the oil a few years back. Most people don't add zinc to the oil before breaking in the cam which will always cause failure. Also many people set spring pressure to high causing failure also. Care must be taken when breaking in the extreme energy series of cams. Just make sure to use a high quality cam lube, quality lifters, 110-115 lbs on the seat and 300-315 open, add zddp additive, upon start up immediately run the engine at 1500-2000 rpm. Most cam failures are do to installer error and not the parts failing. You can also avoid this issue buy upgrading to a hydraulic roller set up but it is more cash.

    For rockers use a full roller rocker from a good company. Comp, crane, Howard's, scorpion, crower.

    The edelbrock heads 60989 will work for your application. They are on the larger side but since you are runnning a 5 speed you will be ok. I have used those heads before and they work well. They will go great with the cam and intake you are planning on using.

  12. #12
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    Apr 2008
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    Newark, OH, / Concord, NC
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    400 HP at the flywheel will be easy with these heads. Do a good 3 angle VJ and do a pocket port in the bowls and port match the intake ports, it also helps if the heads have the 2.02 intake valves. My engine ended up with 10.5:1 compression with flat top pistons and ran well on 93 octane fuel. Use the above mentioned Thumper cam and an Edelbrock RPM Air Gap intake manifold. I had a .030 over 350 (355ci) with the same heads, a Comp cam similar to the thumper mentioned above, a GM Z28/Corvette dual plane intake and a Holley 750 carb and it made 414hp on the engine dyno.

    Dale
    IF COMMON SENSE WAS COMMON EVERYBODY WOULD HAVE IT

  13. #13
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    Default 327 build help

    Another thing to look at is how much money it cost to get the double hump heads to make that power. Valve job, surface, new 2.02/1.60 valves, cost of bowl blend, adding screw in studs, and cost of valve train parts. It will cost 750-1000 bucks just to rebuild a set of double humps. The op would be better off to buy an aluminum head such as the aforementioned edelbrocks, trick flow super 23s, or other aftermarket cylinder head in which all have many features above and beyond the factory double hump heads. The all have more effiecent combustion chambers, flow more out of the box than even a ported set of double humps an have thicker decks just to mention a few.

    With a flat top 2 valve relief piston in a 355 with a 64 cc chamber you can get near 10.5 to 1 with a thin gasket but a 327 with a 4 valve relief piston and 64 cc chamber will be 9.5-9.6 to1. Running a thin head gasket will get another .5 or so but the op may run into piston to valve clearance issues.

    As far as making 400 hp with double hump heads, yes it can be done. But you must run more cam than you would to make the same power with a better flowing cylinder head. To make 400 hp reliably all the aforementioned upgrades would have to be done to the double humps to make that power. Also to make 400 hp with double humps the short block must be spot on. Cylinder walls must be sealed tight, bearing clearances exactly right, balanced rotating assembly and other factors. A stock short block 327 with double hump heads and a performer rpm intake will not make 400 hp with the addition of just a performance camshaft.

  14. #14
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    Nov 2007
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    thanks... heres the plan e-tec heads 200cc, preformer rpm, xe274 cam, full roller rockers. trying to decide on a carb if i should even bother changing it or not.





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