500 stroker comp

[Haflinger]

I'm gonna build me a 500 stroker for my -68 Charger and bought a
kit from 440source, #504. I will use the eddy 84cc heads and the comp
is calculated to 10.9. Isn't that a little bit to high for a cruiser with an
occasional burnout? I am also not a "tuner", having no friends or shops knowing these engines. Should I look for other pistons then the flat-tops
included?

 

[69 Runner]

Don't forget the aluminum heads react differently than steel. They will allow for a higher compression ratio without problems than a steel head. You should be fine. And assuming the CR was figured with a steel headgasket then you can lose about 1/2 a point by switching to a composite like a Felpro blue

 

[rolling_Thunder]

you can always use a thicker head gasket to lower compression slightly... Cometic has a .051" thick gasket - that would drop your compression from 10.9 to roughly 10.55 = very safe for pump gas with aluminum heads... even the 10.9 should be fine.

 

[Meep-Meep]

10.9 is up there, but if you have some good quench you can squeak by on pump 92, especially with aluminum heads because they transfer heat into the water jacket faster. Adding a very thick head gasket will definitely lower the CR but you will also loose some quench. I would rather mill a dish in the piston under the combustion chamber if you want lower CR and I would never sacrifice quench for lower CR. The best thing to do is measure how far the piston sits in the hole and do the math so you know for sure what you got. .040" - .050" head clearance is good but not less than .040". You may want to buy a 5 gal can of race gas and be ready to make your own blend.

500 cubes can do a lot with 8.5:1 with the right cam, plus with the crap they call gas these days you have to be careful with high CR. You should also run the full recommended advance with a performance curve. Retarding the timing to cure detonation is a band aid and you would be better off with better gas or lower CR. This CR screams for a high overlap cam and 6500 RPM shifts!! Woo hoo!!!

 

[Rob R]

With an 11.5 to 1 compression ratio and alum heads and the proper cam you can run on pump gas...it's all in the cam the static compression will give you more Tq. You also need substantial carburation and ign to help things along.

 

[Haflinger]

Thanks guys, I will use a engle K60 cam with .534" lift and 288 duration,
proform 850 racecarburator and MP electronic.
The 10.9 is calculated with .039" headgasket. Guess also the octane here in Europe is slightly higher then in US.

 

[beezee]

I have a very similar build with 440 source kit,415 crank,ross flattops,block decked for ,040-.045 quench with .039 head gasket,with e-brocks ootb ,around 11.3:1 compression.I run sunoco 94 with no detonation problems.My intake is a street dominator single plane topped with a 950 quick fuel primary jet #75 secondary #84 with #75idle air bleed,s(changes to carb out of box.) Using msd ignition 6-al pro-billet dizzy with black 18* advance stop ,light silver and blue spring,set @ 36* total I,ve also installed an adjustable msd timing control#8680 to retard timing if detonation does occur .Cam is scott brown spec intake .525 lift 294 duration [email protected] exhaust .521 lift 311duration,[email protected] 112 lobe sep TTI exhaust 2" headers into 3" pipes to the tips. Trans is a SMR comp eliminator reverse manual valve body ,SMR 3000 tight converter and 3:91 8-3/4 suregrip This combo works very well pulls hard from idle to 6000 rpm,s As far as burnouts go ,no brake and drop the hammer in 2nd gear and smoke -em 200+ with a 295-65 drag radial.This is in a 68 Super Bee and you should expect the same with your Charger. 1/4 mile e.t. will be mid 11,s as Ive run beside my friends 74Charger with a 500 stroker and has run 11.70,s and I can pull on him

 

[Haflinger]

I will assemble the pistons to check piston to deckheight and after that
order a Cometic MLS headgasket, they can fix almost any thickness.
What's the maximum value for best quench effect if 0.040" is min?

 

[beezee]

Ideal quench is .035-.045, lots of info on this over at moparts.http://board.moparts.org/ubbthreads...in=4684003&Words=+Rapid340&topic=&Search=true

 

[Meep-Meep]

You also have to allow for the piston rocking in the bore a bit so I would not go too tight. My 383 has basically zero deck (-.005") with stock steel rods, 915 heads and a .040 head gasket. It ran fine on pump 92 (circa 1991-ish) with full 38 deg of advance.

 

[Haflinger]

If I would like to change to lower comp I guess my only option will be buying to pistons. According to a engineshop here my KB826 (today -4cc) can not
be made a -12-13cc dishpiston. He claims he called KB.
Diamond has a -13cc piston but again costs
Cometic advice me to mill the deck if I should use thei MSL gaskets so I think
I will go for the setup I have, in worst case I can always add some moore
octane for the 10 times a year I use the car.

 

[fishmarket]

I think that 10.9 with a cam that has 238*@.050 and the 108 centerline would build enough cylinder pressure to be teetering on the detonation fence. I would either go with a much larger cam to bleed off some cylinder pressure, or machine the heads or pistons for a bit more volume.
Also, shooting for that .040 quench will help you in the ping dept too.

If you haven't purchased the heads yet, edelbrock sells 88cc versions as well.