Re: Pump gas compression advice 493 stroker
[Re: Mopar-Al]
#1115249
11/16/11 11:33 PM
11/16/11 11:33 PM
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Joined: Jan 2007
Posts: 7,664 IN
ahy
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master
Joined: Jan 2007
Posts: 7,664
IN
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With the big cam the higher 10.8x compression ratio with zero deck should work fine. I'm running 10.2 and zero deck with a smaller 242@.050 cam and no problem with detonation at all. With standard port heads and 493 ci it will be done by 6000 RPM regardless which cam you use.
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Re: Pump gas compression advice 493 stroker
[Re: fiddlestix]
#1115251
11/17/11 12:36 AM
11/17/11 12:36 AM
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Joined: Aug 2003
Posts: 43,129 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
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Bend,OR USA
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I run a very similar cam(Comp Cams lobes, 260 @ .050 intake, 266 @ .050 exhaust, 108 LSA in at 106.5 now ) in my 518 low deck stroker, 4.375 bore with a 4.300 stroke. It is a pump gas motor with a little overe 10. 8 to 1 compression now with a set of Indy SR M.W. ports, it use to be 10.29 to 1 comp. ratio with the Eddy RPM heads and six pak, that cam worked really well pull really well with the Eddy RPMs and six pak to over 7600 with out straining To answer your question on the comp. ratio I would stick with the piston down in the hole and go with Edlbrock head gasket that is(use to be) .031 thick What type and thickness head gaskets are you planning on using now?
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Pump gas compression advice 493 stroker
[Re: ahy]
#1115252
11/17/11 12:40 AM
11/17/11 12:40 AM
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Joined: Jan 2003
Posts: 27,421 Balt. Md
383man
Too Many Posts
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Too Many Posts
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Posts: 27,421
Balt. Md
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I was going to use the Eddy RPM heads on my 493 and have them CNC'd. With the 440Source flattop piston I would have been in the 10.5 to 11.0 area. But I changed and went with the Indy EZ heads with smaller 75CC chambers. So I had to use the 440Source dished piston and I ended up with 10.6 having my pistons very close to zero deck as they came out about .006 down. My EZ heads are opened up to Max Wedge ports but I wanted that as I use a good size cam. Its a flat tappet custom grind from Dwayne Porter and it is 264 & 270 @ .050. With 1.6 rockers it has .624 & .630 lift with a 110 LSA. I have it in at 106 and I love the way it works and sounds. I just wanted to run 10's in my 63 thru the pipes on 92 pump and drive it to the track which it has as it has run 10.70's. I would shoot for a flattop piston at zero deck and you should be in the 10.8 area with 80 CC heads. Good luck , Ron
Last edited by 383man; 11/17/11 12:41 AM.
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Re: Pump gas compression advice 493 stroker
[Re: Cab_Burge]
#1115253
11/17/11 12:51 AM
11/17/11 12:51 AM
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Joined: May 2009
Posts: 511 Temperance, MI
68 HEMI GTS
mopar
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mopar
Joined: May 2009
Posts: 511
Temperance, MI
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i ran that 262/.575 cam in a 11:1 440 on the street with a 3500 stall. it worked fine. i also ran the 244/.550 cam in that same motor (actually both cams ET'd about the same). the .550 cam was probably a little better in the 440 on the street. but in the 493 that .575 cam will work just fine.
put it at zero deck or even a couple thousands out with a 0.040 gasket.
68 Dart GTS "HEMI" 10.30 @ 131 pump gas street car 3780# 69 Roadrunner 511 six pack 10.92 drive to track street car
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Re: Pump gas compression advice 493 stroker
[Re: fiddlestix]
#1115255
11/17/11 06:45 AM
11/17/11 06:45 AM
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Joined: Jul 2004
Posts: 4,384 Worst Weather USA
493_DART
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Here is my experience - 493" flat top ross pistons ( .004 in the hole) eddy rpms 84cc should be about 11:1 610 lift flat tappet/ 268 dur. 34 degrees total .039 gasket (Edelbrock) ran it on 92 pump for a while (all summer racing) . popped a head gasket---could have been anything , but... I replaced the gasket and started running 50/50 blend gas , 110 + 92 pump = no problems after that. hope this helps
Last edited by 493_DART; 11/17/11 06:48 AM.
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Re: Pump gas compression advice 493 stroker
[Re: fiddlestix]
#1115257
11/17/11 12:19 PM
11/17/11 12:19 PM
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Joined: Aug 2003
Posts: 43,129 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,129
Bend,OR USA
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Quote:
I am going to run the Felpro 1009 .039" head gasket. Thanks for all the advice, it really helps.
Make sure the fire ring on the 1009 does not hang into the combustion chamber once it is compressed from torqueing If it does it can cause severe damage from detonation Two ways to check, one is with the pistons not in the motor, install the heads,both, with the gaskets torque down and look into the cylinders from the bottom of the motor to see if the fire ring is compressed into the cylinder, the other way is to torque them down and then remove them and lay them on the deck and cylinder heads to see if they protrude into the combustion chamber or not. If they do get a gasket with a bigger diameter The 1009 are famous for this Evidently they where designed for the 4.250 bores like the 426 wedge and 383 motors are Don't forget about the fire ring requirements for the reciever groove on the 1009 also IHTHs The 8517 PT might be a better gasket for you,depending on the bore size
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Pump gas compression advice 493 stroker
[Re: BSB67]
#1115259
11/18/11 12:36 PM
11/18/11 12:36 PM
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Joined: Jan 2003
Posts: 9,872 Weddington, N.C.
Streetwize
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Joined: Jan 2003
Posts: 9,872
Weddington, N.C.
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that 7200 operating range for the cam is likely sized based on a 440, for an SR the lift is a little short for that @.050 duration but it'll make plenty of torque and power. It's probably a street endurance grind which to me is perfect because with a wedge head the peak lift isn't as critical as long as your in the sweet spot of the head flow (85-95% of peak). Should work great, I'd look at the Indy dual plane (383man, BSB67 and myself all run them on ours ) and look close at a custom calibrated pro-systems 1000HP or similar. 10.86:1 calc'ed should be fine and a little lower than what I typically run on a 500 incher.
Last edited by Streetwize; 11/18/11 01:05 PM.
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