"Detonation problems" rebuild 440-6
#308601
05/05/09 02:17 PM
05/05/09 02:17 PM
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Joined: Jun 2006
Posts: 108 Sweden
6pakdude
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OP
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Joined: Jun 2006
Posts: 108
Sweden
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Rebuild my org 440 this winter. Now detonates over 4800 RPM? Any help appreciated to solve this problem. Engine specs: KB237 030" block 0 decked Moly rings, top ring filed to KB spec 906 heads, 2,14" and 1,81", hardened seats, shaved to 84cc. Fel Pro 8519 PT-1 head gasket 0,029" thick 10:3 comp ratio using KB calculator. Lunati voodoo 60303 hyd camshaft Champion plugs RJ12YC Rocker shaft shimmed for preload Stock dual point distributor, petronix ignition, total ignition at 2300 RPM Stock HP exhaust manifolds, with repro mufflers and pipes. Under 4800 RPM runs strong and great, idle 900 RPM,vacum 15 HG, 16 degree ignition total 36. Gas unleaded 98 octane (sweden) Have tried to set ignition down to 10 intial and total 30 without any result. Carbs stock 1970 auto Center 64 jets, powervalve 65, shooter 31. fuel/air set with vacum guage Front stock metering plate 34R-6153-35 Rear stock metering plate 34R-6153-35 Front and rear fuel/air set with blocking outer air bleed holes. Still detonates over 4800 RPM Changed metering plates in front carb to 34R-9716B Have no idea what size it is. rear carb 34R-5113B size unknown These metering plates was mounted when car had a mech camshaft, Racer brown. pullig hard to 7000RPM. So i figure they give more fuel than the stock plates. Finally checked the spark plugs, they look to white for me, want a more tan/brown color. So here is my question: Is my engine running lean above 4800 RPM and cause the detonations. The voodoo 268 camshaftit should rev to 6200 RPM. any idea what size jet to use, if thats the problem. Or do I need to change to a thicker head gasket? Or change heads, build a Quench engine with the shortblock above. Want to run the car on the strip this summer. Long story, hope to get some input on the detonation problems I have. Thanks Peter
Last edited by 6pakdude; 05/05/09 03:32 PM.
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Re: "Detonation problems" rebuild 440-6
[Re: lewtot184]
#308605
05/05/09 03:00 PM
05/05/09 03:00 PM
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Joined: Jan 2003
Posts: 24,562 Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
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Posts: 24,562
Brookeville, Md
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Quote:
my , too much compression, short cam, no quench; sorry, it'll never work.
I'm using a 440-6 w/ ported 516 74cc heads (2.14/1.81) and a MP 528 solid. Haven't driven the car yet but so far no problems. I think my compression is a tad higher.
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Re: "Detonation problems" rebuild 440-6
[Re: lewtot184]
#308606
05/05/09 03:00 PM
05/05/09 03:00 PM
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Joined: Jun 2006
Posts: 5,166 CT
GTX MATT
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Posts: 5,166
CT
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Not enough cam for that compression, really high cylinder pressures.
Last edited by GTX MATT; 05/05/09 03:01 PM.
Now I need to pin those needles, got to feel that heat Hear my motor screamin while I'm tearin up the street
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Re: "Detonation problems" rebuild 440-6
[Re: Mr.Yuck]
#308608
05/05/09 03:18 PM
05/05/09 03:18 PM
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Joined: Jun 2008
Posts: 3,916 usa
lewtot184
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master
Joined: Jun 2008
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Quote:
Quote:
my , too much compression, short cam, no quench; sorry, it'll never work.
I'm using a 440-6 w/ ported 516 74cc heads (2.14/1.81) and a MP 528 solid. Haven't driven the car yet but so far no problems. I think my compression is a tad higher.
i have two iron head 6-pak engines and both are around 9.3:1 compression with good quench. the short cammed engine makes about 185psi cylinder pressure and has got a little "testy" with 93 octane on occasion. the other engine has a longer solid cam and about 165psi cylinder pressure; its a lot more forgiving with 93 octane. i'm not a believer in 10+:1 compression with iron heads and 93 octane gas, good quench or no quench. just a voice of experience.
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Re: "Detonation problems" rebuild 440-6
[Re: 6pakdude]
#308612
05/05/09 03:41 PM
05/05/09 03:41 PM
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Joined: Jan 2003
Posts: 75,094 A Banana Republic near you.
JohnRR
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I Win
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Quote:
yes, you right about the head gasket.should be 0,039"
I used the shims for compensate for decking and millig the heads.What can I do? shorter pushrods or adj rockers? peter
The correct way to make up for the head and deck milling is to get the correct length pushrods , in this case shorter .
But this has little to do with your detonation issue, you'll have to tune it out.
I wonder if your plug choice has an effect since it's one step hotter than stock ?
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Re: "Detonation problems" rebuild 440-6
[Re: Mr.Yuck]
#308615
05/06/09 09:05 AM
05/06/09 09:05 AM
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Joined: Jan 2003
Posts: 75,094 A Banana Republic near you.
JohnRR
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Quote:
I'll guess I'll find out soon, I'm also running J12's. Don't know if it matters but the 2 1/4 pipes are like drinking a thick shake thru a soda straw. I'd unhook the vacuum advance, bump the jets up 2 and back the timing to 35* at 2400 and see if that helps.
But you have good quench , he doesn't. You might want to find a set of equivalent heat range to JY10's ?
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Re: "Detonation problems" rebuild 440-6
[Re: JohnRR]
#308616
05/06/09 09:10 AM
05/06/09 09:10 AM
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Joined: Jan 2003
Posts: 24,562 Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
Quote:
I'll guess I'll find out soon, I'm also running J12's. Don't know if it matters but the 2 1/4 pipes are like drinking a thick shake thru a soda straw. I'd unhook the vacuum advance, bump the jets up 2 and back the timing to 35* at 2400 and see if that helps.
But you have good quench , he doesn't. You might want to find a set of equivalent heat range to JY10's ?
John I'm dumb on quench.. I've never worried about it much. I've used 906 heads, 915's, 516's, and the rest on 383's and 440's and never had issues. Most were 9:1ish stock bottom end motors, except for the 11:1 383/915/509 cam motor. Whats makes mine a non-quench problem? the 516's? I mean my slugs are only .020 down (or there abouts)
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Re: "Detonation problems" rebuild 440-6
[Re: Mr.Yuck]
#308617
05/06/09 09:14 AM
05/06/09 09:14 AM
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Joined: Jan 2003
Posts: 75,094 A Banana Republic near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,094
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Quote:
Quote:
Quote:
I'll guess I'll find out soon, I'm also running J12's. Don't know if it matters but the 2 1/4 pipes are like drinking a thick shake thru a soda straw. I'd unhook the vacuum advance, bump the jets up 2 and back the timing to 35* at 2400 and see if that helps.
But you have good quench , he doesn't. You might want to find a set of equivalent heat range to JY10's ?
John I'm dumb on quench.. I've never worried about it much. I've used 906 heads, 915's, 516's, and the rest on 383's and 440's and never had issues. Most were 9:1ish stock bottom end motors, except for the 11:1 383/915/509 cam motor. Whats makes mine a non-quench problem? the 516's? I mean my slugs are only .020 down (or there abouts)
Yes the 516's , closed chamber , what head gasket did you use ???
I know of guys with 9.0ish compression that just did poorly thought out builds have detonation issues with lower octane fuel and too much timing . I built a good quench distance 440 for a friend with 10.3 compression and 906's that doesn't have any detonation issues with 93 octane and 38* total timing .
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Re: "Detonation problems" rebuild 440-6
[Re: JohnRR]
#308618
05/06/09 09:23 AM
05/06/09 09:23 AM
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Joined: Jan 2003
Posts: 24,562 Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
|
Quote:
Quote:
Quote:
Quote:
I'll guess I'll find out soon, I'm also running J12's. Don't know if it matters but the 2 1/4 pipes are like drinking a thick shake thru a soda straw. I'd unhook the vacuum advance, bump the jets up 2 and back the timing to 35* at 2400 and see if that helps.
But you have good quench , he doesn't. You might want to find a set of equivalent heat range to JY10's ?
John I'm dumb on quench.. I've never worried about it much. I've used 906 heads, 915's, 516's, and the rest on 383's and 440's and never had issues. Most were 9:1ish stock bottom end motors, except for the 11:1 383/915/509 cam motor. Whats makes mine a non-quench problem? the 516's? I mean my slugs are only .020 down (or there abouts)
Yes the 516's , closed chamber , what head gasket did you use ???
I know of guys with 9.0ish compression that just did poorly thought out builds have detonation issues with lower octane fuel and too much timing . I built a good quench distance 440 for a friend with 10.3 compression and 906's that doesn't have any detonation issues with 93 octane and 38* total timing .
I used the standard Fel-Pros from advice by a local Mopar guy. Said if I used the steel shims the compression might be to high for pump gas.
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Re: "Detonation problems" rebuild 440-6
[Re: Mr.Yuck]
#308619
05/06/09 10:53 AM
05/06/09 10:53 AM
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Joined: Jan 2003
Posts: 75,094 A Banana Republic near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,094
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Quote:
I used the standard Fel-Pros from advice by a local Mopar guy. Said if I used the steel shims the compression might be to high for pump gas.
Well your Quench is not as good as it could be, dare I say not very useful??? , what CC did you end up with on the heads ?
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Re: "Detonation problems" rebuild 440-6
[Re: JohnRR]
#308620
05/06/09 11:07 AM
05/06/09 11:07 AM
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Joined: Jan 2003
Posts: 24,562 Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
Quote:
I used the standard Fel-Pros from advice by a local Mopar guy. Said if I used the steel shims the compression might be to high for pump gas.
Well your Quench is not as good as it could be, dare I say not very useful??? , what CC did you end up with on the heads ?
74cc.
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