Moparts Main Index | READ - Info & Help Page | Moparts Sponsors | Tech Archive

Forums Calendar Active Threads Search Forum Help
Previous Thread
Next Thread
Print Thread
Page 1 of 4 1 2 3 4
"Detonation problems" rebuild 440-6 #308601
05/05/09 02:17 PM 05/05/09 02:17 PM
Joined: Jun 2006
Posts: 108
Sweden
6
6pakdude Offline OP
member
6pakdude  Offline OP
member
6

Joined: Jun 2006
Posts: 108
Sweden
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.
Re: "Detonation problems" rebuild 440-6 [Re: 6pakdude] #308602
05/05/09 02:35 PM 05/05/09 02:35 PM
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck Offline
Not enough dumb comments...yet
Mr.Yuck  Offline
Not enough dumb comments...yet

Joined: Jan 2003
Posts: 24,562
Brookeville, Md
sure your distrib isn't advancing? is it locked down or welded? Is your vacuum advance hooked up? Is this under load only?
Re: "Detonation problems" rebuild 440-6 [Re: 6pakdude] #308603
05/05/09 02:49 PM 05/05/09 02:49 PM
Joined: Jan 2003
Posts: 14,470
renton, Washington
ph23vo Offline
I Live Here
ph23vo  Offline
I Live Here

Joined: Jan 2003
Posts: 14,470
renton, Washington
first see what it takes to make it stop OCTANE wise.. maybe its NOT detonation... ck real engine temp [mech gauge] suspect ign is over advancing ... good luck dan
Re: "Detonation problems" rebuild 440-6 [Re: ph23vo] #308604
05/05/09 02:57 PM 05/05/09 02:57 PM
Joined: Jun 2008
Posts: 3,916
usa
L
lewtot184 Offline
master
lewtot184  Offline
master
L

Joined: Jun 2008
Posts: 3,916
usa
my , too much compression, short cam, no quench; sorry, it'll never work.
Re: "Detonation problems" rebuild 440-6 [Re: lewtot184] #308605
05/05/09 03:00 PM 05/05/09 03:00 PM
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck Offline
Not enough dumb comments...yet
Mr.Yuck  Offline
Not enough dumb comments...yet

Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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.

[IMG]http://i66.tinypic.com/pui5j.jpg[/IMG]
Coming soon!!!!
Re: "Detonation problems" rebuild 440-6 [Re: lewtot184] #308606
05/05/09 03:00 PM 05/05/09 03:00 PM
Joined: Jun 2006
Posts: 5,161
CT
GTX MATT Offline
master
GTX MATT  Offline
master

Joined: Jun 2006
Posts: 5,161
CT
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
Re: "Detonation problems" rebuild 440-6 [Re: 6pakdude] #308607
05/05/09 03:03 PM 05/05/09 03:03 PM
Joined: Apr 2003
Posts: 3,968
North Riverside IL & Lowell IN
GTXKen Offline
super gas
GTXKen  Offline
super gas

Joined: Apr 2003
Posts: 3,968
North Riverside IL & Lowell IN
how big is the exhaust? What kind of mufflers are you running?

I had this issue with my new motor last spring. It fell flat at high RPM and had detonation issues. It turned out my mufflers were too restrictive. When I looked at my mufflers the ends were balloning out like they were going to explode.
Re: "Detonation problems" rebuild 440-6 [Re: Mr.Yuck] #308608
05/05/09 03:18 PM 05/05/09 03:18 PM
Joined: Jun 2008
Posts: 3,916
usa
L
lewtot184 Offline
master
lewtot184  Offline
master
L

Joined: Jun 2008
Posts: 3,916
usa
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.
Re: "Detonation problems" rebuild 440-6 [Re: GTXKen] #308609
05/05/09 03:25 PM 05/05/09 03:25 PM
Joined: Jun 2006
Posts: 108
Sweden
6
6pakdude Offline OP
member
6pakdude  Offline OP
member
6

Joined: Jun 2006
Posts: 108
Sweden
Have run engine with or without vacum hooked up.

Distributor advance is 20 degrees.checked.

Repro mufflers and resonators. 2,5" front pipes and rest 2 1/4".

Last summer drove the car with around 9:0 comp ratio, with a comp 268xe.
No problem with detonation or pinging, same distributor 18 intial 38 total.
stock metering plates front and back.same exhaust.
5600RPM.

I still think the plugs should have more color on them.

Peter
Re: "Detonation problems" rebuild 440-6 [Re: 6pakdude] #308610
05/05/09 03:29 PM 05/05/09 03:29 PM
Joined: Jan 2003
Posts: 74,990
U.S.S.A.
JohnRR Offline
I Win
JohnRR  Offline
I Win

Joined: Jan 2003
Posts: 74,990
U.S.S.A.
Two things I see wrong

First the felpro 8519 is not .029 thick , it's .039 , but the compression is still 10.0ish in a 440 with a zero deck piston .

Next is shimming the rocker shafts for preload , did you have ave incorrect rocker tip to valve tip geometry ? If you did then that's fine , if you didn't then you should check it as it sounds like you used the shims to make up for milling the heads which is the WRONG use for rocker shaft shims ...
Re: "Detonation problems" rebuild 440-6 [Re: JohnRR] #308611
05/05/09 03:38 PM 05/05/09 03:38 PM
Joined: Jun 2006
Posts: 108
Sweden
6
6pakdude Offline OP
member
6pakdude  Offline OP
member
6

Joined: Jun 2006
Posts: 108
Sweden
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
Re: "Detonation problems" rebuild 440-6 [Re: 6pakdude] #308612
05/05/09 03:41 PM 05/05/09 03:41 PM
Joined: Jan 2003
Posts: 74,990
U.S.S.A.
JohnRR Offline
I Win
JohnRR  Offline
I Win

Joined: Jan 2003
Posts: 74,990
U.S.S.A.
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 ?
Re: "Detonation problems" rebuild 440-6 [Re: JohnRR] #308613
05/05/09 04:02 PM 05/05/09 04:02 PM
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck Offline
Not enough dumb comments...yet
Mr.Yuck  Offline
Not enough dumb comments...yet

Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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.
Re: "Detonation problems" rebuild 440-6 [Re: 6pakdude] #308614
05/05/09 07:44 PM 05/05/09 07:44 PM
Joined: Feb 2005
Posts: 4,313
Prospect, PA
BSB67 Offline
master
BSB67  Offline
master

Joined: Feb 2005
Posts: 4,313
Prospect, PA
Gasoline octane here in the states is determined using the (R+M)/2 method. Not sure how that relates to your fuel octane rating of 98.

Like Lew said, I dont think that our premium fuel (93 octane) would be able to support that small cam at that comression ratio. What is your cranking cylinder pressure, in psi if you would.

A couple of things to look at or try.

First, Usually detonation is observed at lower rpm and higher load and may continue through the upper rpm range. If you only have detonation above 4800 rpm, that can be from a lean condition due to low fuel pressure.

Try spark plugs at least two steps cooler and a 160 degree themostat. Make sure cooling system is good overall.

64s center and 0.089 inch dia. plate restrictions in the outboards will put you close if everything else is unmodified, like the MAB

I think that 6200 rpm is optimistic for that cam
Re: "Detonation problems" rebuild 440-6 [Re: Mr.Yuck] #308615
05/06/09 09:05 AM 05/06/09 09:05 AM
Joined: Jan 2003
Posts: 74,990
U.S.S.A.
JohnRR Offline
I Win
JohnRR  Offline
I Win

Joined: Jan 2003
Posts: 74,990
U.S.S.A.
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 ?
Re: "Detonation problems" rebuild 440-6 [Re: JohnRR] #308616
05/06/09 09:10 AM 05/06/09 09:10 AM
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck Offline
Not enough dumb comments...yet
Mr.Yuck  Offline
Not enough dumb comments...yet

Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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)
Re: "Detonation problems" rebuild 440-6 [Re: Mr.Yuck] #308617
05/06/09 09:14 AM 05/06/09 09:14 AM
Joined: Jan 2003
Posts: 74,990
U.S.S.A.
JohnRR Offline
I Win
JohnRR  Offline
I Win

Joined: Jan 2003
Posts: 74,990
U.S.S.A.
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 .
Re: "Detonation problems" rebuild 440-6 [Re: JohnRR] #308618
05/06/09 09:23 AM 05/06/09 09:23 AM
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck Offline
Not enough dumb comments...yet
Mr.Yuck  Offline
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.
Re: "Detonation problems" rebuild 440-6 [Re: Mr.Yuck] #308619
05/06/09 10:53 AM 05/06/09 10:53 AM
Joined: Jan 2003
Posts: 74,990
U.S.S.A.
JohnRR Offline
I Win
JohnRR  Offline
I Win

Joined: Jan 2003
Posts: 74,990
U.S.S.A.
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 ?
Re: "Detonation problems" rebuild 440-6 [Re: JohnRR] #308620
05/06/09 11:07 AM 05/06/09 11:07 AM
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck Offline
Not enough dumb comments...yet
Mr.Yuck  Offline
Not enough dumb comments...yet

Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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.
Page 1 of 4 1 2 3 4

Moderated by  Al_Alguire, Hotwheelsjr, moparts, not_a_charger, RangerDan440, tboomer 
Privacy Policy · Forum Rules · Mark All Read Contact Us · Moparts




Moparts Main Index | READ - Info & Help Page | Moparts Sponsors | Tech Archive


Powered by UBB.threads™ PHP Forum Software 7.7.1