Detonation questions - 440
#677807
04/22/10 11:27 PM
04/22/10 11:27 PM
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Joined: Jun 2006
Posts: 5,161
CT
GTX MATT
OP
master
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OP
master
Joined: Jun 2006
Posts: 5,161
CT
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Ive been playing with the distributor in my 440 for the last two days. I did get the car to pick up alot below 3500 rpm but heres my problem. The distributor is a stock 1966 440 single point unit.
The advance plate is stamped 8, so it has 16 degrees of total mechanical advance. First off this seems extremely low for a stock dizzy. I know alot of people would like this instead of having to weld up their slots, but I would have to run 22 degrees of initial to get to 38, I think the starter would kick back against that.
It doesnt matter anyway because anything more than 13 degrees of initial pings. Thats only 29 total. It is a stock 68 440 with headers and 2.94 gears and it is the 350 horse engine. Is it possible that cylinder compression could be that high with this cam that I can only run 29 degrees of total timing? This is with Sunoco 93 octane.
Also, I occasionally get a weird sound that sounds like the sound of a hot exhaust pinging after you shut the car off. Its not the marble/rattle sound of detonation, but it is a weird sound and seems to happen more on hills, but the amount of gas you gives it doesnt effect it and its not consistent, it will do it once, then maybe ten seconds later, then stop. Is this anything to worry about?
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 questions - 440
[Re: GTX MATT]
#677808
04/22/10 11:51 PM
04/22/10 11:51 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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(1) Stock oe AVS? (2) is your heat riser sending heat up/across the intake? (3) how hot is the eng running? (1) convert to afb/eddy 2 step rods/jets. Check what size of rods/jets your AVs has then get an eddy strip kit w similar size rods/jets in it and epoxy the domed rod caps to make them flat then slightly richen the "cruise" step of the rods. (2) block the heat riser off at the ex manifold flapper valve and install a blocked valley pan metal gasket (3) how hot. EDIT and use 2 step jets from the kit the same or very close to your current size. MORE EDIT swap those 2.94's for some 3.55's especially if you have 15" tires
Last edited by RapidRobert; 04/23/10 12:41 AM.
live every 24 hour block of time like it's your last day on earth
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Re: Detonation questions - 440
[Re: RapidRobert]
#677810
04/23/10 01:24 AM
04/23/10 01:24 AM
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Joined: Jun 2006
Posts: 5,161
CT
GTX MATT
OP
master
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OP
master
Joined: Jun 2006
Posts: 5,161
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Yes it is the heat riser is operating, it will be blocked soon as im switching to a Summit 224/234 cam (which will ease the issues for sure) and swapping the intake and blocking the heat riser. It runs at 185 on the nose and does not change.
The carb is an OOTB Holley 770, I haven't played with that yet because I figured I'd be wasting my time since that cam will be changed within a month. I've heard these run lean on the secondaries but My plugs are slightly carboned with a golden brown underneath and a little bit of oil around the outside (not on the groundstrap). It could just be that it runs on the primaries and idles so often and that those are setup a little on the rich side. It does burn some oil, about a quart in 1000 miles.
I have 225/70/15s and a 3.55 sure grip is in the waiting to swap in, but im waiting as im converting to 11 in brakes and want to do it at the same time since I have to pull the axles for both. I have to buy the drums still.
Last edited by GTX MATT; 04/23/10 01:27 AM.
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 questions - 440
[Re: GTX MATT]
#677812
04/23/10 08:48 AM
04/23/10 08:48 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:
Yes it is the heat riser is operating, it will be blocked soon as im switching to a Summit 224/234 cam (which will ease the issues for sure) and swapping the intake and blocking the heat riser. It runs at 185 on the nose and does not change.
The carb is an OOTB Holley 770, I haven't played with that yet because I figured I'd be wasting my time since that cam will be changed within a month. I've heard these run lean on the secondaries but My plugs are slightly carboned with a golden brown underneath and a little bit of oil around the outside (not on the groundstrap). It could just be that it runs on the primaries and idles so often and that those are setup a little on the rich side. It does burn some oil, about a quart in 1000 miles.
I have 225/70/15s and a 3.55 sure grip is in the waiting to swap in, but im waiting as im converting to 11 in brakes and want to do it at the same time since I have to pull the axles for both. I have to buy the drums still.
You should be able to run about 38* total at 2500 w/ that set-up. Are you sure your distrib is ok? I'm guessing you have switched over to Electronic? If you back the timing down is it a pig? I usually set the timing at 36-38* total and lock it down. Don't forget to unplug the vac advance. I don't worry about initial. Then I adjust the carb for best vacuum reading, set the idle speed and go for a rhomp. FWIW I had the exact set-up (224/234-465/488 cam) in my otherwise bone stock 67 GTX w/ 3.55's and the thing ran 13.80's (14.20's before cam swap) you'll like it once you get it all sorted out.
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Re: Detonation questions - 440
[Re: Dodgem]
#677814
04/23/10 07:13 PM
04/23/10 07:13 PM
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Joined: Jun 2006
Posts: 5,161
CT
GTX MATT
OP
master
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OP
master
Joined: Jun 2006
Posts: 5,161
CT
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Vacuum is disconnected. I wouldnt call it a pig, but it doesn't run like a 440 should. What play should I look for in the distributor? Up and down or??
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 questions - 440
[Re: v10]
#677816
04/23/10 07:48 PM
04/23/10 07:48 PM
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Joined: Jun 2006
Posts: 5,161
CT
GTX MATT
OP
master
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OP
master
Joined: Jun 2006
Posts: 5,161
CT
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Alright that makes more sense. How much play would be acceptable?
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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