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440 issue after swapping to aluminum heads, need advice
- Thread starter Cheapsunglasses
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Tuning 101. Timing and ignition need to be correct first. Just remember that. This is common sense. Intake may not be ideal but its not your main problem. Get a dial back light and check the timing. Or cap the vacuum advance off and drive it. If it still detonates retard it 2 degrees and retest. Keep doing that until it does not detonate. My bets you are way over advancing and that could be whats going on. With improper combustion your AFR will be all over the place. Another simple item could be a weak coil breaking down.
MCODECUDA
Well-Known Member
Actually the 440 Source heads have smaller combustion chambers than the Edelbrocks.
Splangj
Well-Known Member
That manifold is a turd, low and slow. Your aluminum heads should act like a point or more less compression,helping stop detonation. The street dominator is fine, I run one and I like it. When I install heads there’s always some wiggle. Set the manifolid on the heads and set them to were the intake doesn’t wobble. It sounds like an intake leak. I’ve always run just the embossed valley pan, no extra gaskets. Of course, I’ve never used a timing light. I get the engine to start while barely fighting the starter, then adjust full advance by seat of the pants. My last 408 Dart wouldn’t ping with too much advance, just lost hp.
I’ve used Mallory for decades. Only problem EVER was when the more expensive Napa vr over volted the whole car, burning out the unilite module.
It does sound like an intake leak to me…..
I’ve used Mallory for decades. Only problem EVER was when the more expensive Napa vr over volted the whole car, burning out the unilite module.
It does sound like an intake leak to me…..
Well it’s cooled down just enough for me to work on it. I have my 67 440 afb on it still, I plugged the vacuum advance, and didn’t touch anything else, and all my issues went away, solid AFR through the rpm, and no cutting out. So does this mean bad distributor?
Could be ? You should use my "MEF" procedure. Mechanical, Electrical, Fuel. No use diagnosing one system, if the system before it, isn't good. In your case, I see ensuring the electrical ( ignition) is performing satisfactorily.
Most likely the advance is to aggressive. You need to find out the curve. You could have bad springs, broken springs. Then again the timing light will tell the story. was your vacuum supply ported or direct? For sure you are over advanced like I said from the get go.
Yes, I tend to over think things, and then the frustration clouds come in, then I found it’s the simple thing, and then I go well poo should’ve done that first.
Yes, I was paying attention to your response, thank you. I was trying to address other people going after the intake, and other questions. Thank you very much! Do you happen to know how to tune a Mallory unilite?
It's a common thing. Everyone jumps to conclusions, ignoring the basics. I'd learned it through experience and education... and most importantly, mistakes.
You need to know where your're AT, before where you want to go. Again, know what your initial timing is, the rate of advance, the total timing at what rpm. Then... you can determine if there's a fault, and/or you can adjust accordingly.
I would suggest getting the model number and see if you can get a online manual. If its real old parts might be obsolete or hard to find. Mancini Racing has a decently priced ready to run that is just like a MSD.
. This is real deal old Mallory, I don’t know the year, one of my cheap swap meet finds. That’s what I like about Carter carburetors and Mallory ignition, you can score them cheap at a swap meet.
I just want to thank everyone again for taking time out of their day to offer help and suggestions!
I kept checking my timing with the timing light, I didn’t even think about plugging the vacuum advance, it’s always the little things like that.
And to everyone that doesn’t like my offy intake, well I’ve read a lot of good things about the Holley street dominator, so if I get a little extra money and find one cheap I’ll change it. For now it’ll make the right noises and keep my neighbors unhappy
.
Thanks again everyone!
I kept checking my timing with the timing light, I didn’t even think about plugging the vacuum advance, it’s always the little things like that
.And to everyone that doesn’t like my offy intake, well I’ve read a lot of good things about the Holley street dominator, so if I get a little extra money and find one cheap I’ll change it. For now it’ll make the right noises and keep my neighbors unhappy
.Thanks again everyone!
lick it, stick it, and send it on it's way
Geoff 2
Well-Known Member
While there are a lot of Offenhauser intakes performing veeeeeeeeeeery productive work as boat anchors, that intake will work. Just not as good as some others. All the carbs you mentioned, big & small will work.
What you need to do is stop using the A/F gauge & tune initially by sound & feel. Those carbs respond like any other carb to jetting changes, bigger jets richer, smaller jets leaner. Etc...
Some of your info doesn't make sense. The 4966 AVS has tall pri jets & different rods to the jets in the Edel tuning kit you are using?? Can you give more info?
What you need to do is stop using the A/F gauge & tune initially by sound & feel. Those carbs respond like any other carb to jetting changes, bigger jets richer, smaller jets leaner. Etc...
Some of your info doesn't make sense. The 4966 AVS has tall pri jets & different rods to the jets in the Edel tuning kit you are using?? Can you give more info?
If you're running the commonly available 10% Ethanol, your target numbers will not be the 14.7 to 1 number. Since Ethanol requires more fuel to achieve the same energy as pure gasoline, you need to revise the expectations. The target number is lower numerically, something in the mid 13s.
Nobody makes a tuning a kit for the avs. So after looking on this forum and a couple others, you take the 3 step rods and jets out, and put 2 step edelbrock on, replace the cupped caps with flat caps, and you can use the edelbrock tuning chart. I was going by ear, and the exhaust note was very wrong, which prompted me to put the gauge on, and sure enough I was right. I don’t just go by gauges, and timing lights, I use sight, hearing, and smell too
What happens at a lot of swap meets is old modified raced parts are sold. Racers do not need a vacuum advance. So many put an aggressive timing curve into them. A lot of them are done with home brewed ideas. The way you were set up for all you know you could of had 50+ degrees of total advance. A decent dial back timing light is a tool you should use. Never forget basic 101. Timing first when tuning. Once you train yourself to be step by step systematic you will diagnose and solve your problem. I am glad you tried my suggestion. To many just ignore whats in your face and keep asking for help. Intakes, carburetors, fuel pumps, ignition boxes would of never helped your issues.
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