Tuning For Detonation

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MOPAROFFICIAL said:
It is. Set the total number and move the distributor till it shows zero on the balancer with the strobe. What springs, the slotted one? I think I'd lose that one and use two light springs for this.
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Yes, it does have a slotted spring. I also have found that according to my light, the timing mark on the cover is incorrect, so that's attributing to some of this too. When I have the timing set to what reads 15 on the marks on the engine, the timing light shows about 21.
 
George Jets said:
You are saying it long cranks when hot trying to get it started.

You probably want to keep it original with that D, D, D, Dodge factory starter. Put a mini starter in there and it will start like it's got fuel injection.

Don't forget the mini starters don't rob juice from the ignition like the slower turning factory starters do. So you get double the juice for the ignition with the mini, quick starts.

☆☆☆
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Find a mini starter that'll work and I'll get it. I have one. It won't even TOUCH the ring gear. It just spins. And yes, the bendix is working. I covered this on another thread floating around here somewhere. The type of starter isn't going to make a difference with this. If you could be here to hear it, you'd understand.
 
RustyRatRod said:
Yes, it does have a slotted spring. I also have found that according to my light, the timing mark on the cover is incorrect, so that's attributing to some of this too. When I have the timing set to what reads 15 on the marks on the engine, the timing light shows about 21.
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Oh ****.
 
MOPAROFFICIAL said:
Oh ****.
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My new thermostat came. I put it in and it's stuck closed. And no, it's not an air bubble. I took it back out and threw it in a pot on the stove and it doesn't even try to open. That figures. lol
 
RustyRatRod said:
Again, a complete myth for a performance engine. Manifold heat needs to be blocked off on peformance engines. That's why there are gasket sets with block offs included in some sets.
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Vintage 1970's Hotrod, right? Blocking the cross over works great on a V8 where the carburetor sets in the middle of a heat pump.

RustyRatRod said:
This is both correct and incorrect. Lemmie splain, Lucy.

As we all know, combustion causes heat. In a high compression, high performance engine, heat is the enemy. The more heat the incoming air/fuel charge has, for example makes it more difficult to combat detonation in a pump gas situation. So, for this build.....and lots of similar ones, blocking manifold heat is not only correct, but very beneficial to the engine.
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Works great on a V8, an inline is another story.

RustyRatRod said:
Now, were we talking about a stock or mild build I would tend to agree with you. Also, there's the argument for people using headers or Dutra Duals. No manifold heat there.....unless they go to the trouble to make a coolant box under the intake and most don't and they see zero side effects, except maybe a longer warm up period.
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Been there, tried that. I used a water heated carburetor plate. They work great and the car didn't slow down. In fact it made no difference, performance wise, amazing on how the street manners improved thou.

RustyRatRod said:
But they do see increased performance due to keeping heat off the intake charge. All of the "fuel atomization" crap you read and hear about putting heat in the manifold is really only beneficial before an engine reaches it's intended operating temperature. Once there, there's no need for it and it actually costs power and mileage, too.
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Nice story, on a V8 you would be correct. On an inline engine, the heated manifold is a necessity to keep the carburetor from icing up. Below 45*, the carburetor freezes up. The amount of frost that can build up on the base plate is truely remarkable.
 
kesteb said:
Vintage 1970's Hotrod, right? Blocking the cross over works great on a V8 where the carburetor sets in the middle of a heat pump.



Works great on a V8, an inline is another story.



Been there, tried that. I used a water heated carburetor plate. They work great and the car didn't slow down. In fact it made no difference, performance wise, amazing on how the street manners improved thou.



Nice story, on a V8 you would be correct. On an inline engine, the heated manifold is a necessity to keep the carburetor from icing up. Below 45*, the carburetor freezes up. The amount of frost that can build up on the base plate is truely remarkable.
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Let me put it another way. I'm not heating the manifold and I don't give a **** what anybody else's opinion is of it.
 
So, no comment on EGR? Lower the cylinder temperature, reduce knock.
upload_2021-4-30_17-43-59.jpeg
 
pishta said:
So, no comment on EGR? Lower the cylinder temperature, reduce knock.
View attachment 1715731175
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LOL I don't know. I think with the relatively low mannyfold vacuum.....that I've not measured yet LOL, I don't think it would work very well, plus, I'll have to fab a mount for it, since the Offy four barrel intake has no provision.....and I ain't gonna work "THAT HARD" to add an EGR. LOL

and.... @yellow rose my new thermostat was stuck closed, so believe it or not I rummaged around and found another one.....although it's a 195 instead of a 160, it's still the same type high flow thermostat, so I stuck it in and it's actually got it running a noticeable amount cooler on the gauge. 160 going in the radiator 87 comin out. Now, tell me how the hell the thermostat opens when it has 160 pukin into the radiator? LOL Heck if I know, but it is. It may be ironed out with the spark knock now, since I backed it off the five degrees....if you read above, the timing marks were incorrect. When is on the 15 mark, it's actually on 21 degrees, so that's why it had too much total. Now I backed it down to the 15 degree mark which is about 20-21 so now it has 30-31 total. We'll come up with "somewhere" to go tomorrow to test it out. LOL
 
EGR introduces an inert gas into the combustion chamber so the combustion process is no as hot, the inert gas sort of sucks the heat out of the charge and reduces cylinder pressure. It actually increased efficiency somehow. It also reduces NOx but the reduction in cylinder pressure and heat is the knock (pre-ignition) reducer. Many people toss it but it really has no effect on performance, just looks a little busy on the sparse hot rod motor.
 
pishta said:
EGR introduces an inert gas into the combustion chamber so the combustion process is no as hot, the inert gas sort of sucks the heat out of the charge and reduces cylinder pressure. It actually increased efficiency somehow. It also reduces NOx but the reduction in cylinder pressure and heat is the knock (pre-ignition) reducer. Many people toss it but it really has no effect on performance, just looks a little busy on the sparse hot rod motor.
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I agree 100%....I've made reference to it here myself many times.
 
RustyRatRod said:
LOL I don't know. I think with the relatively low mannyfold vacuum.....that I've not measured yet LOL, I don't think it would work very well, plus, I'll have to fab a mount for it, since the Offy four barrel intake has no provision.....and I ain't gonna work "THAT HARD" to add an EGR. LOL

and.... @yellow rose my new thermostat was stuck closed, so believe it or not I rummaged around and found another one.....although it's a 195 instead of a 160, it's still the same type high flow thermostat, so I stuck it in and it's actually got it running a noticeable amount cooler on the gauge. 160 going in the radiator 87 comin out. Now, tell me how the hell the thermostat opens when it has 160 pukin into the radiator? LOL Heck if I know, but it is. It may be ironed out with the spark knock now, since I backed it off the five degrees....if you read above, the timing marks were incorrect. When is on the 15 mark, it's actually on 21 degrees, so that's why it had too much total. Now I backed it down to the 15 degree mark which is about 20-21 so now it has 30-31 total. We'll come up with "somewhere" to go tomorrow to test it out. LOL
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Rusty what am I missing. Why are you so bent on have 20* of initial timing.
I have never had to dial in that much timing to tune an engine.
 
512Stroker said:
Rusty what am I missing. Why are you so bent on have 20* of initial timing.
I have never had to dial in that much timing to tune an engine.
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I'm not. Not at all.....It's simply that the engine responds very well there. You know the old saying.....the engine will tell you what it likes. And it does. That's all I was sayin. I may have to leave it back at the 15 mark.....which IS actually 20 initial. It's just by chance I pulled 20 out of the hat, because that's where it seemed happy. It couldda been 12, 25 or whatever.

Well see here's the thing......normally engines with low cranking pressure numbers will want a LOT of initial. I'm beginning to think that's what we have here....that the cam is actually DOING what I hoped......but that the initial tune I had right off the bat just sucked. I'll know a LOT more when I take manifold vacuum measurements and when I get a good compression gauge. I mean **** man, 40 total mechanical on a 7:1 motor would probably ping. lol
 
RustyRatRod said:
Well, here you go. LOL

View attachment 1715731303
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175 is not out of the park crazy.
Especially in a light weight vehicle.
Do you have the dynamic compression? If so, the various on line DC calculators use different values for the intake valve closed point so it is important to know which one was used.
Also, you mentioned that the timing mark on the timing chain cover is off.
Are you sure it is the mark on the cover that is off? It could be that the outer hub on the damper has slipped. You may want to get your piston stop out and find out where TDC really is.
 
my68barracuda said:
175 is not out of the park crazy.
Especially in a light weight vehicle.
Do you have the dynamic compression? If so, the various on line DC calculators use different values for the intake valve closed point so it is important to know which one was used.
Also, you mentioned that the timing mark on the timing chain cover is off.
Are you sure it is the mark on the cover that is off? It could be that the outer hub on the damper has slipped. You may want to get your piston stop out and find out where TDC really is.
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Yup. Dynamic is 7.9.
 
my68barracuda said:
175 is not out of the park crazy.
Especially in a light weight vehicle.
Do you have the dynamic compression? If so, the various on line DC calculators use different values for the intake valve closed point so it is important to know which one was used.
Also, you mentioned that the timing mark on the timing chain cover is off.
Are you sure it is the mark on the cover that is off? It could be that the outer hub on the damper has slipped. You may want to get your piston stop out and find out where TDC really is.
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The balancer looks new. But I do plan to find TDC.
 
my68barracuda said:
Depending upon which on line calculator was used, like the static compression that is on the high side, but not out of the park crazy.
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I used both the Wallace calculator and the United Engine calculator. They were both very close. Like within a tenth. I'm REAL close to having it tuned out now.....it may be. I've not driven it since I got the total down to 31.
 
RRR,
[1] The newer hi flow [ Chinese ] stats can jam. They have a rubber seal/ring inside the main cup that is probably a little stuff. Dribble some ATF over the seal area it & then try it again in boiling water, it should work.
[2] As you found out, DCR & compression tests do not give a reliable indicator of an engine's tolerance to detonation. I alluded to this in my earlier post, which YR scoffed at, showing he doesn't know what he is talking about. There are PLENTY of examples of engines that, according to 'theory' should be detonating, but are not; & plenty of engines that are detonating [ like yours ] that should not be.
[3] I would richen the power cct of your carb, slightly. This should provide cooler combustion & may get you over the hump...
 
MOPAROFFICIAL said:
And there you go. And it doesn't have a nice plug angle as a small block. You're doing real good Rob. No matter what it ends up being..time it accordingly and enjoy
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Yeah.....and this is an early head with the crappiest chamber of all. I bet the revised chamber would not be having this trouble. I have several heads, I might swap it out if I continue to have trouble. I would really rather work this out, because I know it can make power with that cylinder pressure. We'll see where it is tomorrow.
 
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