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Oh what the head gasket!
- Thread starter Chevy305
- Start date
Right now? Play farmer and student. I like to know things.
Not enough to worry about.
I doubt it. You start seeing major differences when you change it a full point, but that is relational to the camshaft too.
How much timing are you running? The fast burn chambers are *normally* happy around 36* (again with the theory, but at least that mag article mentioned 37* was the sweet spot). Forcing more timing on it may require higher octane, but may not be helping power.
As Folkenheath said, ideally, you'd want 0* of timing, which is theoretical, not practical. But the improved combustion chambers take timing the right way, which is one reason they are so superior to older heads.
How much timing are you running? The fast burn chambers are *normally* happy around 36* (again with the theory, but at least that mag article mentioned 37* was the sweet spot). Forcing more timing on it may require higher octane, but may not be helping power.
As Folkenheath said, ideally, you'd want 0* of timing, which is theoretical, not practical. But the improved combustion chambers take timing the right way, which is one reason they are so superior to older heads.
I'm running 38* total
y5mgisi
1 ton status
Good thread!
Well I bit the bullet and ordered the Dart Pro1 heads, man my wallet feels light 
http://www.jegs.com/i/Dart/301/11121112P/10002/-1
http://www.jegs.com/i/Dart/301/11121112P/10002/-1
79rustyk10
3/4 ton status
Sweet looking set of heads. I'm looking forward to see if you notice a difference with them.
Did they specify that those springs would work with your cam? I didnt look at the Jegs page very closely.
And $950 for just that on the heads is insane. I was quoted by probably one of the best machine shops in the area here, $1200 for ALL the machine work, with a rebuild kit for my 302.
Did they specify that those springs would work with your cam? I didnt look at the Jegs page very closely.
And $950 for just that on the heads is insane. I was quoted by probably one of the best machine shops in the area here, $1200 for ALL the machine work, with a rebuild kit for my 302.
Well I bit the bullet and ordered the Dart Pro1 heads, man my wallet feels light
http://www.jegs.com/i/Dart/301/11121112P/10002/-1
Well hopefully you seem em sooner than my buddy has... And hey i want those patriots maybe
Pm me 
It says I don't have "permission".
That was in a dyno, it's easy to run good in a dyno where the engine is sitting there in a controlled environment, in real world driving conditions with all the variables you are much more likely to see detonation. They have proven that in the engine masters challenge.
I think it gets tested in the real world every day by people like us.
I keep saying this to people, but it seems like nobody understands what I'm getting at.
Premium is way cheaper than regular + octane boost, too. My DD takes premium and I've learned that driving through Indiana and Illinois there are a lot of stations that don't sell it. So it's good to keep an UNOPENED bottle in the trunk (you don't want that stuff leaking on stuff). Sure, I could be mindful to keep my foot out of it for the next 400 miles, but where's the fun?
Anyway, back on topic...
Yeah, I'm with you. It really sucks gas is so expensive, but people act like they need to drive across town to save 3 cents a gallon. Well, guess what, you're worse off doing that now than you were before, because it costs a lot more to get there and you are still only saving 3 cents a gallon. 3 cents a gallon is the same 30 cents for 10 gallons, whether its $1 a gallon or $4 a gallon. So chances are much greater now that you spend more than you save driving somewhere for cheaper gas.
There is a rule of thumb that you gain 10% per point of compression, however, this may be closer to true if everthing changes with it (cam, intake, heads, etc). I have a chart in a book I have from David Vizard, and it shows what he measured as far as performance gains from compression only changes, and I think it was 3% for a point change from 9:1 - 10:1. So from 9.4:1 down to 9:1 you will probably only lose 1 - 1.5%, so maybe 5 hp? you won't feel it. The heads should gain you more power than that, and if you ever stroke then have the heads ported. Dart will CNC port their own castings later if you want, but it probably isn't cheap.
Sweet! I thought that was the case which is why it was more surprising you had a flow bench.
Thats what my 388 likes as well, a lot of SBCs like 38 as long as there is no detonation, it's just not very conservative so I usually don't recommend it to people.
Well I bit the bullet and ordered the Dart Pro1 heads, man my wallet feels light
http://www.jegs.com/i/Dart/301/11121112P/10002/-1
Damn! I thought you'd opt for something less expensive, nice choice! I see it says the ship date is Oct 5, did you get their last pair or are yours backordered?
So those are the straight plug version, will that give you better plug/header clearance? They are the same head they just offer them in straight or angled just for header clearance. I see you got the right 1.437 dual valve springs for hyd roller cams.
So have you talked to the machine shop again yet? Are they going to try and rip you off because they took them apart and quoted the parts to fix them?
Well hopefully you seem em sooner than my buddy has... And hey i want those patriots maybe
Got an email with tracking numbers already
Sending a PM
It says I don't have "permission".
Oops, doesn't matter anymore anyways. It was just a spread sheet comparing all the flow numbers and ratios of intake flow vs exhaust flow. The Patriots flow quite well and have a good ratio throughout the range of lift of the valves so it was hard to see exactly how other heads compare.
That was in a dyno, it's easy to run good in a dyno where the engine is sitting there in a controlled environment, in real world driving conditions with all the variables you are much more likely to see detonation. They have proven that in the engine masters challenge.
I think it gets tested in the real world every day by people like us.
Yeah, I'm with you. It really sucks gas is so expensive, but people act like they need to drive across town to save 3 cents a gallon. Well, guess what, you're worse off doing that now than you were before, because it costs a lot more to get there and you are still only saving 3 cents a gallon. 3 cents a gallon is the same 30 cents for 10 gallons, whether its $1 a gallon or $4 a gallon. So chances are much greater now that you spend more than you save driving somewhere for cheaper gas.
My parents do that and I keep telling them its retarded to burn a $3.92 gallon of gas to save 50 cents across town
There is a rule of thumb that you gain 10% per point of compression, however, this may be closer to true if everthing changes with it (cam, intake, heads, etc). I have a chart in a book I have from David Vizard, and it shows what he measured as far as performance gains from compression only changes, and I think it was 3% for a point change from 9:1 - 10:1. So from 9.4:1 down to 9:1 you will probably only lose 1 - 1.5%, so maybe 5 hp? you won't feel it. The heads should gain you more power than that, and if you ever stroke then have the heads ported. Dart will CNC port their own castings later if you want, but it probably isn't cheap.
Thats good to hear! Maybe I can drop my octane now?
Sweet! I thought that was the case which is why it was more surprising you had a flow bench.
Thats what my 388 likes as well, a lot of SBCs like 38 as long as there is no detonation, it's just not very conservative so I usually don't recommend it to people.
I might have been getting detonation under certain circumstances but its hard to tell with my loud ass exhaust.
Damn! I thought you'd opt for something less expensive, nice choice! I see it says the ship date is Oct 5, did you get their last pair or are yours backordered?
Got the last pair
So those are the straight plug version, will that give you better plug/header clearance? They are the same head they just offer them in straight or angled just for header clearance. I see you got the right 1.437 dual valve springs for hyd roller cams.
So have you talked to the machine shop again yet? Are they going to try and rip you off because they took them apart and quoted the parts to fix them?
I went with the angle plug Patriots originally because the straight plug version was back ordered
. Now its the opposite where the angle plug Darts are back ordered and they had the straight plug version in stock. 
Honestly the Headman Elites I have work well either way and have enough clearance. When I had factory heads with the straight plugs it was a little easier to access all the plugs with a socket. I called the shop and let them know I'm going a different direction, but they have already cleaned the heads and repaired the cross threaded plug hole so I have to give them $100 for that and the parts research they put into it. I figure its fair enough.
Wow. Winder if its summits fault then for my buddies heads. Which is odd because normally we have never had an issue
Honestly I had to compare apples to apples and by that I mean roller cam capable heads. So with that in mind the only cheaper option was the RHS heads by only $100. And for $100 I'd rather have the superior alloy and better known quality brand. I went with a relatively unknown brand first time around and now I'm paying for it.
Well let us know how you like them. Make sure you clean and scrape the deck spotless. And I like to clean both the head and deck surfaces with lacquer thinner right before assembly. If there is any oil residue or old gasket material left then the new gasket won't have the proper surface to adhere too. The thinner leaves a clean dry surface.
I'll be sure to do that. I was going to use acetone.
And I wouldn't plan on using the 87 octane, you are decreasing your compression with less quench, which isn't the best way to do it, proper quench can reduce detonation. You may be fine with 87 octane, or maybe not, you won't know until you try it.
I just find this picture in your old thread...you see the dot in the front of the piston? Lay your straight edge across the center of all the cylinders and measure the piston depth in the hole at TDC inline with the dot(on the edge of the piston between the valve reliefs), and on the same place at the back of the piston to average it. Make sure you are at TDC within 2 degrees or less. Also, do you know the cc of your piston dish? It looks pretty mild, 8 cc?
I ran some numbers and I get over a half point difference in compression between a .036 in the hole and a .005 in the hole, I just guessed on the piston dish though.
I just find this picture in your old thread...you see the dot in the front of the piston? Lay your straight edge across the center of all the cylinders and measure the piston depth in the hole at TDC inline with the dot(on the edge of the piston between the valve reliefs), and on the same place at the back of the piston to average it. Make sure you are at TDC within 2 degrees or less. Also, do you know the cc of your piston dish? It looks pretty mild, 8 cc?
I ran some numbers and I get over a half point difference in compression between a .036 in the hole and a .005 in the hole, I just guessed on the piston dish though.
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That's a .030 over 355 right?
And I wouldn't plan on using the 87 octane, you are decreasing your compression with less quench, which isn't the best way to do it, proper quench can reduce detonation. You may be fine with 87 octane, or maybe not, you won't know until you try it.
I just find this picture in your old thread...you see the dot in the front of the piston? Lay your straight edge across the center of all the cylinders and measure the piston depth in the hole at TDC inline with the dot(on the edge of the piston between the valve reliefs), and on the same place at the back of the piston to average it. Make sure you are at TDC within 2 degrees or less. Also, do you know the cc of your piston dish? It looks pretty mild, 8 cc?
I ran some numbers and I get over a half point difference in compression between a .036 in the hole and a .005 in the hole, I just guessed on the piston dish though.
Ya its a .030 over 350, so 355.
The pistons are a 10cc dish.
I'll go re-measure the quench now.
The shop had dissassembled the heads and look at the wear on the seal retainers:
Look at that they didn't even hold the springs so at high rpm the springs could bounce around and thus pull the seals out of the heads. Talk about a factory defect. They were probably broken before I did a cam swap!
The guy at the shop was pretty disapointed that I took the heads back. I know he would have done a great job and would have been reliable but I can't justify putting that much into heads these heads. Besides they're going to a good home....
Under Adam's hood
Hypereutectic
