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Discussion Starter #1
I have a 565 with afr 335 heads, ross pistons, 10.5 comp. running 93 octane. the chambers are cnc" to 121cc. when we dyno it we had it at 32 degrees until fuel cruve was good then the dyno operator said lets try 30 degrees and it made about 5 more horse and trq so we left it. I have had a guy from reher Morrison told me he wish I had tried 36 so does anybody know where those heads tend to run best at? right now my combination is player hell on my header coating, after 30 hours of running I am getting them recoated, I run them dry with muffler inserts, last day out I ran them open and they ran a lot cooler so I am going to try shotguns instead.
 

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I wouldn't be so quick to think you fell on the right timing for the heads, as much as you fell on the right timing for the jetting. You may have thought you had the jetting down pat, and when you backed the timing up, you in effect, richened it.
You could have pushed 36 into it and lost, but it could back plus some if you put more jet in it. Timing jetting loops are my primary reasons for putting it on the dyno. Lash loops are kind of secondary and useful, but the timing and AFR COMBINED are the main interest.



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just a ski boat with bark
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For what it's worth my friend has a 10.75:1, 565 with AFR 345s with the cnc chamber option and off his mph at the track 36* was better than 32, 34 & 38 degrees timing on 91. I'm running the AFR 305 with the cnc chambers milled to 114cc on a 10.2:1 489 and 36 was better than 32, 34 & 35 by GPS also. 91 octane pump gas deal.
 

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just a ski boat with bark
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I wouldn't be so quick to think you fell on the right timing for the heads, as much as you fell on the right timing for the jetting. You may have thought you had the jetting down pat, and when you backed the timing up, you in effect, richened it.
You could have pushed 36 into it and lost, but it could back plus some if you put more jet in it. Timing jetting loops are my primary reasons for putting it on the dyno. Lash loops are kind of secondary and useful, but the timing and AFR COMBINED are the main interest.
Got to say times 2 on this post based off my experience. How much cam and what induction does the OP's 565 have?
 

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steelcomp was here
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Do you know what your cranking compression is? I just did a 13.2:1 565 with a set of AFR's and it was happy at 35 but we really didn't play with timing a lot. I can tell you it didn't like 34 but your cranking compression will tell a lot.
 

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just a ski boat with bark
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Do you know what your cranking compression is? I just did a 13.2:1 565 with a set of AFR's and it was happy at 35 but we really didn't play with timing a lot. I can tell you it didn't like 34 but your cranking compression will tell a lot.
What was the cranking compression on this deal you just did?
 

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Discussion Starter #9
cranking comp. is around 190, intake is a reher-morrisn victor and gary Williams 1050 domionator, cam is 748 lift 271 &274 duration on a 108 sep 7-4 swap, made 782hp @6800 [email protected] 5100 and I jumped jets to 96 from 93 and ran chp fuel it made 800 @ 6800 & 717 trq @5000 but from 4500 to 5600 was above 700 trq.
 

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steelcomp was here
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cranking comp. is around 190, intake is a reher-morrisn victor and gary Williams 1050 domionator, cam is 748 lift 271 &274 duration on a 108 sep 7-4 swap, made 782hp @6800 [email protected] 5100 and I jumped jets to 96 from 93 and ran chp fuel it made 800 @ 6800 & 717 trq @5000 but from 4500 to 5600 was above 700 trq.
You should be up in the 36-37* timing range. NO wonder you're burning up your exhaust. That's decent power but you're leaving a lot of tq on the table with your timing @ 30.
 

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Discussion Starter #11
my first time to a dyno and went to a well respected place. but I now regret not getting him to do more playing with it,i will know next time
 

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I'm with GN & Steel. I think you are low on timing and lean. Low timing will spike exhaust gas temps and burn the coating. What you want to do is put fuel in it and burn it. What carbs and jetting do you have?

Some timing and fuel might wake up the engine, especially in the area of response.
 

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Discussion Starter #14
gary Williams 1050 dominator with 93 jets, but I am going with a sniper tunnel ram and 2 gary Williams 800 cfm carbs, going to add a dual o2 system and Williams is plumbing a fogger system for me. I do think everybody here for help, first time at a dyno I have a lot to learn but I had a feeling my timing was to low due to my header coating
 

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My combo is similar...

565 chevy
merlin aluminum heads, 355cc runner, 110 chambers
Diamond pistons 10.4:1
Edelbrock victor ram
2 1050's
mike miller solid roller

I run this on 92 oct pump gas and it runs the best at 37 degrees of timing, 6500 rpm on a detailed B/C from B1 racing
 

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cranking comp. is around 190, intake is a reher-morrisn victor and gary Williams 1050 domionator, cam is 748 lift 271 &274 duration on a 108 sep 7-4 swap, made 782hp @6800 [email protected] 5100 and I jumped jets to 96 from 93 and ran chp fuel it made 800 @ 6800 & 717 trq @5000 but from 4500 to 5600 was above 700 trq.
I hope that camshaft is geting a change as well with your new nitrous set up!!
 

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noob
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Surprised you do not have an EGT gauge? Isnt that kind of important. And cheap insurance?

If you are adding timing, and the EGT is dropping off like mad, you are moving in the right direction. Why guess ??
 

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With a 121 CC chamber,You should be able to run up to 40 degrees with the right fuel and spark plug heat range.:))THumbsUp
 

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Degree your damper using a possitive piston stop. If you backed up the timing like you did and it made more power at 30 from 32 its probably off 6 degrees or so. 35-36 is the NA number with the AFR's.
 

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steelcomp was here
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My combo is similar...

565 chevy
merlin aluminum heads, 355cc runner, 110 chambers
Diamond pistons 10.4:1
Edelbrock victor ram
2 1050's
mike miller solid roller

I run this on 92 oct pump gas and it runs the best at 37 degrees of timing, 6500 rpm on a detailed B/C from B1 racing
That puts your HP right about 750 to the impeller (figuring straight B to B+ on the impeller chart). I'd say with that combination you're about 100hp short of where you should/could be.
 
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