Tune down my 355. Combo question
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,010
Likes: 1
From: Sweden/Stockholm
Tune down my 355. Combo question
Sorry to bother you with another of those ”combo” questions.
Story is that Im going to tune “down” my 355 and make a nice daily driver with good idle, that can pass sniffer test without any drama.
I have a combo in mind that I need some feedback on.
This is what I got to build on:
1991 vette 6spd
355 forge bottom end
Converted LT1 intake
Hooker headers to hooker front y-pipe to metallic “race” cat to rear magnaflow exhaust.
Plan so far is:
Cam.
CC XFI™ Xtreme Fuel Injection 260XFI HR13
210/218 .560 .555 ( 1:6 ) lobe 113
Or:
ZZ9 cam
212/226 .483 .520 ( 1:5 ) lobe 112
My exhaust is a narrow point, so perhaps the ZZ9 cam will work better?
Also tuneability is a factor here.
Heads.
Im looking at dart pro 1 alu heads:
180cc intake port, 64cc chambers.
With my pistons I will get 9.8:1 comp.
And the 180cc intake will be a descent match for the lt1 intake I think.
I hope this will make a mild, easy to tune, drama free daily driver.
Am I way off?
Cheers
Story is that Im going to tune “down” my 355 and make a nice daily driver with good idle, that can pass sniffer test without any drama.
I have a combo in mind that I need some feedback on.
This is what I got to build on:
1991 vette 6spd
355 forge bottom end
Converted LT1 intake
Hooker headers to hooker front y-pipe to metallic “race” cat to rear magnaflow exhaust.
Plan so far is:
Cam.
CC XFI™ Xtreme Fuel Injection 260XFI HR13
210/218 .560 .555 ( 1:6 ) lobe 113
Or:
ZZ9 cam
212/226 .483 .520 ( 1:5 ) lobe 112
My exhaust is a narrow point, so perhaps the ZZ9 cam will work better?
Also tuneability is a factor here.
Heads.
Im looking at dart pro 1 alu heads:
180cc intake port, 64cc chambers.
With my pistons I will get 9.8:1 comp.
And the 180cc intake will be a descent match for the lt1 intake I think.
I hope this will make a mild, easy to tune, drama free daily driver.
Am I way off?
Cheers
Safety Car
Joined: Apr 2005
Posts: 3,624
Likes: 431
From: Dale City VA
If I had to run one or the other, I'd say the ZZ9 with 1.65/1.5 rockers....
I think the Howards PN 181145-12 would outrun either and be just as easy to tune.
http://www.summitracing.com/parts/hrs-181145-12
IMO, You need more compression... like 10.25 - 10.50 SCR.
The 180 Pro 1's will run fine on it.
Will
I think the Howards PN 181145-12 would outrun either and be just as easy to tune.
http://www.summitracing.com/parts/hrs-181145-12
IMO, You need more compression... like 10.25 - 10.50 SCR.
The 180 Pro 1's will run fine on it.
Will
Sorry to bother you with another of those ”combo” questions.
Story is that Im going to tune “down” my 355 and make a nice daily driver with good idle, that can pass sniffer test without any drama.
I have a combo in mind that I need some feedback on.
This is what I got to build on:
1991 vette 6spd
355 forge bottom end
Converted LT1 intake
Hooker headers to hooker front y-pipe to metallic “race” cat to rear magnaflow exhaust.
Plan so far is:
Cam.
CC XFI™ Xtreme Fuel Injection 260XFI HR13
210/218 .560 .555 ( 1:6 ) lobe 113
Or:
ZZ9 cam
212/226 .483 .520 ( 1:5 ) lobe 112
My exhaust is a narrow point, so perhaps the ZZ9 cam will work better?
Also tuneability is a factor here.
Heads.
Im looking at dart pro 1 alu heads:
180cc intake port, 64cc chambers.
With my pistons I will get 9.8:1 comp.
And the 180cc intake will be a descent match for the lt1 intake I think.
I hope this will make a mild, easy to tune, drama free daily driver.
Am I way off?
Cheers
Story is that Im going to tune “down” my 355 and make a nice daily driver with good idle, that can pass sniffer test without any drama.
I have a combo in mind that I need some feedback on.
This is what I got to build on:
1991 vette 6spd
355 forge bottom end
Converted LT1 intake
Hooker headers to hooker front y-pipe to metallic “race” cat to rear magnaflow exhaust.
Plan so far is:
Cam.
CC XFI™ Xtreme Fuel Injection 260XFI HR13
210/218 .560 .555 ( 1:6 ) lobe 113
Or:
ZZ9 cam
212/226 .483 .520 ( 1:5 ) lobe 112
My exhaust is a narrow point, so perhaps the ZZ9 cam will work better?
Also tuneability is a factor here.
Heads.
Im looking at dart pro 1 alu heads:
180cc intake port, 64cc chambers.
With my pistons I will get 9.8:1 comp.
And the 180cc intake will be a descent match for the lt1 intake I think.
I hope this will make a mild, easy to tune, drama free daily driver.
Am I way off?
Cheers
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,010
Likes: 1
From: Sweden/Stockholm
http://www.jegs.com/i/Sealed-Power/8...oductId=755727
Edelbrock makes some 60cc heads:
http://www.jegs.com/i/Edelbrock/350/...ductId=2385061
But the runner size is 165, and lt1intake is 170, so I will have to port them.
Is worth the hassle to get the comp up slightly?
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,010
Likes: 1
From: Sweden/Stockholm
Or you got summits 62cc 170 heads
http://www.summitracing.com/parts/su...make/chevrolet
But I need to upgrade the springs on those heads with zz9 cam..
http://www.summitracing.com/parts/su...make/chevrolet
But I need to upgrade the springs on those heads with zz9 cam..
Melting Slicks
Joined: Sep 2010
Posts: 2,422
Likes: 202
I use speedpro forge pistons.
http://www.jegs.com/i/Sealed-Power/8...oductId=755727
Edelbrock makes some 60cc heads:
http://www.jegs.com/i/Edelbrock/350/...ductId=2385061
But the runner size is 165, and lt1intake is 170, so I will have to port them.
Is worth the hassle to get the comp up slightly?
http://www.jegs.com/i/Sealed-Power/8...oductId=755727
Edelbrock makes some 60cc heads:
http://www.jegs.com/i/Edelbrock/350/...ductId=2385061
But the runner size is 165, and lt1intake is 170, so I will have to port them.
Is worth the hassle to get the comp up slightly?
This will change your compression... a few points. Did you install a factory head gasket. A few point deviation. Can be gained or decreased.. here.
Without propper compression.. you will not take full advantage of a performance cam. That cam appears to be in the 10.0 & up bracket.
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Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,010
Likes: 1
From: Sweden/Stockholm
Ok forged is a excellent.. choice.. but are they true flat. 2 or 4 valve relief?
This will change your compression... a few points. Did you install a factory head gasket. A few point deviation. Can be gained or decreased.. here.
Without propper compression.. you will not take full advantage of a performance cam. That cam appears to be in the 10.0 & up bracket.
This will change your compression... a few points. Did you install a factory head gasket. A few point deviation. Can be gained or decreased.. here.
Without propper compression.. you will not take full advantage of a performance cam. That cam appears to be in the 10.0 & up bracket.
I havent decided on headgasget yet as im still choosing what route to go.
Thanks
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,010
Likes: 1
From: Sweden/Stockholm
So what else needs to be done after you have milled the heads?
WHat comes in my mind is, custom length pushrods, shim the dis, .
Will the intake fit without moding it?
Anything else that needs to be addressed?
I dont whant to go crazy on this build, can you make a descent compromise with thinner headgasget?
Thanks
Last edited by devilfish; Feb 19, 2013 at 04:21 AM.
Safety Car
Joined: Apr 2005
Posts: 3,624
Likes: 431
From: Dale City VA
No problems with the dizzy or intake only taking .028 off the heads.
Pushrod lengths need to be determined by a rocker geometry plot.... There is no way to know if your right or not unless you measure.
Has your block been decked? Any idea how far down in the hole the piston is?
You will be able to make some compression up using the VR .026 or Fel Pro 1094 .015 head gasket.
Just a quick look at compression.... FYI all my calculations are using the 4.030 bore, L2256 piston @ -6.1cc. 64cc combustion chamber. Piston .020 in the hole.
Victor 5746 .026 gasket = 10.10 SCR
Fel Pro 1094 .015 gasket = 10.38 SCR
Either of those will work fine with the heads @64cc.... Really depends on where the piston comes out in the block as to which gasket I'd use.
If it's .010-.015 I'd run the Victor Gasket.
If it's .015-.020 I'd run the Fel Pro gasket.
Compression with the heads cut to 60cc - everything else remaining the same.
Victor 5746 = 10.58
Fel Pro 1094 = 10.89
Here I'd go with the Victor gasket.
Will
Pushrod lengths need to be determined by a rocker geometry plot.... There is no way to know if your right or not unless you measure.
Has your block been decked? Any idea how far down in the hole the piston is?
You will be able to make some compression up using the VR .026 or Fel Pro 1094 .015 head gasket.
Just a quick look at compression.... FYI all my calculations are using the 4.030 bore, L2256 piston @ -6.1cc. 64cc combustion chamber. Piston .020 in the hole.
Victor 5746 .026 gasket = 10.10 SCR
Fel Pro 1094 .015 gasket = 10.38 SCR
Either of those will work fine with the heads @64cc.... Really depends on where the piston comes out in the block as to which gasket I'd use.
If it's .010-.015 I'd run the Victor Gasket.
If it's .015-.020 I'd run the Fel Pro gasket.
Compression with the heads cut to 60cc - everything else remaining the same.
Victor 5746 = 10.58
Fel Pro 1094 = 10.89
Here I'd go with the Victor gasket.
Will
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,010
Likes: 1
From: Sweden/Stockholm
No problems with the dizzy or intake only taking .028 off the heads.
Pushrod lengths need to be determined by a rocker geometry plot.... There is no way to know if your right or not unless you measure.
Has your block been decked? Any idea how far down in the hole the piston is?
You will be able to make some compression up using the VR .026 or Fel Pro 1094 .015 head gasket.
Just a quick look at compression.... FYI all my calculations are using the 4.030 bore, L2256 piston @ -6.1cc. 64cc combustion chamber. Piston .020 in the hole.
Victor 5746 .026 gasket = 10.10 SCR
Fel Pro 1094 .015 gasket = 10.38 SCR
Either of those will work fine with the heads @64cc.... Really depends on where the piston comes out in the block as to which gasket I'd use.
If it's .010-.015 I'd run the Victor Gasket.
If it's .015-.020 I'd run the Fel Pro gasket.
Compression with the heads cut to 60cc - everything else remaining the same.
Victor 5746 = 10.58
Fel Pro 1094 = 10.89
Here I'd go with the Victor gasket.
Will
Pushrod lengths need to be determined by a rocker geometry plot.... There is no way to know if your right or not unless you measure.
Has your block been decked? Any idea how far down in the hole the piston is?
You will be able to make some compression up using the VR .026 or Fel Pro 1094 .015 head gasket.
Just a quick look at compression.... FYI all my calculations are using the 4.030 bore, L2256 piston @ -6.1cc. 64cc combustion chamber. Piston .020 in the hole.
Victor 5746 .026 gasket = 10.10 SCR
Fel Pro 1094 .015 gasket = 10.38 SCR
Either of those will work fine with the heads @64cc.... Really depends on where the piston comes out in the block as to which gasket I'd use.
If it's .010-.015 I'd run the Victor Gasket.
If it's .015-.020 I'd run the Fel Pro gasket.
Compression with the heads cut to 60cc - everything else remaining the same.
Victor 5746 = 10.58
Fel Pro 1094 = 10.89
Here I'd go with the Victor gasket.
Will
Block has not been decked.
I can measure the piston. You whant the distance between the piston and the top of the bore at tdc?
The victor gasget looks like a winner, 10.10:1 sounds like a good compromise.
Regards
Safety Car
Joined: Apr 2005
Posts: 3,624
Likes: 431
From: Dale City VA
With an undecked block it should be around .018 - .020 in the hole.
No worries man.
Everyone that contributes, including me, just wants to help.Will
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,010
Likes: 1
From: Sweden/Stockholm
Yes the distance between the block deck surface and piston at TDC. Make sure you check inline with the wrist pin and center of the piston so you don't have to account so much for piston rock.
With an undecked block it should be around .018 - .020 in the hole.
No worries man. Everyone that contributes, including me, just wants to help.
Will
With an undecked block it should be around .018 - .020 in the hole.
No worries man.
Everyone that contributes, including me, just wants to help.Will
I measured between the center of the piston and a metal ruler that I laid flat over the block. I used a digital caliper.
It whas hard to get a consistent value, due the angel I held the caliper kept changing.
But it whas around .022 give or take..
I also saw that summit has these heads that might work better for me, and will pump up the comp to around 10.5:1 with 56cc chambers?
http://www.summitracing.com/parts/tf...make/chevrolet
And cam choise is most likely going to be the LPE211 cam:
211/219 .496/.525, with 1:5 rrs
What do you think?
Thanks
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,010
Likes: 1
From: Sweden/Stockholm