Building a 406 have some ?'s
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Pro
Joined: Jan 2003
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From: Oswego Illinois
Building a 406 have some ?'s
Guys I am going to build a 406 and have a ? about CR. I want to still be able to run pump gas in the car what is the max CR I can go, I plan on using aluminum heads but am not positive. It will be fuel injected with a superram intake, and LT headers. The car is a 87.
Last edited by vetteguy216; Oct 3, 2004 at 12:45 AM.
Thread Starter
Pro
Joined: Jan 2003
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From: Oswego Illinois
Well as of now I was planing on going with
-JE or Weisco forged pistions
-Manely Forged H-beam Rods
-Scat 4340 Forged Crank 3.75in Stroke
-Dart Race Ready Pro-1 Heads (bowl blended and port matched 2.02/1.60 or 2.05\1.60 valves, 1.5 roller springs, chromemoly retainers, and 10* steel locks
-TPIS 700-701 Solid Roller Cam Shaft 242/242 .610 lift w/ 1.6 RR LSA 112
But I am not sure about the cam or heads yet, please make suggestions
-JE or Weisco forged pistions
-Manely Forged H-beam Rods
-Scat 4340 Forged Crank 3.75in Stroke
-Dart Race Ready Pro-1 Heads (bowl blended and port matched 2.02/1.60 or 2.05\1.60 valves, 1.5 roller springs, chromemoly retainers, and 10* steel locks
-TPIS 700-701 Solid Roller Cam Shaft 242/242 .610 lift w/ 1.6 RR LSA 112
But I am not sure about the cam or heads yet, please make suggestions
Race Director
Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
With a cam like that you need 11:1 CR and get the bigger heads I have 2.08 intake valves. The torque is there with a 406ci so build some horsepower, I had 360ft/lbs of torque at the rear wheels at 2000RPM where my dyno run started and it went to over 400ft/lbs 
Thread Starter
Pro
Joined: Jan 2003
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From: Oswego Illinois
Motorhead and ID85 do you guys run pump gas? Also are you guys using 5.7in or 6in rods?
I am not positive on my combo yet so alot can be changed. I am trying to get my hands on a block right now. I have located two one has been hot tanked,magnafluxed, pressure tested the has been hot tanked, magnafluxed, shot blasted and sprayed with rust protectant they both cots $300-$500.
I am not positive on my combo yet so alot can be changed. I am trying to get my hands on a block right now. I have located two one has been hot tanked,magnafluxed, pressure tested the has been hot tanked, magnafluxed, shot blasted and sprayed with rust protectant they both cots $300-$500.
Drifting
Joined: Sep 2003
Posts: 1,325
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From: FRANKLIN GA
Don't know about a 406, but on my 383 I'm running 11.94:1 and it's on the borderline. I'm running alum. heads and .037 quench and a cam with alot of overlap.
It pings some in the summer under full load if I don't back out some advance. Wintertime and cooler air it does ok.
Stick with 11.5:1 or lower and a tight quench and you should be fine on pump gas in all conditions. I would say a tight quench is mandotory on anything over 10:1
Here's some reading that might help you out
http://racehelp.com/article_racing-10.html
It pings some in the summer under full load if I don't back out some advance. Wintertime and cooler air it does ok.
Stick with 11.5:1 or lower and a tight quench and you should be fine on pump gas in all conditions. I would say a tight quench is mandotory on anything over 10:1
Here's some reading that might help you out
http://racehelp.com/article_racing-10.html
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Race Director
Joined: Feb 1999
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From: Indianapolis IN
Originally Posted by vetteguy216
Motorhead and ID85 do you guys run pump gas? Also are you guys using 5.7in or 6in rods?
I am not positive on my combo yet so alot can be changed. I am trying to get my hands on a block right now. I have located two one has been hot tanked,magnafluxed, pressure tested the has been hot tanked, magnafluxed, shot blasted and sprayed with rust protectant they both cots $300-$500.
I am not positive on my combo yet so alot can be changed. I am trying to get my hands on a block right now. I have located two one has been hot tanked,magnafluxed, pressure tested the has been hot tanked, magnafluxed, shot blasted and sprayed with rust protectant they both cots $300-$500.
Le Mans Master
Joined: Feb 1999
Posts: 6,172
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From: somers, ny
I'm at 11 with no problems. If i had to do it over id go 11.5. I think the higher compression makes more of a difference than most people think.
good luck with it.....and watch you rod to cam clearence. my 701 to rod was only about .010 and i had to grind the rods.
good luck with it.....and watch you rod to cam clearence. my 701 to rod was only about .010 and i had to grind the rods.
Melting Slicks
Joined: Jun 2002
Posts: 2,844
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From: Orrtanna Pa.
I run 10.1:1 with the AFR 195's and while I was playing with the recurve kit on a hotter than heck day I did hear slight pinging. This happened only once and I've since limited my vacuum advance to only 10 degrees.(total mechanical is still 35)The point I am trying to make I guess is that octane tolerance is subjective to the fuel quality as well as the temperature,as well as the load the engine is under.I have quite a margin with only 10.1:1 to run well even if I get a tank of crappy gas.The cam is a Comp XE-284 running 1.60 rockers,so if you look at the lift and duration it's right up there with the roller cams I've seen cropping up lately.
Race Director
Joined: Feb 1999
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From: Indianapolis IN
[QUOTE=ralph]I'm at 11 with no problems. If i had to do it over id go 11.5. I think the higher compression makes more of a difference than most people think.
QUOTE]Amen!
I too think the higher CR is worth more than the calcs say
QUOTE]Amen!
I too think the higher CR is worth more than the calcs say
Race Director
Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
I run 5.7 rods and 93 octane, I had my timing set by accident at 45 degs
when I first fired it up and no pinging, personally I wouldn't go above 11:1 CR gains aren't worth the trouble if you have detonation problems
when I first fired it up and no pinging, personally I wouldn't go above 11:1 CR gains aren't worth the trouble if you have detonation problems
Race Director
Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Scat 9000 is a great crank all you need for street/strip motor that only blips to 6000RPM for a few seconds, no problem in the 450 - 550 HP range
Melting Slicks
Joined: Dec 2001
Posts: 2,025
Likes: 1
From: Billings MT
I run 10.7:1 with AFR heads and .039" quench. I run on 91 octane with 38 degrees intial and total timing. No pinging.
This is with 6" rod and SRP flat tops.
Motorhead: I shift at 7200rpm, I can hear my crank weeping when I park it. ROFL
This is with 6" rod and SRP flat tops.
Motorhead: I shift at 7200rpm, I can hear my crank weeping when I park it. ROFL
Thread Starter
Pro
Joined: Jan 2003
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From: Oswego Illinois
Thanks for all the help guys. I have found yet another block on ebay (Item# 7925772441), but I am a little uncertain they say it has been
"THERMALLY CLEANED AND SHOT PEENED, MAGNUFLUXED, BORED AND TORQUE PLATE HONED TO .030, AND THE DECKS OF THE BLOCK HAVE BEEN MILLED. THIS BLOCK IS TRULY READY FOR SOMEONE TO BEGIN ASSEMBLY"
If I do end up getting this block what should be done to check it out before I start assembly.
"THERMALLY CLEANED AND SHOT PEENED, MAGNUFLUXED, BORED AND TORQUE PLATE HONED TO .030, AND THE DECKS OF THE BLOCK HAVE BEEN MILLED. THIS BLOCK IS TRULY READY FOR SOMEONE TO BEGIN ASSEMBLY"
If I do end up getting this block what should be done to check it out before I start assembly.
Race Director
Joined: Sep 2000
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From: The Top of Utah
Usually, when the block in finished honed, the shop wants the pistons on hand to custom fit each hole to a specific piston. Also, the cylinder hone, finish, is for a certain type of ring. You might inquire what rings the cylinders are finished for. You might ask if there is enough meat left to custom fit the pistons. OR depending on how you are building it, do nothing.
"DECKS OF THE BLOCK HAVE BEEN MILLED" What does THAT mean? Are they simply flat? Have they been trued and squared? Is the block decked to some particular "deck height"? Or piston to deck clearance? Again, you may not care.
RACE ON!!!
"DECKS OF THE BLOCK HAVE BEEN MILLED" What does THAT mean? Are they simply flat? Have they been trued and squared? Is the block decked to some particular "deck height"? Or piston to deck clearance? Again, you may not care.
RACE ON!!!
Team Owner
Joined: Apr 1999
Posts: 21,953
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
As i understand it from my friends 383 and a ported superram. your very limited on total ci, head type, and cam duration.
The super ram has upper rpm limits because it's cfm flow is so low. It's tuned design limits cam duration to less than 226 @.050 Most guys use 219/219 cams and only 383 or so ci
The superram is like restrictor plate racing. Sub 6200 rpm on a 383 so they are suited to use lower duration h-roller cams.
You better do your home work first!
The super ram has upper rpm limits because it's cfm flow is so low. It's tuned design limits cam duration to less than 226 @.050 Most guys use 219/219 cams and only 383 or so ci
The superram is like restrictor plate racing. Sub 6200 rpm on a 383 so they are suited to use lower duration h-roller cams.
You better do your home work first!