lq4 build need cam spec help, with stock sounding idle
09-21-2012, 12:27 PM
#1
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lq4 build need cam spec help, with stock sounding idle i am building a lq4 with 12 cc dome pistons with 317 heads. Think that will put me about 12:1 cr right ? I'll be running e85 fuel. I need a cam with good torque and STOCK idle. can anyone help.
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09-21-2012, 03:24 PM
#8
Drokkers thanks for the kind words!
If it's a 4.030 bore than a 12cc dome will put you at 12.02:1 SCR.
The cam I think that would work very well for you is our Stage 1 for 346-370 c.i. motors and it specs out a 226/230 .60x/.60x 114+4 and will make great torque, idle very close to stock and still pull to 6200-6300rpm while making great average power especially with your compression.
With that cam your DCR will be 9.2:1 which will create awesome low end response and power while pulling like a train through the mid-range and stopping around 6300rpm.
If you wanted to go slightly smaller and damn near stock idle we could go with my Stage 1 for 346-364 c.i. motors that is 222/226 .60x/.60x 115+3.
Let me know what you think!
P.S. we have cam packages for both of those cams that start at 679.99 that include Brian Tooley Racing valve springs and Manley .080 wall 5/16" push rods. Timing chain and oil pump options are also available as are Ti retainers.
If it's a 4.030 bore than a 12cc dome will put you at 12.02:1 SCR.
The cam I think that would work very well for you is our Stage 1 for 346-370 c.i. motors and it specs out a 226/230 .60x/.60x 114+4 and will make great torque, idle very close to stock and still pull to 6200-6300rpm while making great average power especially with your compression.
With that cam your DCR will be 9.2:1 which will create awesome low end response and power while pulling like a train through the mid-range and stopping around 6300rpm.
If you wanted to go slightly smaller and damn near stock idle we could go with my Stage 1 for 346-364 c.i. motors that is 222/226 .60x/.60x 115+3.
Let me know what you think!
P.S. we have cam packages for both of those cams that start at 679.99 that include Brian Tooley Racing valve springs and Manley .080 wall 5/16" push rods. Timing chain and oil pump options are also available as are Ti retainers.
09-22-2012, 10:48 AM
#12
Stock rockers are great as they are the lightest available rocker for our engines.
If you want to be thorough in this department you can install the Comp Trunion upgrade which upgrades the trunion bearing the rockers ride on. They just press out and the new ones press in, it takes about an hour to perform at the most and is a very simple process.
09-24-2012, 07:00 AM
#18
And what makes you think adding compression makes it harder to have a car idle properly and that adding compression will make a cam "rowdier"? Let alone that 12.0:1 is "a lot" of compression?
With added compression you will actually have more vacuum at idle helping it to idle better. You really don't start to notice the "cackle" of compression until you get into fuel cars that have ungodly amounts of dynamic compression. His dynamic with that cam will end up being 9.2:1 which is hardly anything to write home about.
Some people tempt fate and run stock push rods. I'd never run an aftermarket cam and valve springs without an aftermarket push rod.
Our cam package for 679.99 includes .080 wall 5/16" Manley push rods.
With added compression you will actually have more vacuum at idle helping it to idle better. You really don't start to notice the "cackle" of compression until you get into fuel cars that have ungodly amounts of dynamic compression. His dynamic with that cam will end up being 9.2:1 which is hardly anything to write home about.
Our cam package for 679.99 includes .080 wall 5/16" Manley push rods.
Last edited by Sales@Tick; 09-24-2012 at 07:09 AM.
09-24-2012, 08:05 AM
#19
As far as "idle properly", I can't speak to that because I did not say that.
Now if you want me to speak to the science of why I can notice larger cams easier with higher compression, I would say it is due to the increased efficiency of the idle combustion.
At idle, your VE is about as low as it gets. Increased compression makes a substantial difference when the VE is low. This is the same reason high compression produces so much better fuel economy than low compression. I would offer that the higher compression ratios make for much more combustion efficiency and that is what produces the extra pop when the exhaust valve opens.
This ability to listen for this used to come in pretty handy when evaluation potential victims at the late night street hang outs back in the day.
09-24-2012, 10:47 AM
#20
What makes me think the cam sound "rowdier" or hit harder? 25 years of experience.
As far as "idle properly", I can't speak to that because I did not say that.
Now if you want me to speak to the science of why I can notice larger cams easier with higher compression, I would say it is due to the increased efficiency of the idle combustion.
At idle, your VE is about as low as it gets. Increased compression makes a substantial difference when the VE is low. This is the same reason high compression produces so much better fuel economy than low compression. I would offer that the higher compression ratios make for much more combustion efficiency and that is what produces the extra pop when the exhaust valve opens.
This ability to listen for this used to come in pretty handy when evaluation potential victims at the late night street hang outs back in the day.
As far as "idle properly", I can't speak to that because I did not say that.
Now if you want me to speak to the science of why I can notice larger cams easier with higher compression, I would say it is due to the increased efficiency of the idle combustion.
At idle, your VE is about as low as it gets. Increased compression makes a substantial difference when the VE is low. This is the same reason high compression produces so much better fuel economy than low compression. I would offer that the higher compression ratios make for much more combustion efficiency and that is what produces the extra pop when the exhaust valve opens.
This ability to listen for this used to come in pretty handy when evaluation potential victims at the late night street hang outs back in the day.
Your theory on idle and VE is correct though.
Sorry for the misunderstanding. You normally have very good theories and comments so I had to call you out on that one, no hard feelings.
