LQ9 based 408 2 part article - GM Forums at GM High-Tech Performance Magazine

LQ9 based 408 2 part article

  
User Name:
Password:
Join FREE Now!
Forgot Password?
Forgot User Name?
Remember Me
Get Adobe Flash player
Home | Active Posts | Search | Register | Terms | FAQs
Rss
Item Posts    Sort Order

LQ9 based 408 2 part article

 
b_onliest b_onliest
New User | Posts: 2 | Joined: 09/09
Posted: 09/10/09
10:08 PM

This articled interested me because my son had previously suggested the same basis for people that want to build their own.  He has a Sierra with the LQ9.
I logged in to ask what the correct spec for the main bearing clearance is, and  what were your final measurements for the successful dyno pull?  Did SAM use the incorrect spec?  Other than getting different bearings, how would clearance adjustments be made?   First time post.  

 
Scott_at_GMHTP Scott_at_GMHTP
User | Posts: 59 | Joined: 12/07
Posted: 09/11/09
11:32 AM

Check out Part 1 in the August issue, just one of the mains was out of spec...easily correctable with a different bearing. No matter how good of a machinist you have, it's quite common to use various thickness bearings to compensate for slight inconsistencies. I will get back to you on what clearance they went with.  

 
mpayne mpayne
Administrator | Posts: 236 | Joined: 10/07
Posted: 09/11/09
01:09 PM

Here is a digital link to the story Scott is referring too. http://www.gmhightechperformance.com/tech/0908gmhtp_lq9_408_stroker_budget_build/index.html  

 
BillK71 BillK71
New User | Posts: 1 | Joined: 09/09
Posted: 09/15/09
05:43 PM

Scott,
I am also very interested in this information. The factory clearance spec for the mains is .0007" to .0021" so .002" or even a little tighter is well within reason. I am also preparing for my first complete LS build based on a 6.0 block and would not have had any problems with that clearance.

In all fairness to your readers, it would be interesting to know if it was definitely determined that the bearing clearance was really the issue with the failure on the dyno. I have built many "traditional" small blocks with less than .002" mian clearance and have not had issues.  

 

Chevrolet Impala Research
Chevrolet Impala Car and Truck pricing can be complicated and sometimes confusing. As an authority on car buying needs we provide information about new cars, such as the Chevrolet Impala and all the features it comes with. Compare the Impala with other submodels and find all you need for your car buying needs. It has drivers side crash test ratings of 5 stars and passengers side crash test ratings of 5 stars. Other similar vehicles are the Chevrolet Monte Carlo and the Buick Lacrosse.