LG4 rebuild: Head bolts selection with higher compression?
09-21-2015, 08:30 AM
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Car: 1982 Firebird Trans Am
Engine: 5.0 l V8 (LG4, with L69 specs)
Transmission: TH200C
Axle/Gears: Posi 3.23 Discs
LG4 rebuild: Head bolts selection with higher compression?
Hello guys,
at the moment, I am in the middle of rebuilding my engine like described in this thread: https://www.thirdgen.org/forums/carb...982-trans.html.
Now, a special kind of question occurred: With my new setup, the compression will increase to about 10.0:1 to 10.5:1. Which head bolts should I use to complete my build?
* It is ok to reuse the old head bolts (they were cleaned very accurately and look great)?
* Is it ok to go with a new set of OEM head bolts (http://www.summitracing.com/int/part...5499/overview/) for additional safety?
* Do I have to upgrade to a (expensive) set of high performance bolts (http://www.summitracing.com/int/part...3601/overview/) because of the higher compression?
Until a few minutes ago, I was REAL SURE that it is absolutely ok to reuse head bolts of a small block chevy. No I want to hear some additional opinions.
Besides the head bolts, I know I have to renew the dampener bolt. Any other bolts I should take care of? I want to reuse everything else, accurately cleaned, of course.
Best regards and thanks a lot,
Marcel
at the moment, I am in the middle of rebuilding my engine like described in this thread: https://www.thirdgen.org/forums/carb...982-trans.html.
Now, a special kind of question occurred: With my new setup, the compression will increase to about 10.0:1 to 10.5:1. Which head bolts should I use to complete my build?
* It is ok to reuse the old head bolts (they were cleaned very accurately and look great)?
* Is it ok to go with a new set of OEM head bolts (http://www.summitracing.com/int/part...5499/overview/) for additional safety?
* Do I have to upgrade to a (expensive) set of high performance bolts (http://www.summitracing.com/int/part...3601/overview/) because of the higher compression?
Until a few minutes ago, I was REAL SURE that it is absolutely ok to reuse head bolts of a small block chevy. No I want to hear some additional opinions.
Besides the head bolts, I know I have to renew the dampener bolt. Any other bolts I should take care of? I want to reuse everything else, accurately cleaned, of course.
Best regards and thanks a lot,
Marcel
09-21-2015, 09:37 AM
#2
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Re: LG4 rebuild: Head bolts selection with higher compression?
If the original head bolts are in good shape - no damaged threads, heads not stripped, etc. - then they're completely OK to re-use. Clean them up, wire-brush the threads and their heads and all, and chase the threads in the block. Use some kind of non-hardening sealer on the threads, since they all go into the water jackets; not shellac, not RTV. High-temp pipe thread sealer with Teflon is best. Put a bit under the head of the bolt as well as on the threads.
Only reason to "renew" the damper bolt is if it's damaged somehow.
There are no bolts on a 305 that "must" be replaced during a rebuild. No torque-to-yield or that sort of thing. If they're in good shape, you can re-use them all.
Only reason to "renew" the damper bolt is if it's damaged somehow.
There are no bolts on a 305 that "must" be replaced during a rebuild. No torque-to-yield or that sort of thing. If they're in good shape, you can re-use them all.
09-21-2015, 09:48 AM
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Location: Near Cologne, Germany
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Car: 1982 Firebird Trans Am
Engine: 5.0 l V8 (LG4, with L69 specs)
Transmission: TH200C
Axle/Gears: Posi 3.23 Discs
Re: LG4 rebuild: Head bolts selection with higher compression?
Hi sofakingdom,
that's music in my ears! I wire-brushed all bolts yesterday, they came out real nice, they are shiny and clean and I will inspect each thread before installation very carefully.
I ordered one tube of Permatex 59235 High Temperature Thread Sealant earlier this day, which should be the right choice for the job.
Thanks a lot!
Marcel
that's music in my ears! I wire-brushed all bolts yesterday, they came out real nice, they are shiny and clean and I will inspect each thread before installation very carefully.
I ordered one tube of Permatex 59235 High Temperature Thread Sealant earlier this day, which should be the right choice for the job.
Thanks a lot!
Marcel
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