Torque'n the heads RIGHT NOW!!!! Need help ASAP!!! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

69GMC910 · 06-30-2002, 05:20 PM

I'm currently installing heads on the 350, finally switching the 305 heads to 350 ones. What should all the bolts be torqued to? I am using the old bolts again, do I have to torque them higher because of threads stretching?

What is the procedure for tightening the rockers, are they all at a specific torque?

Also, My pistons have stamped on them 345NP .030 So I know its 30 over, does anyone recognize the 345NP? They are a flat top piston but I would like to know the compression ratio.

Thanks for the help

P.S. I really like the new board!!

bigvinnie · 06-30-2002, 05:27 PM

70 ft. lbs. on the head bolts.... go thru the order, working from the center bolts out, first torquing all to 30 ft lbs, then do a second pass, torquing to 70...

69GMC910 · 06-30-2002, 05:59 PM

Thanks Bigvinnie.

Anybodt know the torques on the Rockers???

Need help right away!!!!!

Thanks again!

fluffytx1 · 06-30-2002, 06:00 PM

there are alot of ways to find compression ratios. You need to know some things first though. Most heads gives you head chamber volume and pistons do to (the number on your piston is the volume in cubic centimeters) head gasket specs: most head gasket co. list specs thicker head gaskets and bigger bores gives lower compression ratios.

go into these links to find a formula that will calculate your compression ratio with the above info.

www.mindspring.com/~steveflyer/compression.htm
www.smokemup.com/utilities/calc/compression.raatio.cfm

scott

bigvinnie · 06-30-2002, 06:23 PM

If you're talking about adjusting the rocker arms, torque isn't really part of the equation.... you adjust each one individually for valve lash and you're done...

here's a decent link for adjusting valves...

http://www.camaros.net/techref/ftecref17.html

06-30-2002, 05:20 PM	#1
69GMC910 MOTORHEAD! Join Date: May 2000 Location: Devon AB, Canada Posts: 849	Torque'n the heads RIGHT NOW!!!! Need help ASAP!!! I'm currently installing heads on the 350, finally switching the 305 heads to 350 ones. What should all the bolts be torqued to? I am using the old bolts again, do I have to torque them higher because of threads stretching? What is the procedure for tightening the rockers, are they all at a specific torque? Also, My pistons have stamped on them 345NP .030 So I know its 30 over, does anyone recognize the 345NP? They are a flat top piston but I would like to know the compression ratio. Thanks for the help P.S. I really like the new board!! __________________ 82 GMC High Sierra VortecPro 496 12 Bolt, 3.42's AFR 265 Holley 850 Performer RPM Air Gap Hooker 2455's TCI Turbo 400 Super Street Fighter TRRC 12 Bolt Eaton Posi Mark Williams Axles Cal-Tracs Hoosier 30x10.5 Radial Slick Full weight long box pickup Current best- 11.33@117mph

06-30-2002, 05:27 PM	#2
bigvinnie Registered User Join Date: Aug 2001 Location: escondido, ca 92026 Posts: 1,222	70 ft. lbs. on the head bolts.... go thru the order, working from the center bolts out, first torquing all to 30 ft lbs, then do a second pass, torquing to 70... __________________ '72 short step, 350, 700R4, tilt, ps, pdb, a/c, lowered coils, etc., other work in progress... San Diego, CA 72 Stepside Project

06-30-2002, 05:59 PM	#3
69GMC910 MOTORHEAD! Join Date: May 2000 Location: Devon AB, Canada Posts: 849	Thanks Bigvinnie. Anybodt know the torques on the Rockers??? Need help right away!!!!! Thanks again! __________________ 82 GMC High Sierra VortecPro 496 12 Bolt, 3.42's AFR 265 Holley 850 Performer RPM Air Gap Hooker 2455's TCI Turbo 400 Super Street Fighter TRRC 12 Bolt Eaton Posi Mark Williams Axles Cal-Tracs Hoosier 30x10.5 Radial Slick Full weight long box pickup Current best- 11.33@117mph

06-30-2002, 06:00 PM	#4
fluffytx1 Registered User Join Date: Feb 2002 Location: point blank Posts: 113	compression ratio answer there are alot of ways to find compression ratios. You need to know some things first though. Most heads gives you head chamber volume and pistons do to (the number on your piston is the volume in cubic centimeters) head gasket specs: most head gasket co. list specs thicker head gaskets and bigger bores gives lower compression ratios. go into these links to find a formula that will calculate your compression ratio with the above info. www.mindspring.com/~steveflyer/compression.htm www.smokemup.com/utilities/calc/compression.raatio.cfm scott __________________ 1968 GMC CST long wide box http://groups.yahoo.com/group/67-72-collectors/

06-30-2002, 06:23 PM	#5
bigvinnie Registered User Join Date: Aug 2001 Location: escondido, ca 92026 Posts: 1,222	If you're talking about adjusting the rocker arms, torque isn't really part of the equation.... you adjust each one individually for valve lash and you're done... here's a decent link for adjusting valves... http://www.camaros.net/techref/ftecref17.html __________________ '72 short step, 350, 700R4, tilt, ps, pdb, a/c, lowered coils, etc., other work in progress... San Diego, CA 72 Stepside Project Last edited by bigvinnie; 06-30-2002 at 06:44 PM.



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