Decided to LS swap

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0xDEADBEEF

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I have no experience with LS motors other than plugging numbers into a spreadsheet, but the specs on a 706 head are underwhelming. The one thing it has going for it is the small 61cc combustion chamber. The 317s have larger valves and ports, but a large 71cc combustion chamber. I'd stick with the 317s but upgrade the pistons to get the compression ratio up.

Or, even better, you can get L92 copycat heads for $375 a piece.

Cheepier and easier to just slap another set of junkyard heads on.
 

KansasOBS

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I have no experience with LS motors other than plugging numbers into a spreadsheet, but the specs on a 706 head are underwhelming. The one thing it has going for it is the small 61cc combustion chamber. The 317s have larger valves and ports, but a large 71cc combustion chamber. I'd stick with the 317s but upgrade the pistons to get the compression ratio up.

Or, even better, you can get L92 copycat heads for $375 a piece.

Its about building torque lower in the rpm range, and yes they have smaller valve. Watch the video, so I dont have to retype everything said there. Its all been dyno tested.
 
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Sean Buick 76

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I’m glad to see you going with a 4L80E and I agree that swapping to a 3.73 gear would be a good idea. The truck will drive fine with the current gear so do that after you get it up and running. After the gear swap it will wake it right up!
 

open_road_toad

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I have no experience with LS motors other than plugging numbers into a spreadsheet, but the specs on a 706 head are underwhelming. The one thing it has going for it is the small 61cc combustion chamber. The 317s have larger valves and ports, but a large 71cc combustion chamber. I'd stick with the 317s but upgrade the pistons to get the compression ratio up.

Or, even better, you can get L92 copycat heads for $375 a piece.
Yep. I’m putting flat top pistons in it.
 

open_road_toad

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Ok guys, I have some questions now regarding the engine build. Specifically bolts and bearings.

I’d like to put this thing back together with stock GM parts. Went to the local dealer to get pricing on bolts. Here’s what he’s quoted me:
Main bolts (the long ones on top of the caps, I can reuse the smaller side bolts) $149.40
Rod bolts $299.20
Head bolts $100.40
He’ll give me a 10% discount for being a veteran so the total would be $494.10

What about rod and main bearings. Should I go with GM or aftermarket? I am going aftermarket for pistons and rings.

That leads me to gaskets. GM or aftermarket?

Oil pump, timing chain/gear set?

Also, what should I do about the fuel injectors. I’d like to send them somewhere and have them cleaned. Engine ran fine before it was pulled. I will replace all the sensors that were in/on the engine but I plan on reusing the coil packs and injectors.

As always I appreciate the feedback.

Thanks!
Todd
 

Sean Buick 76

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In my opinion I would re use all of the bolts except that head bolts. Use GM replacements. The head bolts are TTY torque to yield which means they only give the proper clamping force once and then once they stretch as designed they need to be replaced if they are ever removed. If you change the bolts in the mains or rods then do ti it properly you need to have the main bore measured and honed as needed. Same for the rods, leave them alone or have them re sized after adding the new bolts.

In the real world however there are thousands of people who are re using these head bolts without an issue. A test was even completed comparing the stock used TTY bolts, cheep Chinese bolts, and ARP. The stick bolts came out on top. I’ve ran 20 psi of boost from a turbo on a 5.3 and no head gasket issue with re used stuck bolts.

Any time you change the bolts it’s a best practice to at least measure the rods and mains.
 
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KansasOBS

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Ok guys, I have some questions now regarding the engine build. Specifically bolts and bearings.

I’d like to put this thing back together with stock GM parts. Went to the local dealer to get pricing on bolts. Here’s what he’s quoted me:
Main bolts (the long ones on top of the caps, I can reuse the smaller side bolts) $149.40
Rod bolts $299.20
Head bolts $100.40
He’ll give me a 10% discount for being a veteran so the total would be $494.10

What about rod and main bearings. Should I go with GM or aftermarket? I am going aftermarket for pistons and rings.

That leads me to gaskets. GM or aftermarket?

Oil pump, timing chain/gear set?

As always I appreciate the feedback.

Thanks!
Todd
I wouldn't change out anything, except the head bolts, and I'm about like Sean on the subject.

As far as rod and mains, Ive always had good luck with Clevite, but if you're hyped about going GM, they wouldn't be a bad option. One thing I haven't seen you mention is cam bearings. Durabond makes some good ones for LS engines. I would not have the engine down this far, and not replace the cam bearings, factory are no good.

Melling makes some nice oil pumps for these. They have some high volume/high pressure options, etc. I tend to go with high volume over high pressure myself, but not even trying to get into that debate. Make sure you have the correct O-ring for the pickup.

Probably good with whatever gaskets, Fel-Pro, GM. MLS on the heads.

Same for the rods, leave them alone or have them re sized after adding the new bolts.
I don't even think the LS style cracked cap rods can be resized, or I'm just dumb to the process. You cant remove material on the faces to re-bore/hone the center. Either way the Gen 3 rods were one of the weaker spots, not sure Id dump much time or money into them. Run as is, or upgrade.
 

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In my opinion I would re use all of the bolts except that head bolts. Use GM replacements. The head bolts are TTY torque to yield which means they only give the proper clamping force once and then once they stretch as designed they need to be replaced if they are ever removed. If you change the bolts in the mains or rods then do ti it properly you need to have the main bore measured and honed as needed. Same for the rods, leave them alone or have them re sized after adding the new bolts.

In the real world however there are thousands of people who are re using these head bolts without an issue. A test was even completed comparing the stock used TTY bolts, cheep Chinese bolts, and ARP. The stick bolts came out on top. I’ve ran 20 psi of boost from a turbo on a 5.3 and no head gasket issue with re used stuck bolts.

Any time you change the bolts it’s a best practice to at least measure the rods and mains.
Aren’t the main and rod bolts tty as well and thus can’t be reused? I’m all for saving money but I’d hate to skimp on engine internals and have an expensive issue later. I’m not building a high performance engine. The only mod I’m doing is a cam. The machine shop will measure and hone the main and rods. Guy did suggest changing the rods but said reusing the stock rods would be fine for what I’m doing with it.
 
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