My Flat Tappet Cam Wiped Out So I Decided To Go Roller

[L31MaxExpress]

May as well budget for a transmission and a rear end

I am dreading the day I kill my factory built 80E in the Tahoe or 85E in the Van. I hope it is a while off on both. This comment reminds me I am on borrowed time with 2 transmissions over 20 years old that have never been apart. My buddies cammed iron LS2 (LQ4 block, LS2 pistons, GenIV rods, 799 heads, TBSS intake) just did something to the 80E in his 2dr Yukon tonight. Tuning in Mexico, it went into limp after an epic tire smoking launch through 1st and into 2nd. Yukon has never broken them loose the way it did earlier. No codes, no weird noises, no slipping, just nothing but 2nd unless the negative cable is removed. Then it had 1st but as soon as it hits 2nd, it is in fail safe again, stuck in 2nd. It will only shift using HP Tuners to command it to shift. I can command 1st, 2nd, 3rd and Overdrive manually all day long with HP Tuners. Hopefully just an internal pressure switch problem that is sending the PCM a signal it cannot compute and thus forcing limp mode.

 

[someotherguy]

Well, he did have a completed 454 out of a '70 Chevelle sitting on the ground, under a jib crane, just waiting for someone to pick it up

Edit - it was an LS7 numbers matching.

Numbers matching LS-7 from a '70 Chevelle? Wouldn't that be an LS-6? I thought that era's LS-7 was crate-only. I could be wrong, not claiming to be the expert here. Either one would be impressive as hell, but the LS-7 is a whole 'nother animal.

The LS-6 was rated at 450hp/500lb-ft, while the LS-7 was 465hp/610lb-ft. Both were rumored to be seriously underrated as well. Seems the online stats show both a 465hp version and a 500hp crate version.. but what I can't find is what 1970 model vehicle would have had an LS-7 installed from factory, even as an option; I don't think it existed.

I once worked for a guy that installed crate LS-7's in plain-Jane sleeper Caprice's for.. uh.. traveling salesmen. That is, after tearing them down for a refresh after having sat in the crate for several years.

Richard

 

[0xDEADBEEF]

You know, if this was not the truck of the year, another 350 would be ok, but this truck is special now.

 

[Supercharged111]

I am dreading the day I kill my factory built 80E in the Tahoe or 85E in the Van. I hope it is a while off on both. This comment reminds me I am on borrowed time with 2 transmissions over 20 years old that have never been apart. My buddies cammed iron LS2 (LQ4 block, LS2 pistons, GenIV rods, 799 heads, TBSS intake) just did something to the 80E in his 2dr Yukon tonight. Tuning in Mexico, it went into limp after an epic tire smoking launch through 1st and into 2nd. Yukon has never broken them loose the way it did earlier. No codes, no weird noises, no slipping, just nothing but 2nd unless the negative cable is removed. Then it had 1st but as soon as it hits 2nd, it is in fail safe again, stuck in 2nd. It will only shift using HP Tuners to command it to shift. I can command 1st, 2nd, 3rd and Overdrive manually all day long with HP Tuners. Hopefully just an internal pressure switch problem that is sending the PCM a signal it cannot compute and thus forcing limp mode.

Why dread it? If they made it that long stock it won't take anything special to make it whole again. My dually's trans needs to be gone through, I can tell it has pump to forward hub bushing wear, the overrun clutches are gone, and so is the intermediate band. It's going to get a fairly basic rebuild, maybe high energy clutches, upgraded sprag, and a shift kit. I can't think of anything more it could possibly need. It's had a supercharger for over 100k of its life and lived for 80k as a work truck before coming to me and grossing over 20,000#. I'd say these trannies are pretty damned stout.

 

[PlayingWithTBI]

Numbers matching LS-7 from a '70 Chevelle? Wouldn't that be an LS-6? I thought that era's LS-7 was crate-only

Duh , you're right, the numbers matching engine was a 365HP 327 out of a 'vette sitting complete is his assembly room. A 327 short block was waiting final assembly too. He had engines in various stages all over the place - a couple F4s and even another TBI block. He said a lot of his jobs were restoration ones.

 

[L31MaxExpress]

Why dread it? If they made it that long stock it won't take anything special to make it whole again. My dually's trans needs to be gone through, I can tell it has pump to forward hub bushing wear, the overrun clutches are gone, and so is the intermediate band. It's going to get a fairly basic rebuild, maybe high energy clutches, upgraded sprag, and a shift kit. I can't think of anything more it could possibly need. It's had a supercharger for over 100k of its life and lived for 80k as a work truck before coming to me and grossing over 20,000#. I'd say these trannies are pretty damned stout.

I agree they are stout! However the Yukon was only showing a delivered torque output of 488 tq @ 4,500 when something let go during the pull. My 8.1L shows over 550 tq @ ~3,000. The 383 in the van shows over 500 tq @ 3,000 as well. So both of mine should be over the input torque that resulted in whatever happened to his.

I have another buddy that is having such bad luck with the 4L80E in his 454 4x4 crew cab dually we have considered using a P59 with the Allison trans segment from the 8.1L to control an Allison. He is planning to Duramax swap the truck anyway and an Allison swap now will make that easier in the future.

 

[tayto]

I agree they are stout! However the Yukon was only showing a delivered torque output of 488 tq @ 4,500 when something let go during the pull. My 8.1L shows over 550 tq @ ~3,000. The 383 in the van shows over 500 tq @ 3,000 as well. So both of mine should be over the input torque that resulted in whatever happened to his.

I have another buddy that is having such bad luck with the 4L80E in his 454 4x4 crew cab dually we have considered using a P59 with the Allison trans segment from the 8.1L to control an Allison. He is planning to Duramax swap the truck anyway and an Allison swap now will make that easier in the future.

Aren't you close to Jake's performance? maybe give him a try?

 

[Donald Mitchell]

Duh , you're right, the numbers matching engine was a 365HP 327 out of a 'vette sitting complete is his assembly room. A 327 short block was waiting final assembly too. He had engines in various stages all over the place - a couple F4s and even another TBI block. He said a lot of his jobs were restoration ones.

Talking about those 327's, I used the L79 350hp 327 cam in a car I had, 4spd headers and carbs but mostly stock. I really liked it, reasonable torque and it would wind as far as it could go and still got 20mpg on road trips.

 

[PlayingWithTBI]

I just got the quote for my engine rebuild. The machine work seems reasonable, so does the parts and assembly. After all is said and done ~$4300 total for a complete motor, a little more than I wanted to spend but, I understand why he wants to do the whole thing.

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Any comments, suggestions?

 

[Drunkcanuk]

Price of not doing an LS swap...... priceless!!! Lol