Upgrade to Crate engine HP?

[k-nuts]

1970 Jimmy 4x4 2.5” all spring lift 33” tires. New thread, since different question.

The turn key zz6 405hp GM crate motor is at my top end of my engine upgrade budget. But is that too much HP for stock driveline??? I would have 350trans rebuilt to handle. Have Stock 205 xfer. Stock axles and driveshafts. Haven’t verified gear ratios and if the spid mentioned “posi” is still in there. At a minimum new joints/shaft.

Not planning on any crazy muddying, rock crawling or racing. But also don’t want to be sitting on the grenade scared to push the pedal ��

Also Not wanting to chase parts for axle swaps, LS conversions, etc. Looking to put crate engine rebuilt trans and drive.

Reason for zz6 was the heads and being roller cam & lifters and of course the extra HP I know I could save $ possibly having something built or getting a different engine and changing cam etc but I don’t have a relationship with a machine shop. And like the warranty on the GM crates.
Free time is what’s limited.

Thanks

[SeventyOne]

Originally Posted by k-nuts

1970 Jimmy 4x4 2.5” all spring lift 33” tires. New thread, since different question.

The turn key zz6 405hp GM crate motor is at my top end of my engine upgrade budget. But is that too much HP for stock driveline??? I would have 350trans rebuilt to handle. Have Stock 205 xfer. Stock axles and driveshafts. Haven’t verified gear ratios and if the spid mentioned “posi” is still in there. At a minimum new joints/shaft.

Not planning on any crazy muddying, rock crawling or racing. But also don’t want to be sitting on the grenade scared to push the pedal ��

Also Not wanting to chase parts for axle swaps, LS conversions, etc. Looking to put crate engine rebuilt trans and drive.

Reason for zz6 was the heads and being roller cam & lifters and of course the extra HP I know I could save $ possibly having something built or getting a different engine and changing cam etc but I don’t have a relationship with a machine shop. And like the warranty on the GM crates.
Free time is what’s limited.

Thanks

An upgraded trans would be all you need. NP205 is bulletproof. 12bolt rear axles are solid as well. Your Dana 44 front axle shafts are likely the weak link in 4wd but ought to handle the 33" tires.

[DeadheadNM]

What’s the present gear ratio? 3.73 might work well with the combo.

[k-nuts]

Originally Posted by SeventyOne

An upgraded trans would be all you need. NP205 is bulletproof. 12bolt rear axles are solid as well. Your Dana 44 front axle shafts are likely the weak link in 4wd but ought to handle the 33" tires.

Thanks. That was What was I hoping. I ran 39’s on my 1990 K5 back in the day. All stock drivetrain except auburn unit and 5.13’s. Wasn’t advisable, but I was i was on a student budget. Pretty sure they were 8.5” 10 bolts.

Originally Posted by DeadheadNM

What’s the present gear ratio? 3.73 might work well with the combo.

Not sure, I need to check! Thanks

[Sand Wrench]

You might consider the HT383 as well, it will make better torque in the lower RPM ranges. You'll have to wrap that ZZ6 up to 5000-6000 RPM to really take advantage of all that power.

[hemi43]

Make sure to budget for EFI. Carbs are good for wheel chocks, IMO.