Engine Replacement

[Maverickrc]

I'm thinking of pulling out my L81 and replacing it with an L82. I was told that the L82 would work, because of it's low compression, but would need a torque converter. My questions : Has anyone done this? Would I have to replace the transmission? Is this a good idea? Thanks in Advance, Mav.

 

[BarryK]

what year L82?
I have the L82 in my '78 and it's not that powerful of a motor to say the least............
if you are doing it to get more power and performance you may wish to either drop in a crate motor which will give you a lot more power or just do some modifications such as cam, headers, better intake, etc on your current motor.

 

[Dave L.]

http://www.crateenginedepot.com/store/350CI290-HP-HO-Engine-12499529-P824C0.aspx
I'd would consider this engine or the 12486041 330 HP engine from GM.

 

[teemar_99]

I recently replaced my L81(Old Tech) engine with the GM Universal 350 crate motor. This is as much power as the L82 with very good bottom end. With Gas prices I was looking for an engine to run good on 87 oct, and fit the budget. You can get one for less than $1600.00 delivered. It's not a 300plus horse power monster, but it still is fun to drive. T

 

[herron]

My '81 has the original motor, but the previous owner modified it by removing the computer and fuel injection, and replacing it with an Edelbrock 4bbl. It runs well, and I have no problems with it...but I was wondering about switching out the original 3-spd auto trans for a newer 4-spd auto.

What are the do's and don't of doing that, and would I be better off just to wait until I can afford to drop in a whole new crate motor (when-and-if this one acts up)?

 

[craig32]

Maverick,
The previous owner of my 81 replaced the original engine with a Jasper rebuild of a 79 L82 and it works just fine. I don't know what differences there are in torque converters that you would need a different one.

Herron,
Your original engine didn't have FI, it wasn't available until 1982.

Craig

 

[Maverickrc]

Replacement

Thank you everyone for your replies and opinions....I appreciate the feedback.

My situation - current stock engine w/ 52k, has some bad compression problems in a couple of it's cylinders. Vette has been sittin' in garage for over 8 years.

I've been shopping around and thinkin' of purchasing a rebuilt performance modified L81 for about $1600 that pushes just over 300. Free shipping and the mechanic that will install it will charge(worst case scenario) $1300.

These are the best prices that I could find and don't sound too bad after shopping around...we'll see.

 

[Jack]

Brand NEW ... not rebuilt ... from GM ... Goodwrench "universal" 350 ... about $1500 at your local GM dealer ... best warranty out there: 3yr/100K mile GM warranty ... GM part number is 10067353. Makes about 250-260 HP. The motor is a virtual equivalent to & specs out about same as early 70's L48. MANY've installed x353 & most very pleased ... best value out there, bar none! If you want more power you will not get near as good warranty. BTW, $1300 is WAY too much to R&R a C3 sbc ... half that is plenty.

*edit* ... that x529 290hp motor that Dave L. references ... with sole exception of a bit bigger cam (similar to L82 cam) it's EXACTLY same motor as x353. x529 makes about 30-40 more hp than x353 ... costs about $200-$300 more ... but has much less GMPP warranty (1yr/12K)... all because of a cam you can buy for $75. Both x529 & x353 are good motors ... just depends on what matters most to you.

 

[mvftw]

Jack, I agree with you that $300 is a lot just for a cam. But if you put a new cam in the 260hp motor you will lose the warranty (I think)... I'm in the same boat or vette, my '78 L-82 goes through 1 qt / hour... I'm thinking of either the 260 or 290, I agree they are of great value. I my get the 260hp, drive it for 3 years, then decide on a cam change...

 

[herron]

Maverick,
The previous owner of my 81 replaced the original engine with a Jasper rebuild of a 79 L82 and it works just fine. I don't know what differences there are in torque converters that you would need a different one.

Herron,
Your original engine didn't have FI, it wasn't available until 1982.

Craig

Thanks, Craig...I'm assuming then, that just the "computer" was removed.

Sounds like there are many options for replacing the motor, should the need arise. I assume (not being a mechanic at all) that the 4-spd auto is no problem, either? Thanks for all the input.

 

[Maverickrc]

2-Bolt/4-Bolt?

Question - What does the 2-bolt/4-bolt engines mean? Are those mounting bolts?

 

[Art Jett]

Reffering to either 2 or 4 bolt main bearings.

 

[Jack]

Reffering to either 2 or 4 bolt main bearings.

Right ... the number of bolts the 3 center main bearing caps have. If you're making less than about 400 hp and not spending much time at track ... 2 bolt 350 is more than enough. FYI ... all OE production GM 350 blocks have 5 main bearing locations. OE production GM 350 4 bolt blocks have 4bolt caps at only the 3 center mains ... with 2bolt caps at front & rear mains. OE production GM 350 2 bolt blocks have 2bolt caps at all 5 mains. Some aftermarket 350 blocks have 4bolt caps at all 5 mains.

 

[Jack]

But if you put a new cam in the 260hp motor you will lose the warranty (I think)

Me thinks that's likely.

 

[Dave L.]

Jack, I agree with you that $300 is a lot just for a cam. But if you put a new cam in the 260hp motor you will lose the warranty (I think)... I'm in the same boat or vette, my '78 L-82 goes through 1 qt / hour... I'm thinking of either the 260 or 290, I agree they are of great value. I my get the 260hp, drive it for 3 years, then decide on a cam change...

definitely voids the warranty.