CA-Legal-Vette

Besides HP, what are the main differences between the L26, L68 and L71 big blocks in the 1969"s?

ETM

Im far from an expert but from what I understand the L36 and the L68 are basically the same engine except for the 68`s tri carb setup..both had hyd lifters...and similar compression ratios..
L36 was rated at 390 gross HP..while the L68 was rated at 400 gross HP.
The L71 is a different animal altogether.Its the big mother..solid lifters..higher comp ratios...forged internels..435 gross HP..but was reportedly underated....probably closer to 450HP..

BarryK

other differences also but some of the main ones were:

L36 & L68 were hydraulic cam and lifter while the L71 was a solid lifter cam set-up

different cams between the motors

L36 had a single Holley 4-barrel carb / L68 and L71 had three Holley 2-barrel carbs

L36 & L68 had 10.25:1 compression / L71 had 11:1 compression

StickShiftCorvette

The L71 also had rectangular port heads with bigger valves. It was a MUCH more serious engine than the other two.

PRNDL

Qjet in 68 and 69 (It was a Holley in 67 and earlier)

BarryK

sorry......
I had two sources of info. One said Holley, the other said Q-Jet so I just picked the first one. My main point was that it was a single 4-barrel carb rather than than the 3x2 setup but thanks for the correction

CA-Legal-Vette

Interesting. Aside from my interest, my reason for asking is that I've looked at a number of these recently and only one had the three carb system still in place. Was this a troublesome or hard to tune setup? Seems that most that I've looked at have long since been removed.

ETM

Some people have told me it is a challenge to tune them...I know an owner of a 69 that ditched the tri carb setup for that reason.Properly tuned though it is very smooth.

Corey_68

It's much easier with progressive linkage.

big_G

My 435 carb. set-up works fine. Just remember you're tuning 3 carbs, not one...

BarryK

the single 4-barrel carb set-up offers better performance. The tri-powered setups were simply a marketing idea. It was "sexy" so it sold.

Perfect example is the L88........ a single carb setup, produces more power so it was used.

Ironcross

Nothing wrong with a tri power unit as long as no one trys to improve them with other than factory vacuum linkage. One notable very important difference in the BB "L" engines is that only the solid lifter high HP engines were 4 bolt mains, all the rest as low HP hydraulic cammed versions were only 2 bolt whether single 4 bore Quadrajet or tri powered.

wildman378

My dad used to own a tripower 69 435 he has told me the same thing about it he hated the 3x2's he likes his l36 he has now much more.

for your 435 guys if it thats much trouble just throw a whooper 1x4 holly on it and just save the 3x2's thats what I'd do.

ETM

I had a chance to compare 68`s tri power and single 4 barrell.They wernt mine so I didnt ring them out but in just fairly aggressive driving the tri power seemed to have better throttle response.Almost like FI..

That was just one instance and it may have just been a anomaly.