[bob macey]

I have a 72 sport conv. Is this 350 2 barrel engine worth trying to get 300 hp out of or should I look for a 400 or 455 engine for this car.Would I have to modify many other items on this car to make this switch. Also how rare is a 72 Lemans with a GTO front end.Should I swap front ends or restore both cars as is .

------------------

[bob macey]

I have a 72 sport conv. Is this 350 2 barrel engine worth trying to get 300 hp out of or should I look for a 400 or 455 engine for this car.Would I have to modify many other items on this car to make this switch. Also how rare is a 72 Lemans with a GTO front end.Should I swap front ends or restore both cars as is .

------------------

[Dan Jensen]

Bob,
I'd replace the 350 with either a 400 or 455, and stick the original engine in a corner somewhere, protected from the elements. You'd have to spend more money, over and above the rebuild, to get the 350 to run at the same level as either a stock 400, or 455. Both the 400 and 455, with little or no modifications, can easily put out 300 horses! Remember, there's no substitute for cubic inches! Plus either of these engines will bolt right in with no modifications needed.

There were 20811 "T-41" Endura Appearance Options installed on the 123737 LeMans built for 1972. That's about 17 percent, so they aren't all that rare.

As far as swapping the hardtop's GTO nose onto the convertible, that's your decision. It's your car, do what you want!

[bob macey]

Dan thanks for the reply. It would be nice to put a 455 in this conv. Are you sure this engine wouldn't need a bigger radiator, TH400,12bolt rear,heavier front springs.Any one out thier have an engine for sale, or ideas.I think I would have to put on the GTO front end with this engine.Thanks Bob ,up near Reno, Nev. [email protected]

------------------

[Maurice Hood]

Bob; on this same board under the "New! Pontiac performance parts for sale/wanted" 'joegio' has a 455 you might be interested in. Sounds like a good street setup!!!! Check it out.

[WillV]

Bob,
I have a great running 69 GTO 400 motor with 400 turbo trans and 355 open rear and includes the car too for $1,500. Car may be sold but if not watch for the ad to appear again under GTOs for sale. Thanks.


------------------

Will

[greg mcdonald]

don,t forget about the frame mounts on your car will be different so pick up a set of any 400 equiped lemans or gto and it will be a breeze

[Jack Peters]

Frame mounts will only be different for 455. Actually they are all the same but 455 is larger to handle more torque.

[PMDRACER]

I hate to disagree, but I transplanted a 455 into my '71 which originally had a 350 and I did not have to change the frame mounts.

Just get the motor mounts for a 455 equipped '71/'72 LeMans/GTO and it will slide right in.

Oh, and some things to think about:
1. The trans will need to be changed to a TH400 and the associated driveshaft.
2. The original radiator for the 350 was only a 2-row, (3 row for A/C cars) so a 4-row radiator will need to be substituted.
3. The factory 2-into-1 1-3/4 inch exhaust will have to be swapped to a set of duals.
4. The electricals will be the same, and the A/C will bolt up fine along with all the original accessories.

[PMDRACER]

As for your original query, I ran my original 350 for the first 19 years I had the car. I rebuilt the motor in 1990.

.030 over, TRW pistons, moly rings.
Stock crank (cut 10/10) and rods cleaned up.
Heads rebuilt with the original springs (they checked out fine), and a port cleanup.
Performer manifold
Holley 600 vac secondaries
Headers and duals
HEI
"204/214" camshaft.

This combo with a stock convertor and 3.23:1 gears with no posi ran a best of 15.02 at a little over 90 MPH. Using formulas of ET vs weight, that relates to 315 HP. No barn burner for sure, but would hold it's own against any ricer easilly, decent on gas, and never overheated. That combo ran for over 90,000 miles until I yanked it for the 455.

Those valvesprings btw had lived for a total of 199,980 miles when I yanked the motor!

[AG]

I have a 1972 LeMans Sport Convertible with the buckets, console, T41 option, 350 2bbl, TH350. I put in a 455 and didn't change a thing with the motor mounts, just got new ones. I did change to a 4-core radiator. I run RA manifolds with a custom bent 2.5" exhaust and Dynomax super turbo mufflers. I just have to replace the original open 2.78 rear with a 3.55 posi since I burnt off the right rear tire. Motor is a 0.030" 455, 7K3 heads with RAIV cam/Rhodes lifters, HO intake and Q-jet. More than enough power for a daily driver.

[PMDRACER]

AG -

But ya gotta love those 2.78 gears. Combined with 275x60-15 tires, 80 MPH was only 2600RPM!

[BenBen]

My '72 came with the 350 2bbl as well. I got tired of it not having enough "oomph" and transplanted a 455 on a serious budget. Didn't have to change a thing (even reused the 350 exhaust manifolds and worn motor mounts). It runs pretty decently too. The car came with the open 3.08 rear end and dual exhaust, so the 455 took advantage of that (75mph is something like 2400RPM). I wouldn't feel too bad about dumping the 350 if you want to go faster. It won't cost any more to do a 400 and won't cost much more to do a 455 beyond the initial "finding the motor" investment.

[PMDRACER]

The 3.08 open rear and the restrictive exhaust are probably about the only reasons that TH350 lives against a 455! LOL!

[AG]

PMD,
I like the mileage I get with the 2.78 rear, but it lays down too much smoke when I mash it and I'd rather burn off two tires at a time than one using a posi. I have the 3.55 rear, I just have to put it in.