chevy Big block into 69 GTO?

[pestkiller05]

will a chevy big block fit in to a 68 or 69 GTO??
468ci

thanks

[marc-o-matic]

Yes the gto is just like a chevelle

[MrPbody]

Yes AND no. The GTO is NOT "just like" the Chevelle, but does share many of the components. To put the Chevy in there (why in the world would you ruin a perfectly good GTO?) the wiring harness must be replaced or modified, as all the electrical underhood stuff is on the wrong side on the Chevy(starter mainly, alternator, etc.). The engine mounts are different, requiring the Chevy pads. The transmission bellhousing is also different, requiring a change of tranny or an adapter. The front springs must also be replaced, as the BBC weighs about 200 lbs. more than the Pontiac V8.

The end result will be a very expensive car that may or may not outrun the Pontiac in a straight line, but will not handle anywhere near as good as it used to. The BBC creates so much nose weight, the car's geometry is no longer correct. Be absolutely certain to install disc brakes up front if not already equipped.

Be sure you understand this: Small block Chevys are less expensive to build at the lower and mid-levels than most other engines. BBCs are NOT! They are actually, among the more expensive engines to build "right". BBC, while a very good powerplant, is very heavy, comparitively speaking. Adding aluminum heads is VERY expensive (more than an aluminum headed Pontiac). If a street car, power will be compromised to make it drivable. "Drivable" is a subjective term, no doubt. But to make the same level of usable power at street speeds and on "pump gas" (93 octane), a BBC needs a WHOLE LOT of attention in the heads and valve train, where the Pontiac does not.

It's true, I'm a "Pontiac bigot". BUT... It doesn't come completely from "emotion". It comes from experience and driving. After 30-plus years "in the business", I've seen and driven at least one of everything. That era of GTO is among the best balanced performance cars ever, and certainly the cream of the late '60s "crop". Don't fall for the old addage "You gotta use a Chevy to make a Pontiac run". We have MANY customers with pump-gas Ponchos running deep into the 10s (in street "trim") and many, many more that go mid 11s all week. One is hard-pressed to make a 454 do that on 93 without any power adders, and still be able to actually DRIVE it somewhere, especially in a 3,500 lb.-plus car. Of course it can be done, but at what expense?

Please note, this is not my opinion. These are true facts about what is being done today, regardless of all the old myths and superstitions.

In parting, I'll say, if you DO put the Chevy in there, more power to you. But be prepared to hear a raft of negative comments from Pontiac owners, and many challenges to race it against Pontiac-powered Pontiacs. The days of a 13 second GTO are far behind us. If you aren't at least in the 11s, stay home...

You build what you like. My ego is not involved here. Just don't surprised if my words turn out to be true!

Jim

[maxwedge]

Seconded, well stated and true!! ( From a Mopar guy too)!

[phillipshaffer]

I have a 69 GTO with a 572 Big Block Chevy motor in it !!!, Best thing
i ever did, Took My pontiac engine everywhere, In south Florida no one could build a decent engine , I spun a bearing Twice in it , Had it rebuilt twice, Pontiac motor will not take the RPM that a chevy will, And yes I am a PONTIAC BUFF !!, The pontiac motors run great. They are torque motors that put out good horsepower, But what you can do or buy out there that is chevy , and will put 450 to 600 hiorse power to the wheels is no contest.
Have matching number to car, Yes I know what it isworth with orig. motor versus chevy in it !!. But I have a heavy foot. I have gone through enough 400 motors in my life. 455 cranks in them , The hole ball and wax.
I baught a motor off craigs list, 2800 dollars , 572 chevy Brodix heads (alum) Eagle crank and pistons, Changed motor mounts and Trans , rest of it bolted in and was on motor , changed harness undewr hood , ran it other direction on firewall, It looks great , Is definately a much strongerrunning car. and I had RaM Air 62 heads Ported , and all the goodies on the Pont motor. No contest . Johny's cages built it once , It let go 5 grand down drain. Some jerk off down off 84 built it , Spun a bvearing wiuth under 500 mioles on it. wouldn't warranty his work , Not worth sueing, Solved the problem , Put a built Chevy in . and with the Aluminum heads , Its liter than the Pont engine was. And I love my pontiac. Chevy is easier motor to build , and it runs better.

[maxwedge]

As you can see I am a Mopar guy and ex NHRA record holder, but I am neutral about engine loyalty, first of all you got burned on the engine builds and I will assume that the shops workmanship was at fault. But even a really strong 455 would be hard pressed to out perform your fairly modified 572. That said it really isn't an apples to apples comparison between the 2 engines, I would think a big cubic inch Poncho with the right heads and compression/cam would be real close to the big block. MrPBody will surely jump in here as our resident Pontiac guy. I agree with the Poncho it is tougher to find a knowledgeable qualified shop to build power and reliability. BTW, welcome to AF, this is an interesting thread!!

[phillipshaffer]

Agreed I got very lucky with the motor and trans I found
On Craig's list the heads are worth what I paid for everything
Pontiac 455 and 428 are fantastic motors
Problem is they won't take high rpm
Chevy will and. In Florida all we have are Chevy builders
Pontiac is a different beast. Funny I almost
Purchased a 70 cuda. About a month ago at a
Government seizure auction the had 2 440 cars
And one hemi ( not a numbers car but all were gorgeous

Phillip

[wldman46]

you most likely didnt do the most important thing a pontiac needs as the factory didnt do a good job balance it.pontiac took the time to properly balance their 326,389 and 421's after 67 it was not a priority it seems.also align boring some reason every 400 has number 7 cylinder off a little.Ive seen blocks that didnt need to be bored just honed until u check number 7 also the first cylinder to have ring leakage(wear).nice to know if your looking for a used engine.455 must be internally balanced to take rpm's i also have the crank knife edged to lighten they are heavy as are the pistons,rods.thats one of the reasons for their large torque numbers.I understand your frustration not that many machinist with experience with these engines.Just wondering u said spun a bearing was it number 7-8.that offset bore causes drag which in turn seems to cause the big end of number 7 and 8 rods to need resizing.

[GTOHunter]

You can put a Chevy engine in Your Pontiac....it just lowers the value in my opinion!Save Your old engine if Your determined to change it in case You want to go back to original later on.Im a Pontiac Fanatic also and believe in keeping them Original but the choice is Yours in the end!

I like You MrPbody.....I hope to read more of Your in-depth Replies!

I have several Pontiacs,most 1969 GTO's,LeMans and a few 1966 Tempest etc....!