[sisco]

Hey all. I recently bought a 73 Ventura with a 350 and it does run great. I remember a friend of mine when I was 18 who had a 73 bird with a 455 his uncle put in that came out of a Safari wagon. That Firechicken was awesome. Anyway I was talking to one of my friend who put me on to a 70 Bonneville that is supposed to have 53,000 original miles and the 455. I went and seen it and its been sitting since 84. The guy who owned it is dead. His wife sold it to me for 500 bucks and it seemed to be locked up. I figured I could get it and have it bored and redo the motor and get a couple of hundred back outta scrap weight. I got it home and was checking the motor out and the belts on the motor were so crusty and the were stuck to the crank pulley. I cut them off and reached down and just tried to move the crank and it did. Amazing! I changed all the points plugs wires and oil and run gas out of a can and it fired right up and really never smoked a lick. The carb float stuck and it poured gas out top but I got that straight.I think this motor is supposed to be 360 hp from what I researched. The heads are stamped 15 in the middle of the exhaust port and the numbers by the distrbutor say the block was cast in sept 69. Am I wrong or is this a 360 hp motor. Im thinking of just cleaning up the motor and changing front/rear seals and dropping it in the Ventura. I read so much and swapping heads on these 455s and Im kinda comfused. Do I need to swap the heads if this is a 360hp motor, or the 15s good for enough for this motor. Ive built a couple of SBF engine but Im really not familiar with vintage Pontiac. Im trying to get a good street motor to play with but I definitely dont want to ruin this 455 as it appears they are hard to come by like this. Sorry for being longwinded and I appreciate the help.

[J_JAMNIK]

Drop it in as is, break it back in slowly, and see how it does. Don't fix it if it aint broke!

[Will]

Agree with above - put it in your car and see how it runs.

The #15 heads are small-valve pressed stud heads that will make about 10:1 compression on that 455. So, they are not the highest performance heads you could be running, but that engine was designed to make LOTS of torque to haul that big heavy car around. Put it in your lightweight ventura and it should haul ass as-is.

If you find you need more power after running it for awhile then you can think about head and cam swaps.

Sure wish I could find a 53K mile 455 for $500...

[sisco]

My friend said I should change out the freeze plugs first as they may be rusty from sitting. The Ventura also has a factory 3spd on the floor and Im not sure but I think the rear has around 350 gears as it seems pretty would up at 70. I dont want to over rev that 455. Should I take those gear back to 308s or whatever pontiac had like that. Maybe the gears out of the Bonneville will swap in but it was a turbo 400. Im super stoked about seeing this big beast pull the Ventura.

[Will]

Changing the freeze plugs wouldn't be a bad idea, and not that hard to do.

The gears from the Bonnie won't swap into the Ventura rear end, they are different types of rears. 3:55 gears would be a bit much for that engine. As you've guessed, it's a low RPM torque monster and won't want to rev past 4800 RPM or so the way it's setup currently. A swap to 3.08 gears would be perfect, even 2.73s would be good.

The '73 Ventura uses the same rearend as the Novas from '73 - '75. The spring spacing is the same as Novas from '68 - '79 but prior to '72 they used the weaker 8.2" rearend. I'm not sure what changed in '76 but the Hollander interchange manual doesn't list the '76 - '79 Nova rear as a direct swap. Not sure why, maybe as simple as a different U-joint. Anyway, most Novas, especially 6-cylinder models came with 2.73 rears, some with 2.56s and some with 3.08s. It shouldn't be hard to find a 3.08 or 2.73 rear out of a Nova and if you get one of the '72 - '79 units it'll be the stronger 8.5" rear.

[Kitch428m21]

Cool deal. Like hearing these stories. Hey, when you plant the torque monster in, put one of those 'Turbo' emblems on the back like the Hondu guys do. That way when you're roasting every ounce of rubber on the rear tires, you can leave them in AWE!

[runningbwdog]

Hi,
I have a 70 YC 455 in my 68 GTO. It has cast #15 heads. I put a comp cam XE268 in it. Car has a M20 4-speed and 3.55:1 diff. Plenty of low end torque. Pulls fine to 5200 rpm. Got it for $300 aircleaner to oil pan pulled from a Bonneville and dropped in the bed of my pickup truck. Had it completely rebuilt for the sake of durability.
Should work fine for you.
Mike

[BruceWilkie]

Are you planning on using the T400 with it I hope? That 3 speed isnt going to take a lot of punishment. You will need a diferent crossmember and a trans cooler to run the T400 though. You could stay with a stick and use a 5 or six speed manual with overdrive vs the gear swap. Lots of possibilities here depending on how you plan to use the car.

[sixt8bird]

I have a 1970 455 that also had 15 heads, It is a 4 bolt main block. Yours could be also. Great score. Those heads are great as the compression is right where you want them. They are small valve but you wont need to rev that 455 anyway.

[Jeff Walker]

Originally Posted by sisco

My friend said I should change out the freeze plugs first as they may be rusty from sitting.

Absolutely change them. And while you are at it I would also suggest changing the timing chain and gear to eliminated the original plastic gear that Pontiac used.

That was one of the few weaknesses that Pontiac V8's had.

[n2ogpsj462]

wouldnt make any sense not to pull the pan and change the gaskets. also you can get a look in the pan for any metal etc. when i first bought my grandprix in 2001 it had ,coincidently, been sitting since 84. even had 84 inspection stickers. it ran AWESOME......... for about a month. then started knockin. i did all the precautionary things you should for a motor thats been sitting but if it sat too long the journals could have gotten dry and even moisture creatin surface rust. not too sure about my deal but when i pulled the pan it was full of crap. with the pan off i would might even pop a cap or two off and see what you have.

[sisco]

I like the manual but Ive always been told that you can outshift a auto trans and I know the turbo 400 was a good tough trans. However the car is an original 3 spd on the floor. Im going to go ahead and pull the oil pan and check the bearings and swap the oil pump. I may also put a cam in while its there. It sure does sound solid and I can see the motor twist hard in the mounts when you rev it. You can tell it has plenty of power as it is. It probably better to go ahead and make sure its ready for the long run before I install it. Ill keep you all posted as I get it going. What are some good streetable cams that would work good with these stock heads. I saw a set of 6x heads at the scrapyard. Would they be better or will they put my compression too high. Thanks for all the great help and advice.

[BruceWilkie]

The 6x will lower compression but are not a bad choice as they have a larger intake valve and screw in studs. With some milling and port work excellent on a street bound 455.

[n2ogpsj462]

you also have to be careful with your compression on todays gas. 10:1 with irons heads and todays crap is borderline area. make sure your tune is pretty good.

[pontorquer]

I would check the compression too since those piston rings have been sitting for so many years. The 6X #4 from 350 or 78 W72 400 TransAm are an excellent choice atop a 455. I too found a 70 Bonneville with the mighty 455 in it, but the engine became a bucket of rust from sitting in a field without a distributor and a carburetor ! When I pulled the dipstick ( real hard that is ) It broke inside the block so I offered 200$ to the guy and he wouldn't take it or sale me any engine parts from the car, like the timing chain cover, brackets, balancer and intake. The only thing I could have save from that motor would have been the crank and caps ?

[1971WARBIRD]

if you are going to replace the oil pump(i think it's a good idea)check with butler or one of the other dealers(p-dude,pacific performance.....) and get the better oil pump shaft.it's cheap insurance at about 15.00.

[YVEYANT]

Drop a cam in there while we all have you tearing it apart...

[BruceWilkie]

Wait on the cam till you port those 6xs and get an RPM intake and Dougs headers and whatever else we can think of to spend YOUR money on!

[1971WARBIRD]

Originally Posted by BruceWilkie

Wait on the cam till you port those 6xs and get an RPM intake and Dougs headers and whatever else we can think of to spend YOUR money on!

isn't it fun to spend someone elses money.

[LOPEZ5]

You did the same that I'm about to start doing. My find was an 86,000 mile '70 Bonneville with a YH 455. I plan to drop it into a '72 LeMans Sport along with the TH400 tranny. Let me know how it turned out, and what you ended up adding, replacing, or keeping.