1968 Pontiac Bonneville

[yourgrandma]

I remember one night I wound up next to a Bonnie the same body style as yours but it was pretty ratty. We basically went like 12 stoplights in a row just eye humping eachothers cars and letting them run a little. It was like a scene from a movie.

[94SilverSSEi]

The way it sits now an L67 would probably leave this car in the dust.

It needs some TLC. On a side note: I'm surprised how cheap a lot of replacement parts are.

Practically everything is half the price or less of what it would cost for my 90's bonnevilles.

Performance parts is where it starts getting expensive.

[66bonnevillechris]

Hey, that's a nice clean 68 4dr ht! The photo you showed is a 69 bonneville. 14 inch wheels make buying tires a challenge- get a set of 15 inch wheels for lower cost tire solution.

Don't know what you paid for it but its a good car...enjoy it. You won't see another like this at your local cruise.

[94SilverSSEi]

Hey, that's a nice clean 68 4dr ht! The photo you showed is a 69 bonneville. 14 inch wheels make buying tires a challenge- get a set of 15 inch wheels for lower cost tire solution.

Don't know what you paid for it but its a good car...enjoy it. You won't see another like this at your local cruise.

Yeah, it's a decent car. Needs some work but not too far gone. And yes 14 inch tires were a challenge but I happened to snatch some up that were on blowout super clearance They only had 4 left.

Ended up getting all 4 installed, balanced and with road hazard warranty for like $450 I think it was.

They were actually for a late-model mini-truck but they are the same car. Michelin LTX. I like them quite a lot.

[94SilverSSEi]

Poor car blew a brake line (I think)


When to move the car put foot on brake to shift gear, and the pedal goes down.

Funny this is the brake light comes on but only when you really pushed the pedal down alot.

And the brakes still work but have very little power.


Hopefully this will be a winter project.


Anti-rust, pulling motor, new exhaust, new shocks and a lot of body work will be in order.



EDIT: Also, need a little advice. There has been some clunking going on. (Dad complains the tranny needs to be rebuilt......ok....)

I have driven it in a while but it was when you were going along just kind of coasting or not needing much throttle, when letting off gas and hitting the gas again. You'd get a clunk/bang.

Things that come to mind are torque converter, U-joints or rear end??

[00Beast]

U joints or rear trans mount.

[94SilverSSEi]

Reviving this ancient thread...

Anyone have ideas for a new exhaust on this car? We will be keeping the stock exhaust manifolds and no performance upgrades to the motor at this time.

I thought of just running new piping and a muffler but dad wants true duals (which will cost more).

Any ideas if I could find a kit or piping and doing it myself or be better off just taking it to an exhaust shop and telling them what I want done. Aside from the manifolds the rest of the exhaust is absolute junk.

[94SilverSSEi]

Digging this up from 6ft under. And you thought I let her die

So I will finally be getting around to giving her an overhaul this summer. The exhaust is complete junk aside from the manifolds. So I'm wondering penny for pound what will net me more power? Doing some type of intake/bigger carb? Or going with headers?

Dad wants headers but I can swallow that $800 bill.

Obviously the rest of the exhaust will have to be replaced one way or another so not too worried about that.

This will be a budget build so any ideas are more than welcome!

[1oldman]

Digging this up from 6ft under. And you thought I let her die

So I will finally be getting around to giving her an overhaul this summer. The exhaust is complete junk aside from the manifolds. So I'm wondering penny for pound what will net me more power? Doing some type of intake/bigger carb? Or going with headers?

Dad wants headers but I can swallow that $800 bill.

Obviously the rest of the exhaust will have to be replaced one way or another so not too worried about that.

This will be a budget build so any ideas are more than welcome!

Fastest and easiest way is to rebuild the carb. Have it re-rodded, and re-metered. Use to be the first thing my dad would have done every time he bought a new Chevy pick-up (like every 3 or 4 months) back in the late 60's and 70's. It was like an entirely different vehicle. Just make sure that it really is a QuadraJet guru doing the work. I still think it was the best street performance carb ever designed and built. Not finicky like the other carbs. All it really needed added was double dash pots. jmo - BC

[MattStrike]

Headers.

If you want a bigger carb there is a fairly common 850cfm Q-jet that you can usually get cheaper than aftermarket and you don't sacrifice fuel economy.

An aftermarket intake isn't going to do much other than shifting the power band, weight savings and aesthetics until you get into a cam/heads/compression. You would get more out of port matching and polishing the OEM intake, a dual plane unit that can flow enough for a 455.

[94SilverSSEi]

Headers.

If you want a bigger carb there is a fairly common 850cfm Q-jet that you can usually get cheaper than aftermarket and you don't sacrifice fuel economy.

An aftermarket intake isn't going to do much other than shifting the power band, weight savings and aesthetics until you get into a cam/heads/compression. You would get more out of port matching and polishing the OEM intake, a dual plane unit that can flow enough for a 455.

Already have a stock 4 barrel Q-jet not sure if it is the 750 or 850 though? Also, are headers worth the "bang for the buck" so to speak? Only ones I can find that should fit: Natural ones are $636 and ceramic coated are $810. Seems like a lot of money.

And they say they only fit floor shift cars. I have a column shift, I don't see what difference that would make?

They also mentioned this:

93 - Requires removal or modification of locking steering columns if equipped.
104 - Some factory heads do not have end bolt holes and should be drilled and tapped to assure proper sealing.

[CMNTMXR57]

I had not seen this (I had seen you had one in your signature). THIS is worth something!!! I heart me old Pontiac's! This one is beautiful.

Have you looked into PYPES (Performance Years Performance Exhaust Systems)?

But otherwise, just take it to any good exhaust shop and they can fab up something completely custom and let you chose your own choice in mufflers as opposed to taking a pre-packaged setup.

I have a good place in Naperville if you're interested in the trip.

[94SilverSSEi]

I had not seen this (I had seen you had one in your signature). THIS is worth something!!! I heart me old Pontiac's! This one is beautiful.

Have you looked into PYPES (Performance Years Performance Exhaust Systems)?

But otherwise, just take it to any good exhaust shop and they can fab up something completely custom and let you chose your own choice in mufflers as opposed to taking a pre-packaged setup.

I have a good place in Naperville if you're interested in the trip.

Maybe, here's the question though. Any idea on price? Haven't seriously shopped around yet as I don't have the cash. But the headers seemed absolutely outrageous. You can get a set for a GTO for $200 but the Bonnie is $630? What's wrong with this picture? One shop I stopped at said $650 to custom fab true duals. (That does not include new headers or manifolds).

There is NO WAY I'm dropping $1500 on headers and a custom exhaust, sorry. That's about what the car originally cost. I think I mentioned before, just want to improve the rusted pile of garbage I have now that is considered an exhaust system, don't need anything extravagant.

I'm thinking the best way would be stick with the stock manifolds and then get a whole new exhaust run from there back.....

[CMNTMXR57]

Hard to say. But I would wager anything you make is gonna get costly pretty fast. I would say the $650 post-headers would be pretty close, based on a high quality stainless for the plumbing (if you start doing an "X" pipe or "H" pipe, it's more stainless so more $$$$, good set of mufflers (especially if you go Magnaflow), and any tips.

Is the plumbing itself that is on there, still good? If so, you could just put in a nice muffler to get some better sound.

[94SilverSSEi]

Here's the current setup. Stock manifolds have at least 1 or two bolts snapped off in each head. Then the Y-pipe. Where the pipes connect together one side of the Y is smashed almost completely closed and the other side of the Y has a big hole rotted through, plus it wasn't welded properly so has major leakage. The rest of plumbing is probably "ok" but its very old. And then the muffler, the car died and filled the muffler with raw gas and then restarted so currently the muffler looks like the Michelin man.

So you can see why I wanted to replace it all.

[Sirius]

In my opinion, forget the headers, keep the stock manifolds, and get the exhaust system replaced. You're not going to see noticeable performance gains merely from a set of headers unless you modify the engine as well. Get the carb rebuilt & jetted properly and tune the engine. That would liven it up more than headers.

[CMNTMXR57]

I think the concern is, if those 1-2 bolts are snapped off, are they providing enough sealing force to keep the manifold properly sealed to the head? If not, it's gonna have to get removed anyway, and then the broken ones drilled out and re-tapped. So while you got it off, seize the opportunity.

I think the issue as to why headers are so expensive, even though both the 389 and the 400 Big Blocks (what you have, right?), use Pontiac's unique head, it doesn't have a traditional setup like a Chevy BBC in that the header doesn't have a full length flange plate. The head itself sort of has a pre-header extending from the head, then the manifolds or headers run almost straight up to it, and the front cylinder, the two middle, and the last, are all on their own flange. Meaning, they're a little more complicated to fab up. Just my thoughts though. Not sure why.

I'm gonna go through all this pain when I start restoring my '66 with it's 389.

[94SilverSSEi]

Yeap, I have the 400 engine. BUT, its not a big block or a small block (like the Chevy's). The block for the Pontiacs is in between sizes of the SBC and BBC. I guess it could be considered a "Pontiac Big Block"? They used the same block for the 326 all the way up to the 455. You probably knew that, though.

You do have a point with the exhaust design. But what makes me crazy though, is I can order a set of headers for a GTO, which has the same engine for $200ish, why should ones for a Bonneville cost $600+. They aren't high demand like the GTO so you'd think they would be cheaper.

Yeah the car is hopefully going to get a mini-overhaul this summer. Plan on pulling the motor, probably eliminate the AC as it doesn't work anyways and is a pain in the ass the way the bracket is positioned. Regasketing everything, new shocks, exhaust, brake lines. Pretty much whatever I can do that is cheap parts wise, most of it will just be labor intensive. Which I don't mind as I've got a lot more time than money at this point.

BTW, the carb was rebuilt. Scratch that, that was 4 years ago, meaning I would have been 17 at the time so..... It has been sitting most of the time after that. My dad did put about 4k miles on it that first year. Didn't have any manual or anything just the crappy directions that came with the rebuild kit to be able to tune it.

Another thing, which I assume is a Carb issue. It doesn't like to start right up. Usually have to pump the heck out of it, multiple cranks, then she'll go.

[CMNTMXR57]

Right in that it isn't an SBC or BBC according to Chevy standards, just that it has always been referred to as a Big Block because the bore was >4" if I recall. 4.062" is the bore I believe for a 389 and 4.12" on the 400.

It is a small journal engine though (3"). The 421+ were the big journal engines (3.25").