Author Topic: Pontiac 400-455 Questions and answers. Subthread  (Read 156213 times)

72blackbird

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #120 on: April 25, 2010, 07:48:41 PM »
If you're gonna 'ride the razor's edge' and run heads that will give you more than 10:1 SCR, you better run a cam that has more than 230 degrees @.050 to bleed off some of that compression. Even that is no guarantee you'll lower your DCR enough to be safe for pump gas, but in most cases it works. For all practical purposes 9.5:1 is the limit for pump gas.

Are you talking about the Lunati 30702?

Geno
1977 SE T/A (sold :( )
1974 455 T/A (sold :( )
1972 Esprit restomod
1976 T/A restomod
1975 Formula 400 4-speed donor car
1978 Martinique blue W72 4-speed T/A, hurst tops

KD9RG

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #121 on: April 26, 2010, 05:00:06 AM »
The number the Lunati guy gave me was 307A2LUN. Which one is better? Looks like the 307A2LUN meets your 230 degree requirement. Mike/KD9RG
1977 TA S/E

KD9RG

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #122 on: April 26, 2010, 10:04:53 AM »
Btw, there was an earlier comment about a missing mounting hole and known fix for that issue. What is the fix? Thanks MikeR.

1977 TA S/E

SolarGold78

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #123 on: April 27, 2010, 01:50:44 PM »
I am using 1968 #16 heads on my 400 with a Comp Cams 268H. I also have had the Q-Jet calibrated for my set up. I have no trouble running it on 93 octane unleaded. I am running about 38 degrees total mechanical advance + the vacuum advance. My gearing is 3.41:1. Hope that helps.

I fixed the missing mounting hole by welding a nut on the back of the bracket for the alternator swivel bolt. That bracket is solid enough and bolted down in enough places that it works fine.

ZDDP additive is a must with each oil change.

-Chuck
Engine code X8 head number 16

KD9RG

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #124 on: April 28, 2010, 06:13:34 AM »
I knew somebody out there had to be running this setup and I was hoping to find them. You have made my day Chuck. Thanks!!!! Mike/KD9RG
1977 TA S/E

Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #124 on: April 28, 2010, 06:13:34 AM »

KD9RG

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #125 on: August 30, 2010, 06:24:04 AM »
Hey Chuck, did you change the valve springs or did you use the original ones.  I am still trying to decide which cam to go with...looking at the Comp Cam 268H that you used and the Lunati 307A2LUN. Since your using the 268H and not having any issues I am really giving it a lot of consideration. Do you have the complete part number that you installed? Trying to get this engine assembled (it is now in a storage unit with the car) Before winter so I can move the engine to a heated building. Finally getting back to the project after a couple of months off and a removal of a wife. Mike/KD9RG
1977 TA S/E

SolarGold78

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #126 on: September 29, 2010, 01:14:48 PM »
Engine code X8 head number 16

KD9RG

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #127 on: October 27, 2010, 07:50:16 PM »
That is the kit I ordered and installed. Thanks


Mike,

Sorry I didn't see this sooner. Here is a link to the kit.

http://www.compperformancegroupstores.com/store/merchant.mvc?Store_Code=CC&Screen=PROD&Product_Code=K51-232-3

-Chuck
1977 TA S/E

KD9RG

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #128 on: October 27, 2010, 07:52:31 PM »
Chuck, What intake and carb are you using? I want to put the same  on my motor. Who calibrated the carb? Mike/KD9RG



I am using 1968 #16 heads on my 400 with a Comp Cams 268H. I also have had the Q-Jet calibrated for my set up. I have no trouble running it on 93 octane unleaded. I am running about 38 degrees total mechanical advance + the vacuum advance. My gearing is 3.41:1. Hope that helps.

I fixed the missing mounting hole by welding a nut on the back of the bracket for the alternator swivel bolt. That bracket is solid enough and bolted down in enough places that it works fine.

ZDDP additive is a must with each oil change.

-Chuck
1977 TA S/E

SolarGold78

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #129 on: October 30, 2010, 07:45:52 AM »
Chuck, What intake and carb are you using? I want to put the same  on my motor. Who calibrated the carb? Mike/KD9RG

Mike,

I have an Edlebrock performer and a Quadrajet. I got the carb kit from HO Racing Specialties. You give them the specs of your engine and for $75 you get all the parts you need to set the carb up and a very detailed instruction book. http://www.horacing.com/

-Chuck
Engine code X8 head number 16

KD9RG

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #130 on: October 30, 2010, 09:45:55 AM »
THanks for the info. I have to ask what could be a stupid question, but its really bothering me. You did not have any issues with the shaker did you? With my block being from a 1968, I am having to us a engine mount adapter from Classic Industries (https://www.classicindustries.com/firebird/parts/c269513.html). They assured me that I will not have any Shaker issues.
I am finally get back on the car. A divorce in the middle of a restoration is not a good thing. Car is totally disassembled, no front end or frame on it. Only thing left on the car are the doors and the truck lid. The rear axle has already been rebuilt and is back on the car. Body is going to be soda blasted in the next week or two and then it goes to my sons to be primed and painted. Trying to get engine closed up and will move it to a warm location for the winter. I have the cam and heads on it. Need to finish installing the push rods and rockers on one side and then I will be ready to put the valve covers on. Currently the whole nine yards is in a storage building. Frame, front suspension parts, hood hinges and other small items have been powder coated and are ready to be mounted back on the car. I have had enough of dis-assembly, dying to start putting this puppy back together. I have about 90% of the new parts I need to reassemble. Heading to Ft Myers in 2 weeks and I think I am going to drive over to Miami and visit Rick at Trans Am Specialties just to chat and take some pictures of a reassembled car. I am not to locked up about being totally accurate with the engine just due to the fact that it is not the original engine. I want to get it close but I am more concerned about it running good and the shaker being in the right place. Thanks again. Mike/KD9RG
1977 TA S/E

SolarGold78

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #131 on: October 30, 2010, 08:11:35 PM »
As long as the engine sits in the stock position the shaker will be fine. I figure you have them, but you also need the correct air cleaner base and shaker for a 400.

-Chuck
Engine code X8 head number 16

KD9RG

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #132 on: October 31, 2010, 08:00:22 AM »
Yep, have all the shaker parts.
1977 TA S/E

KD9RG

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #133 on: November 17, 2010, 05:58:24 AM »
Chuck, What size/number is the quadrajet?
1977 TA S/E

SolarGold78

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #134 on: November 22, 2010, 11:40:13 AM »
Chuck, What size/number is the quadrajet?

I'll have to look for the number, but it's the one for the 180hp Auto.

-Chuck
Engine code X8 head number 16

Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #134 on: November 22, 2010, 11:40:13 AM »

KD9RG

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #135 on: November 23, 2010, 05:03:25 PM »
Wow. That is surprising. I figured your running a lot more ponies than that.  Its been a long time (28 yrs) since I have done any hot rodding,  I figured you were closer to 400 hp.  Am I the bonehead here for missing the obvious?  Mike/KD9RG
1977 TA S/E

SolarGold78

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #136 on: November 27, 2010, 06:58:22 PM »
Wow. That is surprising. I figured your running a lot more ponies than that.  Its been a long time (28 yrs) since I have done any hot rodding,  I figured you were closer to 400 hp.  Am I the bonehead here for missing the obvious?  Mike/KD9RG

Mike,

:) The engine in its current form is around 400HP. I figure about 370 or so with the exhaust in place. The quadrajet I'm using is the one from the car's original 180HP engine. Come to think of it that carb is almost all that remains of the original engine. With the proper tuning it is more than capable of feeding a 400HP 400. You aren't a bonehead I just didn't explain clearly.


-Chuck
Engine code X8 head number 16

red79phoenix

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #137 on: January 07, 2011, 11:11:58 AM »
Im looking to buy these parts from a member possibly I just need to know if you guys think these parts are any good. If the cam is any good what heads would work good with it?

http://www.summitracing.com/parts/SLP-411NP30/

here are the rods:
http://www.jegs.com/i/Eagle/356/CRS6625PP3D/10002/-1

and the cam:
http://www.jegs.com/i/Crane+Cams/271/105082/10002/-1
"I took the restrictor plate off to give the red dragon a little more juice, but lets keep that on the down low it isn't exactly street legal."

Mr. P-Body

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #138 on: January 13, 2011, 12:17:53 PM »


   The rods are good ones if sticking with Pontiac parameters.

   The pistons are stock-replacement "fits all". They have 8 valve reliefs to accomidate both early and late valve angles. Not suited for performance, but fine for a stock "driver".

    Crane cams are obsolete. Nothing new for the Pontiac in many years.

FWIW

Jim

red79ta

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #139 on: January 31, 2011, 09:41:31 PM »
Many people say 400ci and up is a big block. The only TRUE small block Pontiacs are the 301's and 265's. The block is literally smaller! Anything else 326-up is all standard size. but the 301 is not really a motor worth writing this post about either...they are good for giving people something to blow up in their spare time.  :P
1979 Trans am PONTIAC 350

tajoe

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #140 on: February 05, 2011, 01:58:36 PM »
C'mon now Red, don't jinx me with 301 bashing, we all know the motor has it's place, and will agree it's not racing. But I wanted to keep this thread going, and ask this question. Does anyone know the exact yr and why Pontiac changed the flywheel hole diameter, at the back of the crank? Somewhere in 74, 75, or 76. I've only had stick cars, and the early 70s and before w/ the 10 1/2" clutch is a different F/W,( bore diameter) than the 11" on my W-72. I'm assuming the flexplates are effected by this too.
"You can sell an old man a young mans car,
but you can't sell a young man an old mans car"
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red79ta

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #141 on: February 06, 2011, 10:01:47 PM »
C'mon now Red, don't jinx me with 301 bashing, we all know the motor has it's place, and will agree it's not racing. But I wanted to keep this thread going, and ask this question. Does anyone know the exact yr and why Pontiac changed the flywheel hole diameter, at the back of the crank? Somewhere in 74, 75, or 76. I've only had stick cars, and the early 70s and before w/ the 10 1/2" clutch is a different F/W,( bore diameter) than the 11" on my W-72. I'm assuming the flexplates are effected by this too.

It changed over in '76. It was used as one of the ways to save weight. smaller weaker flywheel, along with weaker engines after 1974. They had their prime in the late 60's early 70's, but they slid downhill after 76 by offering the olds 403 in 1977, and other things began to lighten up as well. 
1979 Trans am PONTIAC 350

tajoe

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #142 on: February 07, 2011, 06:44:47 PM »
Thanx for clearing that up Red, and i agree with your opinions.
"You can sell an old man a young mans car,
but you can't sell a young man an old mans car"
                                       Bunkie Knudsen

badmonkey

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #143 on: March 10, 2011, 07:12:11 AM »
You guys must stop stating 9.5:1 is a flat maximum for pump gas and iron heads. Because that doesn't account for elevation. Up here at 4500', I could run 10.4:1, and still have a hair less cranking compression than your 9.5:1 at sea level.
 

LeighP

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #144 on: March 10, 2011, 11:53:48 AM »
True...just don't drive down hill to the bottom....lol. :lol:
Regards,
Leigh

Sydney, Australia
1968 Pontiac Firebird 428 5 speed coupe

Former Firebirds -
1969 Pontiac Firebird 400
1971 Pontiac Firebird 455
1977 Pontiac Trans Am
1976 Pontiac Trans Am
1967 Pontiac Firebird 400 convertible
1967 Pontiac Firebird 400 coupe


tajoe

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #145 on: March 11, 2011, 05:23:21 PM »
True...just don't drive down hill to the bottom....lol. :lol:
LOL!!! (hey Leigh. Did you say that with an accent?)
"You can sell an old man a young mans car,
but you can't sell a young man an old mans car"
                                       Bunkie Knudsen

LeighP

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #146 on: March 12, 2011, 04:54:22 AM »
I don't have an accent....its you guys that sound strange....  :lol: :lol:
Regards,
Leigh

Sydney, Australia
1968 Pontiac Firebird 428 5 speed coupe

Former Firebirds -
1969 Pontiac Firebird 400
1971 Pontiac Firebird 455
1977 Pontiac Trans Am
1976 Pontiac Trans Am
1967 Pontiac Firebird 400 convertible
1967 Pontiac Firebird 400 coupe


Robbie.McKinney

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #147 on: July 13, 2011, 01:53:43 PM »
I have a 1976 TA 400 and it has like no power what so ever can't even spin the tires I was at a car show and a guy told me that you could bypass the main vaccume line directly to the carb has anyone else heard of this?

Clint S

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #148 on: July 13, 2011, 06:16:48 PM »
Have no clue as to what that would be as a vacuum line would have nothing to do with power output from the engine aside from the advance canister or a leak.   Always remember, many people at car shows  really have no clue.
72 Firebird Esprit 455
Get high on milk, my cow's on grass.
http://i198.photobucket.com/albums/aa72/stelmashuck/103_0567.jpg

Robbie.McKinney

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #149 on: July 13, 2011, 10:09:19 PM »
Have no clue as to what that would be as a vacuum line would have nothing to do with power output from the engine aside from the advance canister or a leak.   Always remember, many people at car shows  really have no clue.
that may be true but i still dont see why such a big engine seems to have no power what so ever maybe i need to rebuild the carb or something  :?

Grand73Am

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #150 on: July 13, 2011, 10:31:16 PM »
It's possible that the vacuum advance on your distributor is connected to ported vacuum on your carb. If so, by connecting the distibutor vacuum advance line to a manifold vacuum source instead, you'll have more power. By doing that, your idle speed will increase, so you'll have to adjust your idle screw down a bit. That would be an easy and free thing to look at and try.
If the speed doesn't increase when switched from ported to manifold vacuum, your vacuum advance is most likely bad, so would have to be replaced.

Also, your timing may not be set correctly, so check that with a timing light, with the vac advance line disconnected and plugged at the vac source, which is another basically free thing to try.
Steve F.

bentley26

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #151 on: August 08, 2011, 09:20:51 AM »
New '73 455 owner here... Still trying to learn all of the history and technical tricks associated with the car.  One thing I was curious about... Due to the OPEC embargo of that year, the '73 TA engine was "de-tuned" to meet new federal emissions and efficiency requirements.  True?  If so, any suggestions to re-tune the engine to boost performance a bit without ruining the integrity/originality of the vehicle?  Thanks!
1973 Trans Am 455

Grand73Am

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #152 on: August 08, 2011, 06:13:02 PM »
73's weren't really de-tuned due to the 73 opec embargo, because the embargo happened during 1973. The 73 models were already being produced, delivered and bought in the fall of 1972, before we knew there would be a gas shortage in 1973.

Increased emission regulations meant a drop in the compression ratio, down to 8.0:1, losing 50 hp from the previous year.
« Last Edit: August 08, 2011, 06:20:27 PM by Grand73Am »
Steve F.

KD9RG

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #153 on: August 31, 2011, 05:46:47 AM »
Chuck, your not gonna believe this, I have the car back out and have started the restoration again. I went to put the new Edelbrock intake manifold on the engine last night.........they sent me the wrong one!! I  have had it for a year, can't find the invoice and for the life of me I can't remember who I bought it from. Unbelievable. Did you happen to make it to the Nationals last weekend? I was there Saturday. Mike/KD9RG




Chuck, What intake and carb are you using? I want to put the same  on my motor. Who calibrated the carb? Mike/KD9RG


Mike,

I have an Edlebrock performer and a Quadrajet. I got the carb kit from HO Racing Specialties. You give them the specs of your engine and for $75 you get all the parts you need to set the carb up and a very detailed instruction book. http://www.horacing.com/

-Chuck
1977 TA S/E

Grandvillebob

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #154 on: February 05, 2012, 10:45:58 PM »
I have a set of heads that I bought off a guy not too long ago, and have seen several people with them on 455's making big horsepower, and cannot figure for the life of me how.

When I first got them he told me they were RA/IV heads, but after digging into them, I actually believe they are rarer that those.  They are 197 heads, but, they are stamped on the end with "nunzi" meaning that he ported and polished them.  I had new SS valves with 30 degree stems, and three angle valve job, and the springs set up for a hydraulic 550-600 lift cam, but when I went to figure out compression, they are 111 cc's.  Can anyone tell me how people are getting horsepower from them since no one making a domed piston, without a special molding of your chambers?  I have a small fortune in them, with a ported and matched torker 2, and I saw a guy selling bare casting with "some valve and springs" and he wanted $2500 and have not heard of many people using them.  They are listed as 1971 455/335 hp heads.  Please enlighten me to some wisdom?

chief poncho

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #155 on: February 06, 2012, 01:47:04 AM »
They are '71 455 HO roundport heads, based on your description.  If Nunzi ported them, they are probably good for 450+hp with the right cam selection, headers and proper tuning.  Keep in mind, people made terrific power with the SD heads and they have the same big chamber volume as the HO heads, but flow a bit better.  Basicially what you have is one of the better factory heads Pontiac ever made.  When you say big hp numbers, how big are you saying?  Lower compression does not have to mean low power.
1971 Lucerne Blue Trans Am (455HO, Automatic) - currently my project car.
Previously Owned TA's/Musclecars: 2002 Pewter WS6/M6 Trans Am, 1968 Dodge Superbee 383/4speed,  1975 TA 455/4speed, 1989 Mustang LX 5.0/5speed, 1980 TA Indy Pace Car, 1977 TA 400/Auto, 1989 GTA 350TPI, 1990 GTA 350TPI, 1986 IROC 305TPI, 1989 Mustang LX 5.0/Auto, 1993 Mitsu 3000GT VR4 (and probably a few I've forgotten about)

critter

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #156 on: February 06, 2012, 09:56:32 AM »
And if you contact one of the major Pontiac vendors you can special order a mini-dome piston from companies like Ross. Call Butler. They can help. With Nunzi's touch porting and some compression 500hp is very doable.
Been there, done that, t-shirt is now a shop rag.

Grandvillebob

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #157 on: February 06, 2012, 10:17:33 AM »
Thanks guys, Butler you say huh?  I have been looking in JE Piston catalogs and such, never thought of them. The guy I saw was using these heads was making 510hp on a dyno.  I have a block for them, it is a 69 428 block, bored 060, with a balanced 455 crank and rods.  It has no 62 ported heads on it now and is 11-1 compression and has a 648/655, 308/310 cam in it...way too much for the street, but would like to put a domed piston and these heads and the manifold on it and a smaller cam for a high hp street motor in a 75 trans am I have. 
By the by critter, love the t-shirt is now a rag line...feel the same way myself.
Looking forward to hanging out here a little, thanks for the reply guys
Grandville


Grandvillebob

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #158 on: February 06, 2012, 08:58:41 PM »
Well, I do believe I have figured out how to get pics on the photobucket site, here are some pics of the trans am and one of the parade queen..enjoy! :-P
http://s1145.photobucket.com/albums/o516/GrandvilleBob/

critter

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Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #159 on: February 06, 2012, 09:23:17 PM »
I do like a girl with a big butt! Nice GrandVille. I've driven them and almost bought one but it was 1979 and I couldn't afford the gas at the time. I'd love to take one, drop the top and spend about a month driving out west to check out the Grand Canyon and up to the Tetons and Yellow Stone.
Been there, done that, t-shirt is now a shop rag.

Re: Pontiac 400-455 Questions and answers. Subthread
« Reply #159 on: February 06, 2012, 09:23:17 PM »
You can help support TAC!