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Old 09-11-2022, 08:57 AM
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Default 1970 Grand Prix Value (WTB)

I've been looking at 69-70 Grand Prix cars for a second classic. Yesterday I looked at a 1970 "J" model advertised as a "survivor" car 455/TH400 with 73K miles. I looked at it during a local car meet so wasn't able to get a few answers and after getting home I definitely have some questions. The current owner says he bought it from the original owner in Pennsylvania and that the car was garage kept just about all it's life. It is red exterior with black interior, and has a front electric bench seat with the center fold down arm rests. It is a column shift with tilt column.

*The body is flawless and hard to tell but maybe a very small bubble spot on the vinyl top

*Interior looks great as well - dash pad is mint, factory radio and everything else is intact. There is a small tear on front bench at electric controls

*Owner says it has NOM 455. It is an XF block however the 6 digit stamp (500629) doesn't match the VIN. Also it has 62 heads. I don't yet have date code but based on heads it may be a 428 block.

*Has a 12 bolt rear, but I didn't see POSI tag. Owner says it leaves 2 streaks. I forgot to ask gear ratio.

*Trunk pan and floor pans look great - car has been undercoated

*The frame has surface rust near tail panel area

*Stated original paint but there is overspray on the upper area of tail panel inside trunk and under the front end.

*Original AC car and it works - cold but low fan speed only

* Log manifolds and surface rusted head and intermediate pipes - mufflers back appear to have been recently replaced

* Car starts up easily and runs great - "appears" to be all period correct parts

The engine compartment is representative of a 73K mile engine but if it is a 69 428, seems weird a dealer would have swapped that engine in and the original owner should have disclosed. If it's actually a 70 XF 455, the 62 heads are a weird addition. I plan to get the date code soon to verify. The current owner said he recently changed the timing chain and water pump. He said the timing chain removed did not have plastic gear and had lots of slop.

Assuming it's a 428, my plan with the car would be to do a compression and leak down test to check condition. Then pull engine and re-gasket, pan seal, maybe rear main seal change. Depending on what I find would determine course such as pull heads and have them rebuilt; check bearings, etc.

Video links below and will post more pics - looking for a reasonable value as I may make an offer.

https://youtu.be/2oJOtWzEGbo
https://youtu.be/k0Evg4-RepE
https://youtu.be/8YBPO1T4EcI
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'69 Firebird 400/461, 290+ E D-Ports, HR 230/236, 4l80E, 8.5 Rear, 3.55 gears
'64 LeMans 400/461, #16 Heads, HR 230/236, TKO600, 9inch Rear, 3.89 gears
'69 LeMans Vert, 350, #47 heads: Non-running project

Last edited by grivera; 09-11-2022 at 09:08 AM.
  #2  
Old 09-11-2022, 09:07 AM
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Quote:
It is an XF block however the 6 digit stamp (500629) doesn't match the VIN
That set of numbers is the Engine Unit Number, the partial VIN is down lower next to the timing cover.

Find the date code and the engine block casting number when looking back there. Find the partial VIN but could be harder to see. (usually covered by oil/paint etc)

Sounds like a cool GP though.


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  #3  
Old 09-11-2022, 09:09 AM
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Quote:
Originally Posted by johnta1 View Post
That set of numbers is the Engine Unit Number, the partial VIN is down lower next to the timing cover.

Find the date code and the engine block casting number when looking back there. Find the partial VIN but could be harder to see. (usually covered by oil/paint etc)

Sounds like a cool GP though.

The XF and 6 digits are next to timing cover, horizontally - are you saying the last 6 of VIN would be lower than that? Still seems odd to put 62 heads used on a 1970 XF 455?

Also - just found in an old thread here that in 69 the EUN was changed to a 7 digit number and it always started with a "0": https://forums.maxperformanceinc.com...78&postcount=6

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'69 Firebird 400/461, 290+ E D-Ports, HR 230/236, 4l80E, 8.5 Rear, 3.55 gears
'64 LeMans 400/461, #16 Heads, HR 230/236, TKO600, 9inch Rear, 3.89 gears
'69 LeMans Vert, 350, #47 heads: Non-running project

Last edited by grivera; 09-11-2022 at 09:33 AM.
  #4  
Old 09-11-2022, 09:17 AM
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Will Rivera

'69 Firebird 400/461, 290+ E D-Ports, HR 230/236, 4l80E, 8.5 Rear, 3.55 gears
'64 LeMans 400/461, #16 Heads, HR 230/236, TKO600, 9inch Rear, 3.89 gears
'69 LeMans Vert, 350, #47 heads: Non-running project
  #5  
Old 09-11-2022, 09:30 AM
mgarblik mgarblik is offline
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Quote:
Originally Posted by grivera View Post
The XF and 6 digits are next to timing cover, horizontally - are you saying the last 6 of VIN would be lower than that? Still seems odd to put 62 heads used on a 1970 XF 455?
Yes, the number below the Letter code is the EUN number and of little value. The partial VIN is vertical, right next to the timing cover, between the center and lower timing case bolts. Often pretty full of crud in that area. That car looks like a good, honest candidate for what you are looking for. Personally, the bench seat and column shift is not a big detractor, but a little weird in a GP. Takes away from the cockpit look and idea a little. I have two friends with strange Pontiac optioned cars like that. 1 a 71 GTO 455HO with bench seat, auto trans on column. The other a 74 SD-455 TA with auto on the column. That looks like a car worth considering if the price isn't crazy. Having a working AC system on a car that old is a huge bonus as well. Good luck .

BTW, Haggerty has a 70 GP in good condition around 15K, which sounds about right to me. But they have a wide range: 15-26K in good condition. Do some research.


Last edited by mgarblik; 09-11-2022 at 09:37 AM.
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Old 09-11-2022, 09:37 AM
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Quote:
Originally Posted by mgarblik View Post
Yes, the number below the Letter code is the EUN number and of little value. The partial VIN is vertical, right next to the timing cover, between the center and lower timing case bolts. Often pretty full of crud in that area. That car looks like a good, honest candidate for what you are looking for. Personally, the bench seat and column shift is not a big detractor, but a little weird in a GP. Takes away from the cockpit look and idea a little. I have two friends with strange Pontiac optioned cars like that. 1 a 71 GTO 455HO with bench seat, auto trans on column. The other a 74 SD-455 TA with auto on the column. That looks like a car worth considering if the price isn't crazy. Having a working AC system on a car that old is a huge bonus as well. Good luck .
Thanks - do you know if factory installed 62 heads on an XF 455?

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'69 Firebird 400/461, 290+ E D-Ports, HR 230/236, 4l80E, 8.5 Rear, 3.55 gears
'64 LeMans 400/461, #16 Heads, HR 230/236, TKO600, 9inch Rear, 3.89 gears
'69 LeMans Vert, 350, #47 heads: Non-running project
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Old 09-11-2022, 09:38 AM
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Will Rivera

'69 Firebird 400/461, 290+ E D-Ports, HR 230/236, 4l80E, 8.5 Rear, 3.55 gears
'64 LeMans 400/461, #16 Heads, HR 230/236, TKO600, 9inch Rear, 3.89 gears
'69 LeMans Vert, 350, #47 heads: Non-running project
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Old 09-11-2022, 10:04 AM
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XF in 1970 would have 64 heads.

The zero in the eun is usually hard to see lot of times.

Try to look for the partial VIN down by the lower hose connection on timing cover. This will help determine for sure what it is. Will look something like 20A1xxxxx with the last 6 digits the VIN of the car it came in. The letter 'A' is the plant code which will be different for which plant it came from.


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Old 09-11-2022, 10:12 AM
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I need to clarify - the current owner says it's the original matching numbers engine - in opening thread I incorrectly wrote NOM...

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'69 Firebird 400/461, 290+ E D-Ports, HR 230/236, 4l80E, 8.5 Rear, 3.55 gears
'64 LeMans 400/461, #16 Heads, HR 230/236, TKO600, 9inch Rear, 3.89 gears
'69 LeMans Vert, 350, #47 heads: Non-running project
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Old 09-11-2022, 11:23 AM
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Getting the other fan speeds going, should not be too much trouble.

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Old 09-11-2022, 11:51 AM
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62 heads went on 69 400 and 428 GPs. Check casting dates, they won't be correct for a 70 GP

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Old 09-11-2022, 12:26 PM
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A 455 with number 62 heads would be a ping monster if not rebuilt with dished pistons.

If it’s a 455 block it will say so cast on the front of each side of the block running vertically.

This should be real easy to see from under the car on the passenger side, or even looking down from thru the engine bay with a mechanics extension mirror.

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Old 09-11-2022, 02:01 PM
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I’m looking forward to getting a second look at it

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'69 Firebird 400/461, 290+ E D-Ports, HR 230/236, 4l80E, 8.5 Rear, 3.55 gears
'64 LeMans 400/461, #16 Heads, HR 230/236, TKO600, 9inch Rear, 3.89 gears
'69 LeMans Vert, 350, #47 heads: Non-running project
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Old 09-11-2022, 02:13 PM
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Is an XF 428 a 4 bolt main block? How about a 1970 XF 455?

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'69 Firebird 400/461, 290+ E D-Ports, HR 230/236, 4l80E, 8.5 Rear, 3.55 gears
'64 LeMans 400/461, #16 Heads, HR 230/236, TKO600, 9inch Rear, 3.89 gears
'69 LeMans Vert, 350, #47 heads: Non-running project
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Old 09-11-2022, 02:19 PM
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Look at the cyl head casting codes & date codes very carefully. Those "62"s could easily be the original "64"s that 50 years of heat cycles, under hood rinses, & moisture in the air make the 4 very hard to read.

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Old 09-11-2022, 02:29 PM
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Quote:
Originally Posted by grivera View Post
Is an XF 428 a 4 bolt main block? How about a 1970 XF 455?
Yes, both are factory 4 bolt main capped blocks.

Since the late 80's have owned dozens of '69 & 70 GP's. Mostly as partscars, with three leaving as running projects. Nearly a dozen were SJ's. The ONE desirable enough to keep, & sink a lot of excellent parts into, it's on the back burner, factory loaded burgundy poly '69 J 428HO auto.

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Old 09-11-2022, 02:42 PM
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*Has a 12 bolt rear, but I didn't see POSI tag. Owner says it leaves 2 streaks. I forgot to ask gear ratio.

Most likely a 3.31 ratio and the tag may be that plastic one that goes around the fill plug. Nice car!

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Old 09-11-2022, 02:59 PM
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I hope you can purchase it!!!

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Old 09-11-2022, 03:32 PM
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Quote:
Originally Posted by SRR View Post
*Has a 12 bolt rear, but I didn't see POSI tag. Owner says it leaves 2 streaks. I forgot to ask gear ratio.

Most likely a 3.31 ratio and the tag may be that plastic one that goes around the fill plug. Nice car!
It's a factory AC equipped Turbo 400 car, so no 3.31's.

IF original rear, & no posi, will be a 3.07 coded WT K

Original coded with factory Eaton posi, will be an XT K (with an E)

Original "posi" tags were indeed the red plastic style lettered "Limited Slip" that are held on by the fill plug (passenger side webbing).

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Old 09-14-2022, 05:16 PM
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I can't get past the bucket seats and column shifter. Being a Grand Prix fanatic, my love of the car is the cockpit feel of the console and shifter. Sounds like a 428, it is odd. The low-speed fan issue is common, all you need is the high-speed relay that is inexpensive. You just have to make sure it is the right one, not the coils but the shape of the plastic frame. You need to take a pic of it and compare with what you find.

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