[72projectbird]

Hi guys!

Today I venture out of the F body world, and into the land of A bodies!

I helped my Father pick up a 1970 GTO project. It's a great start to a build he's been talking about for a long time. I'll make sure to post many more pictures soon.

I have a couple of questions regarding the drivetrain.

The setup is as follows:

YC 455 block (unknown internals, or camshaft)
#62 cylinder heads
Edelbrock Performer RPM intake
Holley 4160 750cfm Vac secondary

What are your opinions of this setup? I'll try and get some more info regarding the cam, but it has some serious chop for sure. Right now it's running thru open headers, and its loud as hell, so it's kinda hard to listen for any issues. It seems to run great, and judging by the sound, it's not a low compression smogged out 455.

It also has a TH400, and a 12 bolt rear. The car also came with another complete 1970 455 TH400 setup that supposedly ran well, but developed a lower end noise.

Big plans are in place for this car.

[Forrest]

Starting one of these cars is always a blast!..Nice find!..Was the car an original 455 car? What's the date code on the block? ( by distributor . raised casting like 2/11/70)Have you got the PHS on it yet? (would be great to see how it was originally ordered).. your in the right place lots of info here and great help! I personally would dump the holly and go for a quadrajet unless you are going for BIG H.P>.# 62 heads is questionable for a 455..Say high compression??!, check your compression: PSI?). get some mufflers on there so you can here what's going on..more details on the engine would be great!. could be a nice runner the way it is... Have fun!!

[72projectbird]

Originally Posted by Forrest

Starting one of these cars is always a blast!..Nice find!..Was the car an original 455 car? What's the date code on the block? ( by distributor . raised casting like 2/11/70)Have you got the PHS on it yet? (would be great to see how it was originally ordered).. your in the right place lots of info here and great help! I personally would dump the holly and go for a quadrajet unless you are going for BIG H.P>.# 62 heads is questionable for a 455..Say high compression??!, check your compression: PSI?). get some mufflers on there so you can here what's going on..more details on the engine would be great!. could be a nice runner the way it is... Have fun!!

Thanks!

I'm going to order PHS soon. From what I've gathered so far, its an original Verdoro green on green with a green top, built in Pontiac MI in December of 69. The heads are #62 built in November of 68. It certainly sounds like a high compression setup. I've had other 455's open header, and they were no where near as loud as this one.

I was looking at the other 455 that came with the car, and I got a little more info:

1970 455 block W/#64 heads built in October 1969. The block also has a build date of October if I remember correctly. I found the VIN stamping on the front of the block, but it's awful hard to read.

I'll try and get some more detailed pics tomorrow.

[Mister Pontiac]

Originally Posted by 72projectbird

Thanks!

I'm going to order PHS soon. From what I've gathered so far, its an original Verdoro green on green with a green top, built in Pontiac MI in December of 69. The heads are #62 built in November of 68. It certainly sounds like a high compression setup. I've had other 455's open header, and they were no where near as loud as this one.

I was looking at the other 455 that came with the car, and I got a little more info:

1970 455 block W/#64 heads built in October 1969. The block also has a build date of October if I remember correctly. I found the VIN stamping on the front of the block, but it's awful hard to read.

I'll try and get some more detailed pics tomorrow.

Woot, Woot!! Awesome find!

Sounds like that 70 455 is definitely a "correct" one for the car. If it's original, then double wow! You found a REAL gem. (455/auto combo was 1986 total built, IIRC) The fact that a 12 bolt is underneath is a good indicator you have an original 455 car there!

And if the 455 in the car doesn't have some sort of dished pistons, those 62 heads will provide some serious static compression!

Man, what an exciting project! Please keep us posted, and keep the pics coming. A green/green 70 is a dream combo to me!

[Held for Ransom]

Re: 455 car.
You could check the frame code, located by the rear driver side tire.

[Judge273]

Reminds me of my youth. 70 GTO with cragars, air shocks and fatty tires on rear! Engine juiced too! Nice fun project and cool dad as well!

[72projectbird]

Originally Posted by Mister Pontiac

Woot, Woot!! Awesome find!

Sounds like that 70 455 is definitely a "correct" one for the car. If it's original, then double wow! You found a REAL gem. (455/auto combo was 1986 total built, IIRC) The fact that a 12 bolt is underneath is a good indicator you have an original 455 car there!

And if the 455 in the car doesn't have some sort of dished pistons, those 62 heads will provide some serious static compression!

Man, what an exciting project! Please keep us posted, and keep the pics coming. A green/green 70 is a dream combo to me!

It be great if it's a real 455 car, but for what he bought it for, and what he plans on doing with it, it doesn't matter too much. I cant say it'll be green on green again. I'll need to bust out the borescope and see what pistons are in it.

Originally Posted by Held for Ransom

Re: 455 car.
You could check the frame code, located by the rear driver side tire.

I'll dig around and see what I can find. Thanks for the tip!

[Greg Reid]

Score!
I saw that one on the 'ebay Sightings' thread yesterday. Looks solid.

[72projectbird]

Originally Posted by Greg Reid

Score!
I saw that one on the 'ebay Sightings' thread yesterday. Looks solid.

The owner was a super nice guy. I think the ad probably hurt the car, as there is a lot of work done that was never mentioned.

[72projectbird]

I busted out the bore scope today, and got a little more information.

The pistons are Speed Pro Power Forged W/ Coated skirts, 4 valve relief +6.70cc's, and bored .060 over. If my math is correct, that would make it 468 CI?

I don't know the thickness of the headgasket, but what would be a ballpark guess of the compression ratio?

455 .060 over
#62 Cylinder heads @ 72cc's
4 valve relief pistons + 6.70cc's

[Mister Pontiac]

I’m estimating you’re close to 12:1 Wow!

Try the Wallace calculator here with your specs...

http://www.wallaceracing.com/cr_test2.php

[72projectbird]

Originally Posted by Mister Pontiac

I’m estimating you’re close to 12:1 Wow!

Try the Wallace calculator here with your specs...

http://www.wallaceracing.com/cr_test2.php

Yeah, I found that calculator after I posted lol

Here's what I came up with:

-If the block has been zero decked, and has a 0.39 thick head gasket, it's 11.98:1
-If the block still has a factory deck height of around .023", then it's around 11.36:1

I imagine it's been zero decked, as it's been bored .060. It was in the machine shop anyways, so I would assume they decked it.

Has anyone had any luck running thick head gaskets? I calculated out a few numbers and got the following:

0.98" thick HG = 10.51:1
.120 thick HG = 10.06:1

What's funny (or scary) is the previous owner said he just ran it on 93 pump gas. Needless to say, we're not doing that in its current state.

[72projectbird]

Here's a couple more quick pics. Right now it's in the small garage, but I'm hoping to get it in the bigger garage this week. I already got the exhaust system waiting for it.

[72projectbird]

Got the GTO over into the other garage today to install the exhaust. The car is super solid! Got a couple of pics, including the stamps on the rear axle. I noticed the drain plug on the oil pan is located facing forwards, almost directly facing the center crossmember. All other pans I've had were on the side. Is it an older pan or something?

The exhaust install went great, and fits really nice. Sounds great too!

[72projectbird]

Forgot to add some pics. The Rally II's are off the 71 T/A. They're 275-60's and 245-60's.

[AG]

That is a 1970 12-bolt 3.31 posi out of a Chevelle.

[Greg Reid]

The rallyes look way better on it to me.

[steve v]

Where did you get the exhaust system from?

[scott70]

looking better already! I had a pair of 62's I ran on a 455 for a while. Had JBP port them and they cc'd at 77. The 62's generally had a little bigger chamber than some of the more common 72 cc heads from what Ive read.Ran mid 11's @ 115 with full exhaust ,PS,PB at 4000lb.. with UD 231/239 FT cam,T2 intake. If you drive it hard at all I would get some repro braces that go up to the crossmember in the rear,,came factory and help stiffen the the rear crossmember to flexing in the middle.

[72projectbird]

Originally Posted by AG

That is a 1970 12-bolt 3.31 posi out of a Chevelle.

I was researching that last night after I posted. So it is a 70 12 bolt, 3.31 gear. Is the casting number different from Chevelles to GTO's?

Originally Posted by Greg Reid

The rallyes look way better on it to me.

They do! We got another set of 15x7 Rally II's for it. They don't have tires on them yet, so we mounted these up to check for fitment. They do look 100x better!

Originally Posted by steve v

Where did you get the exhaust system from?

It's actually the Summit Racing brand exhaust. I thought it was going to be a little sketchy, but I was pleasantly surprised! It's full 2.5" mandrel bent, with 3" collectors. The mufflers are actually Heartthrob brand, which is nice. It came with all the clamps and hangers, and fits up under the car really nice!

Originally Posted by scott70

looking better already! I had a pair of 62's I ran on a 455 for a while. Had JBP port them and they cc'd at 77. The 62's generally had a little bigger chamber than some of the more common 72 cc heads from what Ive read.Ran mid 11's @ 115 with full exhaust ,PS,PB at 4000lb.. with UD 231/239 FT cam,T2 intake. If you drive it hard at all I would get some repro braces that go up to the crossmember in the rear,,came factory and help stiffen the the rear crossmember to flexing in the middle.

Man, you had that thing moving! This car is on easy street now, so I'm not too worried about the cross member flexing, but it probably wouldn't be a bad idea to add it anyways.

I think we might put the original 64 heads on it to knock the compression down some.