1973 Pontiac Grand Am LS7 Swap

[sr73bu]

SR73; How do you like the 1 3/8" sway bar? I use a 1.25 factory WS6 T/A bar up front and the original 7/8" rear bar. The car seemed to be fairly neutral with the Pontiac engine, but now I am taking about 200lbs off the nose.

I'll have to check my receipts from a few years ago.... If I remember correctly the front sway bar is a Hellwig 1+3/8" bar... it really compliments the factory rear bar (i'm running the OG one like you)...The car is pretty damn balanced for a budget based suspension like mine...
Just a tip- if you plan on running a large bar up front, weld in some nuts now (inside the frame for mounting the bar) before you send out the frame for coating... i'm not sure how long before the bolts will strip out the factory threads on my frame... although it has held up at a few autocross events.

I'll let you know how the whole 315's up front works out soon, thats the one advantage to these 73-77 A-bodies, they can swallow some massive tires.

Keep the updates coming!

-Sean

[Later-A-body]

Sean: Yeah definitely good advice on the frame studs for the bar. I can incorporate that now before it gets coated. Does the car understeer at all with the big bar? I have to decide which springs to use up front. I was running 550# springs up front with the 455 and it handled well, but now the LS is dropping about 200 lbs. I am not sure if I want the #550's and the 1.25" bar as before, or maybe try a lower rate spring and a bigger bar? The car will get autocrossed and some track time, but nothing hardcore like every weekend.

[sr73bu]

I'm not sure of the spring rate on my springs.. they are OPGI 2" drop springs... I bought them way back when.. before anyone made parts for these cars..haha.

I'd say my OPGI springs are "softer" and they work well with that big bar. Not sure if the tires I have up front would help (285/40/17), but I really can't say it has that much understeer with the setup I have. I'd start with what you've got and see how it works.. that 1.25 bar/ 550# springs may have the same results as a bigger bar and softer springs with the drop in wieght. If anything a wider front tire could be run too... with all these factors I'd just start with what you've got and work from there.

-Sean

[Later-A-body]

Well, I dont have any photos to post this week until the frame is back from powdercoating, but do have some updates on the engine progress. I received the final specs from ERL on the 428" shortblock. Here are some specs I received from Seth at ERL regarding the piston to deck height for each cylinder.
1. +.007”
2. +.007
3. +.007
4. +.008
5. +.009
6. +.009
7. +.007
8. +.009

4.131” cylinder bore size, 4.00” stroke, -8cc dome on piston, 1.1150” compression height on Wiseco piston, 6.125” rod,.051” thick gasket. After getting these numbers, I was able to move forward with a cylinder head choice. I decided to go with Dr.J's Performance AirWolf LS7 castings. I had done a lot of homework on flow numbers and parts selection, and after sitting down with Bryce at Dr. J's, I decided he was the best person to do business with. He crunched all of my numbers including my cam card specs to come to an agreeable compression ratio. We decided to go with a 68cc chamber. This will yield an 11.3:1 static CR, and an 8.6:1 Dynamic CR. Cranking compression will be about 185 which will keep me well within the range of acceptable for pump gas. I am running all factory GM EFI and electronics to keep the performance and reliability I desired for this build. My horsepower goal for this motor was 600. Anything over that will be welcome, but probably overkill since getting that much power to the ground will be futile. The numbers his program gave us were around 640 HP, peaking around 65-6700 which is what I wanted. No need to ring it out to 7k. I hope to have the drivetrain in the car next month. I decided on a color scheme for the engine. Pontiac metallic blue and charcoal grey metallic. The grey will be the color that I am using for the frame as well. Pictures will follow ASAP as everything progresses. Thanks.

[acegto]

Great color choices for the engine bay. Excited to see what they do when they get back from SEMA.

[Later-A-body]

While I am waiting to get the frame back from the powdercoater, I have sent out my front coil-over springs, and rear coil springs to Kevin at Coil Spring Specialties in Kansas. They are measuring the rates and heights against what they are advertised to be to see exactly what I had in the car, and will custom build me anything I want based on the weight of the car and what I want to do with it. The front QA1 springs are suppose to be 550# rated. The rears are from Global West, but I cant remember what the rates are. They are both linear rates and I will be sticking with a linear rate. Since I am losing about 200# off the front end I am not sure what rate to go to. My idea is to get the fronts somewhere in the 550-600# range, and increase the rear rate by about 15% with an extra 1/4" drop. I am going to autocross the car, but I do not want to ruin the ride. With all the improvements I now have in the frame mods, I want to make sure I have the suspension scienced out correctly. I already run a 1.25" front sway bar, and a 7/8" rear sway bar, so I am going to keep them as is and see how that works. Hopefully I will be able to post some pictures next week of the finished frame mods and powdercoating.

[andrewb70]

I have the QA1 coilovers on my GTO with the 550 springs and LS power. That rate is not stiff at all. I've often wanted to upgrade to a stiffer spring but none are readily available. I think the cone spring design might have some rate limitations. I would be curious to see what Coil Spring Specialties says about making a firmer cone shaped spring.

Andrew

[Later-A-body]

Andrew: yeah that's why I called CSS. QA1 does not have an upgrade like you said. How does your car handle on the road course with 550# springs now? Your car is lighter than mine for sure.

[andrewb70]

Andrew: yeah that's why I called CSP. QA1 does not have an upgrade like you said. How does your car handle on the road course with 550# springs now? Your car is lighter than mine for sure.

My car handles nicely on the road course. It is very predictable with some body roll and manageable understeer. On the auto cross it is a wreck. It is just too big and bulky. As it sits now it weighs about 3750 pounds without driver and maybe half a tank of gas.

Andrew

[Later-A-body]

Andrew: Are you thinking the springs are too soft, or do the swaybars need to be larger? I know my car will be at least 3850 with the LS, without me in it. I may decide to step up to 600# springs and see how the current swaybar combination works and change things if needed.

[andrewb70]

Andrew: Are you thinking the springs are too soft, or do the swaybars need to be larger? I know my car will be at least 3850 with the LS, without me in it. I may decide to step up to 600# springs and see how the current swaybar combination works and change things if needed.

On my car I need a rear sway bar. For you, I would stick with the rates that you already have and see how it turns out. You can always change those parts later if you feel that you need to.

Aren't the suspension parts for these chassis interchangable with second gen F-bodies?

Andrew

[Later-A-body]

Yes, the F-body parts do interchange. My front swaybar is a '78 Trans Am WS6 unit that I had pulled years ago. Why no rear bar on the GTO?

[andrewb70]

Yes, the F-body parts do interchange. My front swaybar is a '78 Trans Am WS6 unit that I had pulled years ago. Why no rear bar on the GTO?

For years Global West recommended no rear bar for street cars, so when I built the car originally, I left it off. Having had the car at some events I think a rear bar would help me a great deal. However, secretly I am lusting after a Roadster Shop chassis with the IRS, but don't tell anyone....

Andrew

[Later-A-body]

Yeah, they still say not to run a rear bar, but I would try one to see what improvements it could make for you. I have all of the GW stuff, but the rear bar is staying put on mine.

[Later-A-body]

I had a chance to get back to the chassis shop to see the revisions made to the frame. In the post's I had earlier, you can see that the front crossbar had to be moved in order to allow the steering box and radiator/lower fan shroud to clear. Rob at No Limit took care of those changes. Here is a look at the new location for the crossbar.

[Later-A-body]

Here is a shot of the frame to lower control arm brace that was changed in order to allow header clearance. I am running 1 7/8" headers which now clear nicely.

[Later-A-body]

After going to the chassis shop, I stopped by Global West Suspension. Doug and I spoke about their new long travel coil-over suspension kit for my car. They do not have one for the '73-'77 A-body, but due to the fact that I have my frame at the chassis shop, which is only three miles from them, Doug was interested in creating a kit for this chassis. I will not be able to afford the Penske shocks, but I will most likely be running a QA1 double adjustable coil-over. This kit uses a longer shock which will allow for more overall suspension travel. I stole a picture from another web post in order to show the set up. I will have the ability to run a traditional coil-over spring with a huge amount of rates to choose from. We will determine the rate later. Doug knows I want to keep the ride intact so he suggested to start around 600# or so. The car is a tank even with the LS7 installed. I will be selling my existing QA1 coil-overs in order to afford this latest decision.

Attachment 51397

[cmthomas32]

Awesome work. Like the pictures, very nice..

[Later-A-body]

I have a few updates on the Grand Am swap to post. Today, I took my best friend Vinny with me (see pic below),and picked up my cylinder heads. They are Air Wolf LS7 heads by Dr. J's Performance in Anaheim CA. They are 68cc chambers, which with my 428" motor will yield 11.3:1 CR. The port volume is 265, which will provide great amount of velocity, which is very important for this combination in my heavy car. Flow numbers peak at 404 cfm at .800 lift which is nice to say, but means nothing since the lift on the cam peaks at .640. At .650 lift the heads are flowing 385 cfm, 399 cfm at .700. ERL has already shipped the shortblock, and it will arrive 12/21. The valves are stainless 2.20/1.60. I have been experimenting with different colors to paint the block and intake manifold. I decided to go with the traditional Pontiac Metallic blue which is pictured on the top of the block that is pictured. I have a junk block that I use to experiment on.

Attachment 52694

[alowerlevel]

Damn Im liking that new coilover set up for the front. Cant wait to see this when its finished, maybe it will give me some motivation to get started on my '73. What are you using for a fuel tank with the fuel injection?