SS/GT Engine Choice

Adger Smith · 08-26-2023, 04:04 PM

Car will be a Gen 3 Camaro Badged as a IROC Z-28
Weight should put the car in GT/CA- GT/DA Depending on engine choice.
3 engine choices
Idea is to use parts & pieces I have laying around my shop
I Just want the best .50 - .80 under index runner.
1.
'69 427 425/445
4.311 bore 3.76 stroke
12.7 actual measured compression
401 Alum heads 2.19/1.845
780 Vac Holley carb
2
'70 402 375/405
4.185 bore 3.76 Stroke
12.58 actual measured compression
401 Alum Heads 2.19/1.88
780 Vac Holley carb
3.
'71 454 425/435
4.311 Bore 4 Stroke
10.96 actual measured compression
401 Alum Heads 2.19/1.88
780 Vac Holley Carb
4.
'71 454 425/424
4.311 bore 4 stroke
10.96 actual measured compression
Iron 188 or 990 heads 2.19/1.88
780 Vac Holley Carb
I like what combination Dwight Southerland suggested, but I want to use parts I have available. Yes, I'm a tight Arse!
If you don't want to make a public comment just DM/PM me
Thanks, all comments are appreciated
Adger Smith

john ancona · 08-26-2023, 06:13 PM

[QUOTE=Adger Smith;685052]Car will be a Gen 3 Camaro Badged as a IROC Z-28
Weight should put the car in GT/CA- GT/DA Depending on engine choice.
3 engine choices
Idea is to use parts & pieces I have laying around my shop
I Just want the best .50 - .80 under index runner.
1.
'69 427 425/445
4.311 bore 3.76 stroke
12.7 actual measured compression
401 Alum heads 2.19/1.845
780 Vac Holley carb
2
'70 402 375/405
4.185 bore 3.76 Stroke
12.58 actual measured compression
401 Alum Heads 2.19/1.88
780 Vac Holley carb
3.
'71 454 425/435
4.311 Bore 4 Stroke
10.96 actual measured compression
401 Alum Heads 2.19/1.88
780 Vac Holley Carb
4.
'71 454 425/424
4.311 bore 4 stroke
10.96 actual measured compression
Iron 188 or 990 heads 2.19/1.88
780 Vac Holley Carb
I like what combination Dwight Southerland suggested, but I want to use parts I have available. Yes, I'm a tight Arse!
If you don't want to make a public comment just DM/PM me
Thanks, all comments are appreciated
Adger Smith[/

1972 402

Adger Smith · 08-27-2023, 12:34 AM

John,
I like the oval port as we discussed, but don't have the pieces for it.
The only parts for the rectangle port combinations I need to buy is the pistons.
I have a nice worked 401 heads & intake & carb.
Thanks...

Bob Sherwood · 08-27-2023, 10:39 AM

71 425/435 Would weigh in GT/CA close to smaller motors in GT/DA with only a .10 difference in index --- less likely to get hit with HP ,not many running this motor, plus with 4 in stroke piston speed will flow a lot of air. Bob

Dwight Southerland · 08-28-2023, 08:05 AM

Knowing that when it comes to spending you are tighter than skin on a grape, the 454-425/435 is the best choice since you have the heads already.

What did I recommend before? I don't remember that conversation.

Alan Roehrich · 08-28-2023, 09:57 AM

I'd build the 402, at maximum bore size. With modern rings, good oil, etc, you'll get hundreds of passes on it.

If you have not purchased connecting rods and pistons, or ground the crank, I'd go with small block small journal and small block wrist pins, and a 1.0 MM/1.0MM/3.0MM ring package.

I think that I have a nice, conservative, stock core (billet) camshaft for it, that Billy and Tim did for me.

A certain wise and learned friend and I were discussing this on Thursday. For GT in particular.

08-26-2023, 04:04 PM	#1
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	SS/GT Engine Choice Car will be a Gen 3 Camaro Badged as a IROC Z-28 Weight should put the car in GT/CA- GT/DA Depending on engine choice. 3 engine choices Idea is to use parts & pieces I have laying around my shop I Just want the best .50 - .80 under index runner. 1. '69 427 425/445 4.311 bore 3.76 stroke 12.7 actual measured compression 401 Alum heads 2.19/1.845 780 Vac Holley carb 2 '70 402 375/405 4.185 bore 3.76 Stroke 12.58 actual measured compression 401 Alum Heads 2.19/1.88 780 Vac Holley carb 3. '71 454 425/435 4.311 Bore 4 Stroke 10.96 actual measured compression 401 Alum Heads 2.19/1.88 780 Vac Holley Carb 4. '71 454 425/424 4.311 bore 4 stroke 10.96 actual measured compression Iron 188 or 990 heads 2.19/1.88 780 Vac Holley Carb I like what combination Dwight Southerland suggested, but I want to use parts I have available. Yes, I'm a tight Arse! If you don't want to make a public comment just DM/PM me Thanks, all comments are appreciated Adger Smith __________________ Adger Smith (Former SS) Last edited by Adger Smith; 08-26-2023 at 04:16 PM. Reason: sp

08-26-2023, 06:13 PM	#2
john ancona Member Join Date: Mar 2006 Location: California Posts: 191 Likes: 3 Liked 185 Times in 56 Posts	Re: SS/GT Engine Choice [QUOTE=Adger Smith;685052]Car will be a Gen 3 Camaro Badged as a IROC Z-28 Weight should put the car in GT/CA- GT/DA Depending on engine choice. 3 engine choices Idea is to use parts & pieces I have laying around my shop I Just want the best .50 - .80 under index runner. 1. '69 427 425/445 4.311 bore 3.76 stroke 12.7 actual measured compression 401 Alum heads 2.19/1.845 780 Vac Holley carb 2 '70 402 375/405 4.185 bore 3.76 Stroke 12.58 actual measured compression 401 Alum Heads 2.19/1.88 780 Vac Holley carb 3. '71 454 425/435 4.311 Bore 4 Stroke 10.96 actual measured compression 401 Alum Heads 2.19/1.88 780 Vac Holley Carb 4. '71 454 425/424 4.311 bore 4 stroke 10.96 actual measured compression Iron 188 or 990 heads 2.19/1.88 780 Vac Holley Carb I like what combination Dwight Southerland suggested, but I want to use parts I have available. Yes, I'm a tight Arse! If you don't want to make a public comment just DM/PM me Thanks, all comments are appreciated Adger Smith[/ 1972 402 __________________ John Ancona 717 STK / SS

08-27-2023, 12:34 AM	#3
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: SS/GT Engine Choice John, I like the oval port as we discussed, but don't have the pieces for it. The only parts for the rectangle port combinations I need to buy is the pistons. I have a nice worked 401 heads & intake & carb. Thanks... __________________ Adger Smith (Former SS) Last edited by Adger Smith; 08-27-2023 at 12:34 AM. Reason: sp

08-27-2023, 10:39 AM	#4
Bob Sherwood Member Join Date: Jul 2006 Location: South Dakota Posts: 153 Likes: 70 Liked 388 Times in 60 Posts	Re: SS/GT Engine Choice 71 425/435 Would weigh in GT/CA close to smaller motors in GT/DA with only a .10 difference in index --- less likely to get hit with HP ,not many running this motor, plus with 4 in stroke piston speed will flow a lot of air. Bob

08-28-2023, 08:05 AM	#5
Dwight Southerland VIP Member Join Date: Dec 2001 Location: Arkansas - In the middle of everything. Posts: 2,001 Likes: 64 Liked 779 Times in 193 Posts	Re: SS/GT Engine Choice Knowing that when it comes to spending you are tighter than skin on a grape, the 454-425/435 is the best choice since you have the heads already. What did I recommend before? I don't remember that conversation. __________________

08-28-2023, 09:57 AM	#6
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,113 Likes: 1,571 Liked 1,821 Times in 413 Posts	Re: SS/GT Engine Choice I'd build the 402, at maximum bore size. With modern rings, good oil, etc, you'll get hundreds of passes on it. If you have not purchased connecting rods and pistons, or ground the crank, I'd go with small block small journal and small block wrist pins, and a 1.0 MM/1.0MM/3.0MM ring package. I think that I have a nice, conservative, stock core (billet) camshaft for it, that Billy and Tim did for me. A certain wise and learned friend and I were discussing this on Thursday. For GT in particular. __________________ Alan Roehrich 212A G/S