Stroking G-Body Motors

motorheadmike

Geezer
Nov 18, 2009
6,651
113
Ottawa, Ontario Canada
Have I pissed you off, or do you just not listen. Where in all of my posts did I mention Volumetric Efficiency?? I said I was working on a way to increase stroke with just a crank change and the addition of a kit I am trying to work the kinks out of.

So let's just say that you don't change the crank but you want to improve performance of the low compression, open chamber head engine that you already have in the car. What would you do?? Port the heads, add a cam with more duration and as much lift as the heads could accept. Change exhaust to something that would scavenge better. Upgrade to a better carb.

Wow!! That's just what I would do after changing the crank, EXCEPT that my low compression engine would have higher compression (because of the stroke change and the addition of the kit) and would have more cubic inches which would offset some of the deficit of the open chamber heads. All of the exact same changes you want to make would work even better on the engine after adding the stroker crank. Just like you, I know a couple of things about making more power.

You are missing the whole point of why I am interested in doing this. Try to remember when you had a car and no money. How did you make improvements?? You bought, begged or stole whatever performance improving parts you could find and then installed (or tried to) them yourself. Working under the hood all weekend was worth it if you could get any improvement at all. I remember it and have always wanted to find ways to make it easier on the guys who are coming after us. What I am working on now may or may not have as wide an application as I would like but I have no way of knowing that without communicating with people like the ones on this forum. Because of the cars we like, we almost all start with under performing GM engines of all types. I know sbc. It's almost the only thing I've ever worked on and I know it will work for that. I am hoping to make it more cost effective for others starting out with a car and no money.

I am saving this for posterity.
 

UC645

G-Body Guru
Apr 20, 2020
692
93
Kittanning, Pa
Have I pissed you off, or do you just not listen. Where in all of my posts did I mention Volumetric Efficiency?? I said I was working on a way to increase stroke with just a crank change and the addition of a kit I am trying to work the kinks out of.

So let's just say that you don't change the crank but you want to improve performance of the low compression, open chamber head engine that you already have in the car. What would you do?? Port the heads, add a cam with more duration and as much lift as the heads could accept. Change exhaust to something that would scavenge better. Upgrade to a better carb.

Wow!! That's just what I would do after changing the crank, EXCEPT that my low compression engine would have higher compression (because of the stroke change and the addition of the kit) and would have more cubic inches which would offset some of the deficit of the open chamber heads. All of the exact same changes you want to make would work even better on the engine after adding the stroker crank. Just like you, I know a couple of things about making more power.

You are missing the whole point of why I am interested in doing this. Try to remember when you had a car and no money. How did you make improvements?? You bought, begged or stole whatever performance improving parts you could find and then installed (or tried to) them yourself. Working under the hood all weekend was worth it if you could get any improvement at all. I remember it and have always wanted to find ways to make it easier on the guys who are coming after us. What I am working on now may or may not have as wide an application as I would like but I have no way of knowing that without communicating with people like the ones on this forum. Because of the cars we like, we almost all start with under performing GM engines of all types. I know sbc. It's almost the only thing I've ever worked on and I know it will work for that. I am hoping to make it more cost effective for others starting out with a car and no money.
ECAE7FE7-7DFB-41D0-B29C-1A73F59E2D2A.jpeg

I thought my goodwill evaporated fast on Facebook.
 

motorheadmike

Geezer
Nov 18, 2009
6,651
113
Ottawa, Ontario Canada
Pay attention Fool! This level of insight rarely comes without a hefty price tag. :blam:

Oh I can feel the cost... mostly with my self-destructing brain cells.
 

64nailhead

Goat Herder
Supporting Member
Dec 1, 2014
2,481
113
Upstate NY
So let's just say that you don't change the crank but you want to improve performance of the low compression, open chamber head engine that you already have in the car. What would you do?? Port the heads, add a cam with more duration and as much lift as the heads could accept. Change exhaust to something that would scavenge better? Upgrade to a better carb?

I commend you for trying to think outside of the box, but keep in mind please that hotrodding a SBC has been the mainstay of both the low budget community and high budget community for more than 50 years. I'm indicating that many people have done the same ahead of you. Including many here. So to answer you question(s) that I quoted above, the most popular budget upgrade of a low compression smog 350 SBC is to swap on a set of used Vortec (906) heads - instant 50 HP without a cam. Add the correct cam, Comp 268 or equivalent for another 35hp, and add a set of long tubes for another gain of 30-35hp. The issue has become that finding used 906 heads in useable condition is getting more difficult since they haven't been produced in any volume since the late 90's. The high budget program is the 383 rotating assembly kit. But that program usually consists of a set of aftermarket heads and a cam upgrade.

However it works out, best of luck to you - it's encouraging to see you putting some thought into this rather than googling it and taking the interwebs hoopla as fact.
 

Max Headroom

Master Mechanic
Thread starter
Sep 8, 2011
369
63
No. I left what I had in the car. I did nothing other than preventative maintenance and drove it for years the way it was. Find a good cheap engine, used parts ect. as one should. I scrounged together my entire drive train for less than 250 dollars
No amount of polish will ever change the fact your turd... is a turd.

A turd is indeed a turd. However, I bought a 76 camino years back that had a low compression 8.5 /1 compression, 350 sbc in it. It had 110k +/- miles on it. No smoke. no burn oil, but absolutely nothing to write home about. I put an inexpensive torque cam in it (didn't change cam bearings). Changed the rockers to inexpensive stamped 1.6/1 roller tips. Changed the stock manifold and carb for a used 600 Holley and Edlebrock Performer (old style). Removed the heads to change the head gasket from .045 ths stock to .020 ths shim to increase compression (.13 increase). I had a friend help me swap the stock 273 ring and pinion for a matched but used 303 ring and pinion (largest that would fit the chunk) I used the crush sleeve that came with the (new) ring and pinion.

This took 6 mos., more or less and when I got finished, my "turd" would get about three ft of rubber. When I got the camino, if I stepped all the way in it, the engine would usually bog and then quit. Some turds are better than other turds.
 

Max Headroom

Master Mechanic
Thread starter
Sep 8, 2011
369
63
Oh I can feel the cost... mostly with my self-destructing brain cells.

You know, I have seen you post some pretty savvy stuff. I really don't understand why you are so closed minded to this. If it ain't your brand of whiskey, don't drink but it would be really nice if you would stop pissing in my glass. You don't think its a good idea. I get it.
 

Max Headroom

Master Mechanic
Thread starter
Sep 8, 2011
369
63
I commend you for trying to think outside of the box, but keep in mind please that hotrodding a SBC has been the mainstay of both the low budget community and high budget community for more than 50 years. I'm indicating that many people have done the same ahead of you. Including many here. So to answer you question(s) that I quoted above, the most popular budget upgrade of a low compression smog 350 SBC is to swap on a set of used Vortec (906) heads - instant 50 HP without a cam. Add the correct cam, Comp 268 or equivalent for another 35hp, and add a set of long tubes for another gain of 30-35hp. The issue has become that finding used 906 heads in useable condition is getting more difficult since they haven't been produced in any volume since the late 90's. The high budget program is the 383 rotating assembly kit. But that program usually consists of a set of aftermarket heads and a cam upgrade.

However it works out, best of luck to you - it's encouraging to see you putting some thought into this rather than googling it and taking the interwebs hoopla as fact.


Thanks. I started with the sbc for two reasons: Its what I know and it is everywhere. However, I thought and it looks like I am way, way wrong, that the same thing could be done with and Olds 350 or Pontiac, etc. If not, it doesn't make it a bad idea, just one with limited application. If I make it work on my test motor, I can patent it. That's why I can't explain what I'm doing.

I will ask you this, "How much more power could you be making if the 350 you started with was a low budget, 377 (no overbore) or a 383 (030 over)?"

I have some serious honey dos for my wife that just won't wait anymore. That will keep me busy for the next three to four weeks. When that is done, I will yank the 350 sbc out of my 79 Bu and start my little experiment. It is a two bolt main OEM roller motor and should be a good candidate for what I want to do. I plan on serious documentation and lots of pics. If it works, I will apply for a patent and then post here.

Anyway, I appreciate you and whatever other open minds are out there.
 

motorheadmike

Geezer
Nov 18, 2009
6,651
113
Ottawa, Ontario Canada
You know, I have seen you post some pretty savvy stuff. I really don't understand why you are so closed minded to this. If it ain't your brand of whiskey, don't drink but it would be really nice if you would stop pissing in my glass. You don't think its a good idea. I get it.

I already said show me. So show me. I love being proven wrong.
 

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