engine swap ?'s
- Thread starter 86_cutlass
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Okay, so you want a bigger engine for more power, right? Well, then keep your 307 if it is running and gather up the rest of your parts for the future upgrades.
The dual exhaust that you want will go from your 307 to any other Olds V8 you put in. Even the headers will swap if you use the small block up to 403. So you now have exhaust covered.
The trans is no good. Not in today's world, kid. The TH350 is not a good option for a kid in school who makes a little money and drives anywhere. Forget the TH350. Get yourself a TH2004R, like the Grand Nationals had, and build that to GN specs. You can get a transmission from the wrecking yard from a larger 80's B-body like a delta 88. There's always eBay, too...
Your rear end needs an upgrade. You probably have the little 7.5 rear end. On the cheap you can get some 3.50-ish rear gears from the junkyard for a 3rd gen or 4th gen Camaro or Firebird. Then you need to spend about 300 bucks for custom axle shafts from Summit. Now your rear end can handle the 300 horse or so that you plan on getting.
NOW you are ready for that bigger engine. Once you hunt down a running 350 or 403 olds (you want a running one to guarantee that you don't spend a large fortune in the machine shop) you can buy it and strip it down. You need compression in the 9.5 to 10 to 1 range to stay efficient and make good power. You can buy a reproduction type cam or a stock cam for the 68-70 olds 350. Use the Performer RPM intake. Use 68-70 Olds 350 heads or "C" casting big block heads.
You are now making plenty of power.....
It's too easy to make power with an Olds, don't let the Chevy guys talk you out of it!!
The dual exhaust that you want will go from your 307 to any other Olds V8 you put in. Even the headers will swap if you use the small block up to 403. So you now have exhaust covered.
The trans is no good. Not in today's world, kid. The TH350 is not a good option for a kid in school who makes a little money and drives anywhere. Forget the TH350. Get yourself a TH2004R, like the Grand Nationals had, and build that to GN specs. You can get a transmission from the wrecking yard from a larger 80's B-body like a delta 88. There's always eBay, too...
Your rear end needs an upgrade. You probably have the little 7.5 rear end. On the cheap you can get some 3.50-ish rear gears from the junkyard for a 3rd gen or 4th gen Camaro or Firebird. Then you need to spend about 300 bucks for custom axle shafts from Summit. Now your rear end can handle the 300 horse or so that you plan on getting.
NOW you are ready for that bigger engine. Once you hunt down a running 350 or 403 olds (you want a running one to guarantee that you don't spend a large fortune in the machine shop) you can buy it and strip it down. You need compression in the 9.5 to 10 to 1 range to stay efficient and make good power. You can buy a reproduction type cam or a stock cam for the 68-70 olds 350. Use the Performer RPM intake. Use 68-70 Olds 350 heads or "C" casting big block heads.
You are now making plenty of power.....
It's too easy to make power with an Olds, don't let the Chevy guys talk you out of it!!
86_cutlass said:
Get the olds if this is the power range you want.
As for other opinions on here (I know I've said it before), but when you get into serious power - above 450-500 hp/tq - the cost for the olds 350 build will increase well beyond the cost of a similar SBC.
well my buddy is trying to sell me his dads chevy 350 with flat top pistons and stuff but apparently the bearings got messed up due to metal shavings in the block supposedly if you tear down the block have it boiled then rebuild it it will be fine. he wants $500 for the engine, boiling would prolly be free, then about $300 for new bearings then i got to get the engine in there with a different transmission. Kind of sketchy.
My plan right now. I found a guy in the next state over who buys rotted out g-bodies and sells the good parts. I can get a stock 2004r for $150 or a performance GN spec 2004r for $500 with a guarantee. but rear-ends he has a problem with as soon as he gets them they are gone he has had them sold before the cars were at his shop. but my local junkyard has a 86 442 with 85,*** miles so ill prolly grab that rear end.
side note: my 307 is very sluggish and bogs down i am going to swap the carb to get it to run right i am looking at an edelbrock. and i have 2.42 rear end gears with a th200 metric transmission.
My plan right now. I found a guy in the next state over who buys rotted out g-bodies and sells the good parts. I can get a stock 2004r for $150 or a performance GN spec 2004r for $500 with a guarantee. but rear-ends he has a problem with as soon as he gets them they are gone he has had them sold before the cars were at his shop. but my local junkyard has a 86 442 with 85,*** miles so ill prolly grab that rear end.
side note: my 307 is very sluggish and bogs down i am going to swap the carb to get it to run right i am looking at an edelbrock. and i have 2.42 rear end gears with a th200 metric transmission.
You can choose to believe, or not to believe, but your transmission and rear axle are the main causes of your bogging.
Consider that the 200c and 350 turbo trans have around a 2.50 first gear. The 2004r has 2.76 I believe... and where do I even begin with your horrid rear gear ratio. That is only to justify CAFE standards imposed on GM by the government. Just upgrading your rear to a 3.54 and your trans to a 2004r will make you think you did your engine swap already!!
Trust me, don't throw out your 307 Just yet.
And if you are going old school on your engine (non emissions) by swapping a non standard carb, take a moment and consider this:
Your engine WILL run better with a quadrajet. Go and get yourself a 70's model quadrajet from a Chevy 305 and bolt that on. You will have to change the fuel line hookup but that is all.
Next, go and get yourself a 75-80 Olds 350 HEI big cap distributor without the computer controlled est advance.
Again, you will think that you changed your engine.
Next, with NO OTHER MODS WHATSOEVER, just drop in a stock cam for a 68-70 Olds 350.
Another engine swap feeling!
Now headers!!
You see where I am going with this?
Oh, and the 350 Chevy? That is a really BAD deal. I buy whole cars for less than 500 bucks with GOOD RUNNING 350 Buick, Olds and Pontiac engines from the 1970's in them. I did it in California, Ohio, Indiana, and Florida. You can do it, too. Buy yourself a rusted out Olds with an Olds V8 from the 60s or 70s and pirate the engine from that.
500 dollars and it has metal shavings and needs all that? That is just crazy.
Consider that the 200c and 350 turbo trans have around a 2.50 first gear. The 2004r has 2.76 I believe... and where do I even begin with your horrid rear gear ratio. That is only to justify CAFE standards imposed on GM by the government. Just upgrading your rear to a 3.54 and your trans to a 2004r will make you think you did your engine swap already!!
Trust me, don't throw out your 307 Just yet.
And if you are going old school on your engine (non emissions) by swapping a non standard carb, take a moment and consider this:
Your engine WILL run better with a quadrajet. Go and get yourself a 70's model quadrajet from a Chevy 305 and bolt that on. You will have to change the fuel line hookup but that is all.
Next, go and get yourself a 75-80 Olds 350 HEI big cap distributor without the computer controlled est advance.
Again, you will think that you changed your engine.
Next, with NO OTHER MODS WHATSOEVER, just drop in a stock cam for a 68-70 Olds 350.
Another engine swap feeling!
Now headers!!
You see where I am going with this?
Oh, and the 350 Chevy? That is a really BAD deal. I buy whole cars for less than 500 bucks with GOOD RUNNING 350 Buick, Olds and Pontiac engines from the 1970's in them. I did it in California, Ohio, Indiana, and Florida. You can do it, too. Buy yourself a rusted out Olds with an Olds V8 from the 60s or 70s and pirate the engine from that.
500 dollars and it has metal shavings and needs all that? That is just crazy.
wow you have really opened up my options man but the hard part is finding the rear-end because i want to do that before the transmission
As I stated previously, you don't need an 8.5 ten bolt from a Grand National for the horsepower that you are talking about.
Think about the last LS powered monster WS6 Trans Ams and SS Camaros, they had 7.5 ten bolts like you have. They just had stronger axle shafts with more spline count than you have. I believe our G-bodys have 26 spline axles and the 88 and newer F bodys have 28 spline pieces. No matter, because the stock shafts suck anyway! You can go to the wrecking yard and get yourself some 3.42 or 3.54 rear gears from an 82-02 F-body pretty cheap. Most V6 automatic cars came with that ratio. Then you just need to buy good aftermarket axle shafts for whatever spline you have from your wrecking yard pull.
I know guys that even take the posi units (the zexel torsen style that looks like a meat grinder) and run those stock with stronger axle shafts with great results.
Put your mechanic skills to the test. Be safe and here is how you do it so that you're not broke down:
1. go to the wrecking yard and get another 7.5 ten bolt for a G-body like you already have
2. go to the wrecking yard and get your 3.42 gear set
3. Order your axle shafts from summit or whoever you trust along with a new bearing and seal kit for your G-body rear end.
4. Assemble it all and throw some new brake shoes and wheel cylinders on it while you're at it!
Now, just pull your old one and slap the new one in! If you made a mistake or break it or whatever, you will still be driving after a few hours putting your old rear back in.
I advocate the same thing for the transmission and engine because I hate having my car torn apart for long periods of time!
Good luck!
Think about the last LS powered monster WS6 Trans Ams and SS Camaros, they had 7.5 ten bolts like you have. They just had stronger axle shafts with more spline count than you have. I believe our G-bodys have 26 spline axles and the 88 and newer F bodys have 28 spline pieces. No matter, because the stock shafts suck anyway! You can go to the wrecking yard and get yourself some 3.42 or 3.54 rear gears from an 82-02 F-body pretty cheap. Most V6 automatic cars came with that ratio. Then you just need to buy good aftermarket axle shafts for whatever spline you have from your wrecking yard pull.
I know guys that even take the posi units (the zexel torsen style that looks like a meat grinder) and run those stock with stronger axle shafts with great results.
Put your mechanic skills to the test. Be safe and here is how you do it so that you're not broke down:
1. go to the wrecking yard and get another 7.5 ten bolt for a G-body like you already have
2. go to the wrecking yard and get your 3.42 gear set
3. Order your axle shafts from summit or whoever you trust along with a new bearing and seal kit for your G-body rear end.
4. Assemble it all and throw some new brake shoes and wheel cylinders on it while you're at it!
Now, just pull your old one and slap the new one in! If you made a mistake or break it or whatever, you will still be driving after a few hours putting your old rear back in.
I advocate the same thing for the transmission and engine because I hate having my car torn apart for long periods of time!
Good luck!
7.5 rear ends can put up with alot of abuse and if you don't believe it check out your local circle track speedway and watch the metric car class, thunder car, super stock, or whatever they are called at the track and watch them beat on the 7.5 rear. They are running built or crate engines with around 350 hp and I bet you'll leave with a different opinion of a 7.5
for the wheel cylinders pick up the non power brake cylinders for an S10....bolt in upgrade
for the wheel cylinders pick up the non power brake cylinders for an S10....bolt in upgrade
pontiacgp said:
Isn't that different than street driving? You are not constantly stopping and going, it is pretty much at a constant speed. Don't these rear ends hate massive amounts of torque applied to them from a standstill?
dan2286 said:
If you have massive amounts of torque then yes I would agree a 7.5 wouldn't hold up to it. As far as the circle track cars there is hard braking into each corner then mashing the gas coming out of the corner....and there's plenty of banging and leaning on other cars through the corner. Also the spider gears are welded so in the corner you have a constant strain on the inside tire trying to keep up to the outside tire. There were no failues of a 7.5 last year or the year before that even with the cars that had the axle flanges sheered off by the wall or another car.....
I'm not saying the 7.5 is the ultimate rear end but they are alot more durable and stronger than many people suggest. Another thing is the weight factor of a 7.5 and an 8.5. We have an 8.5 on our camaro this year for the super stock class and it's alot heavier to carry around.
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