307 Stroker Anyone???

[pontiacvince]

I want to add some grunt to my lil 307. I know I'm gonna catch hell for wanting to keep the same engine instead of swapping to some other engine, but that's what's gonna happen.
I want to add a 3.75" stroke crank from Summit and the 400 SBC 5.565" rods. This will make it a 360 (359) cubic inch. The only problem is the available pistons will be .070 out of the hole. I can get thicker head gaskets or mill my pistons.
Ready......GO!!!

[65truckowner]

I like different I say go for it

[HO455]

Do it. Worst case you might have to get some custom pistons made. Have you figured out the static compression ratio? This one from Diamond pistons is my favorite. I've built several Pontiac strokers over the years. Figuring out all the details is enjoyable for me.

https://diamondracing.net/p-10-compr...alculator.html

[Getter-Done]

Sounds like Fun.

The (self proclaimed) Engine Guru's are going to have something to say about this.

[truckster]

I'm just curious what the benefit will be.

[350TacoZilla]

Nothing wrong with hot rodding a overlooked engine like that since its still SBC and parts availability is huge (other than the odd bore piston deal) more cu.in with small bore should pair well with mild cam for low end torque, only thing you would be giving up over a larger bore like a 350 would be airflow around valves but that is mainly higher rpm problem anyhow.

[pontiacvince]

I just talked with a tech guy at Silv-O-Lite pistons and he said my .030 over pistons are .482 thick at the top. That's PLENTY to take .070 off.
My next call was to the machine shop. They can mill all 8 for about $150. My buddy owns a shop and he had a set of 5.5656" 400 rods I picked up.
The 307 (360) stroker is GONNA HAPPEN!!!

[Getter-Done]

Is a Dyno test in the plans (that's if you have a source close to you) ?

[pontiacvince]

Originally Posted by Getter-Done

Is a Dyno test in the plans (that's if you have a source close to you) ?

Not sure where a dyno close to me is. I'm building it for more torque, not high rpm power.

[Ziegelsteinfaust]

For pistons use Summit racing search engine.

If you know the bore you want to one that is feasible. You maybe able to get a piston with a different compression height to work that is commonly available.

[Getter-Done]

Originally Posted by pontiacvince

Not sure where a dyno close to me is. I'm building it for more torque, not high rpm power.

I have not ever had the Need/Desire to want a Dyno readout.

With that be Typed

At the C10 Nationals at the Nashville Super Speedway in Lebanon,Tn

They had a Mobile Dyno Trailer.

It was Cool.

[weim55]

Any way you look at it you’re going to have serious money to upgrade the 307 with additional stroke. Unless you’re absolutely stuck on the numbers matching thing for the truck, 350 is just the way to go.

If you insist on the 307, I would skip changing the displacement and go straight for cylinder heads. The number one Achilles heel on your 307 is not displacement, it’s the outdated original cylinder heads. A cheap and easy that I have been doing for years: ‘96 and up 305 Vortec heads. They use a slightly different configuration chamber and A smaller intake valve than the same era 350 head. The smaller Intake valve will clear the smaller bore on the 307.
They are not as common as the 350 head in the bone yards, but you still shouldn’t have too much difficulty coming up with a set. I have been been using these on 350 rebuilds for many years. The off idle response and low and torque is just incredible.

Steve weim55Colorado

[HO455]

Switching to Vortex heads would require either swapping to a Vortex manifold or modifying your existing manifold. Either way it's well worth it as the Vortex heads are that much better. They were the result of GM's development of the LT1 Corvette heads. Similar gains in efficiency, as the LT1 heads, over all the previous heads without the reverse cooling flow. You won't be disappointed with the power and MPG improvements.

[3757chevy]

Originally Posted by HO455

Switching to Vortex heads would require either swapping to a Vortex manifold or modifying your existing manifold. Either way it's well worth it as the Vortex heads are that much better. They were the result of GM's development of the LT1 Corvette heads. Similar gains in efficiency, as the LT1 heads, over all the previous heads without the reverse cooling flow. You won't be disappointed with the power and MPG improvements.

What modifications need to be made to existing manifold in order to use the Vortex heads?

[HO455]

Here is an article with links on how to modify the intake if you want to go that way. There is a fair bit of interweb arguing about if it is a good way to go. The second article has lots of info on Vortex heads in general.

https://www.jalopyjournal.com/forum/...1-350.1073537/

https://nastyz28.com/threads/vortec-...e-guide.56505/

[3757chevy]

Thanks

[Wikid61]

A pair of HO 305 heads will bolt right up. One other big ticket ($) would be a roller cam custom cut to your everything : displacement/compression/torque/trans/rear gear to get the absolute on the money results & freeing up friction & HP gained.

[LockDoc]

-
Here is my oddball. It's a 305 instead of a 307 but I have often wondered why someone would put that much time and money into this engine.... It came with a truck that I traded for.

305 Engine Specs

1989 1 piece seal block
Balanced
Roller Cam
Hydraulic Roller Lifters
1.6 Roller Rockers
.010, .010, and .030 Over
Scat Rods
Mahle light Weight Graphite Coated Pistons
Low Drag Rings
1978-81 305 Heads, Fully Rebuilt
1.50” & 1.72” Valves
Exhaust Ports Cleaned Up For Smoother Flow
Edelbrock EPS powder coated intake
Powder coated vintage style valve covers
This engine was built for fuel efficiency
0 miles on engine

I started it for the first time the other day.
.

[MikeB]

Originally Posted by pontiacvince

I want to add a 3.75" stroke crank from Summit and the 400 SBC 5.565" rods. This will make it a 360 (359) cubic inch. The only problem is the available pistons will be .070 out of the hole. I can get thicker head gaskets or mill my pistons.

That's .070" out of the hole with a 9.025" deck height. Yours could be higher if it's never been milled. But whatever the height, I'd strongly suggest taking enough off to ensure the decks are flat and square to each other.

Also, what did you plan for a cylinder bore? Hope you're not thinking about anything more than .060"over. In fact, if it cleans up at +.030", I'd stop right there. Finally, you must definitely get the rotating assembly balanced.

As far as a somewhat unusual build, 20 years ago I built a 327 using a 350 4-bolt block, cast 307 crank, and K-B hypereutectic 327 pistons. I did get some flak for not building a 350, but I always liked the way 327s would rev. I put it in a 55 Chevy sedan with a Muncie 4-speed.

[fourspeedwagon]

A few years ago I built a ‘39 Ford pickup hotrod type rig. My uncle had a 307 under the bench that had been pulled from whatever it came in when it was fairly new. No history but people liked to talk down about 307s so it just sat, orphaned. I pulled the cam and found the lousy factory timing gear was so worn that the cam timing was retarded because of it. I put a mild 262 duration / .480 lift cam in, aluminum intake, HEI, and headers, otherwise stock. Sucker ran good and moved that little p/u nicely. Saginaw 4 speed and an 8” with 3.50 gears.
The main issue with a 307 is only its reputation. It was never used in a performance application, just as the basic, bottom option V8.
Physically it is a 283 block with a 327 crank. In my 39 I called it just that- way more impressive to have a 283 stroker with 327 crank than a “boring” 307..
A mid sized cam, some better heads probably 1.94 valves, no need for 2.02s and the usual tricks and you’ll be having fun.
If you do go with the full / long stroke crank and pistons, be sure to have a machinist confirm piston height and quench.

[MikeB]

Originally Posted by fourspeedwagon

The main issue with a 307 is only its reputation. It was never used in a performance application, just as the basic, bottom option V8.
Physically it is a 283 block with a 327 crank. A mid sized cam, some better heads probably 1.94 valves, no need for 2.02s and the usual tricks and you’ll be having fun.

Exactly. The 283 had a lot better reputation, but only because it was available in several versions: 195-220hp with hydraulic cam, and 270-283hp with solid lifters. There was a 245hp version in there somewhere and even up to 305hp in its last year.

Ah, but the lowly 307 was available only in one flavor--200hp with a 2bbl carb. Never mind it was a stroked 283, which was considered to be cool prior to the 327 introduction.

When I bought my 69 C10 back in 89, it had the original 307 complete with noisy lifters and sluggish performance. Frist thing I did was replace the cam, lifters, and the worn-tooth timing set. I used stock parts purchased from an engine rebuilding company in Ft. Worth. The cam was probably the old 195/202 piece that was used in 283, 327, and even 350 engines over the years. Those parts and 2-inch dual exhaust with generic turbo mufflers made a big difference.

Later I bought a used Q-jet manifold (interestingly from a 69 327), along with a Holley Economaster 450cfm Q-jet replacement carb. Man, that little 4-bbl made even a bigger difference, and completely transformed the truck. It was probably faster than the lighter 220hp/283-4bbl cars I had owned over the years. I can only imagine what it would have done with a small performance cam and bigger valves, even with otherwise stock heads.

I eventually went to a 350 and even a 383 for awhile, but sometimes wish I would have just rebuilt the 307 short block and did something about the heads.