Mighty yet tiny 307 sbc.
 

This weekend I got a 69 Nova Sedan with a rebuilt 307, and I want to polish the turd the best I can for my DD.

I have a few Q-jet's, and Pertronix kit laying around. Along with a edelbrock performer intake. It's 2 barrel needs a rebuild, but it runs decent. So why not upgrade at the sametime.

Will the Edelbrock intake ports line up with the smaller i believe 307 ports? Or would it be better to get a 305 aluminum intake for the 307 heads.

Is there any flow advantage to going to 350 exhaust manifolds when I get around to the dual exhaust. Or are they the same casting numbers.

What about a Edelbrock 500 cfm vs Q-jet. Any benefits or just a different carb.

I want to fire up this engine as much as I can as I have a TH700R4 that I want to back it up with for longer drives. Otherwise it will get the same mpg as it lacks power to push the car down the road.

Re: Mighty yet tiny 307 sbc.
 

305 heads, whether 416 castings with a 2701 Edelbrock and 500 with elecrtic choke.
https://www.summitracing.com/parts/edl-2701


or 305 vortec heads intake

https://www.summitracing.com/parts/s...RoCAdQQAvD_BwE

I would add a 4x4 cam to help the 307 out
https://www.summitracing.com/parts/c...make/chevrolet

Re: Mighty yet tiny 307 sbc.
 

I want to stick with bolt-ons especially if I have them lying around.

If I or when I go further. It will be a complete motor

Re: Mighty yet tiny 307 sbc.
 

Bolt on? Headers. No real reason to go further till at least a cam change.

Re: Mighty yet tiny 307 sbc.
 

I would give it an 80's 305 intake and Qjet and an HEI call it a day. I don't even think headers would make enough difference on a 305 or 307.

Re: Mighty yet tiny 307 sbc.
 

The 307 can't breathe due to the tiny valves, big chambers and small cam. The intake and carb will have no noticeable impact.

Re: Mighty yet tiny 307 sbc.
 

Nearly all Mt experience comes with 350's. So going to a 4 barrel q-jet from a 2 barrel. Gave some hp, but also gas mileage due to better fuel control.

So that was what I am trying to replicate

Re: Mighty yet tiny 307 sbc.
 

Edelbrock 500i s a rich carb. Remember my thread on the bluetooth o2 sensor?
If it was my engine I would just get an HEI and a balancer tape. Then dial in the distributor curve along with some dual exhaust and drive it.

Re: Mighty yet tiny 307 sbc.
 

I'm pretty sure the 283's had the same heads and they benefited from a 4 barrel. A nice non-feedback 305 Qjet would work sweet on there.

Re: Mighty yet tiny 307 sbc.
 

283's had smaller chambers.

Re: Mighty yet tiny 307 sbc.
 

I plan to add dual exhaust as quickly as possible. Along with my electric fan that will be here this week.

Would you just leave the 2 barrel on it? If so would you think a Holley 2 barrel would be a improvement over the dual jet.

Re: Mighty yet tiny 307 sbc.
 

I tried a similar experiment with a 79 Camaro that came with a Dual-Jet on a 305. The 2bbl started flooding and I swapped in a iron 4bbl manifold/Q-Jet off of a 327 in a defunct Impala. There might have been a bit of HP gain but not much. Did loose some MPG. (the 327 was worn and would have required a rebuild).

To answer one of your questions - pre-vortec SBC intakes are very interchangeable. You do have to watch out for carb/trans linkage variations between years.

The exhaust manifolds are also fairly interchangeable as far as the motor is concerned. Watch out for accessory mount changes. Don't remember what year the AC/Alt swapped sides.

Re: Mighty yet tiny 307 sbc.
 

I think it switched sides in 65 or 66.

Either way. I am thinking it will just rebuild the 2 barrel, and let it ride. Till I can afford a proper motor.

Concentrating on the interior, and rebuilding the suspension.

Re: Mighty yet tiny 307 sbc.
 

I would put the Edy performer on with a Q-jet if you can tune & dial in the carb. yourself. The Q-jet primaries give good drivability & gas mileage. Then when you get on it the secondaries give good power & neat sound. GM used Q-jet carbs on many small displacement engines with great success.
The Pertronix has a poor reputation for reliability although I have used several ones for years without any problems. The exhaust manifolds are OK but I would ad dual exhaust.

George

Re: Mighty yet tiny 307 sbc.
 

I had a 1977 C10 that the 350 had been replaced with a 307. Put an early non-egr q-jet intake with a q-jet and dual exhaust, saw no need for headers. The 307 came with the same camshaft as a 350 and 400 small block so it is a larger cam than the 305 received. With the above mods it felt more like a 350 than a 305 - they rev nice, fuel mileage was more than decent and it was fast enough for my 17-year old son!

Re: Mighty yet tiny 307 sbc.
 

-They don't make a different intake for different sized small blocks. Its one edelbrock performer fits all. So yes, bolt it on.
-Saying long tube headers won't make a difference is absurd. Of course they will help.
-If the Qjet is good, the edelbrock carb won't make any more power. I'd stick with the Qjet if you are comfortable tuning them. I'm not lol.
-Exhaust manifolds are all the same unless you find some 2.5" ramhorns as opposed to the standard 2" versions.

Re: Mighty yet tiny 307 sbc.
 

When I put the o2 sensor on my 283 with its stock power-pak heads, intake and 2 jet carb, the AFR readings were ideal at idle, at cruise and wide open. It was made for that engine, with that intake and those heads. I don't see a Holly 2 barrel as being an improvment myself. See the last post on this thread for the 2-jet AFR readings. http://67-72chevytrucks.com/vboard/s...d.php?t=838553 rest of the thread was the Eddy 500 CFM

Re: Mighty yet tiny 307 sbc.
 

One other tidbit I learned about the stock 2jet manifold on my 283....the runners/ports are actually smaller than the ports of the head. The head ports are indeed the same size as the aftermarket and larger stock manifolds, but I suspect that in order to keep the small motor with good off idle and around town feel (which it has) chevy must have felt the smaller runners would compliment the smaller carb.

Re: Mighty yet tiny 307 sbc.
 

Just bolt the edlebrock and qjet on and see how you like it. You can always go back if it sucks.

Re: Mighty yet tiny 307 sbc.
 

I am leaning this way since it opens up fuel injection opportunities at a later date if I want too.

Although I would swap motors for a more modern alternative more then likely.

Re: Mighty yet tiny 307 sbc.
 

heads, cam , intake and headers

305 Vortecs could be used from pick-your-part

https://www.motortrend.com/how-to/su...e-performance/

Re: Mighty yet tiny 307 sbc.
 

In 1968 through 1970 the 307 was rated at 200hp. In 1971 the rating went to 135hp which was likely very close to the correct hp. The suffered from poor heads, bad quench and low compression. Since GM never made a 307 with any HP, thus they have a bad reputation, deserved or not.
I do agree others making a stock 307 go fast is a mistake. I would optimize what I had and call it good. If you have to do something I would consider using the Vortec heads as a first choice. Without that you are going to gain very little. Yes, tuned correctly a set of headers will add power, but what is 3% of 135hp anyway? LOL.
We have had this discussion before it was just a 283ci motor we were talking about. None of the facts have changed only the displacement. The choice is yours. Put your $ where it will do some good and possibly have some resale value and build a 350 for less than the cost of a 283? I will never build a motor without a roller cam unless it has some value being original. Too difficult to get the cams to live with the current oils.
Your motor has already been replaced, so you lose the inherent value of “Original.”
A Vortec 350 will have good heads a roller cam and a one-piece rear main. And as a bonus valve covers that don't leak have more power and possible even get better mileage.
With some luck you can find a good used one for less than any of the modifications.
Choices

Re: Mighty yet tiny 307 sbc.
 

^^this is all true of course^^ but sometimes doing something different has its merits. I have a hottroded 283 and whereas it's no drag racer, it is certainly fun especially with a stick shift and proper gearing.

These days the most practical choice is to put an LSwhatever under the hood and have power and efficiency,...I'm sure they are great in their own right, but I'm still a sucker for nostalgia. People who build small old school V/8's and inline sixes do it because they love them. If that's you, then I say do it. The feel and sound of a small hot rod motor giving me its all always makes me happy.

Re: Mighty yet tiny 307 sbc.
 

The Nova is my daily driver, and I don't plan to get rid of it for 10 plus years. Along with being a 4 door. Resale won't be great. It does how ever fill alot of needs, and can be tweaked to get alot of wants.

A 283 in a Nova is worth about 3-4 mpg vs a 350 with a standard th350 auto.

With a Th700 the highway gap narrows, but I can widen the city mpg so it wins by a wider margin.

Am am looking at the 3.6 or 2.5 gas engine out of the Colorado. The big issue is will they clear with a rear steer set up. Mostly coming in contact with the drag link. I have a Chevelle frame to scab part off of to make my sub-frame front steer. Which will provide more then enough room for the 3.6 swap. So in theory the 2.5 should slide right in too.

The big advantage they have is cost for fuel injection, and compatibility with today's oils. Versus building a older 283. Plus both the 2.5, and 3.6 will be easier on fuel consumption during idle time. I like to take road trips, and sleeping in the car to catch a couple hours sleep is a nice option to be able to play.

I won't buy another new car again if I can help it. So let's not go down that road. They are ugly to me, and I am upset every time I bought one. So I want to make something I enjoy driving hit as many high points as I can.

If I want power. I have my truck, and hopefully soon my Camaro again. So I would like this to fill it's needs as ideally as possible.