My 307 Build Up

[w3lfd]

I just got finished with a rebuild / mod of my '69 C10 307 motor and I figured I would document what went into and the results here.

Parts List:
(prices include shipping)

#416 casting 305 heads: 1.84 intake, 1.5 exhaust, 58cc chamber -- $90
Used Edelbrock 1406 Carb (600 CFM) -- $50
Edelbrock RPM Performer 2101 Intake -- $80
Summit Racing Cam SUM-1103 (http://www.summitracing.com/parts/SUM-1103/) -- $55.00
Summit Racing Hydraulic Lifters (16) (http://www.summitracing.com/parts/SUM-HT817/) -- $50
Summit Racing SBC Gasket Set (http://www.summitracing.com/parts/SUM-G2600/) -- $30
Partial total: $355

Additional Parts that I used in the swap that aren't necessarily required:

Motor Mounts (http://www.summitracing.com/parts/PIO-A2282/) -- $10
Oil Filter Sandwich Adapter (http://www.summitracing.com/parts/MRG-1272/) --$23
Chrome Steel Fuel Line (http://www.summitracing.com/parts/EDL-8126/) -- $20
Main Bearing Set (http://www.summitracing.com/parts/FEM-4663M/) -- $30
Rod Bearings (http://www.summitracing.com/parts/FEM-2555CP/) (8) -- $30
Timing Chain Set -- $20
HEI Distributor -- $80

Grand Total: $568

Cam specs:
Duration at 050 inch Lift 214 int./224 exh.
Advertised Duration 272 int./282 exh.
Valve Lift with Factory Rocker Arm Ratio 0.442 int./0.465 exh.
Lobe Separation (degrees) 112

As built, I calculated the static compression ratio to be 10.5:1 with a dynamic compression ratio of 9.33:1.
These numbers may not be 100% accurate, but they should be pretty close.


So far it is running great on 93 octane pump gas.


The 307 I was building was using a press fit harmonic balancer with no center crank bolt. While the motor was out I went ahead and drilled / tapped the hole for the crank bolt (7/16 - 20). It made installing the balancer a lot easier than hammering it on or trying to locate a special tool. All of the loaner tools that I could find in chain stores required the tapped crank snout.

I removed the fenders, hood, grill, and core support. This made the whole process much easier than it would have been otherwise. I pulled the motor without the tranny attached. Upon re-installation, I found that I needed to
jack up the tail of the transmission in order get the motor to go in.

I am loving the end result. I do not have any specs yet on actual horsepower or torque, but the seat of the pants results are enough to get 2 thumbs up in my book. It is a huge difference. The edelbrock is a piece of cake to get setup.

I will be posting pics and hopefully video as well soon.

[fayettecopa]

Why the 305 heads ?

[Hutch]

Great information

[w3lfd]

Originally Posted by fayettecopa

Why the 305 heads ?

Smaller chambers than the stock 307 heads (58cc vs 64cc) brings the compression up. Also, the 305 heads are a close match with good flow for this motor.

Plus they are dirt cheap.

[nickp51chevy]

What do you think about the 601 casting # 305 heads? They are 58cc. I was thinking it would be around 11-1 compression with those.

[w3lfd]

Originally Posted by nickp51chevy

What do you think about the 601 casting # 305 heads? They are 58cc. I was thinking it would be around 11-1 compression with those.

I have read elsewhere that the 601 head ranges from 53-60cc.
If it were 58cc, the 416 is 58 CC also, so I would guess you would get the same results as above.
Gasket thickness will also affect the overall compression.
If I went any higher on compression it would raise my dynamic CR, and I would probably be needing racing fuel or some sort of octane boost to keep the motor from pre-detonation.

[screamin_c10]

Did you consider 062 or 906 Vortec heads? I'm running the 1103 as well....gives the 'lil 307 a nice lope and a very nice power band. Were your pistons flat top 4VR or the dished ones?

[w3lfd]

Originally Posted by screamin_c10

Did you consider 062 or 906 Vortec heads? I'm running the 1103 as well....gives the 'lil 307 a nice lope and a very nice power band. Were your pistons flat top 4VR or the dished ones?

The pistons were flat tops. Considered vortecs, ran with what I could find cheap to get it together. There is probably another head swap in its future, when I get bored again. Lol.

[nickp51chevy]

Originally Posted by w3lfd

I have read elsewhere that the 601 head ranges from 53-60cc.
If it were 58cc, the 416 is 58 CC also, so I would guess you would get the same results as above.
Gasket thickness will also affect the overall compression.
If I went any higher on compression it would raise my dynamic CR, and I would probably be needing racing fuel or some sort of octane boost to keep the motor from pre-detonation.

That's what it was; 53cc's. So from what you're saying; it's probably a good idea to not go any lower than the 58cc head though. I do remember someone telling me to go with the 416 head once before. Do you know what the HP is that your engine is putting out now?

[w3lfd]

Originally Posted by nickp51chevy

Do you know what the HP is that your engine is putting out now?

That is the next tricky question. Unfortunately I am not close to any metro areas with dyno setups, but as soon as this motor has a chance to get broken in I am going to be looking.

Dyno simulators put it right around 300 hp and 385 ft/lb torque, but that is a far cry from putting it on a dyno. I don't trust the numbers from the simulator.

[nickp51chevy]

I can believe it though. Those are about my projections for my engine when I'm done.

[andymarkv]

Awesome!! I'm so glad you posted up results!
Your pistons are flat tops and not dished? Must be early motors got flat tops and later got dished?
Do you know what the factory compression is supposed to be for your 69 307?
Did you measure how far the pistons were down in the cylinders? Seems like they are typically deep in the hole on the 70's smog motors (.020-.030 on the motors I've measured)

You're going to have to try harder to describe how much better it is!!!! Is it worth the effort and time? (looks like you got the budget part perfect)
30% better than stock, more? Does it press you back in the seat? Is the low end torque strong? Can you punch it and it pulls till 4000, 4500, 5000rpm?
With that much compression, that cam should work really well!
Stock manifolds, not headers?
Did you have to do much carb tuning?
What gears do you have?

I'm lucky that I have a local dyno with wideband to tune the carb. If you can get to one, it is really easy to dial stuff in with a wideband.

I'm concerned on my 71 307 build that 10.5:1 would be too much for heavy 2500lbs farm loads, even with 93. If I had more cam that would bleed off some of the cylinder pressure....but I need a lot of torque.

Anyways your results are very encouraging! Keep us updated!

[w3lfd]

Yep, flat tops. Only slight valve reliefs in the top. Top of the piston was even with the plane of the block at TDC. I do know that my 307 (block 3956632) started out as the higher torque truck version of the 307 (200hp, 300 torque).

The build was definitely worth the time invested. It is like night and day on the performance. It also sounds much, much better.
Before the workup, I could just barely break the tires loose by dropping the clutch. After, I can get it to break loose just by flogging it in 1st gear.
The first test run I spun tire for 2 blocks until it dug in.

I haven't hooked my tach up, but I can say that it pulls from the get-go right up through where I start to worry about running it too hard (guessing about 4500 rpm). Pulls hard through all the gears as well.

The edelbrock carb needed the floats adjusted, but other than that it was cake.

Best guess is it's running 3:73 gears. I never got around to confirming what it actually is. It is a stock 3 on the tree tranny and the truck originally came with the 307 so that is my best guess.


Exhaust is the stock Ram's Horns.

As a final note, I had a 1982 928, which was an automatic, and this truck seems as though it is a lot faster than that was. But you know how that goes.

[andymarkv]

Man that's what I wanted to hear!!
So cheap and easy! I have read a bunch of people say that the 307 can run pretty well with compression and cam. Just good to hear it from someone that has done it! Now I just have to keep watching for a nice set of 416's to come up!

Probably the power difference in motors early and late are the flat tops and zero decked block. So my later 71 307 propably wouldn't gain quite so much compression. But I wouldn't know for sure until I opened it up.
Since I already did the cam swap, this would be so simple for me!

Pics and video would be great!!

[redbaron69]

i have a set of these heads im gonna use on my 307. i heard about this setup from some local dirt track racers. like you stated these heads are easy to find and cheap. i paid 50 bucks for my set at a local junkyard. glad to see the great results great job. pics and a video would be sweet.

[screamin_c10]

Originally Posted by w3lfd

The pistons were flat tops. Considered vortecs, ran with what I could find cheap to get it together. There is probably another head swap in its future, when I get bored again. Lol.

yup, cheap is the way to go on these lil engines. I scored a couple sets of Vortec heads during the "Cash for Clunkers" campaign. Alot of nice late model stuff went to the crusher... I definately suggest trying out a set when you get the opportunity....well worth the upgrade. Not trying to hijack the thread but here is a link to my build as well. Makes for some interesting reading....

http://67-72chevytrucks.com/vboard/s...d.php?t=429865

[w3lfd]

Well, here is some video. Not the greatest conditions out, but man do I love how it sounds:

YouTube - '69 Chevy C10 Burnout

[nickp51chevy]

Nice!!!

[andymarkv]

Very nice!!! Sounds really good, strong too!
Must be totally worth the effort!

[kcfirstbuild]

I have a 307 also , I have a question about my Harmonic Balancer. I never noticed a Center bolt when i took it apart. I want to make sure that is one.
I also wanted to know if I have mine pressed in all the way, the distance from the timing cover seal to the part of the harmonic balancer that is not turned is about a 1/4 inch.

This is my first build so I want to make sure im doing everything correctly, I used the proper tool to install until i couldnt turn in anymore.

[1972K20]

It's really cool to see people build a 307. Not something you see everyday. Very cool!

[Pop's C-10]

That sounds good

[5150.4.67]

Wow. Nice write up. Just make sure that thing is not detonating. That DCR is mighty high for iron heads and pump gas. What were your quench measurements?

[splehigh]

Thanks for sharing! I'll keep this in mind when my 307 needs another rebuild.

[stsalvage]

Originally Posted by w3lfd

Well, here is some video. Not the greatest conditions out, but man do I love how it sounds:

YouTube - '69 Chevy C10 Burnout

only one question why do people put tail Pipes out the back Are you just looking to get your Butt kick if your truck is running like crap and you have Blow by and you step on the Gas and all that Black ash and crap come out the back onto some ones new paint Job.Me i like them on the side when i'm on the freeway and i get close to the wall I step on it with my 41 inch glass packs i sound like a Race car