Motor Options (Need Opinions)

[67_C-30]

Originally Posted by 697498chevy

My '69 307 has 256,00 miles on it . Never been out of the truck . I did take the heads off and had them re-built . May have added a new cam and lifters also . I'd be happy with a good rebuild . No need for high performance . My truck's been original for 40 years and I see no reason to change it . Just my two cents worth . Hope I didn't step on any toes .

No stepping on toes. 307's are great engines, but it is 40 year old technology. Just adding heads like Vortecs will make any old SBC perform better and be more efficient. So much has changed and the CAD designed later model heads acn offer more power, better fuel efficiency, and the ability to run high compression ratios without detonation than any 40 or even 15 year old production heads. The spark plug is moved closer to the center of the chamber and the chamber itself is a high-swirl, fast-burn style chamber than was once only found on race heads. The intake ports are taller and narrower and flow more air on the upper rpm ranges for power while also flowing better in the lower ranges for torque. They are truly better in every way. There's nothing wrong with a stock 307, but if you drove one with a little better cam and Vortecs, I think you wouldn't want to go back.

You can see in first 2 pics that the spark plug is closer to center of the cylinder on the Vortec head. The bottom pic is regular 60's - mid 90's style open combustion chamber on the left and the Vortec chamber on the right.

[pat123]

I was told that you can get vortecs with both bolt patterns for the intake manifold

[67_C-30]

Originally Posted by pat123

I was told that you can get vortecs with both bolt patterns for the intake manifold

Aftermarket Vortecs yes, but not on stock production Vortecs.

[697498chevy]

67 C-30 THANKS for the post . Those heads look good . I'm just saying my truck's been stock for 40 years and that's good enough for me . She's tired and needs some TLC , but still gets me back and forth to work . If I ever get my dream shop built , I hope to give her some much needed attention . THANKS AGAIN .

[tdave00]

I think I scored a set of the 305 Vortec heads .

[pat123]

should i be looking for aftermarket vortec heads or stock gm ones?

[tdave00]

In my opinion the stock ones will do just fine. There are guys on here smarter than me though .

BTW...got a used set for $100. Just got to go pick them up.

[pat123]

I also got a 600 cfm edelbrock carb and am wondering if anyone has a book that can tell me what jets i would need for my 307? the carb needs to be rebuilt anyway. also if theirs and kits to pep them up?

[pat123]

Soo iv been hummin and hawing about what i want to do and have decided to go with a set of vortec heads, an rpm edelbrock manifold, and an edelbrock carb(not sure what cfm), and not sure yet what cam. I was wondering do i need to change the pistons and should i go with cast or aluminum vortecs? Also what are a set cast vortecs worth used in good shape (no machining)?
Thnks Pat

[tdave00]

I got mine for $100 used.

[wesmigletz]

You've gotten a lot of good advice in this thread. I would recommend either a pair of 305 heads (#601 or 416) with a good valve job and a pocket port, or a pair of 350 vortec heads #062 or #906 (not the 305 vortecs).

If you went with Vortec , for the price, I would buy new and run a mild cam, so you don't ave to worry about the stock springs or retainer to guide clearance.

As far as intakes go, use a low-rise dual plane. The Vortecs have taller runners compared to the traditional 23* heads, and have a straighter shot from the plenum to the runners. If you went with Vortec heads, I would run the Vortec Performer. If you went with the 305 heads, I would go with a Performer or a Weiand Street Warrior spreadbore intake. I would run a Q-Jet on either intake. You mentioned gas mileage... you won't beat the mileage of a properly set-up Q-Jet with any other carb.

A TH350 would be plenty strong for a 307, and everything else being equal, put more power to the ground compared to a TH400, which will improve bothe economy and acceleration. With that said, I would reconsider an O/D 700R4 or 2004R. An O/D will knock several hundred RPM off of your freeway revs, which translates into a longer engine life and improved economy.

Good luck,

Wes

[pat123]

im still having a hard time deciding on heads. im going to get the heads then match around them. 50/50 some people say vortec some say edelbrock. at the moment im looking at aluminum edelbrocks (70cc chambers, 185 runners, 2.02/1.60 valves) . i didnt realise if i went vortec i need a roller cam.

[Rollie396]

You don't need a roller cam with vortec heads on your 307.The vortec engines are factory roller cams,but you donot need a roller in older engines.
I have new vortecs from summit on my 350 with flat hydraulic cam.I love it!It performs way better than the same set up with 882s.

[68Stepbed]

If you go with vortec heads, get the stock GM set. I recently read in HotRod magazine that GM used a very complicated backcut on the valves that alot of machine shops can't duplicate. They recommended buying new from GM instead of buying used or rebuilt stes.

You don't need a roller cam with Vortecs. What you will need is self-aligning rocker arms. GM started using self aligning rocker arms in 1987. All new GM crate engines have them and all new GM heads require them. I found this out when swapping rockers in my 260HP crate engine.

Personally, I wouldn't go with the aluminum heads on your 307, but it's your money. As far as the carb cfm, I wouldn't go any bigger than a 500. In my experiences, the 500 cfm Edelbrock even works better on a stock 350 than a 600 cfm. Even with good heads, the 307 just won't pull enough air to need a 600 cfm carb.

[boundstaffpress]

Smaller carbs are better for everyone who is not drag racing. Economy and torque come from smaller cfm.
Vortec heads are cool. I don't think I would pay for the Edelbrock name if I was building another engine. AFR has a much better head for about the same money.

[pat123]

would i have to get dished out pistons to keep my compression down to run pumped gas?

[68Stepbed]

No. The original 307 engines had flat tops in them with 62cc chambers and still only made about 8.0:1 CR.

[chev-obsession]

if i were you i would save the money that you would spend to re-build the 307 and spend it on a 350

[jgh64pkup]

put some l31 vortec heads on it

[short-t]

Or spend $1500 on my complete turnkey 383 that includes headers, MSD 6al, hei dist, Holley 750 vac secondary carb, air cleaner assy and a 1.5 year old 700r4. Took it out of my truck in favor of a LS2/4L70E.

Pat, i have built a few engines in my time and let me tell you that you will NOT be happy with that short stroke sbc! In a big heavy truck like ours you need torque to get things moving, Lingenfelter (God rest his soul) said it best, FOR A STREET DRIVEN ENGINE BUILD IT FOR TORQUE AND LET THE HORSEPOWER FOLLOW!

That being said I know you are worried about fuel economy. That 383 will probably use less fuel (if you can keep your foot out of it) than the 307. The 383 will need a lot less driver input to get the same results. Plus you'll have the 700r4 to help you with the launch 3.06 first gear and keep the revs down at hwy speeds .70 OD.

No I am not trying to sway you into buying my 383!

[piecesparts]

I am running a 383 stroker in my 84 truck. The 700R4 behind the engine is feeding into a set of 3.73 gears on a Posi rear end. I am getting a decent 15 MPG on the highway with a 28" tall tire (kind of short for many trucks). I tried a 750 carb a few years ago and that was a definite mistake for a driver. In the city is bogged too much to be operating properly. I ran a 600 CFM Edelbrock carb for a while and that was good, but the install of a 650 CFM Edelbrock AVS carb was the right ticket for the engine combo. I have the RPMs at about 2500 when on the highway running at 75 MPH.

I purchased all of the rods, springs, and jets to do the carb calibrations and that helped me get a fine tune on the operation and transition points from the primaries to the secondaries.