Made an "un-popular" decision with my 307!

[sean1969c10]

I can give you tips to help your 307. When you have your valve job done have the machinist put a 30 degree back cut on your intake valves. This will help flow even on stock valves. Have them spend a few minutes cleaning up the short side radius on the ports, you don't want to go crazy, you just want a smooth transition from the port to the valves. If you can swing it, have the machine shop zero deck the block, then use a .042" thick head gasket to tighten up the quench. Setting the quench this way helps to fend off detonation and aids in more efficient combustion. The rest of your combo sounds good and not too wild for a 307. I strongly agree with the built not bought mind set. Two of my trucks are built by me, my K10 I got in a trade but, buy the I'm done fixing all the PO's "improvements" it will have my signature on it too. PM me if you have questions about the engine build, I am a ASE Master Automotive Machinist for the last 16 years, I don't mind answering questions. Good luck with the project!!

[HEI451]

About the only adversity with the basic 307's I have seen is the later model heads, I think they are called "high swirl". If you look down the intake tract, the port itself looks like half of it just isn't there, like metal was allowed to close half the nport off. That is the way those particular heads are designed, and the only good thing about them is, they are heavy, can be made to stop cars from rolling, doors from closing, etc.

[Redleg]

Originally Posted by sean1969c10

I can give you tips to help your 307. When you have your valve job done have the machinist put a 30 degree back cut on your intake valves. This will help flow even on stock valves. Have them spend a few minutes cleaning up the short side radius on the ports, you don't want to go crazy, you just want a smooth transition from the port to the valves. If you can swing it, have the machine shop zero deck the block, then use a .042" thick head gasket to tighten up the quench. Setting the quench this way helps to fend off detonation and aids in more efficient combustion. The rest of your combo sounds good and not too wild for a 307. I strongly agree with the built not bought mind set. Two of my trucks are built by me, my K10 I got in a trade but, buy the I'm done fixing all the PO's "improvements" it will have my signature on it too. PM me if you have questions about the engine build, I am a ASE Master Automotive Machinist for the last 16 years, I don't mind answering questions. Good luck with the project!!

You my friend might have just opened a can of worms! I will keep your offer in mind and probably be sending questions your way!

[sean1969c10]

Not a problem, I'm glad to help.

[Captainfab]

I stumbled upon this vid while looking for something else on YouTube

'73 Chevy C10 -- 307 SBC w/ Comp Cams 262XE ...

[prostreetC-10]

Looks like a great way to have a truck fall on you and kill you!

[earlthegoat2]

I bought a 68 Chevelle with the original 307 and Powerglide transmission with 2.73 open rear. I had all these ideas of what I was going to do to the drivetrain to "improve" it. This car was a driver.

That 307/Powerglide ran so good I could not bring myself to change anything. I had the 327 and TH350 and 3.73 Posi rear all ready to swap in. It wasnt broke so I didnt fix it.

I did end up installing the 3.73 diff and it made not a lick of difference in driveability.

[Redleg]

Well, picked up my block today! Needs cleaned up but looks in great shape. The pistons are aftermarket flat tops....Will research them more tomorrow. Looks like they are in great shape just need new rings....

By finger feel and look, the cylinder walls are in extremely good shape. From what the owner said, it was pulled from the truck with only 20K miles. Now dont know if i believe that. But its clean enough i might think under 50K.

Turns out the cam was a Comp Cam 270H. Unless im wrong, which i am quite a bit, that is way to big for this 307? He told me he was just throwing in the cam, that it actually came out of his 355.

So, tomorrow i hope to get her cleaned up so i can really check her out.

Oh and the ole boy (he was all of 17), threw in an engine stand. Good kid. Im only 30, but its damn good to see the young ones working on these trucks instead of little imports or something.

So even though he drives a ford now, he was a good kid....

Posting some pics in my build thread if ya wanna look at them...

[Captainfab]

Well, too big is a matter of what you want out of the little 307. I would say the 270H would be okay for myself, but maybe not for everyone. The 270H is probably going to idle and sound pretty much like the one in that green square body in the YouTube video I posted above.

[Warrens69GMC]

The 270 is the maximum I would want to put in a 307.

[hairlesshobo]

Originally Posted by Redleg

Oh and the ole boy (he was all of 17), threw in an engine stand. Good kid. Im only 30, but its damn good to see the young ones working on these trucks instead of little imports or something.

I know how you feel, and this is coming from the person who is (well, technically now it's "was") that kid. I'm 22 now but I've been building American since I was 15 and it drives me crazy to see all this little imports running around town with a fart can and rims and they think it's the fastest car ever made. I've yet to find anyone my age in this town who is also into American cars and actually knows how to work on them.

[Redleg]

Originally Posted by hairlesshobo

I know how you feel, and this is coming from the person who is (well, technically now it's "was") that kid. I'm 22 now but I've been building American since I was 15 and it drives me crazy to see all this little imports running around town with a fart can and rims and they think it's the fastest car ever made. I've yet to find anyone my age in this town who is also into American cars and actually knows how to work on them.

Yep, know what you mean. Hey i just know you want to get rid of that T-5 in the Tranny dont ya? lol

[Redleg]

Ok one more question. WHo the hell carries 307 crankshafts these days??? All i can seem to find is 307 crankshaft sensors.....

[crazy longhorn]

Originally Posted by Redleg

Ok one more question. WHo the hell carries 307 crankshafts these days??? All i can seem to find is 307 crankshaft sensors.....

FYI, the LJ 327 crank is the same pc(save the balance work)...if you plan to balance, you can use either 307 or 327 LJ crank. crazyL

[Redleg]

Originally Posted by crazy longhorn

FYI, the LJ 327 crank is the same pc(save the balance work)...if you plan to balance, you can use either 307 or 327 LJ crank. crazyL

Yeah, still not seeing anything for a 307 or 327. Just 350s and up...

[crazy longhorn]

Originally Posted by Redleg

Yeah, still not seeing anything for a 307 or 327. Just 350s and up...

Do you need a crankshaft, or just want to upgrade to forged?

[Redleg]

well my plan was to build the complete bottom end, then pull my motor and mate up the heads etc. And have everything from my current 307 bottom untouched. That way it would be down a max of 1 or 2 days.....

Looks like i might have to reschedule and replan and pull my block earlier and reuse some of the bottom end....

[hairlesshobo]

Originally Posted by Redleg

Yep, know what you mean. Hey i just know you want to get rid of that T-5 in the Tranny dont ya? lol

Feel free to keep dreaming lol. It took me five years to hunt one down for that car, and I'm gonna hang on to it for when I rebuild my Trans am.
Posted via Mobile Device

[Warrens69GMC]

Eagle forged 307/327 crankshaft

http://www.summitracing.com/search/B...?Ns=Rank%7cAsc

[Redleg]

Originally Posted by Warrens69GMC

Eagle forged 307/327 crankshaft

http://www.summitracing.com/search/B...?Ns=Rank%7cAsc

OUCH!!!! Probably worth the money, but OUCH!!!!

[GASoline71]

Did you talk to the cat at your machine shop? Every crankshaft I have ever bought has been from my machinist.

Gary

[Redleg]

Originally Posted by GASoline71

Did you talk to the cat at your machine shop? Every crankshaft I have ever bought has been from my machinist.

Gary

Not yet. Going to try to Friday! Getting some good reviews about a place here locally that will take your block and evaluate it etc....

[GASoline71]

Awesome! Also... if there is a problem of some sort... you can go look the cat in the eye and ask for help, or whatnot.

Gary

[Redleg]

One thing i have to do is slow down...... I told my wife i would do this slowly so she wouldnt even notice the money being gone that i spend on it!

Of course now that i have pieces of the plan in hand, i just want to rush rush rush and get it done....

From what i was told about the local shop is that they are good, but they have a "waiting list" Apparently they stay pretty busy.

So i will probably clean it up this week and go drop it of on Friday. If he has it a month i am ok with that. Will still give me a couple months to build it....

I will probably take that time to start smoothing out some rinkles and small dents on the bed... If i do that it should be ready for complete paint about the same time as the engine swap.....

THen i just have to find and work on getting the 3OTT swapped out for a 5-speed while on a budget.......

Then go a couple inches lower.......

Then..................................................................

This isnt going to end is it???

[Pyrotechnic]

I always thought the 307 was better than the 305 at least in terms of bore and stroke ratio.

You might want to consider a pair of Vortec heads. They are a huge step up from the 305 heads and would have excellent flow for that 307. You should be able to get a good deal on a pair and an intake manifold if you shop around.