MOTORHEADS--69' 307ci tell me about it...

[mark69k20]

All the knowledge on here I would like to tap into some of it.

My 69 k20 has the 307ci v8 in it, buddy keeps saying go to a crate 350 and stop messing around.

Was this engine reliable? Power? Parts availability? Any know design problems

My plan is to do a compression check, if good, and I find it is a good old motor from you fellas go to electronic ignition, new manifold, carb, headers and exhaust. Any input on these components or "quality" of this motor will make my experience that much better!
Thanks in advance!

[QKENUF4U]

def. not power makers but they can run forever just like any other small block if taken care of. dont know whether i would spend the money on an intake etc. but its your money so you can spend it anyway ya want. i guess my point is...... if your just building a driver then go for it and just take care of it (oil changes etc.)

[SOON2BLAZE]

See the latest or maybe last month of Classic Trucks mag. They did a whole build up on one of these 307's. Even with the aluminum heads ect.. it was still a turd. I've got one in my 68 chev and for the money I would sink into it to get even mild performance gains, I could build a strong 350. ( or even a 292 L6 with more hp and torque) just my .02

[69TowRig]

I'm in the same boat as you with my 307, only I think this one is a bit tired. A nice new 290Hp GM Performance Parts 350 is in the cards for me. Jegs sells a complete, ready to run setup for $2200. A complete rebuild on parts alone is well over $500, and then add in the countless hours of teardown and rebuild, with some extra $$ thrown in for machining. To me I don't think it's worth it. Brand new the 307 was only producing 150 net Hp. I can spend the $$ and get a proven setup with nearly double the power and gobs more torque. Plus that's a 4-bolt main that will stand up to later modifications.

[Green Machine]

Well, I rebuilt mine, but I wanted to keep it original, 212/218 cam and 4 barrel carb, runs pretty good. An expensive part of the rebuild was the heads, new guides, new exhaust valves and seats plus the normal head stuff. Kind of questionable to put that much money in some small valve(1.72) heads.

[mark69k20]

Good stuff, I see what you guys mean about power and $$$. I do know it needs a serious tune up! I got to pull it out this summer past and wash it, lead to a little starting prob that us young bucks are not use to these days!
Of course I had to laugh and realized if that eng was to stay it needs electronic ignition. Any suggestions on new distributers w/ built in electronics...NO MORE POINTS!

[HeavyD]

HEI swap. It is cheap and it works.

[sweet n rare67]

I did a little reearch on these a while back and basically found they are just turds from the factory but they are still a SBC which means they are okay they just arent known for being big power but like any other they should be very reliable if taken care of. It is your call on whether or not you want to put big bucks in it.

[farmtruckIII]

I love my 307, they have strong blocks, and will run forever. I had another 307 in a firebird as a daily driver, small cam, stock 882 heads performer RPM intake and 600 CFM carb it made around 300 hp at the fly wheel, and with 2.73 gear ran 9.90 1/8 miles. It made for a nice driver, the 307 is under rated, by no means a power house though, just and old reliable mill.

[Bowtie67]

The 307 is basically a 327 with a small Piston Bore. It has the 283 bore which limits it breathing capabilities to limited valve sizes. This wouldnt be a bad bet as well the 283 for a set of 194/164 valve vortec heads to increase tourque which after all is more of what we really want on the street.

[SOON2BLAZE]

I will agree with farmtruck, they are reliable

[Yukon Jack]

My 69 K20 also had the 307 - it could lug low and keep lugging with a heavy load behind the truck - they actually aren't a bad motor - just not the choice motor if you are looking for high hp.

[redhead69]

I asked this same Q about 6 months ago. The ideas I got were to build around the block with performance goodies= Better heads- HEI-aluminum intake-4bbl-headers..then when you get sick of it all you will have all the good parts to bolt onto a good short block 350. I think its a good way to go because you can piece it together and pay over a longer period of time. Just my .02

eric

[68haywagon]

HEI swap is an easy way to go electronic as HeavyD said. I did that during the summer because my first fight with points was my last. There is a nice writeup in the FAQ section for this. Just remember to replace the ign wire with something new and heavy.

Mike

[ChevLoRay]

In '69, the 307 was rated at 200 Horsepower (Gross) @ 4600 rpm's and 157 (net) @ 4000 rpm's. The torque rating (gross) was 300 ft lb @ 2400 rpm's, while the net torque rating was 260 ft lbs @ 2200 rpm's.These are values for the CE 20 and KE 20 trucks. There was a slight increase in the net values, compared to the 10-series trucks, but the difference seems to be at the rpm at which the rating was taken.

The Truck Data Book for April 1, 1969, says "Net horsepower and torque were obtained from a dynomometer test simulating actual operating conditions when the engine is in the vehicle."

For comparison, gross values are done without any exhaust system, no fan, generator (alternator) not charging and "optimum spark advance".

With a bore and stroke of 3 7/8 X 3 1/4 inches, a compresson ratio of 9.0:1, and a stingy 2-bbl carburetor, they weren't built for speed/power, just an upgrade from the 250 6-cylinder.

I guess any engine can be "made to run", but the question begs an answer to how badly do you want THIS engine to run. Are you into restoration, or, do you have an end-plan in mind? If the answer is that you simply want a reliable V-8, why not go the cheap route and get a Goodwrench crate 350? They're around $1400, with a 36 mo/36K mile warranty. Labor, of course, is extra.

As for an HEI, there are plenty in the junkyards, but you should be careful with them. While you may find one that is outstanding, you may end up with one that needs rebuilt. The wiring can be brittle, especially the wiring to the pick-up module. Worn bushings can be a problem. Not gonna say it won't work, but my experience is that it doesn't hurt to spend the money for one that is already rebuilt (+ core charge) or do like I did. I bought one from Accel, that they had rebuilt. I got it from O'Reilly's. Seems like it was around $110. I have no regrets, either. Compared to the trouble that I was having with the junkyard HEI, the other folks on the highways are happier with my choice, too. Having it break down at inopportune times, really sucks.

[409biscayne]

If it was me i'd tuck the 307 away in a corner of the shop , and buy the best crate 350 i could afford , that way you have nice power in the truck and still have the original mill if you ever need it . I don't ever see anyone mention it , but we always used Pertronix Ignitor ignition , fits under the cap on your gm distributor ,eliminates points and keeps it looking original . There only about $75 and a quick install

[screamin_c102]

If in good shape the 307 will rev like a Honda! I have the original rebuilt 307 in Screamin' and I love it. I get excellent gas mileage (16-18 MPG) compared to my other two trucks C20s with a 350(13MPG) and 454.(10MPG)

I have an HEI, 4brl GM intake, Edlbrock 1406, three key double roller timing chain. She may not be a power house, but she has NO problem smokin' the 275/50/15 rears.

I will be swappin' it out for a LS1 after we get settled in Portland, just to have a newer injected, overdriven drivetrain. The little 307 will find a new home in something.

[mrein3]

Originally Posted by 409biscayne

If it was me i'd tuck the 307 away in a corner of the shop , and buy the best crate 350 i could afford , that way you have nice power in the truck and still have the original mill if you ever need it . I don't ever see anyone mention it , but we always used Pertronix Ignitor ignition , fits under the cap on your gm distributor ,eliminates points and keeps it looking original . There only about $75 and a quick install

I did a similar thing with my 72 Chevelle's original 307. It was replaced with a mildly (and inexpensive) rebuilt 350. Today, a 1972 Chevelle Malibu with an original 307 isn't worth much. Tomorrow...???
If it ever is worth anything I still have it.

Another good thing about the 307 is that when I had it in my Chevelle with its original 2bbl carb and 273 rear end it got 20-21 mpg.

[farside847]

I love my 307! I also put in the cheapo Pertronix ignition - works great. Get about 14MPG now with a stock setup. My truck is a driver, and that little v8 humms right along. 238k miles on her. I have some fat tires on the back and still squeel if I let the clutch out too fast. And I only have the little stock 2b carb!!!!!

True. True. Its not a racecar. A built 350 will blow the doors off me. But shes got more power than I ever use. A month ago I took about 1.5 tons of glass to the dump and she didnt even break a sweat. Now my breaks were a different story. Had to be pretty carefull and avoided the freeway

[beautimus]

around these parts (north bama) the 307 has a bad rep. i think a lot of those were lemons from the factory. it was not popular here at all. but as time went along i saw several 307's that held up well. no they were not power houses, but if you had a good one, they had good longevity. the fact that yours was still kicking after so many years, says some good things about it.

[Tynee]

Originally Posted by SOON2BLAZE

See the latest or maybe last month of Classic Trucks mag. They did a whole build up on one of these 307's. Even with the aluminum heads ect.. it was still a turd. I've got one in my 68 chev and for the money I would sink into it to get even mild performance gains, I could build a strong 350. ( or even a 292 L6 with more hp and torque) just my .02

I thought they got 315 H.P. out of that 307 with no block work (stock bore, stock pistons). That doesn't sound like a turd to me. That sounds like they spent $500 (give or take) on an engine they bought for $200, and had an engine that would out perform most stock 350's, or even crate 350's for that matter.

[DangerBoy]

I had a 307 in my 68 when I got it and try as I might I could'nt blow that little grease ball up. Of course when we pulled it apart and measured the bores they were somethin like .080 over just from years of use and abuse. Thing still ran like a champ when we pulled it too.

[69TowRig]

Originally Posted by 409biscayne

If it was me i'd tuck the 307 away in a corner of the shop , and buy the best crate 350 i could afford , that way you have nice power in the truck and still have the original mill if you ever need it . I don't ever see anyone mention it , but we always used Pertronix Ignitor ignition , fits under the cap on your gm distributor ,eliminates points and keeps it looking original . There only about $75 and a quick install

Jeg's dropped the price on their NEW HEI distributor with cap and coil to $90:

http://www.jegs.com/webapp/wcs/store...tegoryId=26203

[pissonNOS]

Originally Posted by redhead69

I asked this same Q about 6 months ago. The ideas I got were to build around the block with performance goodies= Better heads- HEI-aluminum intake-4bbl-headers..then when you get sick of it all you will have all the good parts to bolt onto a good short block 350. I think its a good way to go because you can piece it together and pay over a longer period of time. Just my .02

eric

this is exactly what ive done so far in the last 3 years including rebuild i havent even spent $2000 on the motor yet and it has a 292 blue racer cam, edelbrock 650 carb edelbrock intake MSD headers, for some reason it still blows the doors of my buddy 03 GMC shorty 5.7

[mark69k20]

Lots of good info... you guys that got new carbs and intakes... How hard was it to do away with the auto choke? How does it work? This is what is left after the origional plastic one came apart. Thanks!

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