Engine rebuild or replace???

[10drum]

Greetings,

I have a 69 C-10, it is an all original no rust truck. The 307 runs ok, but it has a knock when cold and is using about a quart every 500 to 750 miles. The compression is 175# on all cylinders. I'd lean toward staying original, pulling the engine and rebuilding it, but to do it right I'd probably have as much $ in it as I would if I bought a new 350. I am going to be driving it and may be driving it in higher altitudes. My questions are. The Chevrolet 290hp 350 new crate motor comes ready for a 4 bbl carb, can those be equipped with throttle body EFI? If I rebuild my engine can it be converted to EFI? I hope some of you can tell me some ins and outs from your past experiences. Thanks for all replies, Phil

[big bad orange]

I was in your place last year with my worn out 350, I had it rebuilt and now looking back I wish I would have just gotten a new engine from jets or summit ect. I payed $800 and all that got me was bearings and a hone. With these trucks the vin is not stamped to the engine. I say pull the 307 put it in a corner or use it as a core.

[hamjet]

If it were mine I'd rebuild it myself, which I'm capable of doing. Machine shops will cost you. A lot of guys bought crate engines on here for about $1200.00s, some had problems with them, some didn't. I'm sure they will chime in soon. If you're looking for more power, Get the 350. Good luck...

[10drum]

I don't see a rebuild costing less than $2500, because I'd have the crank ground and balanced, new cam, bored, new pistons, lifters, rockers, ect, and I'd have my machinist buddy build the heads for unleaded fuel. Other than the machine work I'd build the engine. A new Chevrolet crate engine is $3200 without a carb or distributor. I'd really like to install a throttle body fuel injection, mainly for the carburetor look. Thanks for the replies.

[tcrist]

One would think that you would see a big difference in the torque (less) and the fuel mileage (less) if you change to the 350.

Personally I would rebuild the 307, but I am a bit partial to them.

[slow-1]

The only reason to rebuild the 307 would be to keep the truck 100% original, a crate 350 or bigger is the way to go IMO.

[cdowns]

rebuild projects are a bad bet as 50% or more have catastrophic failure within 500miles with no warrenty to save you gm factory crate engines are about 95% or more success rate with no real problems and it is covered by an excellent warrenty program for a long term

[ho70]

Keep the original engine so that is not is part of the keep original or not equation
307's don't have the reputation of a 350, but I had one and no problems
the crate engines have been known to have problems, but have a warranty. You can get one from jegs on sale shipped to you for 1500 bucks-can't go wrong, so for 1500 you have two engines, instead of one if you rebuilt it

[72bowtiestepper]

350 crate motor....$1500 or less at times with free shipping from Jegs...a no brainer.

[leddzepp]

350 crate motor from Jegs and be done with it.

[tcrist]

Originally Posted by cdowns

rebuild projects are a bad bet as 50% or more have catastrophic failure within 500miles with no warrenty to save you gm factory crate engines are about 95% or more success rate with no real problems and it is covered by an excellent warrenty program for a long term

I would like to see the stats on the "50% or more have catastrophic failure within 500miles" statement. I am sure there are some, but 50%?

Who ever has been building those engines should be fired.

[dfrank]

Originally Posted by tcrist

I would like to see the stats on the "50% or more have catastrophic failure within 500miles" statement. I am sure there are some, but 50%?

Who ever has been building those engines should be fired.

+1 you beat me to it.

[10drum]

Everyone is talking crate engines from Jegs at $1500, sounds great, still a rebuilt engine by who knows who??? I've built British car engines and British motorcycle engines for a while now, and other than a defective head gasket I installed on a 69 Triumph Daytona I've had great luck, I think the machine work is the key. We are talking apples and oranges here. I'm comparing a proper rebuild, by me, to a "new" GM 350, at least I think this is new:

http://www.chevrolet.com/performance...50-290-hp.html

I'm wondering if I can install throttle body fuel injection on the Chevrolet built engine, or on the rebuilt 307 I do myself????

[tcrist]

I say sure, why not. Carb's, TBI's or straight up fuel injection just mixes up the air and fuel then sends it to the cylinders.

TBI's and FI's are just computer controlled and "should" get you a bit better fuel mileage.

I do believe though, if you install a TBI or FI, you will need to run a fuel return line back to your fuel tank and possibly change the fuel pump to one with a higher volume.

[10drum]

Thanks Tcrist. I'm thinking about installing a rear tank and get the one out of the cab, but the cab tank is new, so I don't know.

[tcrist]

I was thinking about installing a rear tank in mine but am unsure of where to put the fuel filler. I don't care for them in the bed floor but am unsure where to put them in a step side without looking gaudy.

Guess a rear fill under the license plate would do but I have had issues with that location in my 68 Chevelle leaking fuel. Maybe a racing fuel filler type set up would be best.

[mechanicalman]

Originally Posted by 10drum

Greetings,

I have a 69 C-10, it is an all original no rust truck. The 307 runs ok, but it has a knock when cold and is using about a quart every 500 to 750 miles. The compression is 175# on all cylinders. I'd lean toward staying original, pulling the engine and rebuilding it, but to do it right I'd probably have as much $ in it as I would if I bought a new 350. I am going to be driving it and may be driving it in higher altitudes. My questions are. The Chevrolet 290hp 350 new crate motor comes ready for a 4 bbl carb, can those be equipped with throttle body EFI? If I rebuild my engine can it be converted to EFI? I hope some of you can tell me some ins and outs from your past experiences. Thanks for all replies, Phil

Don't let the "TBI" crate engine listings throw you, the GM TBI engines are one piece rear main seal engines externally balanced in the rear with some funky cylinder heads that are low performance. Any engine can be converted to EFI, and the throttle body set-ups with wide band O2 are the way to go. Read this article:
http://www.hotrod.com/how-to/engine/...iant-efi-test/

The only difference between a GM 350-260HP and a GM 350-290HP is the cam. The compression is too low on that engine for the cam they put in it and you may be disappointed with the low end power and gas mileage. That's like $450.00 just for the different cam, and it's not the right cam. So, just get the 260 and slip a cam in it if you want, something more appropriate for that engine.
http://www.jegs.com/i/Chevrolet-Perf...06#moreDetails

Let me know if you are interested I can recommend a cam based on your application (vehicle weight, rear end gear, towing or not, etc.).

[67 chevelle]

Id go for the 350 create allso , you have a much better chance off it leaking "less" ,,, and more torque ,, what a truck wants and needs

[57larry]

dump the 307 and replace it with a 350 with a good alum intake and carb

[windycity1]

Originally Posted by 57larry

dump the 307 and replace it with a 350 with a good alum intake and carb

I second that. 307s in my opinion are junk. I have on in my 69 and plan on yanking it in the spring.

[10drum]

Mechanicalman, Thanks for the links, it seems to be about the same as what is listed on Chevrolet.com and at $1500 it may be my best solution. I may do some towing, perhaps a light car like an MGB, don't think that will require anything special.

67chevelle, my British car rebuilds don't leak. The motorcycles are a different story, they will leak a little gear oil.

[cdowns]

if you do decide on a crate 350 take all the info you get on them and go into your local gm dealership and see if they will match the mailorder price the dealer here will and I like buying local on princxeple

[70LonghornCST]

I agree, a crate motor is the way to go. If YOU rebuild your engine, you have not warranty. If you buy a crate motor, you have coverage for some time.

[mechanicalman]

Originally Posted by cdowns

if you do decide on a crate 350 take all the info you get on them and go into your local gm dealership and see if they will match the mailorder price the dealer here will and I like buying local on princxeple

And much easier to deal with warranty problems face to face with same people who sold it to you than to talk to who knows who on the phone.

[mechanicalman]

Originally Posted by tcrist

One would think that you would see a big difference in the torque (less) and the fuel mileage (less) if you change to the 350.

Personally I would rebuild the 307, but I am a bit partial to them.

1971 307 R2carb 8.5compression 200HP @ 4600 rpm 300 ft lbs @ 2400 rpm

1971 350 R2carb 8.5 compression 245HP @ 4800rpm 350 ft lbs @ 2800 rpm

1971 350 R4carb 8.5 compression 270HP @ 4800 360 ft lbs @ 3200

My opinion: MAYBE slightly less MPG with the 350 (only at low load conditions), but at least 50 MORE ft lbs torque with the 350.