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Old 08-25-2008, 09:39 PM
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1972 chevy 307 ??

I am wondering if i should spend the cash to rebuild this 307 or buy a 350 and rebuild..I am not looking for a race engine just one that will run well..Ty in advance Tom

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Old 08-25-2008, 09:51 PM
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well how well did the 307 run
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Old 08-25-2008, 10:08 PM
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i think it runs well but i have lost oil pressure after it warms up, so i am thinking it needs barrings before i do that i wanna make sure i am not wasting my money
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Old 08-25-2008, 10:30 PM
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Tear it down and re ring and bearing it. Maybe get the crank turned 10-10 and a new oil pump.
Hone/deglaze the block, clean the pistons up and reassemble. Scrap the stock 307 cylinder heads (most likely 185 castings) . Get some hi compression "416" 305 heads and home port them shave 'em .030-.040" and install with a felpro 1094 gasket. use a mild short duration hyd cam under 214@.050 .450" ish valve lift and a dual plane manifold. Something torky like this lil Lunati cam
You'll have a suprisingly good running lil 307.
Add a lilpower shot and some 3.73-4.10 gears and go beat up on the 5.0 litres.
you'll get your fair share of 350 kills too.

Last edited by F-BIRD'88; 08-25-2008 at 11:02 PM.
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Old 08-26-2008, 04:15 AM
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307's are very sensitive to larger cams.
Anything bigger than the old chevy 929 & you're asking for trouble.

Building a 307 for anything other than a miliage challenge or to prove some kind of point is a waste of time.

Get yourself an older 350 block & crank. 1968-1975 vintage
Make sure the block has the numbers 010 020 stamped on the timing cover area & the inside of the bellhousing area.

You wont need anything other than the block & crank as all the other 307 parts will interchange.

The easiest way out is to get a turnkey 350 http://store.summitracing.com/partde...3&autoview=sku
This engine will work in any application you can think of & even comes with a warranty.

I had a 307 with a 270 degree cam & it wouldn't idle under 1000 & made HORRIBLE vacum (10 inches).

If you just got a 350 block you could build a .030 over 327 which is a good engine as well.

(283 bore & 327 stroke, essentially the 305 of yesteryear)

The problem with the 307 is that for more money you'd be building a weaker engine. Doesn't make much sense.

350's are everywhere & that's boring I know, but don't be stupid just to create variety....
If everyone is doing it, it probably means it is the smartest & cheapest way to go.

With a scat 3.75 stroke crank off of Ebay you could build a 383 & not know what to do with all the 400+ foot pounds of torque!
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Old 08-31-2008, 02:01 AM
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Like the old saying goes: Speed costs money, how fast do you want to go?

It all depends on how much money you want to spend and exactly what you expect to change about the engine. If it's not burning oil, and you just want to get the oil pressure back up, you could just change the bearings and oil pump without even removing the engine from the car, and without spending much over $100.

If you want a noticeable performance boost, put dual exhaust on it and dig up a used stock non-EGR intake manifold & a rebuildable non-EGR Quadrajet carb. A little rework of the ignition advance curve is also cheap and effective. Now you're out $500 or so.

The stock 307 cam is the same pn3896929 used in stock 327's & 350's from the same era. The one F-BIRD'88 mentioned is one step above it, and should work fine in a 307. Anything bigger would kill your low-rpm power more than you'd probably like. SpeedPro makes a similar one that might be a little cheaper. That's another $200 with new lifters & springs.

If you want to get into more serious money, you could look into jbvcw71's block & piston transplant. A 307 crank/rods in a 350 block makes a 327, using stock 327 pistons. Or you could just build a 350.
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Old 08-31-2008, 03:14 AM
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Quote:
Originally Posted by jimfulco
you could just change the bearings and oil pump without even removing the engine from the car, [/QUOTE]

(this suggestion is so stupid I don't even know where to start. I really can't think of a more retarded way of changing bearings...)


[/QUOTE]non-EGR Quadrajet carb. [/QUOTE]
(there is no such thing as an egr carb)


[/QUOTE] The one F-BIRD'88 mentioned is one step above it, and should work fine in a 307. [/QUOTE]
(the cam mentioned Is much more than one step above stock and would produce poor idle quality & throttle responce)


[/QUOTE] If you want to get into more serious money, you could look into jbvcw71's block & piston transplant. [/QUOTE]
(A remanufactured Long block from the local auto parts store is a far cry from serious money. Not to mention most healthy 350's that you can hear run go for little more than $500)
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Old 08-31-2008, 06:28 AM
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How much work does engine need?

First just to let "jbcvw71" know they are lining up on the bridge and there's lots of people there.......................

If your engine has good compression and is not using any major amounts of oil. A set of bearings and a new oil pump may keep it running a long time. I have also pulled engines and put a crank kit in them which is just a reman. crank and a set of bearings along with new oil pump and ran them for years.

A mild street engine can be built from anything it's a matter of what you want. The 307 is not the cheapest choice but it is a sbc so it ain't that pricey. It doesn't matter which engine you build if it is too radical you won't drive it much.

HTH,
Tony
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Old 08-31-2008, 06:58 AM
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First ? what is your oil pressure at hot idle, what exactly are you calling low pressure?We may be putting the cart before the horse.Second while rolling in a new set of bearings may not be the best way it has worked on countless engines in the past and is common practice for oem repairs.(Please note I did not say for high power builds).Third a 307 can be a peppy little engine and return exellent mileage with a cam up grade along with heads.Following F-birds advice will give you a fun little toy.Sure you can go the 350 route but why bother they sell crate 572's afterall if a 307 is worthless because 350's are larger and more powerful it stands to reason that 350 or 383 are worthless because much larger engines are available.In the end and sorry for the rant but Build what you want and will enjoy.If you are just cruisuing and want good mileage and some power build the 307 more power then step up.Or you could just tell everyone it is a 434 and only you would know.
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Old 08-31-2008, 09:02 AM
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Keep in mind that the 307 was never offered as a performance engine in any vehicle it originally came in. The bottom end of the block is not as beefy as a 350 and the heads are fairly poor.

That being said, if you just want to drive the car, many of the above recommedations are fine. Freshen it up, get a mild cam, a good intake and carb, and go drive it. You can have a decent running street car for not a lot of bucks.
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Old 08-31-2008, 07:13 PM
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to start you all have good info, and i thank you all. I just wanna keep the old girl running without spending much cash. my oil pressure hot at idle is 0 i have changed the oil pump, and put 10w40 oil at 55 mph i have 45lbs pressure .

few notes i am running elderbrock performer intake and carb (not sure size) duel exhaust .. again i am not trying to make race truck i just wanna keep the 68 Chevy pickup around... thank you all again Tom
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Old 09-01-2008, 07:59 AM
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Last year I sold a complete, running, good condition 307 for $150 - this was oil pan to intake, water pump to flywheel flange. 3 years ago I purchased a complete, running, good condition, 4 bolt main 350 for $200. I know of a 2 bolt main 350 down the road from me right now, complete, running, good shape - for sale for $200.

Here is my point: for a simple driver vehicle that you just need to move from point A to point B I've always had a lot more success in watching local papers or Craigslist and grabbing a complete running engine. This also minimizes down time.

Good luck with whatever way you plan to skin the cat!
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Old 09-01-2008, 08:13 AM
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The old girl sounds like a prime candidate for 20/50 wt.
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Old 09-01-2008, 09:08 AM
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are you sure the gauge is accurate?
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Old 09-02-2008, 12:18 AM
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Quote:
Originally Posted by jbvcw71
change the bearings and oil pump without even removing the engine
(this suggestion is so stupid I don't even know where to start. I really can't think of a more retarded way of changing bearings...)

It works quite well if you do it carefully. You start with cleaning the underside really well, and go from there. It's not the preferred method for sure, but if you don't have hoisting equipment and the rest of the motor's OK, it perfectly legit.


[/QUOTE]non-EGR Quadrajet carb. [/QUOTE]
(there is no such thing as an egr carb)

By EGR carb, I mean one that's calibrated leaner at part-throttle for use with an EGR system. If you use such a carb without an EGR system, you'll likely get pinging at part-throttle due to the lean mixture.


[/QUOTE] The one F-BIRD'88 mentioned is one step above it, and should work fine in a 307. [/QUOTE]
(the cam mentioned Is much more than one step above stock and would produce poor idle quality & throttle responce)

The stock cam has 195* intake duration at .050" lift, and the aforementioned Lunati has 205*, the SpeedPro 204*. I don't know of a currently manufactured cam with anything in between 195* and 204*, unless they're still making the old 305HO cam, which, at 202*, would also be a viable option.


[/QUOTE] If you want to get into more serious money, you could look into jbvcw71's block & piston transplant. [/QUOTE]
(A remanufactured Long block from the local auto parts store is a far cry from serious money. Not to mention most healthy 350's that you can hear run go for little more than $500) [/QUOTE]

I figured a decent set of 327 pistons and a used 350 block, plus boring and any other needed machine work would add a significant expense compared to using a 307 that he already has. As far as re-man parts-store engines, the ones I've seen some friends and acquaintances buy have been pretty sorry. Last time I looked they wanted $800 or more for something with junk pistons and rod bearings that either bit or would have bitten the dust shortly after startup.
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