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69 GM 307ci engine, a dog?


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Guest Anonymous

I have this motor sitting in my parents garage, came out of a 69 nova station wagen, cast 3956622 I dont know much about this motor other then its a 2 bolt main, somebody told me it was a 289 stroker? I did notice it does have the camel hump style heads on it.. does this thing have more potential then a 305 and is it worth building? Its likely to find its way in the near future into my brothers Z, any ideas for performance (heads / cam) to get 300 hp on this particular motor would be appreciated....

 

ive got another 350 sitting in a buddies shop, but it needs heads and were not sure about the structural soundness of the engine, would take a teardown, do you think I should ditch the 307 and rebuild the 350? I know the 307 runs good.

 

thanks

 

Scarab260

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Back in the day these where concidered the first "smog" motors, they were dogs. But that was in stock form. If you change the heads and cam you could get 300hp out of it. It would make a good first engine since you already have it. But I bet soon after you will want something better. I would look at that 350 first.

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also known as the natoriously crappy 307. I had the same engine in my 69 chevelle. it has a realy bad bore to stroke ratio, and has a piston limited redline of about 4500 to 5000. it just wont rev any higher. this is the engine that helped to coin the term... heavy chevy.

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I've seen built 307s that ran great. It has the same bore as a 283 and the same stroke as a 327. As noted, the combination isn't the best, but if you make smart choices, they can be a good, cheap street motor. You are limited to a 1.94 valve, unless you get an exceptional block that would go .125 over. (Very common with the 283 and they would build a 300 ci motor, less likely chance with the 307.)

 

They are a good source for a large journal 3.25 stroke crank to combine with a 350 block to build a large journal 327. Because of the lighter piston combo with the 307, it does require balancing. I had a buddy score a steel 307 crank from a boat motor(!??) Combined with a cast off 4 bolt block he had, built a cheapie 4 bolt main 327.

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Guest Anonymous

The 350 block I have sat outside for almost a year, it was under a covered

area but it has spiders growing in it lol, and it smoked when it was

pulled so Im thinking I may build the 307.

 

This motor used to belong in my stepfathers nova wagen which was pretty damn fast according to him , he got it 8 years ago and was told it was rebuilt... it hasnt run in a good 6 years, now I dont know what was done to it when rebuilt, but I tore the heads off last night

and the pistons are flat top with stamped .030 so it appears

its been freshend up a bit... i wish I knew what else had been done

or even if its got the stock 307 bottom end.

 

Its almost turn-key right now, were going to replace the head gaskets and

what not, bolt on a Edlebrock performer intake and carb, I did

some research and found this motor is 5.0L and put out 200 - 225 hp stock

dependong on the year, this seems pretty darn low :( Now a question I have is if I add a cam (maybe grumpy's fav), and a set of HiPro 55cc

305 cylender heads off ebay do you think I could get 300~ hp from

this block? or would it take more then that to obtain those figures.... cuz thats the goal for my bro's Z, 300hp.

 

Is it possible that when this motor was rebuilt in the early 90's that

it was turned into a 350 or 327? what needs to be done to this

block to make it a 350? I got this 350 donor motor (which may

or may not have piston issues) maybe I can do some open heart surgery on it and stroke it with a 350 crank?

 

scarab260

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Because of the small bore, it will still be a 307. I guess you could go with a 350 crank and make a "stroker" 307. It would be about 330 ci. My 69 327 was rated at 210 hp, not uncommon. I'd put it back together, bolt on the performer, add an Energizer 266 cam and have fun with it while saving up real $ to build a 355. Work to maximize power in the range the 307 can do well in. The 2500-4500 rpm range. You can think of the 307 as being a better performance design than a 305 since it has a little larger bore, but like I said before, it'll never be a real powerhouse, but 300hp at the flywheel is quite achievable with the 307.

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307 = 3.875" x 3.25" (Gen.I, 5.7" rod)

3956632....307.....69....2bolt

 

theres no reason that you cant get 300hp out of that 307,

put vortec heads like these

 

http://Parts@sallee-chevrolet.com/Cylinder_Heads/Vortec.html

 

 

and headers and a cam like this

 

http://dab7.cranecams.com/SpecCard/DisplayCatalogCard.asp?PN=113841&B1=Display+Card

 

and an intake like this

 

Performer RPM Vortec ....#7116*

and youll have your 300 plus flywheel hp

 

the only problem is it will require several things like head work for extra clearance,new valve covers, new rocker arms,and several other things that will boost the cost to more than its really worth in most peoples opinion, at about $1600-$1700 by the time you add in the gaskets, rings bearings and machine work. now don,t get me wrong youll have about 320hp-330hp for about $1700 so thats not bad its just that youll have about 50 more hp if you started with a 350. and thats with you doing all the work!

 

for a few bucks more you could buy this

install the cam and intake and headers and be ahead by that 50hp (350-380hp)

http://www.sdpc2000.com/cart.asp?action=prod_detail&catid=128&pid=101

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Go for the 350 you`ll end up swaping it out anyways i promise, And It sounds like as much work with the heads and cam as the 350 would take. The 307 will make 300 hp but how realiable. A 350 will make 300hp withoput batting an eye and be the more realiable than a stock z.

 

Chad :)

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I'd gut the 307 and use the crank in the 350 block (327), or just build up the 350. Personally I like the 327 idea. It will rev up faster than the 350, and your cylinder walls will last longer because of the shorter stroke. Whichever way you go, definetly use the 350 block. Bigger bore is ALWAYS better. Better combustion, it unshrouds the valves for better breathing. Check your 350 block to see if it is a high nickel content block also, these are the most desirable because the nickel makes the casting stronger and more wear resistant than standard cast iron. You'll be able to tell by looking under the timing cover, or on the backside of the block berhind the flexplate. If it has the numbers 010 and 020 cast in it, this is the block to have 1%Tin, 2%Nickel. If it only has the 010, its a 1% nickel block. if it has none of these, then it is regular cast iron.

 

As far as rebuilding goes, do yourself a favor and do some research before ordering any parts. I'd strongly recomend a book by David Vizard titled "How to build max performance chevy small blocks on a budget". You can find it at most bookstores, or you can get it at http://www.motorbooks.com. This will save you countless trial and error mistakes down the road, and will probably pay for itself within minutes of reading the first few chapters. Hope this helps. Good luck with you conversion.

 

 

Mike

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Guest Anonymous

Engines.This is the part I like best!

 

In your case, find a guy that is upgrading from a 300hp just because he wants more power. Take this engine home and sit there looking at it. Then get wise, resell it and do what this guy is doing.....LOL. In other words, if you are tired of having your foot on the floor while the other guy pulls away from you, build the biggest cui. you can, pay extreem attention to the cam selected (as to future mods like aspiration, gearing, tire size etc.) and then you can kick back in that department. Later, you can easily add/change the other bolt-on's when you are ready. Meanwhile...you got a very strong Power Base no matter what! But then, maby you like to lose?

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