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Discussion Starter #1
Looking for info, has anyone done this? I have 66 nova 400 deluxe 4dr sedan that has its original 283 - 194 casting block, with a cast crank. Yes I have heard all 283 cranks are forged or steel, not true, some later 66 and 67 283 cranks are cast. I have a small journal forged 327 crank and it appears it will fit to stroke this 283 to a 307 and yes I have heard all bs about 307 being a crap engine but most people don’t realize that the problem with them were the heads being open chamber 76 cc heads. I want to know if anyone has done this stroke and are there any issues with it, anything I need to watch for.

The engine it completely stock, plans are 327 crank, 307 pistons, Vortec 062 heads, Edelbrock 2116 intake; and custom exhaust to get best performance and 200-4R trans. Keeping factory cam, according to Dyno software the stock cam seems to be best cam for this setup since most aftermarket cams are designed for 350 or larger cubes. Dyno software states this setup should yield 440 hp at flywheel so I’m expecting 375 hp at flywheel
 

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I do not see that kind of horsepower from a 307 cubic inch motor in my opinion
I build a few motors a year so I have a little experience but do not do it for a living and I may be wrong

Mike
 

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Discussion Starter #3
440 no, 375 possible

It not uncommon for an engine to produce 100 more horses than it cubes with minor changes if they are the right ones even the GM 062 Vortec heads I am using added nearly 50 hp to the 96 5.7L over the previous years 5.7L with all other components being the same. Hence, why I believe it will do more towards the 375 hp mark than the 440.
 

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You will have to do something more than vortec heads and a stock cam to get the hp you want and are talking about. 307 inches with a "stock" cam, whatever stock is and vortec heads will probably get you around 275-300hp maybe.
 

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Discussion Starter #5
Issues with stroker

This post to request info on issues with this stroker not to argue over horses. And as far as horses I will be happy with anything better than stock. This is in a cruiser, not a street/strip car.
 

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I heard of people in the old days taking a 283 block and boring it out 0.30 and installing a 327 crank and making it into a 301/302 which were high reving little motors Z28 style. Never a 307 which many think are just throw away motors or used for there brackets and pulleys. You should never invest your money in a 307 when 350 blocks are all over the place and priced right.
The original DZ302 that came in the 1st gen Camaro's were the 327 block and a forged steel 283 crank. They were mean little motors. The opposite combo gets you to the 307 as mentioned.
 

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Discussion Starter #7
Original engine to car, in family since new

This is the original block and want to keep it incar just make it better. 307 is a 283 bore (3.875”) with 327 stroke (3.25”), GM actually designed it that way. Also the reason these were so bad was they used piston and head combo that produced 8.5:1 compression ratio with poor flowing heads, intake and exhaust. 307 were rated at 250 hp with 76 cc chamber heads in stock form from GM, with that being said and all the articles and info out there on 062 Vortec heads stating that they give stock engines approx 50 hp by just bolting them on with 64 cc chambers raises compression ratio to 9.5:1 and better flowing heads and intake, that alone will give you approx 300Hp out of a stock 307. Also the cam used in the 307 was designed to be used in the 327 and 350, both larger cubes. I have read many articles in which a cam designed for larger cube engine does not work well in those of small cubes hence the reason to stick with the stock cam that was designed to work with a 283 and 327 placing 307 in the middle
 

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My question is why are you asking questions? You already seem to have your answers. Good luck with the build. My only contribution to this thread is imo you should contact a cam grinder and tell them what you have and let them pick your cam. They know better than you ever will. Jmo
 

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Discussion Starter #9
Stock cam specs note these are seat to seat as produced by GM

I have found this info only a couple of places so this is what I am going with for now till I find info that is different or I can actually degree the cam with a dail indicator - also all info is seat to seat not at 0.05 as modern cams
PN 3732798
Hydraulic flat tappet
78 degrees overlap
Intake open 32.5 degrees BTC - closes 87.5 degrees ABC - 300 degree duration
Exhaust open 74.5 degrees BBC - closes 45.5 degrees ATC - 300 degrees duration
Both intake and exhaust are 0.2658 lift @ lobe
x 1.50 rocker = 0.3987, X1.60 rocker = 0.4253
I plan on using 1.6 full roller rockers, this creates max lift for stock Vortec and all research on stock Vortec states they work best from 0.20 to 0.45 lift. they were designed to work best in this range because the valves are in this range more than they are at 0.45 and above
 

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Discussion Starter #10
The thread was originally to request any info others have on this type of stroke that isn’t visible that may cause issues such as clearances, does the extra length in stroke cause piston slap, anything that may occur after complete assembly that I need to fix or account for before starting the build
 

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Discussion Starter #11
My question is why are you asking questions? You already seem to have your answers. Good luck with the build. My only contribution to this thread is imo you should contact a cam grinder and tell them what you have and let them pick your cam. They know better than you ever will. Jmo
Showdog75 thank you for you comment. I have done my research, like everyone else I don’t have a lot funds, I appreciated that you did not tell me to build something else. My goal is to get as much hp out of original stock GM components I have on hand as possible without going to after market parts with exception of the intake and exhaust
 

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sounds like its going to be a nice ride when your done. an like also pictures will be cool. even if you only end up with 350 horse, that's more than i'm getting out of a 327 in my 66.
 

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I just built a 283 with a 327 crank last year, it was .060 over and I will tell you the problem is the pistons. Nobody makes a 307 piston anymore that isn't junk. I took .040 off the deck and they were still in the hole, you can't even get a real flat top anymore, they have a huge bevel around the outside (most pics don't show this as they use generic pictures) are .020 shorter in height and have monster valve reliefs, killing off any hope of compression.
Unless you sonic check the block and go 4" stay 283' or get some custom forged pistons but that's expensive.
I suppose some used good shape 307 pistons could work if your bore is serviceable. Chad.

I had thoughts of turning a large journal 350 crank down and making a custom stoke to get the pistons to zero deck instead of cutting the deck so much but that's as far as that got.
 

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283 Stroked

For what it's worth--be careful on the heads you bolt on if the intake valves are 1.94s or 202s. Bolting large valve 350 heads on a 305 or smaller bore will result in valves hitting cylinder walls or pistons. If you want more info on this watch--MyVintageIron7512 on YouTube--he has videos on all Chevy heads--the best & worst. According to him Vortec 305 heads are rare as hens teeth & a lot of folks don't know or care what heads they are selling & they think they are Vortecs but aren't.
 

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Discussion Starter #16
For what it's worth--be careful on the heads you bolt on if the intake valves are 1.94s or 202s. Bolting large valve 350 heads on a 305 or smaller bore will result in valves hitting cylinder walls or pistons. If you want more info on this watch--MyVintageIron7512 on YouTube--he has videos on all Chevy heads--the best & worst. According to him Vortec 305 heads are rare as hens teeth & a lot of folks don't know or care what heads they are selling & they think they are Vortecs but aren't.
Thank you for the reply. I have checked this, the 283 has a 3.875” bore on 4.4” center the same as 307. Heads with 1.94/1.50 valves were standard on these engines and hipo 283 came with small chamber camel hump heads in both 1.94 and 2.02 valves so the vortec 062 heads fit. 305s are typical 1/8” smaller at 3.75” bore
 

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Discussion Starter #17
I just built a 283 with a 327 crank last year, it was .060 over and I will tell you the problem is the pistons. Nobody makes a 307 piston anymore that isn't junk. I took .040 off the deck and they were still in the hole, you can't even get a real flat top anymore, they have a huge bevel around the outside (most pics don't show this as they use generic pictures) are .020 shorter in height and have monster valve reliefs, killing off any hope of compression.
Unless you sonic check the block and go 4" stay 283' or get some custom forged pistons but that's expensive.
I suppose some used good shape 307 pistons could work if your bore is serviceable. Chad.

I had thoughts of turning a large journal 350 crank down and making a custom stoke to get the pistons to zero deck instead of cutting the deck so much but that's as far as that got.
I have thought about a 350 crank, that would make it a 326 or 328 i dont remember my engine has only 55000 miles on it, car sat for years and seals started leaking and was running rough so i pulled apart to replace seals and found a valve was stuck and the rocker stud had pulled out of its seat so decided to rebuild and improve bore is standard so standard 307 pistons work for me
 

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I try to stay out of discussions like this, but I really feel that I need to comment on this one. Like DealerDeuce (whose comment has now disappeared), I’ve built several SBC engines over the past 50 years. My personal opinion is that you’re throwing good money out the window, but it’s your project… I’d spend my dollars on a performance-oriented build of the 283.

I’m not sure where you should go on the internet to find someone who has built an engine with this configuration. My first thought would be the HAMB forum on the JalopyJournal.com site. There are folks on there who have done almost any engine combo imaginable.

Highroller54’s comments contain some very good advice. Before I spent any serious money on this project, I’d strip the block and have it tested, whether or not you bore it – and – be sure to have it correctly honed. I’d also contact a GOOD machine shop like Egge Machine for a set of pistons and connecting rods. They won’t be cheap, but you get what you pay for.

As far as a cam and heads go, showdog75 is correct in that you should go to a reputable cam grinder, lay out your plans and let them choose the cam. They do this every day and know what works. I’d also suggest that you go with a hydraulic roller cam to avoid potential problems with today’s motor oils. As far as I know, the Vortec (1.94”) heads and roller rockers are also a workable idea, although I seriously doubt that they will give you anywhere near 50 additional horsepower on this particular build.

Last, I’m not sure where you found the 307 c.i./250 HP numbers, but Chevrolet’s ratings for the 307 ranged from 115 to 200. The 200 HP rating was realistic considering the specs for that engine (9.0 to 1 compression and a decent cam). With the modifications that you’re planning, my guess would be that you might achieve a maximum of around 260 HP at the flywheel.

In any case, I wish you the best of luck with your project.
 

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Discussion Starter #20
I try to stay out of discussions like this, but I really feel that I need to comment on this one. Like DealerDeuce (whose comment has now disappeared), I’ve built several SBC engines over the past 50 years. My personal opinion is that you’re throwing good money out the window, but it’s your project… I’d spend my dollars on a performance-oriented build of the 283.

I’m not sure where you should go on the internet to find someone who has built an engine with this configuration. My first thought would be the HAMB forum on the JalopyJournal.com site. There are folks on there who have done almost any engine combo imaginable.

Highroller54’s comments contain some very good advice. Before I spent any serious money on this project, I’d strip the block and have it tested, whether or not you bore it – and – be sure to have it correctly honed. I’d also contact a GOOD machine shop like Egge Machine for a set of pistons and connecting rods. They won’t be cheap, but you get what you pay for.

As far as a cam and heads go, showdog75 is correct in that you should go to a reputable cam grinder, lay out your plans and let them choose the cam. They do this every day and know what works. I’d also suggest that you go with a hydraulic roller cam to avoid potential problems with today’s motor oils. As far as I know, the Vortec (1.94”) heads and roller rockers are also a workable idea, although I seriously doubt that they will give you anywhere near 50 additional horsepower on this particular build.

Last, I’m not sure where you found the 307 c.i./250 HP numbers, but Chevrolet’s ratings for the 307 ranged from 115 to 200. The 200 HP rating was realistic considering the specs for that engine (9.0 to 1 compression and a decent cam). With the modifications that you’re planning, my guess would be that you might achieve a maximum of around 260 HP at the flywheel.

In any case, I wish you the best of luck with your project.
Dave b. I stand corrected on HP for stock 307 in vehicles, you are correct, but GM did produce some marine engines based on the 307 under the OMC label that did produce 250 HP as such they did have different cams, heads, intake, exhaust, and carbs than those used in cars and trucks.

As far as building a 307 as apposed to the 283, what is everyone’s first comment “ spend your money on a 350 more cubes = more HP” well my block has a cast crank means a it will fit a forge 3.25 stroke crank, it already has forged rods, I already have the crank, heads, intake, and carb, left overs from other projects sitting on the shelf. All I need Is to get block checked out and the pistons, the original cam GM PN 3732798 was used in the 195& 220 HP 283 and the 250 & 300 HP 327 in 1966 so I believe it should work nicely in the 307. Total cost should be around 500-600 all said and done.
My plan is to have this engine dynoed after final assembly and break in, funds permitting, since I can not find anyone that has a similar setup.
Also everyone that says a 307 is pos needs to remember it’s not the part that creates the cubes but the parts that creates the CR and alllows it to breath plays the biggest roll in its performance
IE: 2 350 blocks with identical short blocks but with a different top end and valve train components will perform differently and produce different HP and TQ
 
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