What to look for in a salvaged 302

[Brian]

The shorter rod to stoke ratio makes the piston linger more in the bottom of the bore. It causes more vibration and more piston side load, but offers more time to fill the cylinders on the intake stroke.

These tuning factors are an order of magnitude smaller than the effects of cam duration and runner volume and lengths.

The 347 is a way to get the max out of a 302 block.

The key is your transaxle. If you go with the lower cost Porsche option, you need to make power with high RPM rather than high torque and better match the Porsche smaller displacement higher revving engine. So a 327 or so may be the happier option. (4" bore, 3.25" stroke?)

 

[Randy Folsom]

The shorter rod to stoke ratio makes the piston linger more in the bottom of the bore. It causes more vibration and more piston side load, but offers more time to fill the cylinders on the intake stroke.

These tuning factors are an order of magnitude smaller than the effects of cam duration and runner volume and lengths.

The 347 is a way to get the max out of a 302 block.

The key is your transaxle. If you go with the lower cost Porsche option, you need to make power with high RPM rather than high torque and better match the Porsche smaller displacement higher revving engine. So a 327 or so may be the happier option. (4" bore, 3.25" stroke?)

A 327 is also a good option. I am thinking to use a Graziano. From what I understand it is a good option for lower power band / higher torque engines. I heard the Audi 016 gearing is not V8 friendly. Again, just based on reading, I understand that the lower cost Porsche transmission options don’t stand up well to high torque engines.

 

[Jac Mac]

Right... 302 has a 5.090" rod as standard, lets say you decide to stick with that, to 'build' the engine you would deck the block to get your chosen deck height so you will incur machining costs.... stuff that, lets stick a set of 289 or 302 Boss rods in it, wont have to deck the block & might need to skim the pistons. We now have a 1.718 to 1 rod ratio as opposed to the 1.606 to 1 we stated out with. Nota big deal, but we got a compression increase and a reduction in the squish distance for free. With that in mind we could apply the same thought process to other rods that are available for Ford small blocks, like 5.315" ( Boss 302 TRans Am & Indy rods ), 5.400" ( the 331 & 347 stroker rods ) The 5.400" rod on 302 crank gives you a 1.8 to rod ratio. No good you reckon, didnt GM build a 302 SBC?, gosh it had a 5.7" rod that gave it a rod ratio of 1.9 to 1, guess they were no good then.!!. I reckon the best deal going for a GT40 is the 351w, same dimensions as the SBF 289/302 but about 1.25" wider and 0.75" higher. Same applys to it. the std 5.956" rod gives a 1.702to 1 rod ratio, or if you asked someone on here from aussie nicely they might be able to find a set of aussie 302c rods 6.03" long that will give you a rod ratio of 1.722 to 1, apply the same process as the 302 earlier to get ideal squish height etc. Thats the basics of it. Does it work, hell yes.

 

[Howard Jones]

Here's basically the same motor but based on a 351 with a longer stroke. This is near the limit for low-cost gearboxes like an Audi, Renault, 915 Porsche etc.

A G50 Porsche built with this engine in mind would be perfect for a really fast street car. Gear ratios are available for G50's to suit a 6500RPM V8 as well as a TBD (+$1200) like a Quaife (strongly recommended). Expect to spend $13-15Kish for the GRBX and another $8K for the 408 motor.

My advice put the difference in cost between the 302 and the 408 into the GRBX. That puts you at about $21-22K for the base power train. New motor and ideal 5 speed gearbox (ratios, limited slip, very strong newly built).

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[Jac Mac]

Here's basically the same motor but based on a 351 with a longer stroke. This is near the limit for low-cost gearboxes like an Audi, Renault, 915 Porsche etc.

A G50 Porsche built with this engine in mind would be perfect for a really fast street car. Gear ratios are available for G50's to suit a 6500RPM V8 as well as a TBD (+$1200) like a Quaife (strongly recommended). Expect to spend $13-15Kish for the GRBX and another $8K for the 408 motor.

My advice put the difference in cost between the 302 and the 408 into the GRBX. That puts you at about $21-22K for the base power train. New motor and ideal 5 speed gearbox (ratios, limited slip, very strong newly built).

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Same engine? except its 4" stroke on 6.200" rods = 1.55 to 1 rod ratio. might be more suitable for towing your race car & trailer.

 

[Howard Jones]

Here's an article about rod ratios. Frankly, I don't have the experience or the expertise to give advice on the subject. However, I do believe that a careful selection of quality parts and a properly balanced and assembled engine is IMHO of the foremost importance when considering what to spend your money on when building/buying an engine.

https://oliverracingparts.com/wp-content/uploads/2019/08/UnderstandingRodRatios.pdf

 

[Jac Mac]

Perhaps I should elaborate on three 400cu in windsors ive built, sorry if Ive mentioned them before. First an engine with similar specs to Howards post above, very disappointed, need a decent set of headers which owner would not pay for, was in a 1940 odd business coupe with manual trans & 9".
2nd, a 351w Block, with 400 cleveland crank and the 400c rods ( 6.58" long giving 1.645 to 1 rod ratio ) SVO heads, 4bbl intake to suit, On 3 to 4 shift with 15" slicks it would break into wheelspin, owner very impressed, but his tendency to use 7 to 8 k eventually pulled the enire crank & main web assy out of the block. Interesting that no rod bolts failed, just the cast iron gave up!
3rd similar to #2 , but in a 1/4 mile dirt saloon, huge staggered Hoosiers on rear, electronic injection. Started off with cast iron clevo heads and ended up with SVO -C heads ( the ones banned by Nascar ). It would lift the front end/tires off the ground on both straightaways.
Both of those needed the Dart or similar blocks and a steel crank and the 6.58" or longer rods which were unobtanium.
They were not an easy build, valve to piston clearance along with rod to cam lobe and a small base circle used up a lot of hours/$$$

 

[Randy Folsom]

Right... 302 has a 5.090" rod as standard, lets say you decide to stick with that, to 'build' the engine you would deck the block to get your chosen deck height so you will incur machining costs.... stuff that, lets stick a set of 289 or 302 Boss rods in it, wont have to deck the block & might need to skim the pistons. We now have a 1.718 to 1 rod ratio as opposed to the 1.606 to 1 we stated out with. Nota big deal, but we got a compression increase and a reduction in the squish distance for free. With that in mind we could apply the same thought process to other rods that are available for Ford small blocks, like 5.315" ( Boss 302 TRans Am & Indy rods ), 5.400" ( the 331 & 347 stroker rods ) The 5.400" rod on 302 crank gives you a 1.8 to rod ratio. No good you reckon, didnt GM build a 302 SBC?, gosh it had a 5.7" rod that gave it a rod ratio of 1.9 to 1, guess they were no good then.!!. I reckon the best deal going for a GT40 is the 351w, same dimensions as the SBF 289/302 but about 1.25" wider and 0.75" higher. Same applys to it. the std 5.956" rod gives a 1.702to 1 rod ratio, or if you asked someone on here from aussie nicely they might be able to find a set of aussie 302c rods 6.03" long that will give you a rod ratio of 1.722 to 1, apply the same process as the 302 earlier to get ideal squish height etc. Thats the basics of it. Does it work, hell yes.

Thx for the information.

 

[Randy V]

Might want to google 302 broken block …. They’re not quite up to scratch in higher HP and Torque Applications.

 

[Mike Pass]

OR

Interesting block strength video

David Vizard Youtube video about Ford 302 block strength. Cheers Mike

www.gt40s.com

Cheers
Mike

 

[Randy Folsom]

Might want to google 302 broken block …. They’re not quite up to scratch in higher HP and Torque Applications.

I found this pretty quickly:
“This is one reason that 347s scare me.
Don't freak out, this is just my thought process and opinion, I am not bagging on anyone's choice to run a 347...

The short rod ratio in a 347 puts heavy side load on the block, which is the exact force we are talking about when we discuss the block splitting in half from being pushed apart. Combine that with oil control issues from the piston pin height, and it rules out a 347 for me.”

Maybe a 351 is the way to go. Back in the eighties I had a econline van with, I think, a Windsor and a Bronco with a Cleveland. Despite my best efforts, I was not able break either.

 

[Randy Folsom]

Same engine? except its 4" stroke on 6.200" rods = 1.55 to 1 rod ratio. might be more suitable for towing your race car & trailer.

Thx much. I am starting to lean more and more towards a 351. Also thinking if I want to drive it this decade, I should go with a crate motor.

 

[Ryan L]

Ford Australia sold a factory 347 Windsor stroker motor in the TS50 Falcon. A 347 ci is the same as 5.6 litres.
It was made with a Windsor block, alloy heads, bespoke intake manifold. With an emissions compliant tune, very mild street camshaft, and quiet exhaust, fuel efficient tune and a warranty it put out 250kw / 335HP in a large 4 door saloon car.

 

[Ryan L]

 

[Randy Folsom]

Ford Australia sold a factory 347 Windsor stroker motor in the TS50 Falcon. A 347 ci is the same as 5.6 litres.
It was made with a Windsor block, alloy heads, bespoke intake manifold. With an emissions compliant tune, very mild street camshaft, and quiet exhaust, fuel efficient tune and a warranty it put out 250kw / 335HP in a large 4 door saloon car.

That sounds like an awesome starting point. Exhaust might be all that’s needed to get above 350. What are those cars selling for these days.

 

[Jac Mac]

No mention in those video's of the warranty issues with oil consumption that engine experienced.

 

[Brian]

That 408 sounds like a screaming bargain. If you want to get fancy, take the long block version (I'm guessing they still sell the same engine minus the intake and dizzy) and get 8 stack or 4 webbers.

You'll also need a low profile road race oil pan.

 

[Howard Jones]

I think it is necessary to really pin down in your own mind what you want to do with the car. But here are my thoughts.

Pure street car only, car shows and used to cruse your state and surrounding area out to at least a full fuel load fill it up, and drive home. Maybe even 500 mile plus round trips. Does gas millage matter to you? I would advise effective air cond, low-speed traffic engine cooling, maybe think about possible small storage space. 300hp will work well for this kind of car maybe 325 or so.

Aggressive street car. Canyon runs, back road blasts with some short-range single-day cruises. street tires only, you will want a limited slip in this car. 350-400hp (no more), Real commitment to a proper built GRBX and gear ratios. Add some open track with slicks, quite a bit more spring tension and roll bars setup carefully stay at 400 hp that's plenty.

Open track car on slicks. 500Hp expensive GRBX lots of setup time.

Race car? Consult series rule package.

+550hp bench racer (500 hp on slicks is a really fast car if driven competently) more than that? You don't need it but it's your money.

In all cases on pump gas: 1.25hp per inch is a good rule of thumb. Want more power? Make the motor bigger.

 

[Ryan L]

Animation comparing piston speeds. Same stroke, just different rod lengths

 

[Jac Mac]

Animation comparing piston speeds. Same stroke, just different rod lengths

BS, think about it, if the idea of the animation is to show the difference the two rods should have both big ends rotating around a common main brg center height and the long rod item should show a shorter piston comp height ( half the stroke distance ). No wonder the newbies get confused.