All Small Six 1966 170 vs 200

[66bronco]

A friend has a 1966 Bronco which only came with a 170. But after I started to work on his truck the prior owner(s) changed a handful things on it. But what I noticed right away the motor as 5 freeze plugs. All my 170’s only had 3 freeze plugs.

First is that a dead giveaway it’s definitely a 200?

Secondly are there really any differences besides the freeze plugs that would not make 100% interchangeable?

He wants to keep this bronco as close to stock as possible. Or so should I tell him to look for a true 170 or suggest keep the 200 even tho it’s not correct for his year bronco?

Thanks in advance Jeff

 

[DON]

Yes, dead giveaway, it is a 200
The two engines are similar but the 200 has improvements. Depending on the 200 and the existing transmission, the swap wouldn’t be bad. I would suggest if he wants it original, to find a correct year engine and tranny if needed. Most people will not know the difference, only people looking for original will know. Also what level of original is he trying to achieve and the $$ to spend getting there

 

[alwill923]

Paint it the original color and if possible use the original air cleaner, no one will know unless they count the freeze plugs.

I do not think that the value of the bronco will be compromised unless one is looking for points for judging. If this is so just keep the original engine.

For driving the 200 will provide more torque and hp!

 

[bmbm40]

You can determine what year block and head you have with the casting codes using the link below. I swapped my original 170 for a late 70s 200 that bolted right in using the original transmission. If he wants to keep it as stock as possible it is possible to find all original parts and the easiest way will be to find someone converting an early Bronco from to v8 so check sites like classicbroncos.com to find a conversion. The early Bronco had unique lifter and a modified carb different from passenger car six motor. Just drive the 200 even if he finds original parts. Is he interested in a complete restoration or an everyday driver? Any off-road use planned? Highway driving? Six cylinder Bronco is kind of a limited use vehicle as far as freeway use as they were intended to be a farm and ranch type vehicle. The 200 will have a bit more power but cruising speed is still limited with the 4:11 gear ratio and 4:56 was an option.

Classic Inlines - Ford Small Inline Six Specs

 

[ActionYobbo]

I have a 170 that you can have if you are in the area. Was running but smokey when pulled

 

[powerband]

the less than .001% of people who would notice the difference between 170 and 200 are likely all right here ....
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If the 200 is in decent shape that's good reason to keep it. There's really no such thing as 'numbers matching' with Ford. ( An early 289 block Bronco maybe ... )
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... for a purist (fanatic) , there are 3 freeze plug 170 cid small sixes available from Ford Mavericks at least thru 1970/71. There is a '71 Maverick C8DE 170 in my 1963 Wagon.
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later 60's / 70's 200's have some minor differences most obvious with different year cylinder head / carb setups. 170'/200 swap important parts except accessories may be an issue (alternator / starter / distrib' ). Ford kept the small Automatic/tiny 3 speed early 144/170 bellhouse bolt pattern to use with the iconic C4 through 70's.
'76 Comet 200/C4
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the last genre 200's had automatic only trannys, different starter location and plenty of emission related vacuum hoses and switches in Mustangs, T-Birds, LTD's and a few related Mercury's... .
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have fun
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OEM C8DE Ford 170cid 'small block six', Precision Machine D7 Head . Oversize intake valves/1.50 exh with- silicon springs and HD retainers, . Milled head w/ Steel Shim Gasket. CR= 9.5:1. H/W 5200 - 2.8 series (32/36) progressive 2Bbl carb., Exhaust ¾ siamese port divider, Champion racing spark plugs, Contact Point/Condensor distributor, Diaphragm Clutch. T5 Adaptor/5speed tranny, Short throw Hurst Indy shifter, OEM 3.50:1 rear gears, Shelby sway bar, Addco rear sway bar , Fabricated subframe connectors / crossmember, Hooker 6601 dual out longtube headers. Shoulder belts front and 3pt belts for child seat in rear, Dual chamber master cylinder, OEM wide-wagon brakes, dual air line rear shocks, 14” wheels & 205/195-14 tires, Original Falcon Logo embossed Bench Seats - Fold Down rear seat, Counter sprung Tailgate with manual Window Crank, Fender mounted gun sights, Original tube radio, …
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[DON]

There's really no such thing as 'numbers matching' with Ford. ( An early 289 block Bronco

Notice I said correct year