All Small Six Exhaust Manifold Bronco 170 ci

[tonyduc]

All
I have a 1966 170ci Bronco. Engine was just rebuilt but we kept the exhaust manifold which visually looked ok. There are exhaust fumes coming in the passenger compartment and I suspect the manifold - the exhaust pipes are rust covered but I don't see any holes. I believe the PO installed a manifold from a 200 because with a 170 bolt kit I purchased, the bottom bolts were too short, so this manifold might have a bigger chamber ? - everything else lines up and from looking at the 170 gasket the ports appear to line up although I did not measure. Bolts were torqued according to shop manual instructions. Don't see any cracks although I have not checked for warping. Otherwise, does anyone know if a 200 manifold with fit on a 170 engine ? The Bronco currently has a 2" exhaust pipe not a 1.75" which also makes me suspect the manifold is a 200.

I can purchase new 170 manifolds and CJ Pony has a complete exhaust system (they say for a 170, but indicate the pipes are 2"). So the problem is matching a new 170 manifold (which takes 1.75" pipe) with a new exhaust which all I can find is 2". Reducers is a good idea but for 1.75 -> 2" is impossible to find (I assume one end is flared to 1.75 and the other accepts a 2" flared pipe?). Any suggestions would be much appreciated !

As a side note, here's a bit of information about a 170 manifold Bronco Graveyard sells (which is likely the same as everyone else's)
"
Made for the 170 Cubic Inch 6 cylinder, but will fit 200 cubic inch 6 cylinder.
NOTE: 170 has smaller exhaust ports than a 200 and that is what this piece uses.
Fits 170ci and will work -with modifications- for the 200ci 6 cylinder engines.
"
Thanks
Tony

 

[TrickSix]

Most people would see the 2" exhaust system and 200 exhaust manifold as an upgrade, not a problem to be eliminated! I've installed a custom 2" system and a new 2" outlet manifold on my '66 200 Mustang, which had the 1 3/4" setup like yours. The newer manifold should line up and bolt onto the older head just fine, though the 2" outlet manifold does use a few longer bolts. You may well have some leaks, but it shouldn't be from any kind of inherent mis-match between the old and the new.

 

[B RON CO]

Hi, the exhaust must follow the original style and exit on the right side, behind the rear wheel. If it goes out under the bumper. it will be sucked in the tailgate. On my Bronco the problem was sealing the 3-4 area between the head and exhaust manifold. The old manifold was surfaced flat but the head was not. Good luck

 

[drag-200stang]

I know for a fact that a 69 and up 170 exhaust ports are the same as a 200/250 but have no first-hand knowledge that the earlier 170 is smaller, but I do not think so.

 

[bmbm40]

My 66 Bronco with the 170 had 2" exhaust. Still does but now a 250. There is a certain year stock manifold that is said to be the best but I can't remember which year but you can find that in your Falcon Performance Handbook.
Just curious is it a stock rebuild or some performance parts/work?

 

[tonyduc]

Thanks for your replies. As I mentioned above, all major parts vendors seem to sell the same 170/200 manifold which takes a 1.75" pipe. However I did recently find on eBay a manifold which says "170 200 Ford Comet Fairlane 1963 1964 1965 1966 1967 New Exhaust Manifold" and has a 2" exhaust outlet, so this would solve the problem (link is below). It did not list the Bronco as compatible - maybe because of the 2" inlet size?, but can I assume a 170 200 Comet Fairlane manifold would otherwise fit a Bronco 170ci ? From extensive research I am pretty sure the only differences with the Bronco six is a deeper oil pan and solid lifters.

(https://www.ebay.com/itm/2848224627...eJfkEmu1Vz3TGuJr6mz7gXLHqg==|tkp:BFBMyom7m7Vg)

 

[TrickSix]

Thanks for your replies. As I mentioned above, all major parts vendors seem to sell the same 170/200 manifold which takes a 1.75" pipe. However I did recently find on eBay a manifold which says "170 200 Ford Comet Fairlane 1963 1964 1965 1966 1967 New Exhaust Manifold" and has a 2" exhaust outlet, so this would solve the problem (link is below). It did not list the Bronco as compatible - maybe because of the 2" inlet size?, but can I assume a 170 200 Comet Fairlane manifold would otherwise fit a Bronco 170ci ? From extensive research I am pretty sure the only differences with the Bronco six is a deeper oil pan and solid lifters.

(https://www.ebay.com/itm/284822462793?hash=item4250bde149:g:89kAAOSw3QdiZs5a&amdata=enc:AQAHAAAA8Llm9i6RpDKvLBI8hK4zmAVGe7+95dU6p4FPedCkPydXKfwU3Pqn5uAnxE8cdOL3MFqfsKQZBYAiLLu9eiTp6TC9/tdd4kXpnbY2MMAvrfoYnOagTiE5dhhqW6qu61RfNUrgaimLPCoMRVt4qX8qHx8OihaISuabkzZpP+UBwf3ZywfFDND1fg1+Q7RK0UVlZ3kYka7oP5j0CNwPH03oLqCgkY7l+/06RSz6LDKrxF64a1n90TyC9TtMI+tHup4OYGVmImR+LlnRkc1tU6uMqWm72LJ9WaDuCRKgOKQYeJfkEmu1Vz3TGuJr6mz7gXLHqg==|tkp:BFBMyom7m7Vg)

Yea, that's the manifold I bought for my 200. It fit fine, though I did make sure the gasket surface was flat first. It will fit your 170 as well. Original manifolds are probably a rusty wreck by now. But if you can find one, the '68 and later examples have the 2" outlet and a more crack resistant design that requires a few longer bolts. After a few years though, they start to get some emissions bungs and such, and then become useless once the catalytic converter version came out. And yes, buy the Falcon Six Handbook, all this stuff is covered there.

 

[Old bronco]

I’ve got a 66 bronco with the 170 and had Precision Exhaust (they make the set sold at cj pony) make the 2” for my truck. Bolted right up to the stock exhaust manifold. They make two kits for cj one is 1.75 the other is 2. One is a factory fit exhaust system the other is a more generic kit for multiple vehicles (I.e. for a keep cj cut piece three at end “c” two inches, for a bronco cut piece two end “a” two inches, etc) great company to deal with, very accommodating. the 2” will bolt to the manifold with no issue.
c

 

[chad]

the abve may have hit the nail on the head w/ "later yr bigger"
Simply ask and rec a simple answer.