Need opinions on compression test: 66 Bronco 170 engine

tonyduc

New member
Hi

Newbie here, bought a 66 EB back in September, in good shape except mechanically there is blue grey smoke coming out the exhaust. There is also a slight oil leak (1-2 drops/day) where the engine meets the tranny (rear seal?). Here are some compression numbers:

Cylinder 1 2 3 4 5 6
PSI 125 150 120 150 155 90 (115 after oil added to cylinder)

I followed Chilton's guidelines and since #6 was low, I injected a few tablespoons motor oil according to instructions. Compression went up about 30%. There is also wet oil on the block by cylinder 6 - I assume this means head gasket? But also the numbers at least from cylinder 6 implies worn piston rings?

The engine runs good, no knocking sounds. I therefore planned on pulling the engine, replacing the top end (pistons and rings), sending the heads out to a shop for a valve job. Perhaps replace the timing chain ? I am not a mechanic but I have rebuilt 2 cylinder motorcycle engines before, this is my first 4 wheel project. Seems more complicated but the basic concepts are the similar.

Thanks
Tony
 

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That's a really nice looking Bronco! Yes your thoughts are right with a 65 Lb. differance from the highest to lowest cylinders and blue smoke out the exhaust It's time for a full rebuild of the short block and head, if you want it to run smoothly. Good luck (y) :nod:
 
Agree, very nice Bronco. Its well worth the $$ to do a complete rebuild.
Check with Matt at vintageinlines.com for some specialized componets.
He stocks the full roller timing chain set which is well worth the money.
Since its an original 170 engine, you would probably would not be interested in a 200 engine for a lot more power. Now is the time to make that choice.
 
Hello! How are you? I'm from Argentina I'm very sorry if I do not explain well haha ​​..
The blue exhaust smoke and an oil consumption. It can be transported to the "valve stops" (I do not know how it's said in the United States, I think the valve seals, I'll attach a photo so they know what I'm talking about) are usually dry or broken for years, the oil It filters in the camera.
a reconstruction of the cylinder head would be enough.

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Hi, at this point your engine should get the whole rebuild. Figure the bores are worn, valves are done, timing chain is stretched, etc. These engines all wore out by 125,000 miles or less.
As mentioned, the 200 is a perfect bolt in engine.
I just installed a 200 warmed up with a mild cam, 2 barrel conversion, 2" exhaust, HEI ignition in my 66 Bronco. It makes a world of difference.
Make sure to get the Ford Falcon Performance Handbook before starting your project to get the most out of your Ford 6.
You could drive it around for now, while building a nice little engine.
The drip may just be loose oil pan bolts. I have stopped or slowed down many oil leaks by gently snugging up the bolts.
Good luck
 
Howdy Tony:

And welcome to the Forum. Given the symptoms and compression results I'm guessing your engine has several wear problems. Do you have any information about this vehicles former life? Mileage? Is this the original engine?

A poster mentioned valve stem seal. Add to that a burned valve(S) and the strong possibility of bad rings. A complete engine tear down and rebuild is likely the most complete solution to your problem. I 2 X Bill's observation that it is a nice looking Bronc. What are your plans for it? Before you start tearing into it you might want to ask yourself what the long term plan will be for it. You have lots of options- stock restoration, resto-mod, rat rod, off road, or street driver. Lots of choices.

Anyway Tony, you have a nice Bronc. If you would share a little more information about the truck and what you what to do with it we could be more specific in offering suggestions and advice to you.

Good luck and keep it coming.

Adios, David
 
That is a great looking Bronco. As stated check the block and head casting numbers just to know what you have. They are all similar but you could have a non original component. I think my 66 had a slightly later head. Do you plan to keep it 100% original?
 
Thank to all for the advice.

My plans for the truck is to make it mechanically reliable, and as far as the body, it has mostly surface rust underneath. Spent it's whole life in Texas. So I was just going to use a rust converter or encapsulator and frame paint the underbody. I was going to do the same for the engine compartment while the engine was out, also a new wiring harness.

I will get the handbook. I am up in the air between rebuilding the 170 (I like stock), or a 200 swap. As far as getting a 200 what are the sources ? Is a remanufactured or crate engine a good way to go?

Here' 2 more pics.
Tony
 

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Howdy Back Tony:

Q- I am up in the air between rebuilding the 170 (I like stock), or a 200 swap.
A- IMHO, I'd go for a late model 200. If you want to maintain the 170 '66 appearance paint to period.

Q- As far as getting a 200 what are the sources ?
A- Depends on your area. What is your access to recycle yards? Machine shops? If you can find a low mileage engine from a vehicle that was tail ended and totaled that maybe the cheapest. Next would be rebuilding a core 200.

A- Is a remanufactured or crate engine a good way to go?
Q- If you can find an honest and reliable rebuilder. IF you go that way don't assume that it is a good rebuild. If you intend to add specific performance parts such as a cam, double row timing set, and other items a rebuild is the way to go.

On a side note you may want to pull the head and take a good look at what you have before you decide on a plan.

Good luck and keep it coming.

Adios, David
 
You might get lucky and find a good running 200. Check picnpul periodically, car-part.com and craigslist. I put an ad on CL once seeking a 250 and within a couple of days got a call and ended up buying it. A low mileage 250 with new valve job. You can keep the 170 if you ever decide to go back stock. Look for a later 200 from 77 on. They were in Fairmounts, Comets and other cars.
 
motor:
car-part.com (plug in ur own geographic area)
plenty junk yrds in TX (become familiar w/correct Y/M/M)
ebay
classicbronco.com (or 100 more e.bronk sites' 4sale forum. Ours as well).
depending on prt of Tx U in - Chuck at BCBroncos ((W. of Austin, N. of SanAntonio aftr 40 yrs in SoCal).

Last 2 places get rid of i6 as folks wanna bent8 - ¯\_(ツ)_/¯ (Darn fools).
Y not go 250 like abuncha us? Keep orig for sales time.
As David sez - what do U wanna use the vehicle for (80% of driving condition). A very important Q w/a multipurpose vehicle.

Check vintage inlines dot com for The Ford...Six Cyl. Performance Handbook (? $20) & while waitin for delivery C above 'tech archive' (click on big blue box w/crossed wrench/screwdriver). The 1st will help U (in many ways but 1st off) in selectin a motor, machinin the current, etc. The 2nd will help ID what U have, get it running optimal, drivin great till U got enuff info to ask Qs here/make decisions on possibilities.
 
There is a member here, ledslinger29, that rebuilt the 170 in his Bronco with a performance cam and other mods. From what I remember he was pretty happy with the results. Check out his experience.
 
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