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'69 250 Head/Parts

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65_Stang_170
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Posts: 87
Joined: Sat Nov 11, 2017 12:13 pm

'69 250 Head/Parts

Post #1 by 65_Stang_170 » Tue Mar 31, 2020 10:55 am

Howdy!

Few Questions:

Would a cam from a stock '69 250 be an upgrade if installed it in a stock '66 170? Just curious since I have the 250 sitting in the garage.

If I mill the '69 M code head to up the compression for my 170 would I still be able to use it later down the line if I upgrade to a 200? I cut up and hogged the intake to put on a 2v plate (i'll edit the post and toss up a pic later). I think I'm going to make the plunge to head swap soon.

Can I just buy the the larger intake valves (1.75" from the 1.649") and have them put in or is modification required?

I currently have the '66 170 with a Weber 32/36 carb on a 2to1 adapter, a T5, and tossing on the amazon headers soon if that helps clarify the picture. Just looking for a little extra for daily/street type performance.

Image

Thanks in advance!

-Shawn
1965 Mustang Coupe - 170 I6, T5 Manual Transmission, Weber 32/36 Carb, Amazon Headers w/single exhaust to thrush turbo muffler, Arning Drop

CZLN6
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Re: '69 250 Head/Parts

Post #2 by CZLN6 » Tue Mar 31, 2020 1:30 pm

Howdy '65 Stang:

Q- Would a cam from a stock '69 250 be an upgrade if installed it in a stock '66 170?
A- Yes, but marginally. The 170 cam specs are- Duration 240 Degrees, lift .348", timing is favoring a retarded curve and the lobes have a very peaky profile. The 250 specs are- 256 duration, lift .368", slightly favoring retarded and the lobes again, are peaky.
My opinion- If you are going to the trouble of changing the cam, go for an aftermarket with a more rounded profile. THe stock "peaky" profile lobe open quickly and close quickly. After market profiles are fatter. Though they may open at the same time the amount of lift at .050" will be greater and will remain at max lift longer.

Q- Can I just buy the the larger intake valves (1.75" from the 1.649") and have them put in or is modification required?
A- Modification is necessary.

Q- If I mill the '69 M code head to up the compression for my 170 would I still be able to use it later down the line if I upgrade to a 200?
A- Yes. Mill no more then .075" and do some planning on the rest of the details on the 200 build.

You are sure thinking. Plan ahead. Good luck, and keep us posted on what you decide and on your progress.

Adios, David
co-author of the Falcon Performance Handbook
http://www.falcon6handbook.com/

65_Stang_170
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Posts: 87
Joined: Sat Nov 11, 2017 12:13 pm

Re: '69 250 Head/Parts

Post #3 by 65_Stang_170 » Tue Mar 31, 2020 3:49 pm

CZLN6 wrote:Howdy '65 Stang:

Q- Would a cam from a stock '69 250 be an upgrade if installed it in a stock '66 170?
A- Yes, but marginally. The 170 cam specs are- Duration 240 Degrees, lift .348", timing is favoring a retarded curve and the lobes have a very peaky profile. The 250 specs are- 256 duration, lift .368", slightly favoring retarded and the lobes again, are peaky.
My opinion- If you are going to the trouble of changing the cam, go for an aftermarket with a more rounded profile. THe stock "peaky" profile lobe open quickly and close quickly. After market profiles are fatter. Though they may open at the same time the amount of lift at .050" will be greater and will remain at max lift longer.

Q- Can I just buy the the larger intake valves (1.75" from the 1.649") and have them put in or is modification required?
A- Modification is necessary.

Q- If I mill the '69 M code head to up the compression for my 170 would I still be able to use it later down the line if I upgrade to a 200?
A- Yes. Mill no more then .075" and do some planning on the rest of the details on the 200 build.

You are sure thinking. Plan ahead. Good luck, and keep us posted on what you decide and on your progress.

Adios, David


David, as always thanks for the info. Marginal = not worth the effort to put the 250 cam in... got it. I'll save upgrading the cam for a later date.

I'm assuming if I buy the valves and bring them to the machine shop, they'll know what to do to fit them.

I figured the milling now would be fine, and that I would just need to adapt the 200 to make sure all the numbers line up. Thank you for the confirmation. The 200 is probably a few years down the line...

I'm moving to Korea later this year and the project will be on hold. I'm just waiting on a driveshaft to get back on the road before she's got to be put away for a little bit.
1965 Mustang Coupe - 170 I6, T5 Manual Transmission, Weber 32/36 Carb, Amazon Headers w/single exhaust to thrush turbo muffler, Arning Drop

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bubba22349
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Location: Flagstaff, Az. 86005 near the old Route 66

Re: '69 250 Head/Parts

Post #4 by bubba22349 » Tue Mar 31, 2020 4:21 pm

X2 Yes I also agree on all the above including that a newer aftermarket cam grind is the better choice. However on the other hand if you already have that 250 cam & lifters that are still in good usable condition. Plus you don't mind doing the install work and minor extra expense of a timing cover gasket set than that minor improvement In power still might be worth it to you. If you do this swap always keep each lifter in its orginal order (unless the plan was to replace them) as long as each used lifter goes back on its same cam lobe then there's no cam break in required.

When you take the head in for the larger intake valves and the opening up of the valve bowls, some other things like tapering the valve guides, cleaning up of the intake and exhaust posts as far as you can reach into the port, will increase port flow some. Some other optional items like maybe fitting a center exhaust port divider, and full exhaust porting, ect. But be sure to ask them to back cut the valves during the valve job too. Best of luck the head swap it should be a real good improvement. :thumbup: :nod:
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

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