|
Sponsored Links (Register now to hide all advertisements) |
|
|
Thread Tools | Display Modes |
12-13-2016, 12:31 PM | #1 |
Senior Member
Join Date: Jun 2015
Posts: 128
|
Offy 1069-400 aluminum heads
Hi, flathead noob here. Looking at Offy 1069-400 heads and regular dual intake for a 1950 8BA I'm rebuilding. Engine is bored .060 over with Kiwi L-100 cam (.368 lift, 246 duration) and Johnson lifters.
Doing a search on site it looks like I'm good to go with this head concerning piston clearance. I'm planning to use Best graphite head gaskets. Anybody with any experience with this head see any potential problems in my plans? TIA, Tony |
12-13-2016, 03:51 PM | #2 |
BANNED
Join Date: May 2010
Posts: 3,019
|
Re: Offy 1069-400 aluminum heads
Tony,
To avoid heart aches think about taking a used head gasket....usually squashed down to .040. Wind 4 studs in the head bank spread apart. Spread a thin coating of grease on the piston crowns and valve heads. Slip the heads on the motor over the 4 studs. Push the head in place firmly while a compatriot cranks the motor over. Believe me you'll feel any interference and when you remove the head you will see the grease 'witness' mark/s. This may not be the conventional method but it sure works for me. If you see no witness marks you will know you have at the occasionally recommended .040 min clearance. Charlie ny |
Sponsored Links (Register now to hide all advertisements) |
|
12-13-2016, 06:39 PM | #3 |
Senior Member
Join Date: May 2010
Location: Chester Vt
Posts: 8,855
|
Re: Offy 1069-400 aluminum heads
In the past, I have found that the L-100 would not clear the 425 head. Not sure if they've improved their quality control
|
12-14-2016, 11:46 AM | #4 |
Senior Member
Join Date: Jun 2015
Posts: 128
|
Re: Offy 1069-400 aluminum heads
Thanks for the responses Charlie and Ron. Out of the box which head; the 400 or 425 would give you the most clearance?
Tony |
12-14-2016, 11:53 AM | #5 |
Senior Member
Join Date: Apr 2015
Location: Sweden
Posts: 3,045
|
Re: Offy 1069-400 aluminum heads
The numbers indicate how much valve lift they allow.
|
12-14-2016, 01:16 PM | #6 |
Senior Member
Join Date: Jun 2015
Posts: 128
|
Re: Offy 1069-400 aluminum heads
Sponsored Links (Register now to hide all advertisements)
Thanks, Tony |
12-14-2016, 01:28 PM | #7 |
Senior Member
Join Date: Apr 2015
Location: Sweden
Posts: 3,045
|
Re: Offy 1069-400 aluminum heads
The difference is in the valvepocket area.
Piston to head isnīt a problem usually. You better make some measurements...cheaper then to start over fixing bent valves... |
12-14-2016, 01:28 PM | #8 |
Senior Member
Join Date: Oct 2011
Location: Shelton, WA
Posts: 3,799
|
Re: Offy 1069-400 aluminum heads
As Ron said, depending on QC. I just helped a friend get a head machined where the difference in the depth of the combustion chambers from one end to the other was .025. Probably due to sloppy setup in mill that finished the chamber.
You need to check everything, can't just use stuff out of the box if you want to be sure. |
12-14-2016, 01:44 PM | #9 |
Senior Member
Join Date: Jun 2015
Posts: 128
|
Re: Offy 1069-400 aluminum heads
Thanks guys, appreciate the info. I agree, and did intend to check clearance regardless of which head I end up with.
Tony |
12-14-2016, 02:25 PM | #10 |
Senior Member
Join Date: May 2010
Location: Michigan
Posts: 505
|
Re: Offy 1069-400 aluminum heads
I thought the 400 numbers related to compression ratios, not valve clearance.
|
12-14-2016, 03:07 PM | #11 |
Senior Member
Join Date: May 2010
Location: Chester Vt
Posts: 8,855
|
Re: Offy 1069-400 aluminum heads
The problem here is: I don't think they mean anything. Back when I was building engines I had to mill the Offy and Edelbrock heads for valve clearance and piston clearance. Then Edelbrock began CNC milling the heads and that solved the valve problem, but the piston problem is still there and you have to measure them. The recent Offys look the same as the old ones. I did like them for one reason they were thicker than the Edelbrock heads and I milled them .060" and made my own combustion chamber. But the 400/425 heads never cleared the .360 net valve lift of there L-100 cam. Things may have chanced since, but you have to start measuring, if you want to BUILD and engine.
|
12-14-2016, 05:08 PM | #12 |
Senior Member
Join Date: May 2010
Location: Masterton, New Zealand
Posts: 3,828
|
Re: Offy 1069-400 aluminum heads
I don't think the L100 cam is the way to go with that particular engine. Works best with big cubes,hi compression. My opinion only.
__________________
Unfortunately, two half wits don't make a whole wit! |
12-14-2016, 07:48 PM | #13 |
Senior Member
Join Date: May 2010
Location: Chester Vt
Posts: 8,855
|
Re: Offy 1069-400 aluminum heads
Personalty, I think it's the best cam for a 276 and 8:1 CR. I drove Richards Kuns 53 Ford HT and can vouch for it's performance and economy. There were no other mods to the engine just pistons and cam. However it was the best tuned engine i ever drove.
|
12-14-2016, 09:30 PM | #14 |
BANNED
Join Date: May 2010
Posts: 3,019
|
Re: Offy 1069-400 aluminum heads
Tony,
Remember the cheapest way to more power is compression. I fit each head to the bank it will be mounted on, usually 8 or 10 hours per head. Even if the heads you choose do not have an interference problem you are short changing yourself and your motor by not squishing and quenching the heads. Charlie ny |
Thread Tools | |
Display Modes | |
|
|
Sponsored Links (Register now to hide all advertisements) |
|