Go Back   The Ford Barn > General Discussion > Early V8 (1932-53)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 03-22-2021, 04:51 AM   #1
fredeuce
Junior Member
 
fredeuce's Avatar
 
Join Date: May 2010
Location: South Australia
Posts: 13
Default 8BA Valve Seat Insert

I am starting a rebuild on an 8BA motor on my brother in-laws 54 Customline. (Here in Australia , the '54 models still had a flathead). This engine was pulled down and put into storage years ago following a valve seat insert dislodging .

I am now assessing this block to determine what we need to do to rebuild it.
Generally it appears to be a good candidate as it has a standard diameter bore and standard diameter crank.

There is about a 0.004" ridge in the bore so I am thinking of a .020" overbore and new pistons. This is a stock rebuild . No hot rod stuff here except perhaps a set of headers.

I am curious about the dislodged valve seat insert. I have cleaned out the block to examine for cracking in the block that may have caused it to release. I can't see any cracks at this time . So far so good.

Can anyone offer any other reasons why these valve seat inserts might dislodge?

I did notice that the valve was burnt in two locations 180 degrees apart. Its not clear to me if the burnt valve may have caused the seat to dislodge or resulted after the valve seat became loose.

I look forward to any comments or advice.
Attached Images
File Type: jpg IMG_0123 resize.jpg (70.7 KB, 220 views)
File Type: jpg IMG_0124 resize.jpg (63.4 KB, 223 views)

Last edited by fredeuce; 03-22-2021 at 04:31 PM.
fredeuce is offline   Reply With Quote
Old 03-22-2021, 07:59 AM   #2
chuck stevens
Senior Member
 
chuck stevens's Avatar
 
Join Date: May 2010
Location: upstate new york
Posts: 719
Default Re: 8BA Valve Seat Insert

I have a 8RT (52 TRUCK) that dislodged the exhaust seat two different times, on the center cylinders, there were no cracks in the block.. I have had it repaired, in the car, and the repaired seats have been aright, but I'm worried about the other ones. Speedway makes a over sized harden seat, then have the block bored to fit the seat. It made it home both times!! I would put the new seat in the freezer over night, for a good tight fit.
chuck stevens is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 03-22-2021, 07:03 PM   #3
Bored&Stroked
Senior Member
 
Bored&Stroked's Avatar
 
Join Date: Jan 2011
Location: Central Ohio
Posts: 3,139
Default Re: 8BA Valve Seat Insert

There is no reason that I can see for the block not to be usable. What is normally done is that the seat pockets are machined for over-sized seats and then the new ones are pressed in. Make sure you have a machine shop that knows flatheads! You cannot cut the pocket deeper - there is "water down below". The new seat will be too tall, so they'll use carbide seat cutters to cut the seat down to the correct height.

Given the size of the block, normally these types of operations are done in a special machine that can be correctly setup for the correct valve angles. The valve/seat angles on each side of the block are different - so they need to know what they're doing when they setup the block to re-bore the seat pockets.

At my machine shop, all this work is done in a vertical milling machine that has a special "crankshaft saddle" fixture to mount the block in (it indexes off the crankshaft main bearing bores). The saddle guarantees that the block is correctly aligned. If your machine shop isn't setup for this specific work - find another one . . .
Bored&Stroked is offline   Reply With Quote
Old 03-22-2021, 07:45 PM   #4
Pete
Senior Member
 
Pete's Avatar
 
Join Date: May 2010
Location: Wa.
Posts: 4,195
Default Re: 8BA Valve Seat Insert

Valve seat rings usually come loose for 2 reasons.
1- The valve stops sealing for various reasons and the seat overheats, cracks and comes
loose.
2- The ring was not installed with enough press. Should be .005 in cast iron.

It is a bad idea to put a new ring in an old hole without skinning the OD and squaring the bottom.
Pete is offline   Reply With Quote
Old 03-22-2021, 08:22 PM   #5
mercman from oz
Senior Member
 
mercman from oz's Avatar
 
Join Date: May 2012
Location: Queensland, Australia
Posts: 5,735
Default Re: 8BA Valve Seat Insert




Here are larger pictures showing the Valve Seats. Very interesting.
mercman from oz is offline   Reply With Quote
Old 03-22-2021, 10:45 PM   #6
GB SISSON
Senior Member
 
GB SISSON's Avatar
 
Join Date: Jan 2014
Location: Orcas Island Washington
Posts: 3,038
Default Re: 8BA Valve Seat Insert

Sponsored Links (Register now to hide all advertisements)
For me and my eyesight, I can see this valve seat image much more clearly on my laptop screen than I could if I was staring at it from a foot away in person with my reading glasses on...... I have noticed the same thing with such things as frame stamping of serial numbers. This is amazing technology. Was this taken with a cellphone or a digital camera? I have a similar valve seat situation on an otherwise excellent looking 8ba block, but has some differences so will start my own thread later.
__________________
'47 1/2 ton pickup next project, '47 one ton panel 99% stock nearing completion, '47 2 ton with 8ba and 9' script stakebed, '46 1/2 ton woodie project,'59 F350 9' flareside pickup with cummins 6at. 'Rusty ol' floorboards, hot on their feet' (Alan Jackson)
GB SISSON is offline   Reply With Quote
Old 03-23-2021, 07:43 PM   #7
fredeuce
Junior Member
 
fredeuce's Avatar
 
Join Date: May 2010
Location: South Australia
Posts: 13
Default Re: 8BA Valve Seat Insert

Thanks to all who responded. Good information and tips.

Time for a chat with my machinist to get the ball rolling.
fredeuce is offline   Reply With Quote
Old 03-24-2021, 02:44 AM   #8
vincent
Member
 
Join Date: Jun 2020
Location: Germany
Posts: 76
Default Re: 8BA Valve Seat Insert

I once made an expandable insert in the valve guide location with a hardened, steel pin. When this was locked into the valve guide hole I was able to put my homemade little adjustable cutter onto the pin and drive it with a handheld drill. The cutter cleaned the recess of the valve seat perfectly on the circumference and the bottom of the pocket. Thus the pocket was ready for a new seat without pulling everything apart. I think it should be possible to heat the casting enough and cool the ring to get the desired overlap. Would save you pulling the engine. To cut the seats I use the PEG10. https://theultimatetooling.com/en/pr...-seat-grinder/
vincent is online now   Reply With Quote
Old 03-24-2021, 05:56 AM   #9
Bored&Stroked
Senior Member
 
Bored&Stroked's Avatar
 
Join Date: Jan 2011
Location: Central Ohio
Posts: 3,139
Default Re: 8BA Valve Seat Insert

Also, if it was mine, I'd probably take a close look at all the seats and ask myself should I be replacing others as well. Usually I have all the seats done at the same time on the mill - such that they're all cut to the same heights/depths and I know the press fits are correct. You can tell from the photos that some of the other seats are pitted/worn - so consider doing them all.

As Pete noted, you'll need to go to an oversize seat and redo the seat pocket - for the correct fit on the new seat - at the very least for the problem one. Make sure they just skim the bottom and don't try to cut it deeper for the too-tall seat they will undoubtedly purchase - the new one needs to be cut down to size.
Bored&Stroked is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 09:17 AM.