Boring 390's

[67428GT500]

The Being '66 was the first year and 70 the last year of the 428 as far as vehicle installed most I looked at to replace my block with that split two cylinders are relatively thin at 4.130. I have sonic checks on four blocks I considered for purchase. The thickest wound up being a 105 D4 block. I have .140- .156 and this is at a 4.155 bore.  One of the lessons learned with the new block is how important it is to bore the block with a torque plate. Charles at Charles machine was showing me that the distortion is usually .005 or more.  Not one of the earlier FE specific book offerings mention this.  Very little about it until Barry's books.
I am going to fire the new engine this weekend.  Hopefully all goes well. It seemed strange to grind the tangs off of the Cleveland mains. I hope all is well there too. Perhaps the cam is the largest concern. Always nerve racking breaking in flat tappet cams.

                                                                                                           -Keith

[Tommy-T]

The Being '66 was the first year and 70 the last year of the 428 as far as vehicle installed most I looked at to replace my block with that split two cylinders are relatively thin at 4.130. I have sonic checks on four blocks I considered for purchase. The thickest wound up being a 105 D4 block. I have .140- .156 and this is at a 4.155 bore.  One of the lessons learned with the new block is how important it is to bore the block with a torque plate. Charles at Charles machine was showing me that the distortion is usually .005 or more.  Not one of the earlier FE specific book offerings mention this.  Very little about it until Barry's books.
I am going to fire the new engine this weekend.  Hopefully all goes well. It seemed strange to grind the tangs off of the Cleveland mains. I hope all is well there too. Perhaps the cam is the largest concern. Always nerve racking breaking in flat tappet cams.

                                                                                                           -Keith

Keith, I wish I was as fortunate as you when I went searching for a thick 390 block. The thickest I found was also a D4TE block. The machine shop sonic'd it and said it would be thicker than .100 everywhere after a 4.130 bore. Got it done and in the meantime got an Ebay sonic checker. Naturally, when I sonic'd it myself after the boring, I found a place .079 was the thinnest, and 3 other spots below .090. Filled it to the water pump holes and am going to run it. Wouldn't have started this project if I didn't already have the pistons and crank.
No more .080 over 390 blocks for me. I do believe the "thickies" are out there...but really hard to find.
Good luck on the cam break-in.

[falcongeorge]

The Being '66 was the first year and 70 the last year of the 428 as far as vehicle installed most I looked at to replace my block with that split two cylinders are relatively thin at 4.130. I have sonic checks on four blocks I considered for purchase. The thickest wound up being a 105 D4 block. I have .140- .156 and this is at a 4.155 bore.  One of the lessons learned with the new block is how important it is to bore the block with a torque plate. Charles at Charles machine was showing me that the distortion is usually .005 or more.  Not one of the earlier FE specific book offerings mention this.  Very little about it until Barry's books.
I am going to fire the new engine this weekend.  Hopefully all goes well. It seemed strange to grind the tangs off of the Cleveland mains. I hope all is well there too. Perhaps the cam is the largest concern. Always nerve racking breaking in flat tappet cams.

                                                                                                           -Keith

Keith, I wish I was as fortunate as you when I went searching for a thick 390 block. The thickest I found was also a D4TE block. The machine shop sonic'd it and said it would be thicker than .100 everywhere after a 4.130 bore. Got it done and in the meantime got an Ebay sonic checker. Naturally, when I sonic'd it myself after the boring, I found a place .079 was the thinnest, and 3 other spots below .090. Filled it to the water pump holes and am going to run it. Wouldn't have started this project if I didn't already have the pistons and crank.
No more .080 over 390 blocks for me. I do believe the "thickies" are out there...but really hard to find.
Good luck on the cam break-in.

Very little mention on here of WHERE the thick or thin spots are, which is vitally important. .079 between the bores? Meh, who cares? .079 on the minor thrust side? I'd be pretty nervous. .079 on the major thrust side? Its scrap.
The other question I would be asking myself, is my ebay sonic tester as accurate as the one the machine shop used. I realize they pinged it before they bored, and you pinged it afterwards, but that's still a question worth asking. Is it possible to get them to re-test the area in question against your tester?

[thatdarncat]

The Being '66 was the first year and 70 the last year of the 428 as far as vehicle installed most I looked at to replace my block with that split two cylinders are relatively thin at 4.130. I have sonic checks on four blocks I considered for purchase. The thickest wound up being a 105 D4 block. I have .140- .156 and this is at a 4.155 bore.  One of the lessons learned with the new block is how important it is to bore the block with a torque plate. Charles at Charles machine was showing me that the distortion is usually .005 or more.  Not one of the earlier FE specific book offerings mention this.  Very little about it until Barry's books.
I am going to fire the new engine this weekend.  Hopefully all goes well. It seemed strange to grind the tangs off of the Cleveland mains. I hope all is well there too. Perhaps the cam is the largest concern. Always nerve racking breaking in flat tappet cams.

                                                                                                           -Keith

Keith, I wish I was as fortunate as you when I went searching for a thick 390 block. The thickest I found was also a D4TE block. The machine shop sonic'd it and said it would be thicker than .100 everywhere after a 4.130 bore. Got it done and in the meantime got an Ebay sonic checker. Naturally, when I sonic'd it myself after the boring, I found a place .079 was the thinnest, and 3 other spots below .090. Filled it to the water pump holes and am going to run it. Wouldn't have started this project if I didn't already have the pistons and crank.
No more .080 over 390 blocks for me. I do believe the "thickies" are out there...but really hard to find.
Good luck on the cam break-in.

Very little mention on here of WHERE the thick or thin spots are, which is vitally important. .079 between the bores? Meh, who cares? .079 on the minor thrust side? I'd be pretty nervous. .079 on the major thrust side? Its scrap.
The other question I would be asking myself, is my ebay sonic tester as accurate as the one the machine shop used. I realize they pinged it before they bored, and you pinged it afterwards, but that's still a question worth asking. Is it possible to get them to re-test the area in question against your tester?

I’ve seen a 427 split a cylinder wall between cylinders at around .100. Personally I wouldn’t dismiss that location.

Recently I spot tested a 390 with my eBay sonic tester that I had previously tested by a professional machine shop - all the readings I got were within .000 to .003 of what the shop noted on the sheet, I was pleasantly surprised by that, considering I may not have had my transducer on the exact same spot. It’s common practice of course to check your sonic tester on a spot on the block you can actually measure with a micrometer or caliper, so it’s easy to see if your eBay sonic tester is accurate. One nice thing about having your own tester is the ability to test as many places as you want, one FE block I was playing around with this spring I noticed a small area significantly thinner than the surrounding areas, and outside of the normal 0, 90, 180, 270 degree areas you check. Would it be an issue, maybe not, but good to have the info.

[jayb]

Late to this thread, but I have a few things to add.  When I started hot rodding in 1976, Ak Miller was quite the revered name in Ford circles, and I grabbed every bit of information I could get that he wrote, including some articles on running 105 octane propane and turbocharging FEs, which I found quite interesting.

One of the articles Ak wrote back in the day showed how to "wake up" a 390 using an Offenhauser 360 degree manifold with a Carter Thermoquad carb.  Sometime in the mid 1980s I grabbed one of those manifolds at a swap meet, and stuck it aside for a future build.

Fast forward to 2005, when I started doing the intake manifold testing that resulted in my book.  I had high hopes for that Offy 360 manifold; it looked different than everything else, and Ak said it really worked.  However, to call the manifold's performance sub-par would be being kind.  It was one of the worst manifolds I tested.  That intake wasn't going to wake up any 390, more like put it to sleep!

All my respect for Ak Miller pretty much went out the window at that point, because no matter what dyno mule I put that intake on, or what carb I used, it did not perform well, certainly not as well as the Ford performance intakes that were available at the time.  A 428CJ intake or a PI intake would best that manifold by 30-40 horsepower on most engines.  Maybe Ak had an arrangement with Offy or something, and wrote the article for publicity.  I referenced the article in the Offy 360 manifold section of my book, although I didn't mention Ak's name, referring to him only as a "well respected Ford engine expert".

In any case, that experience makes Ak Miller's advice pretty suspect in my opinion.  Also, regarding weight of a 390, my 390 stroker with aluminum water pump, aluminum heads and intake, steel tube headers, and an aluminum flywheel weighed just under 500 pounds.  No starter, no alternator, but everything else required to run the engine on the dyno was included.  There was even oil in the oil pan.  Probably add about 50 pounds to go back to cast iron heads.

I happen to have a 391 truck block here with the "428" cast in the water jackets, and it sonics so well that I wouldn't be afraid to take it to 4.16 if it needed it.  I've never seen another 390 block close to as thick as that one.  The advice to the original poster to overbore as little as possible is spot-on, in my opinion.

[blykins]

The Being '66 was the first year and 70 the last year of the 428 as far as vehicle installed most I looked at to replace my block with that split two cylinders are relatively thin at 4.130. I have sonic checks on four blocks I considered for purchase. The thickest wound up being a 105 D4 block. I have .140- .156 and this is at a 4.155 bore.  One of the lessons learned with the new block is how important it is to bore the block with a torque plate. Charles at Charles machine was showing me that the distortion is usually .005 or more.  Not one of the earlier FE specific book offerings mention this.  Very little about it until Barry's books.
I am going to fire the new engine this weekend.  Hopefully all goes well. It seemed strange to grind the tangs off of the Cleveland mains. I hope all is well there too. Perhaps the cam is the largest concern. Always nerve racking breaking in flat tappet cams.

                                                                                                           -Keith

Keith, I wish I was as fortunate as you when I went searching for a thick 390 block. The thickest I found was also a D4TE block. The machine shop sonic'd it and said it would be thicker than .100 everywhere after a 4.130 bore. Got it done and in the meantime got an Ebay sonic checker. Naturally, when I sonic'd it myself after the boring, I found a place .079 was the thinnest, and 3 other spots below .090. Filled it to the water pump holes and am going to run it. Wouldn't have started this project if I didn't already have the pistons and crank.
No more .080 over 390 blocks for me. I do believe the "thickies" are out there...but really hard to find.
Good luck on the cam break-in.

Very little mention on here of WHERE the thick or thin spots are, which is vitally important. .079 between the bores? Meh, who cares? .079 on the minor thrust side? I'd be pretty nervous. .079 on the major thrust side? Its scrap.
The other question I would be asking myself, is my ebay sonic tester as accurate as the one the machine shop used. I realize they pinged it before they bored, and you pinged it afterwards, but that's still a question worth asking. Is it possible to get them to re-test the area in question against your tester?

I’ve seen a 427 split a cylinder wall between cylinders at around .100. Personally I wouldn’t dismiss that location.

Exactly.  It may not be a thrust surface, but a thin cylinder on any "side" is weak....also gets back to that ring seal point......a weak cylinder will flex.

Tommy T, your intuition to fill the block was spot on. 

[falcongeorge]

The Being '66 was the first year and 70 the last year of the 428 as far as vehicle installed most I looked at to replace my block with that split two cylinders are relatively thin at 4.130. I have sonic checks on four blocks I considered for purchase. The thickest wound up being a 105 D4 block. I have .140- .156 and this is at a 4.155 bore.  One of the lessons learned with the new block is how important it is to bore the block with a torque plate. Charles at Charles machine was showing me that the distortion is usually .005 or more.  Not one of the earlier FE specific book offerings mention this.  Very little about it until Barry's books.
I am going to fire the new engine this weekend.  Hopefully all goes well. It seemed strange to grind the tangs off of the Cleveland mains. I hope all is well there too. Perhaps the cam is the largest concern. Always nerve racking breaking in flat tappet cams.

                                                                                                           -Keith

Keith, I wish I was as fortunate as you when I went searching for a thick 390 block. The thickest I found was also a D4TE block. The machine shop sonic'd it and said it would be thicker than .100 everywhere after a 4.130 bore. Got it done and in the meantime got an Ebay sonic checker. Naturally, when I sonic'd it myself after the boring, I found a place .079 was the thinnest, and 3 other spots below .090. Filled it to the water pump holes and am going to run it. Wouldn't have started this project if I didn't already have the pistons and crank.
No more .080 over 390 blocks for me. I do believe the "thickies" are out there...but really hard to find.
Good luck on the cam break-in.

Very little mention on here of WHERE the thick or thin spots are, which is vitally important. .079 between the bores? Meh, who cares? .079 on the minor thrust side? I'd be pretty nervous. .079 on the major thrust side? Its scrap.
The other question I would be asking myself, is my ebay sonic tester as accurate as the one the machine shop used. I realize they pinged it before they bored, and you pinged it afterwards, but that's still a question worth asking. Is it possible to get them to re-test the area in question against your tester?

I’ve seen a 427 split a cylinder wall between cylinders at around .100. Personally I wouldn’t dismiss that location.

Recently I spot tested a 390 with my eBay sonic tester that I had previously tested by a professional machine shop - all the readings I got were within .000 to .003 of what the shop noted on the sheet, I was pleasantly surprised by that, considering I may not have had my transducer on the exact same spot. It’s common practice of course to check your sonic tester on a spot on the block you can actually measure with a micrometer or caliper, so it’s easy to see if your eBay sonic tester is accurate. One nice thing about having your own tester is the ability to test as many places as you want, one FE block I was playing around with this spring I noticed a small area significantly thinner than the surrounding areas, and outside of the normal 0, 90, 180, 270 degree areas you check. Would it be an issue, maybe not, but good to have the info.

good info on the ebay sonic testers. I have thought about buying one a few times, but at my age, I will probably just be building the stuff I have and not acquiring much in the way of new blocks, I am not sure how much use I would get out of it.

[falcongeorge]

The Being '66 was the first year and 70 the last year of the 428 as far as vehicle installed most I looked at to replace my block with that split two cylinders are relatively thin at 4.130. I have sonic checks on four blocks I considered for purchase. The thickest wound up being a 105 D4 block. I have .140- .156 and this is at a 4.155 bore.  One of the lessons learned with the new block is how important it is to bore the block with a torque plate. Charles at Charles machine was showing me that the distortion is usually .005 or more.  Not one of the earlier FE specific book offerings mention this.  Very little about it until Barry's books.
I am going to fire the new engine this weekend.  Hopefully all goes well. It seemed strange to grind the tangs off of the Cleveland mains. I hope all is well there too. Perhaps the cam is the largest concern. Always nerve racking breaking in flat tappet cams.

                                                                                                           -Keith

Keith, I wish I was as fortunate as you when I went searching for a thick 390 block. The thickest I found was also a D4TE block. The machine shop sonic'd it and said it would be thicker than .100 everywhere after a 4.130 bore. Got it done and in the meantime got an Ebay sonic checker. Naturally, when I sonic'd it myself after the boring, I found a place .079 was the thinnest, and 3 other spots below .090. Filled it to the water pump holes and am going to run it. Wouldn't have started this project if I didn't already have the pistons and crank.
No more .080 over 390 blocks for me. I do believe the "thickies" are out there...but really hard to find.
Good luck on the cam break-in.

Very little mention on here of WHERE the thick or thin spots are, which is vitally important. .079 between the bores? Meh, who cares? .079 on the minor thrust side? I'd be pretty nervous. .079 on the major thrust side? Its scrap.
The other question I would be asking myself, is my ebay sonic tester as accurate as the one the machine shop used. I realize they pinged it before they bored, and you pinged it afterwards, but that's still a question worth asking. Is it possible to get them to re-test the area in question against your tester?

I’ve seen a 427 split a cylinder wall between cylinders at around .100. Personally I wouldn’t dismiss that location.

Exactly.  It may not be a thrust surface, but a thin cylinder on any "side" is weak....also gets back to that ring seal point......a weak cylinder will flex.

Tommy T, your intuition to fill the block was spot on.

Totally agree on the fill. I didn't want to discourage the poster, but to be honest, I would be hesitant to build a motor that had a .079 spot in a cylinder wall ANYWHERE, filled or not. I know some guys do it, and skate by, but that's pretty bloody thin. You might skate by depending on where, down low between cylinders would be best scenario, but that's awfully thin, regardless. Too bad its already filled, if it were only one cylinder that thin, I would sleeve the hole.

[plovett]

The OP was only about when the FE changed to a thin wall casting and at this point, no one seems to know or where to point me, to find out. But, I did ask how much you can bore a late engine and find out that if you bore a later FE to .040, it will not last.

The answer is the FE never changed to a thin wall casting.  It always was a thin wall casting.  Sure, they are not all exactly the same thickness, but they are all "thin". 

The other answer is bore as little as possible and yes a 0.040" overbore is doable on almost all FE's.

[falcongeorge]

 but they are all "thin". 

[/quote]
Ignorance is bliss, who am I to ruin anyones happiness?

[67428GT500]

He is correct as the FE is considered new technology and a "light weight casting". Certainly you aren't indicating Mr. Lovett is incorrect. They are light weight thin wall castings, as are the 221-302 castings.

[falcongeorge]

Certainly you aren't indicating Mr. Lovett is incorrect.

Yup.

[frnkeore]

I'm a old dog but, can be taught new tricks

I will concede that they are fairly thin wall with the early block measurement of that EDC block (I'll call it .281) by thatdarncat. But, on a well centered core, it would still give you a .112 wall and doable for a 4.125 bore, at least in my day. Sonic testing would have only been a dream, in my early years. Maybe my Unicorn is the '58 Edsel 361 engine, the first 4.05 bore FE.

To that end, yesterday, I did a search of 1958 Ford advertising to see if I could find a reference of the "New Ford Thin Wall technology" I did not find anything that said that. If anyone has any real literature on the '58 FE's new thin wall castings, I would appreciate it being posted. It has to be out there, Ford was never silent about new developments.

I do appreciate everyone input and I am surprised at the length of this thread. I'm a retired  machinist and do like and appereciate the measurements that your giving.



'58 was a big year for Ford, they also came out with the MEL and a new line of truck engines

[blykins]

For crying out loud. 

A lot of Ford engines around this time were thin in the cylinders.   Clevelands were thin at standard bore.  I don't know how many blocks I've sonic tested to see .090-.100" cylinder wall thicknesses with no machine work.  I've seen some that were down around .040-.050".   They got sleeved or filled. 

A lot of 351 Windsor blocks are done at .060", if they go that far.

Just because there are a few 390 blocks out there that will take a large overbore doesn't really mean that it's wise to do it.  In fact, you're not accomplishing anything at all if you do it that way, besides perpetuating 60's thinking of "if it's bigger, it's better".   

Who in the world cares if it was advertised that they were thin or not?  Grab a block, sonic test it, and found out whether or not *that* block is thin because every block is a craps shoot. 

I'll be the first one to say that thick blocks do exist, because I had a '63 390 block that went that far without issue.  However, I wasted 2 to get to that point, and in hind sight, I accomplished ABSOLUTELY NOTHING by taking the one block out to a 4.130" bore.  Going from a 4.08-4.09 bore to a 4.130 bore doesn't open up magical gateways to head flow!  It does nothing but endanger the block's strength by making the cylinders weaker and it opens the block up to really weak spots due to pitting on the back sides of the cylinders that you can't see. 

If you do have a block that could go 4.130" and have plenty of meat left over, think about how rigid the block would be if you didn't do more than a clean-up cut. 

[My427stang]

I am with Brent, some 2 bolt motor mount blocks you can get lucky, but a thick 390 or 428 is a unicorn. I would rather stroke or live with a smaller bore, not worth chasing around for, put more time in other parts