Frank, I don't claim any special information. Having said that, I have never read anywhere that early FEs were not thin wall. I have read that Ford's reason for the FE architecture was the thin wall casting to create a lighter block. My mention of 4.63 spacing is that it tends to limit production bore sizes, and later over bores, particularly when combined with the casting techniques and metallurgy of the period. The Lincoln Y-block 368 was a 4 inch bore, I imagine limited to some degree by the spacing.

BTW, the comment in the article about 428 bore sizes on 390 blocks does NOT describe what tests he did to do it, you can almost guarantee a lot of blocks didn't pass the test, and that some that did still failed.

Sadly, there isn't a treasure trove of special FEs out there we can use.

What you do not realize, is that Fords "Thin Wall" technology  did not occur until the release of the 1960 Falcon 144/170 engine. It was advertised a lot when it was released. It was again advertised when the 221/260 came out in '62, never before that. I would be interested in your citation of the FE being designed as a thin wall engine.

The FE engine was not, what you would call a light weight engine. The industrial engines, weighed in at 711-720 lb (I have the specs for those) based on that and my recollection, the car engine was in the 670-680 lb class, with cast iron intake and water pump. Has anyone weighed their engines with aluminum intake and water pump?

The 317-368 Linc/Merc engine was another one commonly bored 1/8". All engines, designed before '60, where commonly bore 1/8", including the SBC 283's. Although, I don't remember 327 and 350's being bored 1/8" but .060, for sure.  For those that say a Ford can not be bored even  a 1/8th, I have to refer you to the flathead engine, that was commonly bored 3/16 (I had one) and could be bored 1/4" on some blocks.

With the "thin wall" engines, Ford was able to decrease the distance between bores to .38 and still use .040 over, SBC to .40 with .060 over and Siamesed cylinders to .255-.275  and still allow a overbore. Take that technology to the FE and you get 4.25 - 4.375. Only the limited production, 427 had anything like that. Another reason I don't believe the early engines were "thin Wall".

Regarding block testing, I don't think anyone did that, prior to '80 and as a mechanic, between '62 and '70, I never heard of a cracked FE (hell, they weren't even called FE's before at least '75). The only racked blocks I ever saw was a std bore 350 SBC, cracked in the bore and a 312 cracked in the main bearing web. You also have to remember that the FE stands for Ford Edsel and that Edsel engine started life, in '58 at a 4.05 bore with .060 over pistons available.

Just a guess on my part but, the 352 casting numbers might mean that they used the original 352 sand cores on those blocks.

I'm not trying to say, the criteria that you are using is wrong not at all! What I started out looking for was the approx date that the FE was changed to a "thin wall" type engine and I would be interested in knowing the weight difference from that, if so.

I do not have a citation to back up, that they where changed, it's just something I read, at some time. From the response, that I'm getting, it sound like the if there was a change it may have occurred early (like '65/'68) and then a change that involved truck and 428 type blocks?

I'm a old mechanic, hot rodder/street racer and later a formula car, road racer.

Back in the 60's, it was common practice, to bore all engines 1/8", with the exception of the SBF. I know that Ford started using it's thin wall casting technique on the FE at some point. What was the year that that started? 

I've started looking for a 390 block for my base and would like to find one of the earlier ones as, I would like to do a 4.125 or 4.13 bore but, I'm not going to use Ford rods so, 428 pistons won't be a option.

If I can't find a early block, how large can you bore the thin wall 390?

 

Back in the late '60's, I had 3, 271 HP, 289's (all 5 bolts). I only tore one of them down, but all 8 forged (TRW I believe) pistons had cracks in the oil return slots. I did flog it a lot, in those days. I've never bought any kind of pistons, that used slots, after that. Overall the slots create a very weak area in the piston. That said if, if these L-2291F, are sloted.

If they are sloted and your going to run them, I would install them at .002 and no more than .003. I think any additional clearance will cause them to crack early.

Frank