Boring 390's

[falcongeorge]

You’re getting good info from everyone, I’m sorry it wasn’t what you wanted to hear.

And that's the crux of the matter, right there. I was thinking about digging out the original article in Hot Rod magazine in late '57, when they wrote about the introduction of the FE series, and bragged about how it was a new-fangled thin-wall casting, but I didn't think there was any point, as "it wasn’t what he wanted to hear".

[plovett]

Since you asked. What I'm looking for is free HP and a less expensive build.

4.125 adds 10 cubic inches, over 4.080 and I have a set of 4.125 forged pistons.

Whether or not, in your opinion Ak Miller and others, are wrong, is irrelevant to me, I only know that it was done by many and a usable platform.

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.

I thought that there might be some technical info from Fords engineering dept available on this forum.

Thank you all, for your input.

10 cubes is only about 12-13 hp.  Not really worth the effort.

Whats 13 cfm@.500 lift worth? Now, add that to the 12-13 hp from the extra 10 ci, and all of a sudden, its 20-25 hp. Because that's the difference in intake port flow I saw on my bench just by switching from a 4.03  bore fixture to a 4.155 bore fixture on a brand X head.

13 cfm is worth a lot.  10 cid, not so much.  Bore size and cfm are not the same as displacement.

JMO,

paulie

[plovett]

Answer to the original question is, bore as little as possible.  It is that simple.

paulie

[falcongeorge]

Since you asked. What I'm looking for is free HP and a less expensive build.

4.125 adds 10 cubic inches, over 4.080 and I have a set of 4.125 forged pistons.

Whether or not, in your opinion Ak Miller and others, are wrong, is irrelevant to me, I only know that it was done by many and a usable platform.

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.

I thought that there might be some technical info from Fords engineering dept available on this forum.

Thank you all, for your input.

10 cubes is only about 12-13 hp.  Not really worth the effort.

Whats 13 cfm@.500 lift worth? Now, add that to the 12-13 hp from the extra 10 ci, and all of a sudden, its 20-25 hp. Because that's the difference in intake port flow I saw on my bench just by switching from a 4.03  bore fixture to a 4.155 bore fixture on a brand X head.

13 cfm is worth a lot.  10 cid, not so much.  Bore size and cfm are not the same as displacement.

JMO,

paulie

go back and read what I posted and you just quoted.13 cfm isn't "JMO" or a wild-assed guess, that's what the flow bench test SHOWED when I tested the same head on a .125 larger bore fixture, no other changes. Im posting tested results, not supposition or guesswork. Getting the cylinder wall moved back from the flow cone around the valve probably does MORE than the 10 cid, and THATS the point of the whole exercise. I'm done here.

[cammerfe]

there are a few 390 blocks around that will go +.080 and still be thick enough, but they are not common, and to go out and hunt one down is probably an exercise in masochism, if not futility. If you are really determined, you can pre-sort them with the allen wrench test, but you will still need to sonic test any potential candidates, and if they are pitted on the water jacket side, you can still be in trouble. Brent alluded to the primary reason to do this, unshrouding a 2.19 intake valve. Its always about the cylinder heads.

You can take a look here as well, starting at reply #2. I wouldn't even consider trying to take any OEM FE block to +.125.

http://fepower.net/simplemachinesforum/index.php?topic=7778.0

I was part of the 'action' on one of the first dozen '68 CJ Mustangs. We flew to Romy Hammes Ford in South Bend to pick it up and drove it back to Detroit. Part of the build-up was to create an engine using the heads and crank, but we were told to find a good 390 block and use it as the basis for the new engine. There was, at the time enough difference in block weight to make it a good idea for the class---Super 'E' automatic. We must have gone through about a dozen to find one that made sense to use---and that was 1968. Back about '03, I pulled a '63 330-390 (PI) engine out of the corner of my garage and went through it. If I had gone to 4.13 on it, there were a couple cylinders that would have had .080 spots in them. We took it out to 4.080 and called it good.

KS

[blykins]

Since you asked. What I'm looking for is free HP and a less expensive build.

4.125 adds 10 cubic inches, over 4.080 and I have a set of 4.125 forged pistons.

Whether or not, in your opinion Ak Miller and others, are wrong, is irrelevant to me, I only know that it was done by many and a usable platform.

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.

I thought that there might be some technical info from Fords engineering dept available on this forum.

Thank you all, for your input.

10 cubes is only about 12-13 hp.  Not really worth the effort.

Whats 13 cfm@.500 lift worth? Now, add that to the 12-13 hp from the extra 10 ci, and all of a sudden, its 20-25 hp. Because that's the difference in intake port flow I saw on my bench just by switching from a 4.03  bore fixture to a 4.155 bore fixture on a brand X head. That little test happened because several of us noticed that the flow numbers on some of the RHS heads a few years back looked a little "happy", and that the published flow numbers were obtained on a 4.155 bore fixture. Everything affects something else.
But the fact is, anybody that thinks that what he reads in the magazines is God-given gospel, and is going to ignore 2 sonic maps, and everything else that's been posted here, is in over his head boring a 390 block to 4.13. Sorry, that's just the way it is. Man, if I had a dollar for every piece of pure, unadulterated horsecrap I have read in the magazines over the years, I wouldn't NEED to worry about boring a 390 block to 4.13, I'd be able to buy a BBM block on the proceeds...

How much power do you lose because the bores are now weaker and you’ve lost some ring seal???  How much flow do you gain on a bore size that's relative to the discussion that we're having here?  Going from a 4.030" bore to a 4.155" is a huge difference and is a lot greater than the difference between a 4.080/4.09/4.100" and a 4.130". 

I’ve ruined at least two 390 blocks that sonic’d well, trying to go to 4.130”.  I’ve also made over 540 hp with a 4.080” bore 390 and some Trick Flow heads with 2.190” valves, on pump gas, with a hydraulic roller, not going over 6000 rpm. 

Tell ya what, you all can go on thinking you’re big power makers with your extra bore size, but just don’t ruin all the 390 block cores.  Save some for the rest of us.....

Little bit of jest there, little bit of seriousness.  All in fun. 

[64PI]

I have one of those "unicorn" 390's from a dump truck with a C scratch on the back. I got it at .030" over, put 2 .090" wall sleeves in it and never hit water. I run the block .060" over and still half filled it for piece of mind.

I had a '64 390 that I bored .020" over (no fill) and it split from the center cam bore to the cylinder on a 500hp pull @ 6000rpm on the dyno.

I'm with Brent on this one.  Take minimal amount of material and leave em thick as possible. If you want cubes stroke it. Or buy an aftermarket block. The money your going to pay your machine shop boring .125" over and then putting in sleeves when they hit water can be better spent elsewhere.

Fred

[falcongeorge]

  How much flow do you gain on a bore size that's relative to the discussion that we're having here?  Going from a 4.030" bore to a 4.155" is a huge difference and is a lot greater than the difference between a 4.080/4.09/4.100" and a 4.130". 

[/quote]
Well, as to the question of whether a test based on chevy bore sizes is going to tell the whole story on the FE, fair enough, I tested the two SBC bore sizes because we were trying to get a handle on how much the larger bore fixture inflated RHS published flow numbers, and I think the test gave us a handle on that.
But consider a couple other factors. 1) a 2.19 in a +.030 390 is closer to the cylinder wall than a 2.05 in a 4.03 chevy and 2) And I think this is the big one. The chevy has a 23 deg. valve angle, the FE is 13, so the valve is coming down much straighter towards the bore, so moving the bore away from the edge of the valve is probably going to help flow numbers even more on the FE. Maybe some further testing is in order, its not a big hassle to switch the bore adapters out on a flow bench, and maybe I will try the same test on an FE head some time. I would probably use a 4.03 because I already have one, and the 4.05 isn't much difference, and compare it to a 4.13. Of course, there will probably STILL be bitching, but if the bitchers don't learn anything, well that's the normal order of things.
As I said in post #24, I understand your position and why you wouldn't want to do it on a customers motor, it probably doesn't do down well when they spend the money for a sonic test, half fill, and boring, and after all that you find a porous spot in the cylinder wall, and its junk. That's fine, I get that.
But it IS do-able, I've DONE it. And as I hinted at in my first post, and made clearer in the last post above, its not about the 10 CI, That's not the big gainer, its about moving the cylinder wall away from the flow cone around the intake valve.

[plovett]

How much flow do you gain on a bore size that's relative to the discussion that we're having here?  Going from a 4.030" bore to a 4.155" is a huge difference and is a lot greater than the difference between a 4.080/4.09/4.100" and a 4.130". 

its not about the 10 CI, That's not the big gainer,its about moving the cylinder wall away from the flow cone around the intake valve.

Now you are starting to make sense.

JMO,

paulie

[falcongeorge]

How much flow do you gain on a bore size that's relative to the discussion that we're having here?  Going from a 4.030" bore to a 4.155" is a huge difference and is a lot greater than the difference between a 4.080/4.09/4.100" and a 4.130". 

its not about the 10 CI, That's not the big gainer,its about moving the cylinder wall away from the flow cone around the intake valve.

Now you are starting to make sense.

JMO,

paulie

I don't really consider the opinion of someone who responds to my posts without reading them to have any validity. Thanks.

[plovett]

I read them. I sometimes get angry, too.   No worries. 

paulie

[plovett]

The first 5 words in the first reply to the OP's post were all that were needed. LOL!

JMO,

paulie

[blykins]

Yes, your point is absolutely correct.  There is no incentive for me to spend a ton of time trying to find a block that will go that large.  Even if it did make a difference, it's a lot of wheel-spinning.  I'd most likely tell a customer to find a 428 block if they want that bore size that bad, or spend the extra money on the cylinder heads, where the power really is.  I'm perfectly content shoving a 2.190" valve up against the cylinder wall in a 390 to make as much hp as most guys were making with 482's, 10 years ago.   The intake valve clearance isn't as detrimental as what you think; but the exhaust valve will get close quick if it's too big.

Now, how about that ring seal loss?   

[falcongeorge]

there are a few 390 blocks around that will go +.080 and still be thick enough, but they are not common, and to go out and hunt one down is probably an exercise in masochism, if not futility. If you are really determined, you can pre-sort them with the allen wrench test, but you will still need to sonic test any potential candidates, and if they are pitted on the water jacket side, you can still be in trouble. Brent alluded to the primary reason to do this, unshrouding a 2.19 intake valve. Its always about the cylinder heads.

You can take a look here as well, starting at reply #2. I wouldn't even consider trying to take any OEM FE block to +.125.

http://fepower.net/simplemachinesforum/index.php?topic=7778.0

Ok Paulie, I'll put the hatchet down. But heres the thing you said "now you are talking sense".
Above is my VERY FIRST POST on this thread. Note the two bolded lines at the end of the first paragraph. Its been what I was saying since I started, three pages back, its all about getting the cylinder wall away from the valve .
Brent and I may not agree, but its clear from his responses that he carefully reads what I say, thinks about it, and then responds to what I have said. That tells me that even though we disagree, he is respecting the points I am making, and thinking about them.
I watched both this thread and the thread on correct wall clearance for TRW L2291's, and I watched and waited for a long time before I responded. In both cases, I was hesitant to respond, because frankly, I am just not interested in entering into pissing matches. This thread is largely about opinions, but in the case of the TRW thread, the info he was getting was just plain wrong, factually incorrect.
I have been on internet automotive forums since the 1990s, and for me, the first thing that goes through my mind when I see a thread like that is "hell, its no skin off my ass if the info this guys getting is crap, and hes going screw his stuff up if he follows it, but if I speak up, theres going to be a pissing match, so I am just going to keep my mouth shut, its not my problem, and I don't need the grief". And I can tell you for a stone cold fact, I know a HELL of a lot of other guys that feel the same way. I know several guys that are VERY EXPERIENCED engine builders, chassis builders, and fabricators who lurk these forums, see all KINDS of totally stupid stuff being repeated over and over again, and just sit back and watch and laugh about it. Hell, its one of our favorite topics when we are sitting in restaurants over coffee.
They take the attitude "Why the hell should I waste my valuable time typing something out when some keyboard commando is going to be blowing smoke up my @$$, just repeating some crap that he read in Car Craft or Yellow Bullet? Theres nothing in it for me, I don't gain anything, and I gotta put up with the grief". And honestly, I am starting to develop the same attitude, I see lots of stuff that just flat out wrong, and I ignore it, because I am not going to gain anything, and its going to trigger a flame war. Who needs it? And we all suffer because it, because it kills off any chance of a respectful exchange of knowledge and experience.
Im not saying you are doing this, its a more extreme example, but hell, its all over the place on the internet, and I can tell you, the MAJORITY of the guys that I respect and learn from will not post ANYTHING on ANY interent forum because of the lack of respectful discourse and discussion.
So the point of all this is, ANYBODY, EVERYBODY, ME INCLUDED, before you go off half-cocked on something you disagree with, 1) make sure you have REALLY read it, and understand it. If you don't, swallow your pride and ask for clarification, maybe you will learn something new and 2) when you respond, realize that there are LOTS of other eyes reading what you say, and based on the nature of your response, they may be thinking "ha, forget this bs, I'll keep my knowledge and experience to myself", and believe me, LOTS of VERY experienced race car builders are reading this stuff and thinking exactly that.

[Drew Pojedinec]

So uhhhh I got some super duper thick wall 390’s for sale