390 short block ????

[George vega]

Jay if you are referring to the triangular hole to the right of the bolt hole, yes the floor is way beyond the bottom of the threads of the head bolts.
Nevermind I get it. I guess my block failed that test also. I'm convinced it's just a regular block. It doesn't even have the ribs.

[mike7570]

I was talking about the shape of the water jacket holes in the deck.  The 428 water jacket cores leave a hole in the deck that extends down below the head bolt hole, while a 390 water jacket core hole doesn't, see the pics below.

390:




428:

This is a pic of the deck Jay. It has flashing that hasn't been removed yet in some of the cooling holes.

We had this conversation before about my block. I have the same (I think) 390 block. Mine is crossbolted and it's already bored to 4.13.
I have it in being sonic checked right now and should have it back on Friday.

[George vega]

It's getting harder to find virgin fe blocks of any kind. I'm going to keep my eyes and ears out there from now on. I won't turn down any 390 blocks. I've only interest in 428 and 427 but not any more.

[jayb]

Jay if you are referring to the triangular hole to the right of the bolt hole, yes the floor is way beyond the bottom of the threads of the head bolts.

I was talking about the water jacket holes at the top of the deck, next to the head bolt holes.  What you have there is a normal 390 water jacket block.

[George vega]

It's getting harder to find virgin fe blocks of any kind. I'm going to keep my eyes and ears out there from now on. I won't turn down any 390 blocks. I've only interest in 428 and 427 but not any more.

Let us know the results.

[fekbmax]

I'll probably get blasted for this (again) but i always liked using the 105 mirror blocks. Especially the D3TE and a few D4TE . Most all have the webbing around the mains, most have decently thick cylinders  BUT they should always be checked. I have had a couple D4TE blocks that checked out initially with thick cylinders but were so sloppy with core shift that by the time you straightened out the bores at 4.130 there would be some pretty thin spots.  I always use block fill though being there race only engine's.  As has been mentioned though, now with all the stroker cranks and custom piston's, theres really no need to force the issue and stretch out the bore so much. You can get a decently sized valve combo with modern aluminum heads in a 4.080 bore.

[George vega]

Agree. The block that I'm replacing is a c4te with the nubs and ribs. It's a race only block. I'm  looking to maybe converting my mustang back to a street and strip car.  If I start with a small bore it will leave material for growth.

[scott foxwell]

IMO adding a bunch of stroke just to increase displacement is not always the way to go. Adding stroke increases piston speed. Increasing piston speed increases induction demand, and induction is not the FE's strong point.

[blykins]

There are no absolutes....and there are a ton of STRONG 445's out there running with a 4.250" stroke. 

But trying to bore a block just to get a magic number is most certainly not the wisest thing to do. 

I had a BBM head that we did some R&D on....raised the floor, did a little SSR work, and with a 2.100" valve it got us 340 cfm with around 170cc port volume.  A 2.100" valve will work with pretty much any bore size.  On a 4.030" 352 bore, I could get to .800" lift before any valve/cylinder interference occurred.

[scott foxwell]

There are no absolutes....and there are a ton of STRONG 445's out there running with a 4.250" stroke. 

But trying to bore a block just to get a magic number is most certainly not the wisest thing to do. 

I had a BBM head that we did some R&D on....raised the floor, did a little SSR work, and with a 2.100" valve it got us 340 cfm with around 170cc port volume.  A 2.100" valve will work with pretty much any bore size.  On a 4.030" 352 bore, I could get to .800" lift before any valve/cylinder interference occurred.

This conversation could go in SO many directions...
I'm used to the BB Chev world where we work with much bigger displacements, bores, and heads but still, while
others are building 600 ci pump gas engines (4.60 x 4.5) and happy to get 700hp, we have focused on a 4" stroke combination (4.60 bore, 532ci) that makes 840hp and 720 lbs ft. at 6500/5000 respectively, hyd roller on 93 oct. "Philosophically" adding stroke, especially going over square, brings other things to the table that aren't very conducive to making power especially when rod ratio starts getting short. Making power is all about piston speed. Sure, you're going to make more power by increasing displacement, that's a given, but not at the rate you could be if the rest of the combination was there to match. A short stroke large bore 440ci engine is a lot less demanding than a long stroke, small bore engine of the same displacement and easier to make more hp/ci and without turning a bunch of rpm. RPM is an easy way to make HP but it also brings it's challenges.
I'm going to do an experiment this winter. I'm going to build a 422 ci combination that I started to describe above; 4.11 bore (.060 over 390) 3.98 stroke, but with a 6.8 rod and about 10.5:1 CR with a Straub hyd roller. I'm either going to use a set of Edelbrocks or FElony heads. My induction systems are all designed around cross sectional areas. Port volumes, especially with an FE head (because the port is so short) really don't tell me much. The "port" starts at the valve job and ends in the plenum. Where the head and intake come together is pretty arbitrary and insignificant. I'll have to do some cross sectional measurements on the FE heads and intakes to see what I'm working with. I work around a designed minimum cross section/restriction in the port ahead of the short turn and the location of that minimum restriction is relatively critical. I know all this stuff about a BB Chev like the back of my hand, but never dove onto the FE like this. I've made 1.57, almost 1.58 hp/ci with the 4" stroke combination BB Chev. No vac pump, no crank trigger, no trick oil pan, hyd roller, pump gas, but a lot of focus on induction and valve train. I'm going to see if I can apply everything to the FE that I've learned in the last few years developing this combination. If it works, I should be looking at somewhere around 665hp and hopefully high 500 tq, like 570 or so. A lot will depend on what intake I end up with. Not many good selections in that regard.
LOL...I'm rambling on...I know...

[blykins]

I don't necessarily disagree with what you have said, but I don't think it's a general rule and doesn't always apply.  Lots of very excellent small bore/large stroke combos out there. 

Good luck to you on the horsepower goal.  Barry had a similar combination for his 433 ci EMC entry.  You'll either need to approach it from that direction, or go catch a ride on Jim Morgan's dyno. 

[scott foxwell]

I don't necessarily disagree with what you have said, but I don't think it's a general rule and doesn't always apply.  Lots of very excellent small bore/large stroke combos out there. 

Good luck to you on the horsepower goal.  Barry had a similar combination for his 433 ci EMC entry.  You'll either need to approach it from that direction, or go catch a ride on Jim Morgan's dyno.

Sure there are some very good running small bore/large stroke combinations. They have the induction to support the demand. It's not an opinion, it's just physics.
I guess I don't get the dyno comment... 

[blykins]

I don't necessarily disagree with what you have said, but I don't think it's a general rule and doesn't always apply.  Lots of very excellent small bore/large stroke combos out there. 

Good luck to you on the horsepower goal.  Barry had a similar combination for his 433 ci EMC entry.  You'll either need to approach it from that direction, or go catch a ride on Jim Morgan's dyno.

Sure there are some very good running small bore/large stroke combinations. They have the induction to support the demand. It's not an opinion, it's just physics.
I guess I don't get the dyno comment... 

 

[Barry_R]

I have kinda kept quiet lately and stuck to getting projects finished - was pretty backed up.  But a couple thoughts need to be mentioned.

First is cylinder wall thickness needs to be sonic checked on any FE going beyond perhaps .030 or .040 over from the factory dimensions.  Its not an option - its a true necessity.  I have seen one 390 that would not safely go 4.100 - was already at .080 wall at 4.090.  And I have seen only a couple that were safe at 4.130 - one of those had all the 428 markings including "C" scratch even though it started at 4.050 bore.  The drill bit test is a useful quick tool for picking through cores, but is an exclusion tool only and not in any way definitive for block decisions.  Same is true for the deck ID.

Scott - compared to BBC stuff you are in a completely different universe when dealing with factory FE castings.  Your discard thickness on a Chevy block would be considered as a "really good thick one" in our universe.  The flexibility of the cylinder cores means that a thin cross section high conformability ring package is even more valuable in our FE engines than is normally the case.  In the FE environment another .020 or .030 in bore diameter is not anywhere near as important as wall thickness and ring seal when measured on a risk vs reward scale.  Aftermarket 427 blocks change the entire discussion.

I am generally in favor of bigger bore and shorter stroke for a given displacement, but when other factors are limiters, such as wall thickness, you go with the best available option.  I have built similar engines dues to rules that were radically different.  One was 429 cid with a 4.250 bore and a 3.780 stroke, another was at 4.33 with a 4.350 bore and a 3.640 stroke.  The big bore was (is - its still in my car) a better piece, but the variances were far smaller than I expected considering the investment and effort.  My larger displacement stuff is stronger anyways.

I agree with the head cross section and induction from valve to plenum concepts.  Remember that an FE head has the pushrod pinch in the intake, which changes things a bit.  It would be interesting if somebody developed a head package with a chunk of manifold mounted to the head (ooops - Cary and John did that with me in like '05). 

I am not as strongly "sold" on the piston speed as a big determinant of power deal.  I tend to look at cylinder volume delta instead - at a given displacement you are going to see one side of the bore options pull harder on that port initially and then they are going to equalize.  An initial hard pull might not be a bad thing on a flow limited port - use what you can steal early while overall flow is at a lower and less limited point.  Those long strokers on an FE outperform what should be the case and I think this is one of the reasons why.  If I sound a bit like Marcella its because I listen to him when he talks.  Sharp cat and just a bit scary smart....and he live 20 minutes away.

I tend to look at things from a torque per cubic inch viewpoint as a result of all the EMC efforts.  Horsepower is really an RPM equation - want more - spin any given combo higher and you will get more with cam/valvetrain until you run out of physics or money.  That is the path of every single successful professional race effort on earth.  Build as much displacement as the rules allow using bore first until you reach mechanical limitations, and then stroke, and then turn as many RPM as rules, parts, and wallet permit.

Torque ain't so easy to move.  Most of my street stuff seems to dwell between 1.15 and 1.25 to 1 on lbs per cube.  Your BBC example is at the 1.3+ range which would be a really strong street/race engine.  My best EMC FE stuff gets into the 1.42-1.44 TQ/cube range and takes a ton of cool parts, machining and tuning effort to get there.  When I see things posted with otherwise "normal" parts that are claiming 1.5-1.6:1 torque per cube I tend to question the data since that is EMC winning output from engines developed by really sharp folks using far better base architecture to start with.

[scott foxwell]

Couldn't agree with you more Barry, especially about cyl wall thickness. I realize the difference between the BB Chev's I'm used to and the FE. My comparison was mostly philosophical regarding stroke, piston speed, induction, etc. Marcella is a sharp guy...I agree but we're probably not on the same page regarding a hard initial pull on a small port...if I understand you correctly. Also, when I refer to stroke being detrimental, that usually includes a shorter rod ratio. If you can keep the rod ratio decent then the added stroke is far less detrimental but you're right, at the end of the day (or beginning) the rings have to seal. This is the sort of thing I'm learning about the FE and it's limitations. I'll definitely be sonic checking my block before I do anything. Thanks for your input.
Curious, since you mentioned it, do you know where the minimum cross section is in the FE induction? Is it at the pushrod pinch or @ the opening, or is it in the port? Do you have an area number for your heads?
As far as tq/ci my best is 1.68 (611 BBF, 1030 tq)...I've had a few in the 1.42 - 1.44 range. The pump gas stuff usually runs in the 1.3 - 1.35 range but I have an unfair advantage with Straub doing the cams.
Thanks again.