What is the thinking these days for boring a 351c to +40 or even more. It used to be a big no no over here with the machine shops to not go more than +30 as the 351c has such a thin bore casting. People have reported increase temps and hot spots having gone over +30.

A friend of mine has a 4 bolt main 351c already at +30 but now has a bit of a lip. One machine shop are telling him they will bore it +40 as they have taken 351c to +60 without problems.

I have told him I'm not sure. What do you guys think especially George with his expert 351C knowledge

Cheers
Original Post
When I rebuilt my Cleveland I had to bore it 30 over. The machine shop I used was really aware of the cleveland having thin bores. He sonic tested each cylinder to find the thin spots. In my case he told me I can bore it to 40 over but that's it. If I ever need to rebuild my engine again and 40 over is not enough I will be looking for a stout aftermarket block.

I recommend you sonic test the bores to be sure.
You can put a lot of expensive parts in an engine, I'd be hesitant to go more than +.030". As aftermarket blocks are once again available I would seriously consider that route and build for longevity.

I know someone here locally who has a WOOD Bros. (high nickel Cleveland block) short block assembly for sale.

Julian
0.030" oversize is Ford's recommended limit.

Sonic testing to insure a minimum cylinder wall thickness of 0.120" on the "thrust" sides is another method. As you have been advised by others this sometimes allows a bit more overbore.

When taking the cylinder walls to the limit, I highly recommend using replacement pistons having full round skirts, i.e. endurance racing skirts. Such as those sold by Ross Pistons. This spreads piston skirt loads over a wider area of the cylinder wall, and is very effective at preventing cylinder wall cracking. This was standard practice for all forms of racing back in the engine's hey day.

The other thing a machinist can do to lessen the thrust forces on a cylinder wall is to "index" the boring machine to the crankshaft axis during the boring process. This insures the bores are perpendicular to the crankshaft's axis, rather than being canted to the side, or fore to aft.
My original numbers engine is 30 over and I intend to build another engine and leave my numbers engine in good running condition.
An after market block and rotating assembly is the way to go in my view. It cost a bit more but 500HP is easy and you have a nice relaxed engine. Besides, I worry about my gearbox getting soft above 500 ft lbs.

Personally, I would stop at first bore on a numbers block. If something bad happens on an overbore you will be buying a new block anyway and your original is now gone. Just skip that part Smiler and go get the other block now and slide your original under the bench.
I tend to agree with PLT and will be taking the same approach with mine should I find I want some more ponies in the car.

If you still have matching numbers cars I think in the fullness of time they'll hold or see better values for the purists out there looking to add to their collections. I could well be wrong too and I'm good with that. Time will tell.

Based on the same era Holdens and Fords here in Australia especially now local manufacturing is dead matching numbers cars are becoming more attractive to buyers when they're out there much the same as matching number classic European marques like Ferrari, Porsche etc..

Either way, it's not really all about the money while we have them, it should be about enjoying them as much as you can. But, there is significant investment potential in these cars just now being realistic and practical looking long term.
All good, but a matching numbers block in a Pantera is not akin to other marques.

The engine number on a Pantera was assigned by De Tomaso and is just hand stamped on the rear of the block with varying degrees of quality. Unfortunately there is no correlation or record to actual Ford engine number that I know of.

Julian
Agreed - its not like a Ferrari or Porsche with their own brand engines in their car, but I would think any with the hand stamped Detomaso Number on the block particularly would be considered "matching numbers" even though the engines are dime a dozen 351 Ford units. I'll have to do some homework on where to find the Detomaso stamping - mine may not be original...
As was said, do not even think about boring a 351-Cleveland (or a 351-Windsor, either!) without sonic testing for wall thickness! The finished thrust surface should be a minimum of 0.100 thick especially if you pump up the power. More power needs more wall thickness. In a similar engine (the big-block Chevy), builders get nervous when their wall thicknesses get to 0.200"; no Cleveland ever had such thick walls except maybe the rare race blocks. Good luck.
If you are considering rebuilding.....certainly have the sonic testing done to tell you where you are! (....or have left!)

What many do not realize is that you don't need to immediately go to +.030 overbore!

Ford 428 and even 427 owners for years have used Chevy pistons to preserve block meat!

I think the progression was something like this.....

1st bore- +.007 Chevy piston
2cnd bore- +.010 Ford Piston
3rd bore +.017 Chevy
4th bore +.020 Ford
5th bore +.027 Chevy
6th bore +.030 Ford
7th bore +.037 Chevy
8th bore and perhaps final, +.040" FOrd

Again, depending on your results of the sonic testing, you could nurse this further....obviously skipping bores that won't clean up enough.

I just hate it when machinists jump straight to +.030" overbore without even considering less...because they might have to do some work.....!

I think guys like Tim Meyers back in the midwest can do custom sizes for bores, rod lengths, deck heights, and strokes....and supply rings. Not going to be el-cheapo Silvolite off the shelf cast pistons though....!

A lot has to do with "your intended purpose" of the end results..... track....or just street....?

Cheers!
Steve
I agree to sonic test any Ford Cleveland block prior to boring.
As far as engine numbers IMHO, with the escalating prices of our cars. If you can find a donor motor to build I would do that, and save your numbers matching engine for originality.
Some things to note DeTomaso stamped the blocks on the drivers side(as seen in the above photos), versus Ford stamped the blocks on the passenger side. My car has the block stamped on the left, plus the heads were stamped with my cars VIN. Wasn't very pretty but they were stamped.
Jeff
Is a sleeved block more or less solid than another? A french "specialist" of Pantera told me that they are less solid, I thought the opposite but I do not have much confidence in this person, it is especially a "good" seller who would like to sell me a very expensive not sleeved engine.
...I agree with Steve! You don't BORE for Larger Pistons! You HONE to 'Cut the Glaze' and to the VERY Next size of Piston. Should Not take more than .005"-.010" Over, that's .0025"-.005" PER SIDE.

You would Bore to Correct a Misalignment, as George stated.

I have Honed 100's of Bores, By Hand! Even did the #8 on My Cleveland, when it Broke a Piston Ring and Bent the Ring Land. Just needed .002" Total, polished off and install a New, same size Piston and Rings. Can put it right at the .0002" No Hourglass, No Barrel, No Taper! No Nothing, on the Bore Gauge. Grumpi Jenkins does it in the Pits, between Races. Yes! Paying Close Attention for the Correct 'Hash-Mark' Angle.
Um, i don't understand the urgent need to reply to the OP 18 mos old?

or to respond to i'm not even sure what?

Today:

quote:
Originally posted by René #4406:
Is a sleeved block more or less solid than another? A french "specialist" of Pantera told me that they are less solid, I thought the opposite but I do not have much confidence in this person, it is especially a "good" seller who would like to sell me a very expensive not sleeved engine.


FWIW Rene just start a new thread next time, but sleeved vs non sleeved blocks both have their strengths & weaknesses. the unsleeved block is an unknown quantity without a sonic test report. it may not 5 miles before it opens a window in a cylinder or it may be a factory super block that can successfully be bored .100"+ there's no way to know. IMO a knowledgeable & reputable engine builder would not proceed to build any 351C block without first sonic checking the block and documenting the results for the buyer. it's in the sellers interest to protect his own reputation and financial investment unless he's a dodger

a sleeved block has already proved itself to be flawed to some degree but may be successfully repaired? then again it may not be suitable to resume service especially under more stress than ever designed for. how many of the 8 cylinders are sleeved? how many are to thin to be put back into service? again the sonic test report is the key. entirely possible that only 1 cylinder suffered core shift during the casting process and the other 7 are good, maybe not how do you know?

what warranty is the seller giving?

return shipping covered?

has the engine been run tested at all?

video documentation?

do you care to share the source of the engine, maybe someone can vouch for the seller or knows of a reason to run away?
4V,

Old post, new question, good answers thru-out...!

First, the idea of talking about a strong block and a 351C in the same sentence is sorta futile. This was a "thinwall casting" from day1 and never really meant to be a dragstrip queen! Albeit the Boss 351C was very strong on the strip!

Drag racers I have spoken with said that at the strip, a 2bolt main block was just as good as a 4 bolt, because you never really were at a speed or RPM more than a couple of seconds AND if you scattered something, you could pick up a 2V block out of another station wagon in the junkyard!!

Well, not so much any more!!!

There are other tricks to strengthen blocks.....half-filling the water passages with "block fill" but you still need some water for cooling the heads etc....

Adding a block girdle on the main caps can help prevent twisting the block....

Sleeves might possibly be furnace brazed in place...but that introduces other issues potentially....unplanned for shifts....more machining!

BUTTTTTTT, you are talking about EXTREME racing....not bench racing or drag racing in your daily driver.

If you are a racer, likely you've moved on to modern castings.......

If you are a preservationist, then sleeving a block will not hurt anything, providing you are not doing 8 cylinders! One or two, perhaps even three shouldn't be an issue in a car meant to hit the backroads. Done properly, a sleeve should never move and could provide more strength combined with the original casting....newer metal in the sleeve....

Honing to a next size with custom pistons rather than immediately jumping to +.030 still stands as a wise thing to do. +.010 and +.020 pistons are still available, and guys like Tim Meyer would probably get you anything that you could get rings for! But it will cost you.

Another thing you numbers correct guys forget, is that there are casting number and date codes on these blocks! Most people are oblivious, but if you showed up with a pushbutton car with a D2AE-CA casting and a 3A25 date code, I'd tell you that your numbers correct expert should be strung up! Not a bad block to have in the car......just not "numbers correct"! (So what else has been faked......?)

Cheers!
Steve
Thank you for your answers.
I had not put the question correctly when I talked about block, I should have talked about a cylinder.

So you confirm to me that if the sleeve is properly installed, a sleeved cylinder is at least as strong as a unsleeved cylinder because the material of the sleeve, if it is a centrifuged sleeve, is stronger than the original cast iron; that is what I thought.
I talked to Pat Michal a few weeks ago about a couple of things. One was the headers, the other was he purchased what he calls a four axis boring machine.

He was saying that Jack Rousche just bought one and there are only a few machines around because of the cost of it.

He was saying that this machine is showing on several blocks that he did that the bore angle to the crankshaft center line is typically off about one degree.

This machine is capable of correcting it to .00001" according to him.

I just mention this because of these weird failures that have no other obvious causes?

He explained what the fourth axis was but not having the machine in front of me I understood it but it went in one ear and out the other.

He spoke of not overboring the block also and talked about going only a couple of thousands over standard where possible.

He DIDN'T say what it costs to bore the block on his machine though.
4 axis knows what you want to do before you do it....or was that the 5th.....

Used for contouring and doing work on a cylindrical shape while moving around the piece! 3D in a circle so to speak.....

Apparently there are 5 axis systems too....!!!

Crazy tools!!!!
This is about saving a block for street use. If you're trying for 500+ bhp or high rpms, this post is irrelevant. One should understand that most bore wear is at the extreme top of the cylinder. That area gets no oil, is above the ring contact area and does NOT need to be flawless. All it needs is enough of the wear-step tapered so you don't break ring lands when removing/replacing the pistons. That's why I typically HONE cylinders that are not badly damaged, rather than boring. Even minor pits left after honing are not cause for scrapping (or boring) a block.

Forged 2618-alloy pistons expand when hot & running, so they can accommodate up to about 0.005" of oversize: e.g- a 4.005" cylinder can use a 4.000" 2618-forged piston but NOT a cast/hypereutectic. Such mismatches will rattle on startup but quiet down within seconds. Forged alloy 4032 has quite a bit of silicon in it which makes those pistons not expand as much with heat, and are more brittle. They won't tolerate 0.005" oversize bores without cracking.

As far as sleeving, one cylinder on each bank will work fine. More than that is iffy for high horsepower. The weak spot in a stock block is at the bottom of the cylinders where the bores get close to the main bearing saddles. That area is weakened even more in the huge overboring needed to add sleeves. Good luck.
Dry sleeves shouldn't be a problem, never heard of a block with them installed failing, I think it prudent to limit any engine with a production block to 450 bhp, 7200 rpm, 8.0:1 dynamic compression ... especially those with sleeves. Keep in mind that a poorly tuned engine will beat on a reciprocating assembly and its support structure worse than anything else.

Example, a former member of the forums did a tune-up on his Pantera's engine. His son installed a new set of plug wires, and crossed a pair of wires. When they started the engine it was running roughly, so the owner took the car out on the road and "floored it" thinking the engine just needed to be "blown out". Well, he blew crank through the oil pan, and left it laying on the road behind the car.

We used to tell people the stock block was OK to 500 bhp, but now that a new heavy duty block is available from T.Meyer Inc, I prefer the lower limit. Anyone wanting to build an engine producing over 450 bhp, revving over 7200 rpm, or with more than 8.0:1 dynamic compression should use the heavy duty block as a foundation. That is what the Buttermore block endeavor (that Tim has brought to fruition) was all about.
quote:
Originally posted by George P:
Dry sleeves shouldn't be a problem, never heard of a block with them installed failing, I think it prudent to limit any engine with a production block to 450 bhp, 7200 rpm, 8.0:1 dynamic compression ... especially those with sleeves. Keep in mind that a poorly tuned engine will beat on a reciprocating assembly and its support structure worse than anything else.

Example, a former member of the forums did a tune-up on his Pantera's engine. His son installed a new set of plug wires, and crossed a pair of wires. When they started the engine it was running roughly, so the owner took the car out on the road and "floored it" thinking the engine just needed to be "blown out". Well, he blew crank through the oil pan, and left it laying on the road behind the car.

We used to tell people the stock block was OK to 500 bhp, but now that a new heavy duty block is available from T.Meyer Inc, I prefer the lower limit. Anyone wanting to build an engine producing over 450 bhp, revving over 7200 rpm, or with more than 8.0:1 dynamic compression should use the heavy duty block as a foundation. That is what the Buttermore block endeavor (that Tim has brought to fruition) was all about.


+1.
I agree completely with George. Remember also that stock diameter fuel lines in the tank & sender will ALSO only support about 450 real horses, if a carburetor and high rpms are used. Typically, big horsepower only happens above 6000 rpms so when you run lean up high on the tach, your most useful tool may be a broom to clean up the mess!

Multiport EFI runs at 6-8X the pressure of a carb, which then flows a little more fuel thru still-smaller-than-desired stock steel fuel lines. Adding big lines only from pump to carb does approximately nothing to increase high rpm fuel flow. You're still sucking from the tank thru a small straw...
quote:
Originally posted by Bosswrench:
This is about saving a block for street use. If you're trying for 500+ bhp or high rpms, this post is irrelevant. One should understand that most bore wear is at the extreme top of the cylinder. That area gets no oil, is above the ring contact area and does NOT need to be flawless. All it needs is enough of the wear-step tapered so you don't break ring lands when removing/replacing the pistons. That's why I typically HONE cylinders that are not badly damaged, rather than boring. Even minor pits left after honing are not cause for scrapping (or boring) a block.

Forged 2618-alloy pistons expand when hot & running, so they can accommodate up to about 0.005" of oversize: e.g- a 4.005" cylinder can use a 4.000" 2618-forged piston but NOT a cast/hypereutectic. Such mismatches will rattle on startup but quiet down within seconds. Forged alloy 4032 has quite a bit of silicon in it which makes those pistons not expand as much with heat, and are more brittle. They won't tolerate 0.005" oversize bores without cracking.

As far as sleeving, one cylinder on each bank will work fine. More than that is iffy for high horsepower. The weak spot in a stock block is at the bottom of the cylinders where the bores get close to the main bearing saddles. That area is weakened even more in the huge overboring needed to add sleeves. Good luck.


Is a simple honing of a few thousandths made with a pressure plate able to eliminate ovalization and barrel shape?
Usually not economical to hone more than about 0.004" (0.001" or .002" is usual), because of the time & labor invested- honing is slow. It's also easy to build a taper into a deep-honed cylinder if you're doing it by hand. And more than about 0.004" removed by any means usually calls for new forged pistons (2618 alloy which expands more with heat).

So if you have a cylinder or two that has more problems than 0.004" can fix, you should have your shop bore the engine, or find a different block. And if you bore, you should first sonic-check the cylinder wall thicknesses- many shops can offset the boring machine to partially compensate for a cylinder that is thin on one side. Std gaskets will allow this slight misalignment with no problems.

If bored, you will then need new pistons and today, custom sizes are available for not much extra. You are NOT stuck with the usual std or 0.030"-over off-the-shelf pistons; either cast-hypoeutectic or forged can be made. This can be a lifesaver for scarce 351-C thin-wall blocks.

If you have more time than money and are doing the engine yourself sort of as a hobby, you can hone out more than 0.004" but it will take days to do eight cylinders. I also suggest sonic-checking the cylinder walls just for your own information, even though with hand-honing you will not be able to compensate.

You are right on mentioning the torque plate; many years ago, I wrote an article on how much a typical thin-wall 351-C changes bore measurements with and without a plate torqued on. Before honing or boring, I suggest adding a torque plate and re-checking for cylinder problems. On several cylinders in the article, the bore changed in one direction, while one cylinder changed the opposite way. The biggest change was around 0.002". So if your block was prepped WITH a torque plate and its bores are later checked without it, the block may show distortions or ovality that will disappear once the heads are torqued on.

As an added note, precision engine builders are now using torque plates on iron 351-C CYLINDER HEADS before doing a valve job. OEM cylinder heads were cast thin-wall, too....
Thank you for this answer, but my question was about the geometrical shape, when they are worn the cylinders are no longer cylindrical, they are oval and barrel-shaped, the area where the piston presses towards the mid-height is more worn than the top and the bottom. I wanted to know if a simple honing done at a machinist, not done by himself with a tool to a few dollars, catches these defects of geometric shape.

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