IMPORTANT NOTE: This engine was rebuilt as described here but while it remained unsold as a "turn-key" engine, some of the "completion parts" were "borrowed" from it for a 912 project. So, it's now a long-block, but can on request be returned to similar status as seen here but with a standard C muffler, a different color oil filter, different air cleaners, among other minor differences.
This engine has had some important "upgrades", as described below.
ABOVE RIGHT: This engine, mounted to the dynamometer, just prior to being run-in. As noted above, the engine was returned to "Long-Block" status after the run-in process was completed.
This engine has been Run-In on our Stuska water-brake engine dynamometer as per Porsche factory specifications as outlined in the Workshop Manual, operations 52 EN, 53 EN, and 54 EN, pages E83 and E84.
AT RIGHT: This engine in long-block status. It has a stock 6v flywheel and takes a stock tachometer cable attached at the oil pump.
Contents of this page:
This late B era 356 engine has been fully balanced for smooth running, long life, and a few more HP.
This engine started life as a "1600 normal" - type 616/1. During this rebuild, not enough of the original "normal" components were serviceable to justify keeping to in "normal" form, so it has been upgraded with:
AT RIGHT: This engine in long-block form, the flywheel end!
During this rebuild every detail of the long-block has been attended to; nothing was ignored, as documented here.
This engine was a core received from the customer who bought this engine. This engine was incorrect for his C and he wanted to put a more correct one in the car.
There was "nothing wrong" with this engine, it just wasn't the one for his car. So, upon receipt I put it on the dyno and ran it through its paces. By luck of timing, this happened literally just as the new Stuska digital load control system had been fitted to the dynamometer, as well as the new Performance Trends digital data collection system. So, it was a lucky thing that the new equipment was tested with this 356 engine attached!
AT RIGHT: This engine being uncrated. Do note that we made the crate and shipped it to our customer "flat" (disassembled) and his local mechanic assembled our crate around his (this) engine and sent it back to us. ...We were rather displeased with the wood blocks nailed in here and there to keep the engine from shifting, but it arrived OK.
As sometimes happens with new equipment, the digital data collection system's RPM sensor was not working properly, so I wasn't able to get HP data, but I was more interested in oil pressure information! HP on a stock engine only tells you about the state of tune, but oil pressure tells you about the condition of the parts in a way you can't get any other way (except perhaps to measure absolutely everything). (As an aside, we had to replace the data collection system's RPM sensor.)
I was a bit disappointed that the engine had a Bosch 050 distributor installed in such a way that the engine would not easily accept an electric oil pressure sending unit, so I had to settle for the old-school direct-readout pressure gauge. Oh well, at least I HAD such a thing on hand!
ABOVE LEFT AND RIGHT: Note the direct read out oil pressure gauge is resting on top of the left air cleaner - air cleaners we had to provide, by the way, because the mechanics who shipped the engine kept it with the car for some fool reason! Oh well, no worries, at least we HAD correct air cleaners available!
Interestingly, the oil pressure was fully up to "new" specification - three atmospheres at 70C (158F) at 2500 RPM with 20 weight oil (20/50 is what we use)- and even a little bit more. Nice!
Of course, note that the customer had us move all his original parts from this engine over to the C long-block he purchased from us. So, only the long-block under all these pieces was retained as a "core." It was completely dismantled as a part of its evaluation before reassembly began.
This crankcase cleaned up nicely and didn't need any special preparation before reassembly. The case is standard bore size and is virtually perfect as is - only needed cleaning. Thorough inspection uncovered no flaws.
ABOVE: Cleaned and ready to go. The crankshaft bearing bores remain their original "standard" size - no align-bore needed!
Someone had gone nutso on the case sealant on a previous assembly, so I had to take a thread die and run it along some of the studs so it wouldn't interfere with the torquing of the fasteners, but otherwise, no special action was needed.
The crankshaft is a B series, just like it should be. The journals are in good shape and it isn't cracked. So, there's no reason not to put it back in.
The connecting rods were not, however, they were earlier "A" rods. I tossed them into the A rod pile and pulled a set out of this grouping of late C/SC/912 rods (below right).
...Actually, I had put this particular set of four aside for one of my own engines. It happened that the batch of six sets in the image below had been depleted but I didn't care to wait for the next batch of rods to be done. So, I pulled this set out of "my own stash."
Of course you know, with the exception of the Hirth roller cranks (or possibly Denzel), I won't put an engine together without "rebuilding" the connecting rods - too much is at stake; if a rod lets go, the whole engine is lost, and if either big or little end has trouble, at the very least you'll have a bad day. ...I also won't put an older rod type into a younger engine, though, as in this case, I will do the reverse from time to time. While the late B rods aren't bad, THESE rods are the best plain-bearing rods Porsche ever made for 356 or 912 engines.
All these are "late type", the best of the breed. All have been rebuilt carefully. I rebuild rods in batches - it's easier / faster / cheaper that way as it keeps setup time to a minimum.
AT RIGHT: Batch of 6 sets of late rods. One of these sets went into this engine.
BELOW RIGHT: The crank, ready for bearing and gears. Note the ink used in balancing the rods (recording weights in grams) can still be seen on a couple of the beams, just below the wrist pin. You can also see the line where removal of material on the big and little ends occurred during the balancing process. They're balanced end-for-end and total weight to 0.1g.
For me, "rebuilding the rods" means to:
This is all standard work so there aren't any photos of them in-process.
The flywheel is a stocker (180mm, 6v ring gear), in fine shape - well, at least it is now, after I cleaned it up and refaced the friction surface. I didn't fit a pressure plate to it because this engine could be put into an earlier or later car and there are two different pressure plates one might choose from - better you choose! Or, just run your old one! (I can mate it to the flywheel and balance the two together for you if you'd like - this is highly recommended.)
ABOVE LEFT AND RIGHT: Just doing a thorough job - the flywheel was thoroughly cleaned and then resurfaced. It has a lot of life left in it. That warm red glow was caused by sunlight reflecting off something in the workshop - I kinda like it.
Originally, this engine was being rebuilt as "an original 1600" with its original cam, which in pretty good shape, pistons and cylinders and so on. So, after trial fitting everything, selecting a better (new!) cam gear, installing the refaced lifters, etc, I got the bottom-end assembled and started to move on. However, there was a change in plans due to the fact that when I got around to actually honing the original cylinders in preparation to installing them, I found they were NOT in fact runable. So, it was a VERY unusual circumstance that I have ever needed to do this, but sometimes, it happens: I tore down the short-block so I could install a different camshaft to go with the Big-Bore pistons and cylinders which I do have available. (Useable 82.5 cylinders are vanishing - in addition to wear, people bore them out for use in big-bore applications.)
AT RIGHT: The "short-block" going together, act one, with the stock ("normal") cam. The lighting isn't the best, but here you can see it all coming together. The main bearings are old-school Kolbenschmidt (KS on the box) - they're notable for their often dark coloring. I do have a preference for KS bearings. (See bearing image below.)
Remember, an engine is a system. All the parts have to work together! So, the switch to a different cam is an important choice that's coupled to the choice of pistons and cylinders for the simple reason that the stock "normal" cam would not have provided enough breathing to adequately fill those hungry big-bore cylinders!
When it comes to engine building, one of my motos is:
Clenliness is next to Godliness!
The cam followers were refaced, of course. All my rebuilds are the whole deal... ...You CAN re-use lifters but only if you keep the lifters in the same position on the same cam in the same case; otherwise you're asking for trouble. It never hurts to reface the lifters! Certainly, if you replace the cam, you must reface the lifters!
BELOW RIGHT: KS bearings have this dark protective coating - a bit odd, and very distinctive, but it does come off. Also note in this image a region of the left half-bearing with none of the coating (near the upper parting line) - sometimes, they weren't fully coated, other times they are and sometimes the coloration goes through weird shades of yellow-green; you find whole KS bearings that are more pale sometimes or one side but not the other, so not having the dark coloration doesn't mean they're not KS, but if they do have it, they are!
BELOW LEFT: Yes, doing things in batches helps save time. Here's a batch of three sets of lifters that have just been cleaned, refaced and had their stems polished where needed - one of these sets went into this engine.
BELOW: Since this is SO RARE, of course I took photos of what it looked like when I got the case apart after having just been put together! It's interesting to see where the case sealant actually goes! Note the different camshaft! Because the cam is hard to see, there's a closeup, below right - it's beautiful.
If you look closely, you can see the numbers (upside down) "102" - this indicates it's a "Super" camshaft.
OK, one more time the halves go together! And out-pops a short-block! Yay! (Note all the new hardware.)
Geez I love how a clean, freshly assembled engine looks! But I guess I'm a fanatic!
BELOW RIGHT: Yes, there are more being assembled now - if you look carefully, there are FOUR 356 engines in this image, on engine stands, being assembled! Can you pick them out?
ABOVE: For those who may wish to "concourse" your efforts, in recognition that it's pretty much impossible to detail the case acorn nuts without disassembling the engine down to a short-block, new acorn nuts were fitted!
This engine's original pistons and cylinders were nominally 82.5mm in bore. They are becoming extinct through attrition. Indeed, I had thought this would be the lucky one that had a good runable set and even assembled the bottom end of the engine - into a "short-block" - using an original camshaft to match! How cool to have one of those rare all-stock engines today?! Well, it wasn't to be: when it came time to hone the cylinders, I realized I had been optimistic about the cylinder to piston clearance and it was a bit large. Oh, they'd have worked, but I wouldn't have felt good about it because the engine would have had a shift in the wrong direction on all these points:
ABOVE RIGHT: NPR big-bore pistons, cleaned, balanced to 0.3g (including pins) and ready for rings.
Therefore, I went with a set of genuine NPR Big-Bores - the old-school big-bore set. These are in fantastic condition. We, the 356 community, have long experience with these pistons and cylinder sets. They are very successful and while they are no longer available, they are the piston / cylinder everyone has copied in the modern era for the new parts we can get today.
AT RIGHT: The NPR big-bore cylinders, cleaned and honed.
Note that this shift to Big-Bore also requires a change to the cylinder heads. There's more on this subject in the cylinder head section below.
We always check the match of pistons to cylinders and match piston weights as a set, and provide any remedial action to correct any errors before installation. For example, by shuffling around the connecting pins among the pistons, one can usually improve the matching of piston weights. This set balanced to within 0.3 grams without removing any material - the stock tolerance is 10 grams, so they're nearly two orders of magnitude better balanced than stock!
For many shops, from this point, installation goes very quickly, but we think this is where one needs to take one's time! The key reason one needs to take time here is that there are production tolerances on every part in an engine, and while a set of parts may look identical, there's often subtle variation between members of a set, and there are sometimes significant errors in production that weren't caught by the manufacturer's quality control processes. These errors can "stack up" and cause problems if not discovered and corrected.
Here's our process: Two of these steps require special tools most shops don't have.
ABOVE RIGHT: Here you can see the height comparison check (for cylinders 1 and 2) - this is done to ensure that there are no difference between the cylinder heights that the head itself "sees." The book value for tolerated error is 0.1mm (four thousandths of an inch), and this engine has no measurable difference between cylinders 1 and 2, or between cylinders 3 and 4. This is remarkable!
We like to carefully measure everything and then mix-and-match the parts for superior fit. We have also discovered significant manufacturing errors with this process which would likely have gone unnoticed without these measures. It is remarkably easy, for example, to overlook the circumstance of the crankshaft bore not in the true center of the crankcase, angled on the horizontal left or right of center, or not on the same horizontal plane at all. Yet examples of errors like these are not as uncommon as we would like.
The next thing we do is something nobody else does (that we know of - at least, not the way we do it) in the engine building process, and that is to measure the height the piston crown comes above the plane of the top of the cylinder. I call this the CAC, or "Crown Above Cylinder." This value is important because, firstly, it can reveal deeper problems, and because it helps us get the compression ratio equal in all four cylinders.
Note that most other people use clay or some such and let the piston squish it against the head, then measure the thickness of the material upon disassembly - effective, but not particularly illuminating on the points made below. Neither does filling the combustion chamber with liquid, as many shops do, provide this kind of information.
Here are some of the deeper problems that can be discovered through a CAC check:
AT RIGHT:Cylinder 3 having its CAC value measured. All four cylinders are measured this way, and should any significant difference be found between cylinders, swapping pistons, cylinders or even rods around can help make a better match and find out exactly where the discrepancy may lie. This measure is extraordinarily accurate.
In order to do this for these engines, you have to have special tools. Here, you can see them in action on these images.
The distance between the smallest tick marks is one hundredth of a mm, or 0.0004", and you can discern to perhaps a tenth of that! So, this is a very accurate measure, performed while the cylinder is under torque, so any shims are squished flat, etc. In this instance, the heights at which the pistons protrude above the plane of the top of the cylinders were all remarkably close, within 0.07mm on one side and 0.085 on the other, well within tolerance (which is, by the way, unspecified by Porsche - Porsche only specifies the maximum difference between combustion chamber volumes under one head), which, in this case, is better measured in its effect on combustion chamber volume than as a length.
The accuracy of this measure is so good, that if you take the time to swap parts around, you can accurately determine discrepancies in the manufacture of the various parts! But, we ARE splitting hairs here! However, a benefit to both engine builder and customer is that the ability to move parts around for better fit means that perfection is more easily achieved, and the more equal the HP production of each cylinder, the smoother the engine will run, and the more HP the engine will produce overall.
Because this process includes the entire assembly, torqued as in service, and measures the height each piston protrudes out of its cylinder, all errors in connecting rod lengths, cylinder heights, crankcase spigots depths (cylinder bore deck), piston connecting pin heights, and shim thickness' are accounted for in the measurement results. There is no superior method.
The heads had zero observeable problems as the engine was dismantled, and the heads weren't even particularly dirty, but, as stated elsewhere, the idea is to have a consistent, reliable product, so the heads received this (standard) treatment:
ABOVE RIGHT: No broken fins, no cracks, no bad threads - these heads are in fine shape. ONE exhaust stud needed replacement.
AT LEFT: these heads with new guides installed.
One thing that was apparent as the engine was dismantled was that someone diddled with the combustion chambers with a die-grinder, presumably to try and match up the combustion chamber volumes - at least that's what we presumed as we cleaned it. However, a second realization came to light later.
It turns out that the original combustion chamber shape changed by 8 degrees from the B (and earlier) era to the C era (including SC and 912), and the Big-Bore kits are all designed for the later shape. The good news is you can take material out of the earlier head to get it to match the later shape, and you must do this if you are fitting big-bore pistons.
During assembly it was realized that these heads are were clearanced for the Big-Bore pistons through this die-grinder activity, whether intentional or not! In carefully examining the work it is most likely that indeed this was the purpose because the material was taken out all around the edge, just where an interference would occur. And, thankfully, they didn't take out too much, either! If someone wanted to, the compression ratio could be raised to over 9.2:1 without too much trouble, though with today's gasoline, that's not advisable. Instead, we set it to about 8.5:1, which is about as high as you can go safely without requiring premium grade fuel under all conditions.
AT RIGHT: The valves (foreground left), springs, shims, retainers and keepers used in this engine, ready for assembly.
Long term running experience illustrates that the stock spring pressure is a bit light at 61.5 lbs @ 41mm, and with such pressures it was not uncommon to have an occasional bent valve when it can't get out of the way of a piston - we've even had it happen to us, personally! And, as a practical matter, drivers tend to push their engines until the valves float - a risky situation! So experienced 356 / 912 engine builders have been using stiffer springs for a great many decades.
Given the Big-Bore pistons and cylinders and the Super camshaft, it seemed prudent to plan for higher-RPM. With SC and 912 engines, a typical choice is 90 lbs, or more for enthusiastic drivers, to, say 100lbs or so, but this engine type was never intended to run to 6000 RPM (no counterweights on the crankshaft), so these springs are a compromise at 85 lbs - still more spring pressure than genuine C / SC / 912 engines, providing more protection against floating the valves, but without unnecessary "internal losses" in compressing the springs since presumably this engine won't be floating at red-line all the time.
Also note that we match up slightly stiffer springs with the heavier valves (intakes are about 2% heavier than exhausts), so they're very close sets, matched up, so all the valves tend to float at the same time. However, in this case, all the springs were virtually identical - a somewhat unusual circumstance. ...Of course, each valve and retainer are position-specific through the shimming process as the spring-heights are set. This close-matching of spring tensions helps the driver know when they're over-revving because all the valves will tend to float at exactly the same time, thus sending the clear signal of a drop-off in power. When one or two valves float before the others, the driver may not realize they're harming the engine and continue on, getting into trouble!
BELOW: Here they are, ready for installation.
At this point the engine is ready for its cylinder heads, and this work went very quickly - as it should! - as all the prep work was already done.
Prepare the head "bolts" and washers, prepare the pushrod tubes, prepare the lower cylinder air deflection plates and their wire retainers, and get the torque wrenches set, and bolt on those heads!
My pattern is to mount one head, torque it to 7 ft lbs (as per the manual), then mount the other head the same way, and then alternate between the heads with an ever-increasing torque up to the final torque value, then repeat the final torque value until the fasteners no longer turn when torque is applied.
OK, mount the valve gear, adjust the valves and pop on the valve covers. Yeah, sounds simple, but, to do a great job, there's more to it than that...
Then fit the oil drain plug, and sump screen and plate. I painted the sump plate with rattle-can black... Then, fit the two oil control pistons and the oil pump. Both oil control piston springs were replaced with new along with one of the two oil control pistons.
...The careful engine builder is constantly running into problems like either worn out rocker arm contact faces (where they contact the valve stem), or mis-ground by someone who didn't have the wherewithall to grind them properly, as happens all too often, and as can be seen here.
BELOW LEFT: Here's a mis-ground rocker arm someone "refaced" in the past. Note how the rocker is only making contact on the extreme left edge of the valve stem! The result of this situation is both excessive wear of the valve stem and also that a "pocket" develops on the rocker arm, making valve adjustments difficult! The rocker was, no doubt, refaced "by hand".
AT RIGHT: Here's the completed longblock. ...Almost. The flywheel will be mounted after it's taken down from the engine stand - and the oil pump still has to be mounted!
At some point it was decided to go ahead and built it out to a complete, ready to go engine, but then before it sold, some of the "completion parts" (sometimes called "accessories") were borrowed, returning it to long-block status. ... On request, we can repeat the steps seen here, but with slightly different parts.
AT RIGHT: Some additions: the pulley oil seal, the oil pump and a pair of Zenith manifolds.
AT RIGHT: Some more additions: a generator stand, rebuilt fuel pump, rebuilt, original type BR18 distributor, a plated pulley, and various powder-coated tinware. The flapper boxes, J-tubes, and the not-yet mounted muffler are from a 912 core we took in recently.
At the top of this page is a photo of the engine, completed, mounted on the dyno which shows most of the engine as it was completed.
AT RIGHT: Here, you can see the water hookup to the dyno when this engin was run-in. Remember, those air cleaners are loaners for the run-in process and do not go with this engine.
Because some people are keeping logs of VIN and engine numbers and then purport to tell people what someone else has, out of respect and concern for a buyer's privacy, exact VIN and engine number data are not published here.
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