I’ve read about the procedure (mostly i’m just speed-reading a whole bunch of things to stay afloat). It doesn’t sound complicated, but, with so much being new and the van being in a garage for a year, there are a lot of things that a professional should probably check over just to be safe. Sent from my iPhone using Tapatalk
Max revs for a T1 based stock crank engine is 4,600. This is why the reaction to 5,000 cold is Do you have your numbers mixed up?
I don’t think so. Here is what i’ve written down. RPM: Max rpm in neutral = 6,400 1st Gear Max rpm = ??? (didn’t note) 2nd Gear Max rpm = >5,000 3rd Gear Max rpm = >5,000 4th Gear Max rpm = ??? (didn’t note) I would have been fairly tentative in checking these. Sent from my iPhone using Tapatalk
If it had a counterweighted crank and the rotating assembly had been dynamic balanced...yes. otherwise...NO!!!
PO said the crank was a “heavy crank which lowered rpm”. Now I suspect it’s the gearbox that did this. “Lightened Flywheel” he probably meant the crank pulley because it has the 5 holes in it. It’s hard to know any ‘truths’ from him though. Supposed aeronautics mechanic too. Engine builder says the crank was nothing special. It was scored and already at 0.75 grind (no idea what that means). He recommended the Scat 69mm Volkstroker as being far superior. Could it be my tachometer is wrong? Almost everything else was wrong about the van. Sent from my iPhone using Tapatalk
Ain’t that the truth...and I can’t tell! The camper was advertised as having a Porsche engine. Porsche emblem on the boot lid (which I need to remove)...little porsche trinket on the keyring. He clarified that it was based on a 356. You can imagine the disappointed faces at my first Techenders, when half a dozen blokes crowded round to have a look under the hood. In my defence, it looked very similar to a 356 and on the market at that time it seemed to be the only one with twin carbs. Sent from my iPhone using Tapatalk
Volkstroker or Volksaver? Scat Volkstroker cranks are more than 69mm stroke, if it’s 69mm it’s probably a Volksaver cast crankshaft, don’t spin it to 6,400 revs, maximum is 5,500.
Looks like i’ll have to double-check that. Just to confuse things further, the screenshot he sent me was actually for a Scat 69mm Volksracer - which is rated @ 6,500rpm. He was insistent that it wouldn’t be a high-revving engine though. There is a Volkstroker 3 that is 69mm. I need to confirm this, so leave it with me. Really though, whilst driving I was between 2,300 - 3,900rpm. Changing gear @ 2,600rpm seemed to suit it. Only at startup was it crazy high...but lesson learned on that front and maybe with the rebuild, thermostat and Powerlite starter motor it will temper those revs. Sent from my iPhone using Tapatalk
[QUOTE="PanZer, post: 1773005, member: Really though, whilst driving I was between 2,300 - 3,900rpm. Changing gear @ 2,600rpm seemed to suit it. Only at startup was it crazy high...but lesson learned on that front and maybe with the rebuild, thermostat and Powerlite starter motor it will temper those revs. Sent from my iPhone using Tapatalk[/QUOTE] I temper the revs on start up by not pushing down so much on the accelerator pedal! No need to thank me for this top tip
I can’t see it in the Scat catalogue, but I could be looking in the wrong place – I usually only look for Type 4 parts. If it’s a Volksracer it’s a good crank, 4340 Forged Chromoly (the Volksaver is cast). Just because it’s rated to 6,500 revs doesn’t mean that the engine is designed to run at 6,500 revs, it means you have more safety margin before the crank is the bit that breaks. With the cam you have there probably isn’t much power gain above 5,500 revs so there is no point in revving it harder, it’ll just make more noise.
Neither the rebuild, thermostat or Powerlite starter will temper the revs; the nut behind the steering wheel does that.
I also liked your 009 distributor specially modified for 26 degrees of advance at idle and 22 degrees at 3000 rpm .. that was pretty special too.
[mention]paulcalf [/mention] & [mention]77 Westy [/mention] do you not put a brick on the accelerator and go in the back to make a cup of tea when starting? [mention]mikedjames [/mention] & [mention]paradox [/mention] I remember that vividly. I was trying to nod and tut in all the right places as you explained what was going on...but my timing was off! Sent from my iPhone using Tapatalk
[mention]snotty [/mention] had a quick look to see the thermostat setup. Images i’m finding don’t show the tinware in place or the pieces that I have. Looks like the bolt for the bracket is just underneath the bottom tinware (it might squeeze in), but I think the rod goes between the barrels, but above them is another piece of tinware. Sent from my iPhone using Tapatalk
The rod goes further out from the block, in to a slot in the head. It is cranked to get it through. The crankshaft grinding process.. you begin with a standard size bearing in a standard sized case. If the crankshaft journals are worn, common practice is to grind 0.25mm off the diameter to make them smooth and round again. If the outsides of the bearings have moved in the engine case and worn away metal ( high rpm ..) then the case is align bored to make the hole the bearing sits in 0.25mm larger diameter. This is because bearing sets are sold with 0.25mm steps in inside diameter and outside diameter. After you have ground a crank 3 times or the case 3 times it is reckoned to be scrap as making a crank thinner cuts through surface hardening and makes it weaker so it flexes more and wears faster. It is quite possible to align bore an engine slightly off true diagonally across the block so you need different cylinder spacers each side to get the pistons to go up to the same distance to the top of the cylinder. With a high speed engine, you also start to need modifications to the engine case, as what happens is the crank stops being "straight" at high revs even with extra balance weights welded on (" welded crank") and the centre bearing starts to be waggled back and forth at the speed the engine spins. So the halves of the case start to move against each other. To stop this the builders fit extra "shuffle pins" locking the engine case halves together either side of the bearing. Other engine designs have these from the factory, but with a 90ish year old cheap design using then state of the art tech its not surprising that not everything is 100% right. At least we dont have gearboxes with aluminium gears as were briefly a thing in the 1930s.. This is progressive wear, a few seconds at high RPM does less damage than sustaining it. Messing with the weights of the crank pulley and flywheel alters the flex of the crank system. Both flywheel weight and crank pulley wight affect the snaking - why Gene Berg sold extra heavy pulleys to go with lightened flywheels (or is that more marketing fakery ? ) It is reckoned that a stock VW crank would survive 7000rpm regularly without actually breaking but the engine wear is fast.
0.25 x 3 = 0.75, so ground thrice. Hence kaputt and replaced. Thanks. No machining done to the case...by us. Hard to see under the engine with it sat on blocks, but feeling around, if the rod comes down about 1.5” from the Head then there is a gap there in the tinware (which i’ve not seen on a diagram) for it go through. Hard to gauge all this from photos and videos. Having your description they start to make more sense. Sent from my iPhone using Tapatalk
I only do that when on the motorway and if its a straight bit. Brick on accelerator, nip in the back to make a brew but I return to the front to drink it, i'm not crazy!
Here's a pic of the setup. You seem to be missing the bracket mounting stud on the case (or maybe the tinware's covering the tapped hole in your pic). A removable plate (the RH lower tinware is in two parts) covers the whole lot. If there's no hole for a stud, you'll have to drill/tap one.
