Stroker engine question

[liquidrush]

I bought a 1968 engine, the sheet says 74mm crank and 5.5" rods. I'm not familiar with what it takes to put this together and I have oil leaks. I can stand a little but this is more than a little. I replaced the pushrod tube seals that were leaking and of course they still leak. I cleaned it all off with brake cleaner and added some dye to the oil, ran it just a few minutes and the oil is coming from the pushrod tubes and cylinder bases. Damit, just my luck. So my plan is to take it off, get it on the stand and go to work. I plan on replacing these 2pc tubes with factory type ones and I understand that there may be shims on the bottom or top of the cylinders. If they're on the bottom how does a guy seal that up? Any advice is appreciated.

Thanks!

[BFB]

I never understand how a post like this gets to 75 views and not one reply...

same as if there isn't any shims, RTV of your preference. only difference would be if you wanted to put it on both sides of the shim(s) or just between the bottom shim & case. I usually just do the latter.

there's good spring loaded tubes that don't leak. if it were me I think id get a new set of tubes, clean up the bottom of where the cylinders meet the case real good and put a little smile of RTV on the bottom of them and see what happens before I went blowing the engine apart. you go down that rabbit hole then next thing you know you've got the case split and rebuilding the damn thing.
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"how am i supposed to torque the rear wheel nut to 250 ft lbs??? " - clonebug
An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
Most experts aren't.

[liquidrush]

So goop it up with silicone and hope for the best?

[sub-hatchtim]

the new cb performance pushrod tubes are nice
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58' pg/sg silo fridge westy
58 Dove blue singlecab
76 911S

[Brian_e]

[sub-hatchtim]

[Brian_e]

[sub-hatchtim]

I'm just trying to build an affordable runner with what I already have to stuff in my single cab until I can build something fantastic

I'll stick with a 69x85.5


thank you
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58' pg/sg silo fridge westy
58 Dove blue singlecab
76 911S

[modok]

When I deck a case or machine for a sleeve, I like to check the fit....so I color the sealing area with marker and put the cylinder on there and spin it a bit, it should wipe off all the marker evenly all the way around, showing you have a good contact surface.

Now, some of you might think that's not possible to get it to fit that well, but, it is, you could just do it with a hand file and an afternoon if you just.... get in there and figure it out. Test fit, find the high spots, knock em down, test again.

But anyway, it's leaking, you've got some kind of GAP, and, you need to find that, and it could be something simple or maybe not. Maybe a case saver is sticking up and the cylinder is sitting on that, or you have bad cylinder shims that aren't flat, or....just a gap, a blown out spot near a case saver, or the case deck is very warped. Now, if you DO have a gap like at a case saver, then, maybe grey silicone can fill a small gap, if it's a big old gap, then maybe JB weld or something like that could be used to fill the void then file it flat again.

Pushrod tubes.....also just common sense, not too tight, not too loose, seals need to fit the pockets right. It's more about what to do about it when it doesn't fit right. If the pushrod tubes are too tight you can use 40horse ones, those are shorter, if they are too loose, you can stretch them a bit, or possibly put some washers between the seal and the pushrod tube, just VSI shims of the right size. I like to use silicone pushrod tube seals seals like CB sells, and don't use sealant on them. Sometimes you use sealant on them, they get too slippery and climb out of place. But some pushrod tube seals are made of different kinds of rubber and some could benefit from sauce, but, not all.

[nsracing]

The simplest build for a 74mm stroker crank is to just use stock rods and A-series pistons. All you need are the proper spacers under the cylinders and cut the proper length pushrods.

But- if you want to go w/ longer rods, you can go w/ A-pistons and shim more. Or go w/ B-pistons and shave the cylinders a little.

Either way, you will need some machine work.

But I will recommend a 74mm crank and 94mm pistons = 2054cc. It is stout and will do burnouts in 2nd gear. You can go mild pistons like 88mm and 90.5mm. Also very good choices.

A 74mm crank and 85.5mm bore will be tight on the skirts. You will have to trim the skirts as they will hit. The bore is too narrow to accommodate the swing as it were.

Enjoy -

[BFB]

[mikedjames]

Use stock pushrod tubes, make sure they are stretched to the correct length before installation
New seals, all traces of RTV silicone removed from mating faces. As you put the heads on you crush the concertina part of the pushrod tubes by about half an inch which providesthe pressure. The crush is not even as the pushrod tubes do not fit exactly at 90 degrees to the head or the case.

If you do not stretch them before installation, they will keep their old uneven crush and tend to not seal properly unless you put them back exactly as they came out.

The spring pressure in the telescopic tubes is much lower than the concertina crush force pushing the seals into place.
Plus the telescopic tubes have another O ring seal to leak at the joint.
I keep one spare telescopic tube in case of damage on the road, but my stainless tubes are a fair bit stiffer than the stock steel ones.
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Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[Brian_e]

[BFB]

[Zed999]

I've built just 2 engines in my entire life, both VW type-1.

First just cobbled the top end from one with the shortblock from another with new bearings. Took months as I hadn't the feintest idea what I was doing and had to read up on everything. It turned out great but there could have been some luck involved.

Second was 76 x 92. IIRC b pistons, 5.5 rods and a smallish shim. Yes there is some case clearancing but that's not rocket science. That one turned out great too and having done the first it was easy.

I wouldn't be put off building a stroker as a first engine if you're patient and like problem solving and calculations. Considering stock parts don't just slap together these days, that advantage is lost so might as well go for it.

Also the way my mind works, if I'm going to the effort of a complete rebuild I want it to be more powerful, that way I feel like I got "something" for my trouble and it doesn't really cost much more.

[Rome]

For the OP:

[Pelle]

[Alstrup]

As Brian said... There is more than one way to skin that cat.
There can be space issues in the car, say an early model or something which would make it preferable to have a narrower engine. A narrower engine does have its advantages. But as long as we are talking mild engines there is no real difference.
I have built my fair share of odd combo´s in my time. Some works well, some not so well. Some are a PITA to assemble, others are relatively easy.
Next. IF one is to build an engine on a used case today you have to be aware of the fact that the cases´s contact points are NOT straight anymore. 9 out of 10 cases need to be decked if you want success with your build. I have seen NEW cases which needed to be decked before use.
Now, from a technical point of view, long rods have always been favoured in racing for several reasons. This has spilled over to the regular people´s build too. It is true that with different lenghts of rods you can move the power around a bit (in a few cases a lot) but again, for milder applications this is minor.

I am aware that not everybody lives in an area where there is a decent machine shop withing a decent radius, thus the "no machine" engine kits being interesting. The smaller the bore the more adapting there is if you use otherwise stock parts, as NS points out.

If you have the parts already then by all means build it. If you are still on the buying end of it, dont. Pay the fee for getting the case machined and decked properly at the same time, build a 1776 or similar and be done with it. As Brian noted, the 1776 is a tried and true combo which will last till the sun turns black if you build it properly.

Some time ago I built/rebuilt an 1800 cc engine (76 x 87 mm) for a person who also thought it was a no machine thing, but ended up having all sort of issues. I had to reuse as much as possible because he had spent his money already (Same ol´story) Even though this engine had only done something like 1500 miles it was basicly a rebuild with extra toppings.
Case needed to be decked, so there went the first machining.
Barrels shims waried 0,15 mm. so they needed to be surface ground. Luckilly he assembelled it with too much deck, so I had room to correct them.
He had bought a slightly used 30 mm Melling oil pump which already had battle scars (I hate those pumps in the first place, so in the bin it went, and got replaced with a blueprinted 26 mm)
Cylinders were scuffed, but luckilly I could hone it away with taking 2/100 So new rings were in order too.
Heads were AA500 copies, new and from that 4 letter company you know, they needed new guides, new valves and new retainers as they were about to let go So I did the classic by cleaning up the bowls and chambers, got a proper valve and seat job done to them.
Due to the fact that this engine was supposed to be a little agressive and therefore also have some static compression (which it didnt have the first time around) and due to the fact that the barrels were 87 mm. I opted for taking 1,4 mm off of the top of the cylinders and then step cut the heads so the deck was in the heads. (To get most possible heat away from the cylinders)
In spite of the engine now being over 1,8 mm narrower per side the pr´s ended up fitting perfect becaus ethe valve train geometry was off before.
Carbs, ignition and exhaust remained the same.
When the owner got it back in the car he said "This is what I wanted in the first place"
At the end of the day, if he had paid someone knowledgeable to build his short block at least he could have gotten at least 1955 with 20 hp more for the same money. Budget and no machining is not always good.
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993

[Fender38]

[Brian_e]