Need guidance on building a vintage speed stroker motor

[jbannon]

I wanted to throw this out the community given I need some help with my next vintage speed build. I plan to build a stroker motor and need some help on the finer details. Currently I have my 36hp block, WW Okrasa heads, 32 NDIX carburetors, Airflow Systems oil cooler, and Stefi G. manifolds. I also found a very competent machinist who understands air cooled VWs. For background I have read “Souping the Volkswagen”, the July 2014 Hot VW article on Shin’s stroker project, and built a mild vintage speed motor for my 59 beetle. You can find the link to that build here:

https://www.thesamba.com/vw/forum/viewtopic.php?t=...p;start=40

I have also read a lot of articles in this forum, which has been very helpful. However, planning and building a stroker motor is new for me and I had some questions that I hope you could help with. My goal is to build a reliable motor to get me up to speed and make driving a little safer and responsive. I won’t race this motor or smoke the tires at stop lights.

Here are some questions:

- CRANKSHAFT: WW 69mm or WW 74mm crankshaft? Is there any penalty with going 74mm? It seems like the WW 74mm crank is relatively new compared with the 69mm, and more seems to be written about the 69mm crankshaft. Given they are the same price, and you get more displacement with the 74mm, I am trying to figure out why you wouldn’t automatically go with the 74mm.

- PISTONS: WW 81mm or AA 80 mm pistons? Do you gain any advantage in terms of clearance with the WW 81mm pistons? Do the AA 80mm pistons require anything special in terms of machining?

- CONNECTING RODS: I assume with the 74mm crankshaft I would use the WW shorter H-beam connecting rods. Does this eliminate the need for barrel and pushrod shims? If I go with the 69mm crank, does using the shorter rods also eliminate the need for shims? What is the optimal setup for both scenarios?

- PUSHRODS: One-piece or two-piece pushrod set up? I assume using the two-piece pushrod set eliminates the need for pushrod shims in either scenario.

- HEADS/VALVES: In discussions with my machinist, he recommended using a bigger intake valve and foregoing the use of ratio rockers to get the same benefits of increased fuel/air mixture flow. His reasoning was less wear from having to compensate for the ratio rockers and pushrod geometry changes. From what I have read on the Samba it seems like people increase the intake to 35mm. Is this correct? Any thoughts on this? What about exhaust valves? Is it possible to purchase the bigger valves? I plan on having the machinist do a three-angle valve job and match the openings between intake manifold and heads. Anything else to consider?

- CAMSHAFT: I was considering using either WW’s high performance cam or BBT’s Okrasa / Pre-A camshaft (https://www.bbt4vw.com/en/catalogue/5-engine/2-low...sa-style-/). Thoughts for which one is optimal given a 69mm or 74mm crankshaft set up? Can I use the stock cam gear or should I upgrade to a new cam gear?

- IGNITION: I plan to use CSP's Pacemaker distributor (https://www.csp-shop.com/en/electric/distributor-csp-pacemaker-usb-905-205-csp300-30200b.html). I used this on my other build and enjoy the fact that you can make it look "stock" while being able to dial it in for one's specific engine needs. Its a great product.

- EXHAUST: I plan to use CSP’s High Flow Exhaust (https://www.csp-shop.com/en/exhaust-heating/csp-high-flow-exhaust-251-001-030hf-30494a.html). I used the same exhaust on my mild vintage speed build and find the sound to be ideal. Is this enough exhaust though? Would an Abarth exhaust be better?

- FLYWHEEL: I don't plan to lighten the flywheel.

Anything else I am missing? Any advice/suggestions/considerations are warmly appreciated. In addition, any links to other builds are welcome. Thanks in advance!

[[email protected]]

The reason most use the 69mm ww crank / okrasa crank is because this crank will allow you to use the stock 5.110 36hp rods now days AA Performance makes much better than stock 36hp H beam rods ..the 74mm crank/ porsche 356 you have to use the porsche rods or have the crank turned down to chevy journals porsche parts are more expensive bearings cost alot more than vws so folks tend to go the 69mm because of expensive ....if I Remember correctly 72mm crank was the biggest size for 36hp rods not much rod length 36hp rods out in the market there is only one size being made ...74mm you would have to do more clearancing to case and cam lobs ....also most who build to the 74mm crank/ porsche rods also use the porsche 356 83mm cylinders to fit the 36hp by redrilling them to 36hp pattern and use the vw 1500cc 83mm piston ...but it's alot of modifying and expense can be high .... porsche 74mm crank and rods use a 22 wrist pins ...69mm crank /36hp rods use 20mm wrist pins so its all about pistons on the market lots of 1500cc 83mm and 40hp 83mm pistons out there ..most folks mix and match parts to make it work but also folks are using what's on the market not much for these 36hp builds .. A 69mm crank you can use the 36hp rods stock or h beam and use 40hp 83mm pistons since these pistons are 20mm pins I would use 1500cc cylinders since they are longer and turn them down so no cylinder spacers are used but expense can add up.....but if you Insist on the 80mm /81pistons I belive they were made for the 64mm crank but can use with the 69mm crank with them but spacers maybe needed but not a Difficult things to get or have made ...... much simpler way to use a 69mm than a 74mm .... I see no difference in the 80mm and 81mm

Pushrods ....go with 2 piece cut tho length pushrods you can't use stock pushrods with 69mm crank or 74mm crank also new lifters will be needed AA performance sells them ....

Head/ valves.....some will insists the the stock 33mm intake valve is more than enough with 80 or 81 pistons but if your builder insist on bigger valves 35mm joe ruiz aka mr.okrasa here on thesamba use to sell them ...exhaust should be fine but if your builder insists on bigger valves you can use the 33mm intake and use that as an exhaust ....35x33 stock is 33x30

Camshaft ..is kind of difficult you have to get a cam that works with your build and Compression that you tend to use ..just because a cam is for sale doesn't mean it will work with your build first see what your gonna build and than go from there sometime a custom grind will be needed remember it all has to work together .... new cam gear are a good thing but the last time I looked no 36hp cam gears are being made yes porsche 356 are being made they are the samething but expensive do to it being a porsche part those use to be vw 36hp gears but the sellers need to cash in and sell them as porsche 356 gear and expense
went up on those.... no the vw type 1 gears are not the same can't use those but the straight cut cam gears will work with these 36hp engines lots of those on the market but than again some will say that the straight cut gear can get Annoying over time some love it ..depends on the owner on that but they are much much cheaper than those porsche 356 gears ..

[jbannon]

Jerry, thanks so much for the reply. Per your comments on the 74mm crankshaft, I was familiar with the challenges of fitting a Porsche 74mm crank in a VW case, including rods, pistons, clearance issues, etc. However, I was wondering if the Wolfsburg West 74mm crank (https://www.wolfsburgwest.com/cart/DetailsList.cfm?ID=111198600A), plus their shortened rods (https://www.wolfsburgwest.com/cart/DetailsList.cfm?ID=111105401B), and 81mm pistons (https://www.wolfsburgwest.com/cart/DetailsList.cfm?ID=111198081) solved these challenges or at least made going with this type of set up easier? I haven’t found much on the Samba about the Wolfsburg West 74mm crank/rods/combo, and was curious if it was a viable option or provided any benefits over the 69mm crankshaft without loss in reliability.

Per your thoughts on the cam I’ll speak to my machinist.

Thanks again for the other conment—all were appreciated and useful.

[[email protected]]

Yes I've seen those/ that ww 74mm crank I've emailed them in the past about its specs and I wanted to know the rod jounal size on them but was never emailed back from them ...its ether 36hp or a porsche jounal but like I've said before I was told in the past that a 72mm crank was as big of a crank to use the 36hp rods with .....so who knows if that ww74mm has ...I'll try to email ww again to see what's up .... they should be clear about specs so folks know what parts to buy or look to buy for it .....

[jbannon]

Thanks for the update. Please let me know what you find out.

[[email protected]]

Ok after many emails 👏👏....ww emailed me back and told me that the 74mm crankshaft they sell is indeed vw 36hp journals ....but modifying Existing pistons skirts will need to be modified or clearance..I remember that Mr motorhead informed me along time ago that 72mm was the biggest size with 36hp rods since rod ratio was smaller ...but I remember telling him how for the 40hp with 69mm crank you can offset the crank to 74mm with 36hp rods and they didn't seem to have a problem but thats how far we went ...... but than again he was building high performance engines so I can see why he liked the higher rod ratio ....so i guess 74mm with 36hp jounal should be fine for a street engine ...they even sell the cylinder spacers for their 74mm cranks with 81mm pistons setup as well ......so it seems that their 81mm piston are all ready have the clearanceing Supposably for the 74mm crank so that shouldn't be a problem with theirs but if you use a different piston or company most likely piston skirt will need to be cut down for clearance......

[henry roberts]

With your exhaust valves, can I suggest reading page 3 of the thread below before you add larger valves.

https://www.thesamba.com/vw/forum/viewtopic.php?t=757037&start=40

[scotty timmerman]

Look up Blackline Racing on facebook for info on heads/valves. They use honda/acura valvetrain parts. I didnt know of them when I built my okrasa 36hp but if I did thats what I would have done.

With the 74mm crankshaft and a Porsche 356 pre-A cam grind you have to grind quite a bit off of two rods to make them clear the cam lobes. I had a WW cam blank ground by web cam to the Porsche 356 pre-A specs. I also was using a crank done by DPR. I used a stock cam gear, it has to be machined to be used with bolts.

83mm big bore 40hp pistons and cylinders are also an option if you want to put the work into cutting and clearancing the cylinder fins.

things I would suggest: drilling and tapping the oil galley plugs for pipe plugs. drilling and tapping for full flow oil filter. Scat chromoly Porsche 356 gland nut. case savers/8mm studs. one thing you have overlooked is clutch choice.

you can find details of the vintage speed 36hp I built in the link in my description under 57 oval build thread.
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84 vanagon westfalia wolfsburg edition

[jbannon]

I wanted to close out my part if this discussion and let you know what I ended up going with. First, a big thanks to those who replied and offered suggestions. All of your comments were very helpful.

I spoke to Tony from Wolfsburg West (WW) who was very helpful and sent me WW's requirements/recommendations for both their 69.5mm and 74mm crankshaft. Tony also provided suggestions regarding other equipment, which I will share below.

I decided to go with the 69.5mm crankshaft. This decision was based on the machining requirements the 74mm needed, as well as my goals for the engine. In addition I will use the following equipment:

- 2 piece lifters from AA Performance Products and chromoly pushrods from CSP. I will cut the pushrods to the appropriate length to avoid using shims.

- Heavy duty rocker shafts from Stefi G.

- WW H-beam clearanced rods.

- WW 81mm pistons with shims recommended by WW.

- WW performance camshaft.

- 32 NDIX carbs and CSP bell crank linkage

- Carb manifolds from Stefi G.

- Oil cooler from Airflow systems

Once machine work is completed and assembly begins, Ill post some photos.

Thanks again for your help!

[Alstrup]

Hello.
Did´nt see this thread until today.

1. Even at 1525 cc there is no real advantage in going larger on the intake valve unless you are really chasing power. The 33 mm intake with a good valve job flows about 120 CFM @ 0,500" and 28" depression. The 32 NDIXés will stop supporting power way before the heads are done.
2. If you have not already punched the buy button I would recommend against the WW cam. It is VERY inaccurate and not that nice. May I recommend an Elgin cam instead. These guys know their stuff also with the old cams. https://elgincams.com/
3. The warning about ratio rockers is basicly bs. and a result of not understanding what is going on along with poor camshafts. Inaccurate and poor camshafts need much more spring pressure to make the valves seat properly. Higher than needed spring pressure puts strain on the lifters and causes premature wear on the guides and seats. AA sells 1,15 rockers. Speedwell has 1,4.
The Elgin 66506-19 cam will be perfect with 1,4 rockers ending out at 0,424" lift. Right at 0,33 L/D
If you are affraid of lift the 102-16 or the M6708-18 with 1,15 rockers will give you about 0,368" lift. - Personally I prefer more lift to get more rpm band.
4. Compression was mentioned. That is a valid point, but you willl not get in trouble on that account. If anything the CR will be on the low side. You want to be as close to 9-1 as possible. When you have corrected the chamber around the intake valves especially you will be around 8,5-1 if memory serves. That is bare minimum imho.
5. Ignition. - You mentioned the Pacemaker. That is well. Just get the BT (programmable) version as NONE of the preset curves in the cheaper versions are what your engine will want when you are done. Also, I assume you want to keep the whole thing 6 volt. fine. Get the Lucas Viper ignition coil while you are at it. And also, remember to swop the rotor to a 0 ohm or 1 K ohm at the most or you will experience starting issues.

Good luck.
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993

[jbannon]

Thanks for your reply. I wish it would have come a little earlier! Regardless, it was very useful info and I can add a little more to my knowledge base. Thanks for the info on the intake valves, compression ratio, and coil! I purchased the programmable CSP Pacemaker distributor for the exact reasons you mentioned. I will forego adding the bigger valves given stock seems plenty enough for my application. I have already bought the parts but will take a look at your camshaft recommendation as I can always sell the WW cam if needed. Im curious what camshaft you would recommend if I didn't go with ratio rockers?

[Alstrup]

Several people, some buliders included, use the 102-16 grind for anything from "stock" Okrasa and up to 1500ish cc. It works well, but is a little gutless imho.
If you pay a little attention to detail, not being affraid of a little higher compression to properly match the cam, and some more valve lift it is very easy to pick up 10 hp and loads of driveability.
If you are determined to stay with stock rockers there can be an idea in increasing intake valve size because you need all the time area you can get in order to fill up the cylinder at only 320 thousands lift.
One advantage with the 81 bore apart from the obvius is, that the larger bore creates a little bit of squish on the outer diameter. So if you keep the deck tight this squish will help improving the mix quality quite a bit which again will release both power, driveability and a cooler running engine.
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993

[jbannon]

Any thoughts on BBT’s Okrasa camshaft?

https://www.bbt4vw.com/en/catalogue/5-engine/2-low...sa-style-/

[Alstrup]

Ohhh, I went deep into that when they first came out. It is a 356 pre A grind. i believe its from the 1500S. I do remember that I found that it was only interesting if it was used in conjunction with 1,4 lifters. (At least for me.) It only lifts 7,45 mm @ cam (0,293") and about 233 @ 0,50" Don´t take my word for it since its from the top of my heads. But its close to that.

If you want a cam that can actually support some real power in your Okrasa style engine Elgin is the man. I have not found better.
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