006 or 004

[Paul1953]

The engine in my buggy is a standard 1600 twin port type 1.

Mike H has almost completed my exhaust system. When I have this fitted I will need to assure myself that the noise level that a db metre picks up at each exhaust outlet at mid range revs does not hit 100db. The test rig that vosa uses shows a real time continuous read out to two decimal places. Although the official limit is 99db the readout can show 99.99 and you have a pass. Just 1 instantaneous indication of 100 is a fail.....  Technically the db reading should be that of the exhaust system and nothing else but in a buggy the engine is exposed and there is so much additional mechanical noise that it`s not easy at testing point to a). determine how much of the total noise is exhaust and how much is not... b), there has to be mutual agreement that any method you use to attempt to use to prove actual exhaust noise is theoretically sound.   It`s not impossible but the aircooled engine hanging off the end of a buggy is a rarity at IVA. The "normal guys" usually have front engined vehicles with rearward exhaust outlet giving plenty of room for silencing along with cats and unless you had fitted a 70`s 7 litre Hemi you would have to try hard to fail.

Right to my point finally......   Rocker clearance..  All my early Beetles were 1200 single ports and everyone had a sticker on the fan housing indicating a valve clearance of 004. Always measured with the engine stone cold. It was a rare event to have to adjust them once set correctly. Later, somewhere mid 70`s I remember talking to the Mill Garage mechanics who had seen the new beetles come into the showroom with .006 clearance stickers. Strangely Wolfsburg did not forewarn the franchise outlets and a full year went by before an official update was issued. There was no official reason given for the change and the rumour mill went into overdrive.
There has been much speculation ever since especially towards cylinder 3 dropped valves. Weirdly this was a much much earlier issue with type 1 engines pre- doghouse mod. The oil cooler sat directly in the cooling air flow to number 3.

Ok..... a question if I may now I have touched on the above to indicate I understand valve clearance issues and my query is just this..

At a clearance of 004mm the noise level is significantly lower than at 006mm.   So is there anyone on the forum who has and is running a type 1 engine of 1600 twin port type with a 004 rocker clearance. Can it be done without long term issues. (Appreciate I can close them down pre test and open up again post test but thats not my query).

[Doon L001]

Interesting what you say re noise. I have a modified engine with chrome alloy pushrods and the builder said rum at zero lash.

When I first fitted the engine I put  (I think from memory) 002 on inlet and 004 on exhaust as I wanted a safety margin while running in and before tweaking head bolts.

Engine sounded fine but as always the rattle as you passed a wall was evident.

When well settled I changed it to zero lash and was amazed at the reduction in noise, and the noise I lost was not a noise you really want,. Bit like a boil on the bum, you can get used to it but it's lovely when it's gone

Doesn't answer your question but there's a lot of noise in the rockers. Don't know if good solid (CSP?) ally covers could reduce it a bit

Doesn't answer your question though, sorry

[Merscury]

I have a 1641 tp standard cam and standard vw push rods.. I check/adjust valve clearances  every year. I do 2 to 3k miles per year. I set them to 004 with no problems and have done 11 to 12k miles. Tappet noise wise it is a lot quieter once the engine is fully warmed up

[pepsi81]

Paul,

I too run my tappets at .004. Farmer Rob recommended this when my engine was built. Think I too have chrome moly pushrods, I’ll check my spec’.
Managed around 3,000 miles, mind you my Mike (Beezledub) exhaust still sets off parked car alarms😂

[snoopy]

as long as you have clearance when the engine is at operating temperature you will be ok but personally never checked what 6 thou cold gives on a hot engine. My suggestion would be 4thou cold, then check when hot if you have clearance happy days and you get an extra 2 thou lift.

[IDA]

 004 to 006 was about 71? As people would Drive there VW's to a Garage for maintenance etc and It takes hour's for the engine to go back to size So the valves would be set why the engine was still Wide/Hot So VW made it 006 to be on the safe side.......So as long as the engine has not been used for like 24hrs? Set it at 004....

[pepsi81]

004 ‘ stone cold.
💋👍
Snowing again. Get them set 👍😂

[Dave DND]

As people would Drive there VW's to a Garage for maintenance etc and It takes hour's for the engine to go back to size So the valves would be set why the engine was still Wide/Hot So VW made it 006 to be on the safe side.......So as long as the engine has not been used for like 24hrs? Set it at 004....

Makes a lot of sense - just never heard it explained like that before   

[Paul1953]

Yes.... only way for engine to be truly cold is an overnight stand.  Old school thinking since the dawn of motor engines has been cold setting whereby the cold meant exactly that. On all of my 1200 single port beetles, and each one was ancient before coming into my hands, never lost their rocker gap setting regularly. The head cover gaskets never leaked. The push rod tubes never leaked. I can only think that the original VW supplied gaskets/seals were old school materials with consistent batch quality.

Pleased to hear that there is experience of  004 cold setting running for extended periods.  One of those odd things that stick in my mind for some reason despite it being 50 years ago and that is I have a two "pictures" in my head. The 004 sticker on the fan shroud just above and to the right of the dynamo being of red graphic on what may have been white background when new and the 006 being a silvered sticker with black graphics.

Thank you to those who have replied to my query..    As for a Mike H buggy exhaust`s being noisy "a la buggy norm" this one probably "breaks the mould".  ( Mike is a tremendously helpful, very friendly guy). I was quietly impressed when he agreed to create a system without seeing my buggy. Silverstone is a good 6 hrs non stop trip from my home and when I first spoke to him at the beginning of May we had gone into lockdown. As soon as I can I will add to my build thread.

[Manxdavid]

Rule of thumb in the dealers used to be .004 if you check them every 3000 miles, .006 if you don't.

[IDA]

I all ways for years did 006 Exhaust and 004 Inlets If the car! was used a lot ... But new they are just toys 004 unless sodium then 008 ..  I have been told at the same time as going 004 to 006 they were doing the 10mm to 8mm head studs swap..

[cunningstunt]

Mine are zero lash as HP parts.