Bigger valves is better? Maybe not

I am getting my 1835 heads rebuilt. I spoke to couple of people about the advantages of having bigger valves put in. As you expect, nearly everyone had a different opinion. One said its not recommended because most likely they don't get the seats right. One said there is no point unless you go with a mild/wild cam. One said no point at all, he is running 2.1 stroker using standard valves and he loves it. But he also mentioned something quite interesting. He reckons that the drag guys are now experementing with smaller valves not bigger ones. Apparentley smaller ones create better airflow (kind of a compressed airflow aka turbo) and create more power. I thought that is quite a different view from the norm
Raf

Raf

this is what you put down as experience and what seperates the great from the dog engine builders.

An example is the 1300 twin port motor that came out in later years.
It had small valve heads and yes they flow really sweet. I had a drive of one the other day and you wouldnt pick it as a 1300!

As for your motor - what cam, carbs and exhaust are you running.

My opinion ( :o ) is if you are running heater boxes stay with stock valve heads

You can get 40/35 put in an 040 head and that will flow better but you have to be able to pull the gas with a bigger cam and you have to feed it with carbs ( Webers - not the kads ) and you have to be able to exhaust properly ( not heater boxes and pea shooters )

What sort of heads are you looking at?? and what size valves are you thinking of???

Yes you can run a stroker with stock heads BUT you could make HEAPS more top end power with an expensive set of decent heads. You can still have HEAPS of torque and FUN with the stockers though

Barry

Its the standard cam. I do have a mild one but don't want to split the case at this stage. I will be running 40IDFs or 40DRLAs. And I will be running heater boxes. How does heater boxes affect it compared to J pipes?
Raf

2 ways Raf

First they are stock diameter and "can" be restrictive in flow.
Some people (Berg for example) make a larger dia heater box. They are expensive though.

Secondly the heater box retains heat and can lead to cracked heads by not being able to disapate the heat.

This is why J tubes were invented.
Nice cheap solution to the problem of bib motors and exhausts

The 40 drlas are to big i think you should sell them to me.😀

Larger valves in a stock head won't give you much without extensive welding and porting. with stock cam you'll still end up with less power throughout the rev range. Having the valve guides topped, running heavy-duty or dual springs and fitting high-lift rockers would be a far better proposition at this stage. When you're ready for the larger valves, ie; when you're running more than 1900cc and/or your cam produces peak power above 5000rpm, you really should consider the 044s as a starting point.

You might also find the carbs mentioned won't work too well with your combo.

Why do you need dual valve springs ?
Do you really think a stock cam will give valve bounce :jesus I don't think so.

ratio rockers................... no use opening the valve more if you don't have the duration.

Really an 1835cc should not be running a stock cam.

Well I have got to admit I am new to vw motors but have built many drag V8s and it was more important to get everything to match. Basically what craig was getting at I think. Bigger is not always better.

So what you are saying, for an 1835 with dual 40 DRLAs and heaterboxes, I am better off with a mild cam, ratio rockers and standard valve?

Yep - NOT that i know but from the info i have scavenged that would be my guess.

You "might" consider 40/35's instead of 35/32's (stock) in some 040 (stock) heads but i dunno if i would. Extra money and stuff.

You said you dont want to split the case as it is a standard cam there.
A stock cam will accept 1.4 ratios and this is good. Dunno if i would waste the money on 1.25's. Ratios are not cheap.
The cheapest i have seen is like $400 a set.

By the way - what sort of crank have you got in there. If it is a standard cam is it a stock crank.
Dont want to wake the engine up too much if it isnt a counter weighted one.

Depends what you're using the motor really. If it's going to be a daily driver, you don't want everything dig. Particularly on a street engine where figures really mean nothing. Ultimately, it's important to match it with everything your motor currently has, to compliment the other parts and therefore make the best sort of power for the job. With what you mention you already have, I'd say stick with stock valves. They'll do the job beautifully and you'll have nice smooth power, which is most important for daily use. Perhaps some 1:1 ratio rockers?!?!

Yep, it will be a daily driver. It has stock crank as far as I know. I know nothing about ratio rockers, why is 1:25 bad or not worth it? Being that it will be an 1835 daily driver (city mainly not even highways) with twin 40 DRLAs and stock everything, what ratios would work with it?

http://www.aircooled.net/new-bin/viewproductdetail.php?keyword2=ECV0008&cartid=0113200427463973

1.25 Scat $250 US = @ 75c = $333 Aus + 15% duty + 10% GST = $420 Aus + shipping

1.4 Scat $250 US

1.4 budget $190 US

For over $500 delivered get the most you can.
1.25 over stock 1.1's just not worth it for that sort of money.


Raf
have a read here

http://www.aircooled.net/gnrlsite/resource/articles/mods.htm

and

http://www.aircooled.net/gnrlsite/resource/articles/t1hpeng.htm


Those ponies start to get expensive.

Where do you stop????

You are not wrong Barry, I have a big hole in my back pocket which is bound to get bigger, bought the engine for $1k to discover it was stuffed. New P&Cs cost me $600, 6v 200mm flywheel and clutch $450, reco. heads $300, dual 40 DRLAs $600. So nearly $3k so far and still have to sort out ratios & exhaust :jesus

Then stock heads and rockers it is!!!

That is what i have!

For the exhaust a Thunderbird header and a trip to Mr Muffler to chop up the muffler and get it tucked up underneath

karmannghia60 wrote:You are not wrong Barry, I have a big hole in my back pocket which is bound to get bigger, bought the engine for $1k to discover it was stuffed. New P&Cs cost me $600, 6v 200mm flywheel and clutch $450, reco. heads $300, dual 40 DRLAs $600. So nearly $3k so far and still have to sort out ratios & exhaust :jesus

What a bummer 🙁 That's why 10 years ago I decided to always by new.

With valve lift, it is proportionate to valve size. Lift should be a % of the valve diameter. If you go over this % then you are openning the valve to far and you are gaining no benefit. With standard 040 valves 1.4 ratio rockers will open the valve more than what is needed. The problem you will then have is that you are putting additional strain on your pushrods! Then you will spend money on Chrom Moly pushrods all to fix a problem that should not of occured !

Like Andy said , its all about the combo :thumb

One more question, if I decide to go the full hog (mild cam, balanced crank, ratio rockers, twin 40DRLAs or 40IDFs, 009 dizzy), what valve size would be better in this case? 40x32 or 40x35.5?

"Install Ratio Rocker Arms: 1-2 hour installation time. If you can adjust valves, you can install these. They MUST be used with shorter pushrods. We recommend 1.4 rockers (which DO work on stock engines). 1.25 rockers give you almost no gain for your work; waste of effort. 1.25's work well with some high performance cam shafts but you have to know what you're doing! 1.4's will really wake up a stock engine, especially if it's a dual port, and if you have additional carburetion. Replace your valve cover gaskets at the same time. If you have problems with leaky valve covers, make sure that you use genuine VW valve covers and bails." - from John C at AC.net

Craig - why do people (not just ACnet) recomend putting 1.4's on a stocker as a hot up??
It certainly be recommended to me with my cam and my stock heads????


Raf
There is no simple answer. You will get many. Hot Rod Matt has 40/35 040's in his 1776 and i think you will find 2 Guns will as well. Both these were CBB based motors.
I have 35/32.
I think Jak was/is 040 and 40/35

Jak was definitely running J pipes and i dont
Dont know about matt???

On the last dyno day we were all in the mid 60's.
Matt runs Kads.
I run IDF's

IF you have money then i think i would go for 040 and 40/35

Do it and have an experienced answer 😉

Last question, promise. I can get the heads I have now reco (ie replace guides) for between $200 & $240. While I can get full reco ones from the US (I will be there next week) including new 40x32 valves, new 3 angle seats and new silicon bronze valve guides for about $300. The later option looks better value, what do you think?
Thanks a lot

There is no simple answer. You will get many. Hot Rod Matt has 40/35 040's in his 1776 and i think you will find 2 Guns will as well. Both these were CBB based motors.

My heads were done for the bigger valves by someone else some time ago.

2guns uses standard valve sizes but they have been reshaped and swirl finished around the stem and the back surface. The porting job on his heads is awesome and flows beautifully.

Raf

i just like blabbing so i will answer

The US ones DO sound like good value BUT.......

They also sound like 041's which were big inlet and stock exhaust.
The head casting was different and didnt cool as well.
Cant get the 35 exhaust in these???

Either way that is an awsome price.

Can hardly buy new stock heads in US $ for $300

If they were 040 castings i would buy them

blue74l wrote:"Install Ratio Rocker Arms: 1-2 hour installation time. If you can adjust valves, you can install these. They MUST be used with shorter pushrods. We recommend 1.4 rockers (which DO work on stock engines). 1.25 rockers give you almost no gain for your work; waste of effort. 1.25's work well with some high performance cam shafts but you have to know what you're doing! 1.4's will really wake up a stock engine, especially if it's a dual port, and if you have additional carburetion. Replace your valve cover gaskets at the same time. If you have problems with leaky valve covers, make sure that you use genuine VW valve covers and bails." - from John C at AC.net

Craig - why do people (not just ACnet) recomend putting 1.4's on a stocker as a hot up??
It certainly be recommended to me with my cam and my stock heads????


Do it and have an experienced answer 😉

I guess you will read so many varied opinions, and each to their own in which ones you want to beleive .:thumb

I remember reading about a fantastic "black box" , that would do wonders to my holden, written by Peter Brock, it was called a "polariser" !!😀😀

Barry I guess we can agree to disagree about using 1.4 ratio's on a stock cam/stock head combo.

I would ask, for my learning benefit 😀 what do you think/read should be the overall lift for a standard size valve. What lift would be to much ???

Also what is the increased valve spring load ?
Do you loose HP with this added load ?
How much shorter do the Pushrods need to be ?
Do you need to fit chromoly pushrods?
what will this cost ?

What is the added HP to the stock motor ?
I have read that the ratio rockers will increase a standard 1600 tp motor's Hp by 2-3hp, this same book also said you can get over 100hp from a 1600 ??!!

Not saying your wrong Barry, I just dont' see the benefit on this combo, but maybe you can clarify for me the above points.
:thumb

Blab as much as you like Barry, I am getting a lot out of it. Looks like I will go for the US heads. I just have to struggle with airport security & customs

Craig

the whole problem i have is i now only have 2 VW cars

I have the Type 4 Kombi and the beetle

I have owned and worked on
1200 stock , 1300 stock , 1600 stock Progressive IDF same with 1776 with cam and head work

I should have started when i was 17 instead of all the other stuff i did. I would have a lot more motors under my belt.

After the 90.5 Vs 94 i find the 1.4 arguement a close second. Probabally not as much talked about here.
Bit like the 040 Vs 041 Vs 044

Oh - i wish i had built/driven more motors and cars!!!

Oh well - maybe by the time i am 85 i will have a lot of info but everyone will say - "what a grumpy old fart!"

That's cool Barry, I was not looking for and arguement, just some info I may not have been exposed too.:thumb

Piston size will always be a debate because it is influenced by crank stroke.

But the opening of a valve will always reach a point where it is no use opening it any more. If you want more benefits you then need to go a larger valve, you can then increase the lift to the max advantage of this valve and so on, you then move onto multivalve heads etc.

karmannghia60 wrote:Last question, promise. I can get the heads I have now reco (ie replace guides) for between $200 & $240. While I can get full reco ones from the US (I will be there next week) including new 40x32 valves, new 3 angle seats and new silicon bronze valve guides for about $300. The later option looks better value, what do you think?
Thanks a lot

If your goin to the US of A bring these back with you,there brand new 100% better than yank recons, http://www.cbperformance.com/catalog.asp?ProductID=77 and there only $250AUD :thumb

This price is of each bare head (no springs, no valves, no guides nor seats) + delivery. I am getting the PAIR complete ready to bolt one for $300 delivered

One more thing, do I need to change the push rods if I use 1.4 ratios?

"Proper length ensures that at "half lift" the rocker arm is pushing the valve straight in. If "rocker geometry" is off, the valve will be pushed up or down, and this results in valve guide wear. Get it right! This is one of the most intricate parts of engine building. Cutting and assembling your pushrods is a real pain (I hate it). For assembly purposes, you need an adjustable pushrod to have any hope of achieving optimal rocker geometry. You use the adjustable pushrod to cut your chromoly pushrods to the desired length then tap the ends in using a hammer and two old lifters (to keep from screwing up the ends of the pushrods). Sometimes, depending on the pushrod brand, they have to be drilled out to match the pushrod ends! Sound arduous? Well it is, but guess what!? Aircooled.Net offers the service of cutting and assembling your pushrods, saving you the do-it-yourself grief!" - from ACnet

MMMMMM gets back to my point, why bother on a stock head and stock cam combo. All this headache for what ????

But it is not a stock head.
Raf said they are 40/32 valves.

Why do it?
1) hopefully to have a better breathing head and a few more ponies to boot.

2) to have an opinion as to whether or not any one else should do it.

This way when i finally get around to doing mine Raf will post and say "yes - do it. My motor happily sings up to 6500 and feels like it can go some more!"

Barry

I think Craig is puzzled by the use of a stock cam with the new heads and ratio rockers.

I'd be interested to hear your thoughts.

Cheers

Craig is just confused.
Last time he asked a question he wanted to know why his motor blew up cause he put water in the radiator tank in the front boot!!!

It is a discussion we are having as to the benefit of running 1.4's on a stock cam/heads.

Craig thinks there is no benefit.
I believe there is a breathing benefit.

Dunno.
Never done it. Want too. Just short of $$$$

Do you have one???

Just at $750 a set of 1.4's here i aint gunna race out and but a set.

Might consider a set from AC.net at $190US though if i can find some one to bring em back for me :bounce

63dub wrote:Barry

I think Craig is puzzled by the use of a stock cam with the new heads and ratio rockers.

I'd be interested to hear your thoughts.

Cheers

ummm not puzzled, I just know it doesn't work.

blue74l wrote:Craig is just confused.
Last time he asked a question he wanted to know why his motor blew up cause he put water in the radiator tank in the front boot!!!

It is a discussion we are having as to the benefit of running 1.4's on a stock cam/heads.

Craig thinks there is no benefit.
I believe there is a breathing benefit.

Dunno.
Never done it. Want too. Just short of $$$$

Do you have one???

Just at $750 a set of 1.4's here i aint gunna race out and but a set.

Might consider a set from AC.net at $190US though if i can find some one to bring em back for me :bounce

So tell us the benefits Barry, you still haven't answered my other questions ???

I don't "think" there's no benefit, I know there's no benefit !!!


As for your first sentence in your post :jesus, ?????

blue74l wrote:Why do it?
1) hopefully to have a better breathing head and a few more ponies to boot.

2) to have an opinion as to whether or not any one else should do it.

This way when i finally get around to doing mine Raf will post and say "yes - do it. My motor happily sings up to 6500 and feels like it can go some more!"

mmm Barry you need to change the Duration of the cam not just the lift to increase overall engine RPM. If you think that bigger valve heads with ratio rockers and a stock cam will give you 6500rpm then you better brace yourself for a steep learning curve !!

Now I know why "Stans the Man", and my engine happily out performs others !!


Anyway each to their own, you can lead a horse to water.......................

mmm so no 1.4's on a stock cam, stock head combo 😀 bummer

I have 1.1 ratio rockers (standard) on a mild 1916cc😀 and have 111hp@wheels 😉

So verdict: Go a mild cam, slightly bigger heads with some 1.25 rockers:thumb

karmannghia60 wrote:Last question, promise. I can get the heads I have now reco (ie replace guides) for between $200 & $240. While I can get full reco ones from the US (I will be there next week) including new 40x32 valves, new 3 angle seats and new silicon bronze valve guides for about $300. The later option looks better value, what do you think?
Thanks a lot

Don't do it!!!

The 041s were originally produced by VW, but after their wins in the 60s had caused the authorities to limit them to a 28mm carb in order to give the competition a chance.

If I catch you before you hit 'merica, try aircooled.net's ported heads on special, also for US$300. You'll get more power, more torque, and they won't crack between 5&15k miles (unless you go for too high a compression ratio.)

Sorry to sound like a bit of an ad (but I will say that aircooled, while a bit more expensive than some, have always treated me well,) but I wouldn't like to see anyone waste their money on 041-style heads.

And Craig:

I agree with you on most things, but I think you oughta rethink the ratio rockers on a stock cam bit...

Grab a stock head and your caliper and think about the flow at various lifts. I think very soon you're gonna realise why the Engle W100 and a stock cam with 1.4's have about .417" lift...

Do some sensible porting and lift a little farther and you'll start to see why some of us are a little partial to stroking...

Where is the reply from Jak gone? Disappeared!
Hey Jak, would the cam I bought off you work with this? I am getting too confused with all this (but learning a lot). To summarise, this will be a daily driven engine in the KG. What I have so far is:
- new heads bored for 92mm with 40x32.5
- new 92mm P&C
- dual 40 IDFs or Kads (I am tosing which set to use)
- Extractors
- 009
- 200mm clutch/6v flywheel
- standard everything else
Under consideration, 1.4 ratios, swivel feet rockers & Jak's cam. Although I'd rather not split the case but I will if I have to. I am not about to drag race it. Now make it simple for my little mind
And thanks a lot

70AutoStik wrote:And Craig:

I agree with you on most things, but I think you oughta rethink the ratio rockers on a stock cam bit...

Grab a stock head and your caliper and think about the flow at various lifts. I think very soon you're gonna realise why the Engle W100 and a stock cam with 1.4's have about .417" lift...

Do some sensible porting and lift a little farther and you'll start to see why some of us are a little partial to stroking...

Some understanding of cams maybe needed, its not all about the lift !

duration and overlap ???

And yes I know all the various measurement etc.

Doug I have no problems with the benefits of "lift", just with the right sized valve.

So what do you think is the maximun lift a valve should be opened to , proportionate to the diameter ?

Just wandering what everybody thinks it should be ? regardless of cams and rockers etc
Happy for someone to tell me 🙂

If you can find some flow figures for a stock 1600 head you will find the flow incrases quite steadily up to about .400" before the rate of increase starts to drop off. Increases remain useful up to nearly .500", in fact. This means some rather useful increases in flow, therefore HP (especially top-end) can be gained by increasing the lift of the valve while retaining the same theoretical duaration (the actual useful duration actually increases slightly with ratio rockers.)

I can't quite remember where the 1.4 ratio comes from, I think it was Mopar, but it just happened to be just right for VW heads and led to the lifts you'll find on the old-fashioned cams... The other end to the mild cam lift figure is .476"; which is the maximum theoretically possible lift that can be used with a stock head and springs.

So do you believe that you can open a valve to 35% of its Diameter ?

I don't see why you are hung up on this ratio bit. I do know that if you stick larger valves in a stock head without re-shaping the combustion chambers properly you will have to lift them a lot further to get close to a stock flow (hence power.) In fact, stock heads fitted with 40x35.5 valves in general need more lift to get them flowing properly. This is not due to any magical ratio of lift to valve head diameter, simply shrouding and the need for the gasses to turn further around the valve head.

70AutoStik wrote:I don't see why you are hung up on this ratio bit. I do know that if you stick larger valves in a stock head without re-shaping the combustion chambers properly you will have to lift them a lot further to get close to a stock flow (hence power.) In fact, stock heads fitted with 40x35.5 valves in general need more lift to get them flowing properly. This is not due to any magical ratio of lift to valve head diameter, simply shrouding and the need for the gasses to turn further around the valve head.

Its not magical, but it is a ratio or proportionate to the valve size. The fact that you have just said that a larger valve needs to open more confirms that each valve needs to be opened to a certain point in relation to its size. You have just proven my point that I'm trying to make, lift has a direct relation to the size of the valve. The lift should equal to about 25- 28%of the valve diameter. Any more and its not really doing anything.
So a 35.5mm valve max lift=9.94mm or .390"approx.
And without changing any other characteristics of the cam except lift with the rockers, max power will still be at the same rev ranges as before.

So in my opinion I wouldn't bother opening a standard valve any more than this. Larger valve then a different lift etc etc

Anyhow I'm sure we all have different ideas, and that's cool:thumb
But at least we agree the bigger the valve the more lift it needs to achieve the same end results 😀

what's all this high liftin doing momentum-wise? revs go up... flow goes up... valvetrain load compensates the blue thingy starts talking to the red blob... left hand starts talkin to the right hand...:alien

What you been smokin', Craig? You're trying to tell us that all VW aftermarket cam manufacturers (and VW's own racing division) don't have a clue?. Ever heard of Super V? Ever done the maths on 99.9% of performance engines?

In fact, the early 1200 and the 13 & 1500 engines (and the 1600 on the exhaust valve) exceed your recommendation!