# Hydraulic or solid head on JH block?



## Rabbitissimo (Dec 21, 2009)

Okay, so here it is... Can you use a hydraulic head on a JH 1.8l block that came with a solid lifter head? 
Will it just bolt in? What other modifications have to be done? If yes, what engine could you take a core head from? Can you run CIS with a hydraulic head? Are the injector inserts different sizes? Will you have to weld aluminum into the little ports?


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## crazygearhead (May 13, 2009)

why do ou want a hydro head? solid lifter is great, your not going to go faster because of a hydro head


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## Roc'N'Green (Apr 1, 2010)

Like stated above, you will need a bigger oil pump. 

You can use any Hydro head whether it is CIS-E or digi. You can find these heads on VW's 85-92. 

To do the digi head you need to get some CIS-E injector cups. I am currently running a 92 digi head on my 85 JH block on CIS-E. Only reason I did this was because the 92 head was recently refreshed and had a g-grind cam in it (found it for 50 bucks). 

All you should expect from switching to a hydro head is slightly quieter operation, and less maintenance.


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## Glegor (Mar 31, 2008)

Roc'N'Green said:


> Like stated above, you will need a bigger oil pump.
> 
> You can use any Hydro head whether it is CIS-E or digi. You can find these heads on VW's 85-92.
> 
> ...


 CIS injector cups in a digi head dont work right.. idk how you did it and got it to work.


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## ps2375 (Aug 13, 2003)

There are two diff size (as in outer diameter) CIS cups. I found that out when I did my MS install.


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## Svedka (Jul 4, 2008)

Used 85 and up cis cups when i was CIS on a 92 AA hydro head no issues


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## Rabbitissimo (Dec 21, 2009)

So in 85 all fuel systems went CISe? Techtonics sells hydraulic heads, and solid lifters are no longer available, unless you have a lathe. The Techtonics head has little (vacuum?) ports which would have to be properly blocked off to run CIS. Still, these are made in Brazil or ???? and some things are scratched off. I have heard hydraulic is much less maintenance.


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## Roc'N'Green (Apr 1, 2010)

^^^^ 
Hydro heads are less maintenance only because you do not have to re-shim the followers every 10k miles. If your car is a daily driver, it may be worth it. If you want performance go with the solid lifter head. 

Not that there is a power difference or anything. But, there are talks of valve float at I believe 6500 on the Hydro heads, where as I have read about solid lifter heads revving to 8k (granted that is on a race car with a big cam to justify revving that high, most of us are lucky to still be making max hp at 6250). 

In regards to CIS-E and Digi heads...... 

In my experience the outer diameter's are the same, inner diameters are different. 

A few months back I had one of each of these heads in my living room for mock up. I had to choose between two heads one a cis-e the other a digi, I was set on using the digi since it had a recent refresh, my only problem was the injector cups. 

The cis-e injector cups worked in the digi head so thats what I am now running.


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## Rabbitissimo (Dec 21, 2009)

CIS has a rev limiter built in, correct me if I am wrong, in the fuel pump relay as a safety precaution which shuts off the fuel pump at 6500 RPM, in case of a crash. There are replacement units available to allow 7000 or 8500 RPM, to allow a modified head to perform in that range. 
What about 83-84 1.8 blocks using CIS? Can you fit them with hydraulic heads? 
So, if hydraulic heads are all from CISe or Digifant, how do they interact with CIS? If you can find the injector holder to fit non air shrouded injectors, is that all it takes? I read there may have been older GTI's (83, 84) factory equipped with hydraulic.


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## kamzcab86 (Feb 14, 2002)

Rabbitissimo said:


> What about 83-84 1.8 blocks using CIS? Can you fit them with hydraulic heads?
> So, if hydraulic heads are all from CISe or Digifant, how do they interact with CIS? If you can find the injector holder to fit non air shrouded injectors, is that all it takes? I read there may have been older GTI's (83, 84) factory equipped with hydraulic.


 1988-1989 Cabriolets use hydro heads and CIS-Lambda. If you want a hydro head but have CIS, go get an '88-'89 Cabriolet JH head. As far as I know, the injectors and injector cups are the same on them as they are with the solid lifter JH engines. 

As already stated, the hydro heads require a high-flow oil pump. 

No A1 GTI came with hydro lifters/heads.


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