Street porting a 1.9 big valve head

[GTJIM]

I have always rough cut the seats and put the 60 degree cut into the port before starting porting - mainly to give a guide as to where everything will end up. Always leave some metal on the actual 45 degree valve seat though as a carbide burr or stone skating across a finished seat is a disaster!
The first step I use is put the exhaust seat insert in then blend the area.

BTW: Using the bigger 1.85" or 1.88" inch intake valves will leave precious little metal between the valve seats and leaves the area real prone to cracking. The risk is justifiable for race engines but for a high milage road engine stick with 1.72" intake and 1.5" exhaust - there will be pee-all difference with performance on the street.

[Tru-Craft]

Todd, I guess you could port the runner area around the intake and exhaust manifold mounting area, before machining. But, I don't see how you could port around the valves before installing the exhaust seat, new guides or doing the valve job! I did all the porting after the valve work was semi-finished, just final valve seat finishing was done after.
Lots of porting work after the valve job!!!
I milled the manifold mounting surface, and head gasket surface last. Then broke the sharp edges left by machining.
Lyle

[RallyBob]

Originally Posted by neuropel Bob, I had a question regarding porting the heads. Another person on the list told me he was doing the porting BEFORE having any of the machine work done, which didn't make much sense to me. He is going with the 1.72" valves as in this thread. In your thread here you showed a funky little "lip" in behind the valve that you had to carefully blend in, and mentioned this is often why you go with a 1.84" or 1.85" valve. Is it possible or feasible to properly port a head before having the larger seats cut? I don't see how. It appears you have to work from the edge of the seat back, and I also noticed how you take away part of the guide (which in this case would be put in AFTER the porting). Ever hear of anyone doing it this way? He claimed that by doing the porting first, the "lip" area is already gone when you cut the seats. Todd

I would strongly suggest porting after the seats are cut. If you over-port the head before the seats are cut, you have no where to go, you can't back up! It's a good reference to have the seat diameter in front of you as a guideline.

You will not eliminate the 'lip' under the intake seat with 1.72" valves unless you over-port the head. So that would be a bad thing. You'd end up with no venturi at all before the seat, and airflow will suffer as a result.

[cristian68rekor]

Is it any difference beetwen 1.7 and 1.9 heads ? I ask because I have one 1.7 head and I want to port it . I think it has a smaller chamber and the valves re the same 40 & 34 mm diameter.

Regards,

Cristian

[RallyBob]

Originally Posted by cristian68rekor Is it any difference beetwen 1.7 and 1.9 heads ? I ask because I have one 1.7 head and I want to port it . I think it has a smaller chamber and the valves re the same 40 & 34 mm diameter.

Port sizes and shapes are the same as a 1.9. Combustion chamber is indeed smaller than a 1.9. It is smaller than a 1.9H as well, but not as small as a 1.5 or 1.6 chamber.

If you have standard valves in that 1.7 head, I would suggest you do not port it. You risk damaging the airflow, making it worse than standard. With larger valves then you can see some benefit from porting.

Bob

[caramiciu]

Hi,
All of this is great.The lessons I am learning from you guys are,as they say, "priceless".You guys are so far ahead.
But here's my situation.
I have a 1.9 and am ready to change it to a 2.0 but the larger valves are not available from OGTS .. so
Is there a simple, easy to read list of partnumbers/make and related machining that can/should be done to achive my goal.
I only want to get more (120HP?) out of this engine and not race.
If I can get away with minimal machining would be great

thanks

[neuropel]

My advice is for you to talk to a local machine shop. Many people go with aftermarket small block chevrolet (i.e. SBC) valves and guides. They are cheap and high quality. Many people here use Manley stainless steel valves, which you can buy individually from Summit Racing. Most any decent shop can cut the seats for the bigger valves and install the new guides for the valves and hardened seats for the exhaust valves. You will need help with valve springs, seals, and retainers but perhaps Bob or someone (including your machine shop if they're decent) can chime in for specific details on which springs can be recommended for certain valve configurations such as the 1.72" intake and 1.5" exhaust valves in the examples in this thread. Don't forget your cam specifics either. Schneider Cams is one place that will regrind your cam to new higher performance specifications (one grind they have is called the 290H, for Hydraulic lifters, and is said to be a nice profile for performance). There are MANY options for this. Have your lifters reconditioned at the same time. Cams and lifters are available from Opel GT Source as well. You may also want to consider taking the porting details mentioned here to your machinist and see if he will do it for you. None of this stuff is impossible...just take the time to read and learn what should be done and then go and find someone to do it. There are part numbers posted in earlier entries in this thread. I copied a link below for you as an example of the manley valves you might consider:

http://store.summitracing.com/partde...5&autoview=sku might work for your intake valves. (It's really an exhaust valve, but it would work for an intake valve in your case since it is the right size).

http://store.summitracing.com/partde...5&autoview=sku might work for your exhaust valves.

You would then need guides installed (ask your shop), and once you decide on springs, you could have any necessary machining for new spring seats completed. Your shop may also have recommendations (or perhaps someone here will?) for seals and retainers.

It's a bit overwhelming when you first look into it, but once you read and ask the right questions you'll arm yourself with the knowledge you need to get a nice, sound, high performance engine.

Search the archives...nearly all the information you need is likely already here somewhere.

Todd

[caramiciu]

Thanks,

So this is what I'm thinking..
I can get all the parts for the change from OGTS except for the valves.
If I get the valves you mentioned, can I install them with the new OGTS parts(pistons,lifter and the "combination" cam)without changing the valve springs,seals and retainers?
or
should I just wait for the OGTS valves?
talking to Dennis (OGTS) he does not mentioned any machining with the larger OGTS valves, except the seats

Thanks

[neuropel]

Can't use the chevy valves with the opel springs I don't think. You CAN use the larger opel valves with the stock spring setup and be just fine I've heard...probably your easiest way it sounds.

-TK

[GTJIM]

Use SB Chevy valves - the BB exhaust listed above is too long (5.350")

Any 1.72" Intake/ 1.5" Exhaust from any SB Chevy V8 can be used though the swirl polished, reduced stem ones are nicest. Standard length (4.88"). With SB valves you will have to get springs, retainers and collets to suit plus a spacer to replace the Opel exhaust valve rotator. Also the valve guide bores have to be sleeved to the smaller (11/32" - 0.343") Chevy size down from the Opel size (9mm - 0.354")

If you can be patient (THAT word again!!) the 2.0 Opel valves fit in with your original springs and retainer caps - but watch that you have the necessary "round groove" Opel collets as there are two types. These valves are only marginally smaller than the SB Chevy valves (In 44mm - 1.73" Ex 37mm - 1.46") and fit with the Opel parts - you may need to 'fresh-up' the valve guides though. These valves and the standard springs can be safely used with up to 0.425" lift cams.

Using either type of valves you will have to get the seats recut bigger and blend the ports to suit. Don't forget the hardened seats for the exhaust valve!

[neuropel]

Originally Posted by GTJIM Use SB Chevy valves - the BB exhaust listed above is too long (5.350")

Yep...you'd have to go with this one:
http://store.summitracing.com/partde...5&autoview=sku and have it cut down (no big deal for the shop). This one would likely work for you for the intake side. I just ordered 4 myself for a 2.4 head!

But don't limit yourself to just these...they're just examples!
Bob apparently likes 1.85" in looking back through this thread.

-TK

PS...by the way, all Opelers I've met here ARE patient Jim! With the fact that you have to wait on parts, you often have little choice. I have an entire car I've been waiting on for 6 years!

[RallyBob]

Originally Posted by neuropel But don't limit yourself to just these...they're just examples! Bob apparently likes 1.85" in looking back through this thread.

Yup, like these:
http://www.opelgt.com/forums/32251-post272.html
Part numbers of the valves, plus you can see the comments written on the box as they were custom-cut to size by Manley. (intakes only)

Bob

[RallyBob]

Originally Posted by caramiciu thanks guys, as always you come through. I will spend all of this evening getting into it deeper and hopefully solve this puzzle. We'll let you know soon enough

Another nice option is to use the stock valves from a 2.2 or 2.4 head. The intakes are sized well at 1.77", while the exhaust valves are a bit too large for a 1.9 head at 1.57". I have cut these down to 1.50" on a crank grinder (very accurate), and put them into a 1.9 head so there is no need to change the guides/retainers/keepers/springs.

Bob

[lewdawg]

So how hard is it to get your paws on 2.2/2.4 valves?

[Paul]

Caramiciu,

On this sites' home page there is a link to the Opel Tech Center. Under the "General" tab you will find a file that can be down loaded called Engine Specs and Modification Specs. This list of info was compiled from several years worth of posts. This will give you a heads up on valves sizes, springs, flow improvements, etc. You should even find some part numbers. This list was last up dated a year or so ago, so its not the end all, but it will give you a head start.

From my experience with narrow minded auto machine shops, some shops don't have the tools to install new valve guides and properly size them for 9mm valves.

GL

[Betta Carotene]

just a quick question. Does grinding on the valve guide reduce the life of valvetrain? Just curious.

[GTJIM]

Originally Posted by Betta Carotene just a quick question. Does grinding on the valve guide reduce the life of valvetrain? Just curious.

By this, I guess you mean grinding it shorter when porting.
The 2.0 'E' head has considerably shorter guides and does not have reliability problems. With Lyle's head the guides were shortened back about 1/4" to 5/16" (6.35mm to 8mm ) so that the inside end lined up with the 'step' on the reduced stem valves - weren't any use having them longer as there was not any stem to contact them ..... So judicious shortening is OK but R. Bob advises that the 'bump' around the guide end be made to look a bit like the aerodynamic 'bump' on the GT hood - over the carb!

[Washout]

Does anyone know if the big valve kits are still available from TGSI racing? That looks like a much easier way to install the bigger valves without all the issues of finding the right combinations. I emailed them but haven't heard back yet.

[GTJIM]

Originally Posted by Washout Does anyone know if the big valve kits are still available from TGSI racing? That looks like a much easier way to install the bigger valves without all the issues of finding the right combinations. I emailed them but haven't heard back yet.

I think you will find that TSGI has bowed out of low volume (no profit!) Opel bits and pieces and now concerntrates on Fieros and Ricers ............... nice web site though!

[Tru-Craft]

I would follow Bob's blueprint for valve selection. Find a local Chevy engine shop to work with. Use Bob's info as a guide and let the shop find a cheap source for a pro-flow type (under cut) valves.
Stainless steel valves are about $10 a piece! I used 1.880 intake valves turned down to 1.800, and 1.50" Chevy exhaust valves. Dont let them do what they think is right for a V8!!! Give them a copy of Bob's information and make them follow it!
Very happy with Bob's design!
Cam Techniques (NOT! Cam Effects!) ground my cam and it is awsome for a hot street set-up.
Lyle

[Washout]

Great information here RallyBob!

I do have one question for anyone that has installed the big valves. I've installed the 1.84 Chevy valves and now need to unshroud the intakes as recommended by Bob. My question is how much to relieve them? As they are installed they have about .050 clearance from the combustion chamber wall. I used the headgasket and layout paint to determine where the headgasket contacts the cyl head. From the valve edge to the edge of the gasket edge only gives me .150. Is that enough unshrouding to do the job? According to one blueprinting book I've read they recommend the distance between the edge of the valve and the combustion chamber be equal to the valve lift, in this case that would be .430. Of course it's impossible to remove .430 so will .150 with a radius be sufficient and is that about normal for what you had to remove?

[GTJIM]

That is the basic problem with "BIG" valves - smaller valves with better unshrouding often flow better!

The difference between 1.77" intakes and 1.84" ones will probably only have any effect way above 6,000 rpm as far as peak horsepower is concerned.

The only cure is to run a bigger bore - a 2.0 block bored out to 96.5/97 mm will give more room for unshrouding the 1.84" intakes.

The other big problem with oversize intakes is that the piece of cylinder head between the valves gets very thin ..... and cracking becomes a problem on street motors that need to "live" for more than the few thousand miles a racing motor does.

The mania for really "BIG" valves on street motors is just another Vale of Tears!

[RallyBob]

Originally Posted by Washout I've installed the 1.84 Chevy valves and now need to unshroud the intakes as recommended by Bob. My question is how much to relieve them? As they are installed they have about .050 clearance from the combustion chamber wall. I used the headgasket and layout paint to determine where the headgasket contacts the cyl head.

I unshroud right to the edge of the gasket being used. Make sure the gasket is properly located on the head when you lay it out! But for this reason (gasket diameter), a larger-bore engine tends to breathe better when large valves are used. I've found that a 1.9 bore diameter breathes well with up to 1.85" valves IF the chamber is unshrouded. If no unshrouding is done, then the 1.72" valves are a better choice. When using a 2.0 bore or bigger, then 1.88" valves start to perform better at all valve lifts (even low lift), and will achieve their peak airflow at a lower valve lift than a smaller valve.

Bob

[Washout]

Thanks Bob,
I did bore this from 1.9 to 2.0 and have the 2.0 head gasket. I had pretty much decided this was the correct way to go but there is just something about taking the mill or burrs to a head that makes me nervous! As always, thanks for the constructive input.

Regards.

[Paul]

Bob, I'm taking the liberty to post a picture of an unshrouded chamber of yours. It might not be the correct example, but it should help get the idea across.