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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 |
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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. |
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1.7 & 1.9 heads
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 |
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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 |
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1.9L to 2.0L change
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 |
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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
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"I'd rather have a bottle in front of me than a frontal lobotomy"... ________________ 1969 Lenk GT 1974 Manta 1973 Manta Rallye |
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1.9L to 2.0L change
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 |
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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
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"I'd rather have a bottle in front of me than a frontal lobotomy"... ________________ 1969 Lenk GT 1974 Manta 1973 Manta Rallye |
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SB Chevy Valves
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!
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GTJim Opel Owner since last Century! Copyright © 2000-2008 J D Henry All Rights Reserved Last edited by GTJIM; 04-06-2006 at 03:02 PM. |
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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!
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"I'd rather have a bottle in front of me than a frontal lobotomy"... ________________ 1969 Lenk GT 1974 Manta 1973 Manta Rallye |
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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 |
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Bob |
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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
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Paul |
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Shortening?
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!
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GTJim Opel Owner since last Century! Copyright © 2000-2008 J D Henry All Rights Reserved |
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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.
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I call her Laticia, Costs more than she's worth, but what a set of headlights! |
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Bowed Out ...
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GTJim Opel Owner since last Century! Copyright © 2000-2008 J D Henry All Rights Reserved |
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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 Last edited by Tru-Craft; 04-07-2006 at 01:39 PM. |
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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?
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I call her Laticia, Costs more than she's worth, but what a set of headlights! |