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Puny Bird
 
Mark Henry's Avatar
 
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Question Rebuilding 2.0L heads

I'm trying to find a tech. article or thread on rebuilding 2.0L heads.

I want to do the best job that I can, I have 2 sets of crack free heads, 1 set smogs, 1 regulars, going into a D-jet with the OK mods. Machining not a problem, newbie to 914's not aircooleds. Tried to find this out on the STF but not much help there.

Should I replace the seats?
Sodium or SS exhaust valves? (I have 4 used valves that spec. OK)
If I use the SS exhaust valves, do I just use intake guides on them?
Intake Valves, Replace? SS?
Lbs of new springs, what used is acceptable?
Anything else?

Thanks Mark
Old 11-23-2002, 06:56 PM
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I'd probably replace the seats just on general principle. Check very very thoroughly for cracks. Spark plug hole cracks are very common on 2.0 heads. Cracks on the short-radius bend of the exhaust port are not quite as common as that.

For a stock motor, I'd say all stock parts. Sodium-filled valves included. Stock spring rates on the valves and so on.

I don't have any real input for you on a more-advanced-than-stock motor...

--DD
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Old 11-23-2002, 07:36 PM
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I've done my share of 2.0 heads. Make sure you bead blast them before you check for cracks. They like to hide. The SS valves seem to be more seat friendly in my experience especially on the exhaust side. Dont waste your time messing with the original seats, they will fall out eventually. Re- seat the heads and use the 911 guides and stem seals, it'll use less oil that way. Fly cut them moderately and like DD said, check and recheck the plug holes for cracks. I have had the best results in not using a head gasket from the cylinder to head mating. Use a .25 spacer for the cylinder to block gasket and you should be fine. Dab a bit of gaskasinch on all mating surfaces to ensure a good seal when not using a head gasket. I would stay with the stock springs and intake valves. The stock intakes have never given me problems in the past and the spring rate of the stock springs are more than adequate for what you are wanting.Hope this helps...
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Old 11-24-2002, 12:54 PM
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Todd,

I'm very impressed with your write up on the 2.0 heads.

About the only thing I didnt see you reference was the interference fit of the new seats to the heads. I feel this is the most critical part of installing new seats along with the procedure for doing them.

Could you describe your method for installing the new seats ?? I know how my guy does it and would be interested to see if a few people are on the same page for this procedure.

Oh.. you can buy guides that are oversized. When you remove the current guides.. it will remove some material.

B
Old 11-24-2002, 03:00 PM
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Yeh Baby!!! Now I'm getting some answers!!!

I want to know your press fit also!

I'm a T1 guy, and on those heads stock press is .007, but I always heat the head to 400 degrees F. and put the seats on dry ice and press them in at about .012 to .015 press fit. I then peen around the seat and when its cool I blend the chambers and measure the cc's to make sure they are the same and voila.

Is this good for the Porsche heads or what?

thanks, Mark
Old 11-24-2002, 04:11 PM
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The method is the same, but my guy uses a .030 fit for the exhaust seat and .015 on the intake seat.

Sounds like your on the right track. I'm hoping Todd sees this and speaks up.

B
Old 11-24-2002, 04:14 PM
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Peening the seats seems to be looked down on in the Shoptalk Forums BBS. No real experience myself, though...

--DD
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Old 11-24-2002, 04:17 PM
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Quote:
Originally posted by Brad Roberts
The method is the same, but my guy uses a .030 fit for the exhaust seat
WOW! thats a lot of press!!
Old 11-24-2002, 04:20 PM
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There is such a issue with losing the seats, he takes NO chances.

Dave has been through this at least 2 times.


B
Old 11-24-2002, 04:25 PM
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Three... LOL! (All intakes, BTW.) But I'm still not satisfied I know any answers about it.

--DD
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Old 11-24-2002, 04:35 PM
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Damn. I knew about 2 times. No wonder you dont to drive the damn thing. Soon I will have the water tank back up at SSI for the chassis dyno and the engine dyno. I'll be able to tune cars without leaving the shop.

B
Old 11-24-2002, 04:37 PM
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Thanks guys, I think I'm on the right track now! Mark
Old 11-24-2002, 05:46 PM
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Mark,
It looks like you got your answers over here. I'd be more than happy to ship you my 2.0 heads to experiment on. I also have access to another set of them!

Randy
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Old 11-24-2002, 07:06 PM
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Well, thanx for the kind words. I'm only 23 years old I like to score the surfaces with a drill mounted 1" cup brush with heavy bristles once you've removed the old seats to make the new seats really not want to come loose even when abused(ie. gas foot gets heavy). The 2.0 heads like to heat up so try and find any way you can to ensure a good surface for the new seats to cling to. The specs Brad gave you are the same I use. .030 exhaust and .015 on the intakes. I stay away from peening if at all possible. I have a nice press that I use to install the new seats. If you really wanna go the extra mile, I have installed the titanium valves in my old 2.0 and I would rag the hell out of the motor with the stock springs and could not float the valves. Plus the titanium valves are made out of aircraft grade titanium. The titanium willl not hold heat like the steel valves will and they are 10 times lighter. You'll never find them for VW's but the chevy aftermarket ones are all over the place. Just take an old valve to any reputable motor shop and ask around and they should be able to cross reference them for you. They are definately worth the extra money. I bought a set of 8 for $120.The titanium valves will not heat your seats up like the steel ones will so the odds of losing a seat are next to never. I really would like to talk to someone else who has used the titanium before with more experience than myself. It seems like I'm the only one around with any input on them. The guy who sold me on titanium took a steel valve and a titanium valve and heated each with a blow torch for 30 seconds. The steel one, very hot obviously. He then heated the titanium valve and quickly threw it to me. Of course I dodged it but he went and picked it up. It was warm but you could hold it in your hand. Good luck!! If you have any more questions keep em coming!!
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Actually,the 914 is a "Poor Man's Porsche". You buy one and you end up poor...Or it ends up covered with Por 15? Either way, something's poor...
Old 11-24-2002, 07:38 PM
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I cant run them in any of our cars we use for competition (or I would have already)

B
Old 11-24-2002, 07:42 PM
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I would also be careful Mark when using heat to install seats. Remember that your heads will normally run around 350+degrees at normal operating temp. The best results are usually a cold press with more interferance than you are using.
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Old 11-24-2002, 07:44 PM
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I have been looking for a good used 2.0 to tinker with. Anyone have one?
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Old 11-24-2002, 07:46 PM
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This is great!

Randy, I would do your heads, but I know shipping back and forth across to border is a totall drag and not cheap.

Todd, I heard that the titanium valves were very tough but that the valve job didn't last long.
How do you find the VJ lasting?
I thought the valves were more money than that?
Doesn't the chevy have a different keeper/retainer set-up?
Do you stick with the stock sizes?

I think I will practice on some junk bus heads first.

The local independent Porsche dealer came over to check me out yesterday, and including my engine I now have 3-2.0L 914 and 1-2.4 911 engine to rebuild, plus I have a couple of bug engines on the bench. A lot of work, seeing as this is only my part time gig.

Thanks again, Mark
Old 11-24-2002, 08:52 PM
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10,000 miles and still going strong on my titanium valves. I havent had a problem with them. I was using the Chevy as an example but I believe that the ones I bought were from an early chevy corvair 6 motor. I could be wrong. I'll have to dig up the receipts from when I bought them. You do have your hands full though. What's your timeframe for completing the motors? That 2.4 should be alot of fun ! Are you doing a complete rebuild on it or are you going to stick to the top end? I've been doing a few corvair motors recently and those are neat as well. Will you be timeserting that 2.4 (PITA) or does it look ok? Sounds like a barrell O' monkeys. If you need any more help, let me know. I'm sure any of us can point you in the right direction.Todd
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Old 11-24-2002, 09:38 PM
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Can you cut down the chevy titanium valves to whatever size you want?

PD
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Old 11-25-2002, 05:40 AM
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