Single Port Valve Guides

[philthy]

Just picked up some 311.101.373A heads (4 for $50, 2 of which are usable) and am doing some port work on the exhaust side. I want to replace the guides but I'm kinda confused which ones to get. I know the silicon-bronze is the material- but what about size? I've seen them range from $1.95 to $6 each. Also the exhaust guide is shorter than the intake. Any advise? Also- if the locks and retainers look good (under a big magnifying glass) is it ok to re-use them with stock springs (new of course)? I'd get new valves too but I know those are the 35 and 32 variety.
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74 Baja 1600 Dual ICT

[modok]

The guides and valves in 1500/1600 SP heads are no different than DP heads. If the ex guides are shorter that means they have been replaced with aftermarket ones. The stock guide OD is about .475, you'll have to measure the bores to see if you need oversize once you have removed the old ones.

Are you gearing up to do the work yourself or just putting in guides to save $$ at the machine shop?

[philthy]

I'm having the heads tanked, guides installed along with seats as well. The guy I have doing it has done VW heads before but it's not his normal work so he wanted me to order the parts I want installed. He usually does other imports and I have looked his work over. What's the best way to remove the guides myself? thought about putting the head on the stove for a little bit to get it warm then knock the guides out carefully (so as to not burr or mushroom them).
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74 Baja 1600 Dual ICT

[modok]

no, that is for iron guides. Heating has no benefit.
The bronze guides are removed by coring them out, or threading and pulling them out, or some combination. It may be worth briefly trying to drive them out like normal just to see if they go, but if they drive out easily then they were probably too loose.

If he's got a serti or VGS machine, tell him to put the head on upside down and core the guides out 2/3 of the way at about 7/16".
If he doesen't have a 5/16 to 7/16 dreamer then I spose it isn't quite so easy........ one or the other of you need to take it upon yourselves to tool up to do the job.

[philthy]

Well if they were loose good thing there are oversizes It couldn't hurt to try and knock them out. the exhaust guide is flush anyways. WTF were they thinking when they designed that port?? I love dremel's
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74 Baja 1600 Dual ICT

[modok]

The exhaust port looks stupid, but it works ok, or lets say, more than adequate to keep up with the intake, the intake manifold on a 1500 SP is only like 27mm ID!


Often the PORT side of the ex guide is really burned/crusty, and that crusty stuff won't like being driven through the head, so it is better to drill off the spring side of the guide flush with the boss, and then drive it toward the port. From there, another very old school trick is to tap and thread a 3/8 bolt into the port side, then stick a 5/16 rod in the guide and drive that, this way you cannot mushroom the end.
I think everybody cores them these days, but it isn't the only way

[philthy]

I cut the guides flush on spring side (very carefully) and may take over to friend's house to use his drill press. Rockauto (my fav) has guides in 2.395" and 2.625" lengths. I'm going to say the shorter is what's in the exhaust and should also work for the intake as well right? Says they're bronze and .475 od so if I use those I'll have to very careful not to screw up the bores (if they are stock size). Hell, at $1.67 ea it sounds like a deal lol

PS, the intake side has little silicone o-rings on top of the guides (the rings themself had a square profile). Are those re-usable?
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74 Baja 1600 Dual ICT

[modok]

Cool. I'm not a fan of rock, but I admit some of their parts re very good, such as pistons.

I always use bugpack or PEP guides, PEP is always good quality material.

I must warn you that a regular drill and bronze can be dangerous, the angle of the flutes makes the drill grab. For bronze generally the angle of the flutes is 0 degrees or sometimes reverse. I have done it this way but i used a step drill (chinese copy of unibit), modified so the last step was 7/16. a regular drill cn be re-sharpened to work ok on bronze but that is also tricky to get right, but maybe doable by cutting the very end of the flutes with dremel cut off wheel??

I do not know about these "o-rings", perhaps some kind of aftermarket valve seal?? the old vw used a rubber o-ring that usually disintegrated, and the new mexican ones used posi valve seals, have not seen silicon ones, but it sounds like a good idea

[philthy]

Ya i'm going to have to find a diff bit to use. I tried to drill brass once and it shot me in the eye (under my safety shield). Basically it needs to be more like a machining bit? Since we're on the subject- how does a person install them? I've done hundreds on iron heads, but never a VW AC head.
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74 Baja 1600 Dual ICT

[modok]

Make sure there is between .001 and .002 press-fit. Lube both guide and guide bore with ani-sieze. Drive em in.
I've tried several different kinds of lube, the anti-sieze works best by far, but I hate the stuff, horrible mess, gets everywhere!

[philthy]

Ok got all the guides out. Bored them about 3/4 way then tapped out like you said (towards chamber). The bores them self mic out to .474 so I'm guessing that would be perfect as you said you want a slight interference fit? I took the heads to the carwash and cleaned them up and look much better. I don't think I'll need to do anything to the intake ports. besides being a single they look like they did their homework.
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74 Baja 1600 Dual ICT

[modok]

Good!
Oh yeah, one more hint.

Before you lube em' up and drive em' in, put a generous chamfer on the guide bosses. Maybe even go 1/4 inch down, you know, "generous" it is easy to end up cracking those guide bosses, and that really helps to prevent it.
This tip courtesy of Jeff D.

[Bashr52]

I've had good luck covering the guide with vaseline, and then heating up the guide bore slightly with a propane torch. The vaseline melts nicely and creates a nice thin lube to slide it home with

[philthy]

Sooo...what you're saying is I need to get a few fingers in before I go balls deep? Roger that
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74 Baja 1600 Dual ICT

[philthy]

FYI the bit I used was a normal steel bit, but cut the "leading" edge down to where it was vertical, instead of ramped. So then the bit scrapes the bronze instead of cuts. Works like a charm and with a cordless drill it takes less than a minute each. The bore helps keep the bit straight.
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74 Baja 1600 Dual ICT