924Board.org

[ricomartinez]

Getting ready to mod my head with thinner copper head gasket, port/polish, cam. Doing it all myself (except for cam regrind, of course) and have a few questions:

1) I know in the last 2 years on this list and doing some surfing I saw something specifically on how to port a n/a head. Does anyone know where I can find this?

2) Hoping to not need new valvesprings, but if I do...does anyone know where to get replacement springs for cheap? Thought I saw something about some Honda springs that fit and were better and cheaper. Anyone know about that?

3) If I have the current cam reground, do I need to do anything to the cam bearings? What if I get a different cam from a junkyard and have it reground?

4) I am going to talk to these cam grinders myself, but does anyone have any experience with Elgin, Schneider, or Crower?

Thanks.

[Dave]

If I were yo I would try web cams. Also if you are going to do all that I would put new springs in and do the cam bearings while you are there.

[eturbo924]

Schneider is much cheaper than web cam. Also I have a crind from them and it seems to have given me some good improvements. I believe Joe also got a cam (more radical than mine) from schneider. Cost difference about $120 or so from Schneider... about $350 from Web cam!

You will need to compensate for the lash created from the grind though. Larger follower screws or lash pads.

If you perform a grind, inspect the bearings and mark them for their position. If they are ok... re-install them in their proper position. Make sure you use some good lube on all the new components before you start that puppy up.

As far as the proper way to port and polish... sorry I just gave mine to a shop to do this for me. Check out my cars mods. http://www.geocities.com/eturbo924 also check out Jons site for his engine... nice!

Eric

[larso]

valve springs are cheap, the high rpm ones are something like 8-10 bucks per spring i think at tweeks or one of those catalogue places i saw.

[larso]

oh and yeah don't waste money at webcams schneider is cheapest.

[Joes924]

I havent got mine yet but go with schnieder cams they seem really good. I talked to them a few times. I have a junkyard came I picked up for 10.00 then when i had to do a new clutch I spent alot of money so any way another month or so I just did the ignition any way ..

[AppleBit]

Who's this Jon character and how can I kick his butt?




I would recommend not going for a thinner head gasket- you will change your cam timing and that's no fun. If you are taking your head off, port & polish the head and put a nicer cam in. Don't spend more than $125 for a cam but get a grind that works best for you.

What are you going to use the car for? Street, Street racing, autocross racing, road racing, or roundy-round?

- Jon


_________________
Classic British Sports Car Restoration v6 + v8 Engine Conversion Swaps

Porsche 924 Wide Body LS1 Corvette 500 Horsepower Engine

[ricomartinez]

Already bought the thinner copper headgasket. My understanding is that the difference is so small as to be insignificant. When I take out the old, I'll measure it against the new and crunch some numbers to see how many degrees it will be changed. If greater than 1 deg, I'll buy the Mopar offset-key kit that Vaughan tried.

I was thinking about that Franco gear too.

Just planning on using it for the street.

[larso]

yeah, your timing belt tension and it's stretchabilty with heat changes the timing too.

[Rick MacLaren]

Re: Techniques for head work

See the 924 Turbo manual. There's a section there about it...or maybe it's Haynes? It talks about a three point grind.

I've been honing the intake manifold, 924 Turbo intake arm, throttle walls and have been learning a lot about 'porting'. I think the basic trick is to be patient, look over the object, find protrusions, cavities, bumps, and make them smooth. You should also have an eye out for 'matching' various ports.

Test your work by both feel and sight. Get a small powerful flashlight.

At the intake side, the manifold hooks up to the head, but between the two are gaskets. You should match the gaskets to the head to the manifold so all three items are without 'ledges' or 'relief' between each other...it should appear as one smooth path for air to follow.

The same goes for the exhaust side.

Matched ports (intake or exhaust) = increased 'balance' in the system.

[ricomartinez]

What are the tools of choice for porting? I was thinking about using my dremel and getting the flex shaft attachment for a little more control. What about the bit? Should I use a grinding stone or just rough sanding scroll? Since this is new to me and the head is aluminum, I figured the sandpaper type.

[Rick MacLaren]

Good questions. The Dremel is the tool of choice, but you should also have a good electric drill and some Scotch brite pads or a whack of steel wool.

The drill is for two things: Coarse grinds and finishing. The Dremel is for everything in between.

For the drill, get a piece with a wire brush feel and strength...a wheel, and grind the shxx out of it. The Dremel wheel attachment discussed below can help to take down the rough grind. And finally, the drill with some steel wool can take it down to a fine finish.

The flex attachment for the Dremel is excellent. I use the 'flap' attachment, which is about $10 CDN, and it's a 1" diameter item with about 40 'flaps' of sandpaper. Use LOTS of oil at every step of the way...use a 3 in 1 oil. I used the grinding stones with the Dremel, but they are very aggressive. I use those for seams or outright protrusions that need to be aggressively ground away.

btw, you can cut Scotch brite pads into round disks and use them to polish...also, get some Silvo...

Rick
_________________
1980 Porsche 931 C2H5OH/H2O injected 15 PSI
1979 Porsche 924


[ This Message was edited by: Rick MacLaren on 2001-10-02 00:32 ]

[Joes924]

And this works whats to be gained from this and not taking it to a shop ..Ill talk to a shop seems to me I heard something about making the combustion chambers the same size. I saw somewhere pics of porting and polishing ... just cant remember.

[Joes924]

Patrick from stockholm,sweden he has some pictures of I think the proper way to port and polish the head..

[ This Message was edited by: Joes924 on 2001-10-10 11:20 ]

[Rick MacLaren]

You should let an expert port the head piece. I wouldn't experiment on any head that I valued.

Haynes outlines a number of choices you can make regarding how to rebuild the head. You can get the garage to do it, take apart portions and send them to a shop, etc. Read the Haynes and it'll point you in the right direction and it clearly sets out your and my limitations re: Ability.

_________________
1980 Porsche 931 C2H5OH/H2O injected 15 PSI
1979 Porsche 924

[ This Message was edited by: Rick MacLaren on 2001-10-09 00:01 ]