Porsche E cams for a 1970 911t

[dpetteng]

Having to do a top end rebuild for my 1970 911t and EBS are boring my barrels to 85mm and supplying 9.4:1 JE pistons. Thinking of changing to E cams at the same time but can't seem to find a supplier?

Also, what change to I have to make to the E cams as they are build for MFI drive and I will still be using zeniths?

[roblav]

If you want to change cams, and you should with 9.4:1, recommend Solex type over E. Elgin, Daughtery, and Webcam will likely have what you need. Your Zeniths will likely need larger venturis and perhaps some re-jetting.

[Flat6pac]

https://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/1035480-e-cams-cut-t-billets.html
Bruce

[horizontallyopp]

Dougherty DC30
http://www.drcamshafts.com/911profiles.htm
you can have this ground from a 911E core or from new billets

Web Cam makes something similar for new billets.
http://www.webcamshafts.com/pages_vehicles/automobile/porsche/452.html

Elgin does as well
https://elgincams.com/porsche911/

[Helix8]

Originally Posted by dpetteng

Having to do a top end rebuild for my 1970 911t and EBS are boring my barrels to 85mm and supplying 9.4:1 JE pistons. Thinking of changing to E cams at the same time but can't seem to find a supplier?

Also, what change to I have to make to the E cams as they are build for MFI drive and I will still be using zeniths?

make sure you check the RA - I had to have my recently bored/plated sent back to Millennium to do over - EBS did not specify a low enough RA (6-10) and they came back 20-26. This was on a 3.4L YMMV?

[cmcfaul]

DC 30 cams hands down. They compliment the higher CR with increased overlap, lift and associated VE. You will be amazed at the performance.

You CR will actually be a bit higher as they resurface the mounting side of the heads by taking off a bit of the surface.

You will LOVE it.

Chris
73 MFI E

[Trackrash]

T cams should be able to be ground to E specs. If you get stock E cams you will have to cut off the MFI drive on the left cam.

However, as mentioned, new cams with a DC 30 grind would be worth the extra money.

[dpetteng]

Originally Posted by Helix8

make sure you check the RA - I had to have my recently bored/plated sent back to Millennium to do over - EBS did not specify a low enough RA (6-10) and they came back 20-26. This was on a 3.4L YMMV?

I understood absolutely zero this. I feel like a real dumbass now!

[Trackrash]

Originally Posted by dpetteng

I understood absolutely zero this. I feel like a real dumbass now!

This only applies to Nicasil coated cylinders.

[dpetteng]

Thanks all, especially Trackrash.

I have head about the DC30 cams and looked at their site but where can you buy them from?

So For a good top end rebuild, do I need new head studs? None of mine are broken but I am not sure if they need to be replaced? Also, how do I find out if my pistons will clash with the valves if I use a DC30?

A few people have mentioned larger ventures for my zeniths but can't find details or supplies anywhere?

Also,I made a lot of what I think I need, can you highlight anything else?

Cam chain ramps, new cam chains, gasket set, seals for oil tubes, anything else?

[Trackrash]

DC cams are bought directly from Daugherty Racing cams.

Head studs on a 2,2 are not a worry. However, they will pull out of the soft mag case. If your motor has been apart before, hopefully CASESAVERS were installed. If not, you should seriously consider having it done. I don't know if it can be done with out splitting the case.

With those cams, I would recommend 30mm venturis. I don't know if they exist for zeniths and you may have to have yours enlarged. You could send a PM to 1quicks asking.

Now for your homework.....

[dpetteng]

got three of those books already! Case savers are not installed which sounds like being a complete rebuild if I need it...

[dpetteng]

And there is a guy in Italy that makes all sizes of venturi for Zeniths so 30mm is easy. How do you change venturis?

Is it a complete no-no to rebuild the top end without installing case savers?

[Helix8]

Originally Posted by dpetteng

I understood absolutely zero this. I feel like a real dumbass now!

Nope not you at all - just me not knowing your cylinder material.
I see EBS/boring/plating and I am immediately reminded of the additional $600+ it cost me to bring my cylinders to spec (beyond the initial work expense) - god speed with your build

[Hi_Fi_Guy]

Re: Zenith carbs there is an eBay seller, alfa1750, who has all sorts of parts that fit Zeniths at very good prices. If you have patience you can sometimes score a sale around major holidays. I put in larger Venturi when rebuilding my zeniths along with many other new parts and it made a world of difference. Partsklassics also carries some zenith bits at somewhat higher prices but handy when you only need a few items.

I’m not a big fan of the available zenith rebuild kits as some of the o rings and gaskets don’t fit as well as the originals. You may find it worth the effort to order some of those bits separately for best results.

That said, if you have the budget for real Weber or PMO Carbs you may find even more gains by going that route.

[dpetteng]

So, I checked with Dougherty and cams are going to take a while so I will do the cams at a later stage.

Should I make any zenith changes to account for the increased piston size and CR? I understand I won't get much power gain without the cams.

[dpetteng]

anyone?

[Trackrash]

Originally Posted by dpetteng

So, I checked with Dougherty and cams are going to take a while so I will do the cams at a later stage.

Should I make any zenith changes to account for the increased piston size and CR? I understand I won't get much power gain without the cams.

May as well.

[cmcfaul]

T cams can be ground to E cams. T cams can not be ground to DC30's (mod S). E cams (not ground from T cams) can be ground to DC 30;s (mod S).

With more compression comes greater cam options.

Chris

[dpetteng]

Ah ok, do I would need to buy new DC30 cams? Anyone know how much these are?