3.0 SC Top End Upgrade Options -- worth the mods?

[wannaporsche]

Hi -- a real newbie here. Have a 1980 SC I bought in August, my 1st. Found out having valves adjusted 3 head studs were broken (ouch), so I'm having the top end rebuilt. I'm meeting with the shop tomorrow and want to ask appropriate questions concerning upping the HP from stock -- is it worth the mods?

Especially having the cams reground to 964 specs. I've read the few threads on here and opinions seem mixed between lost torque and high end power. I'm not planning to track the car and will be using it for normal in-town driving mostly so I'm inclined to stay stock.

I guess I just wanted to double check here for advice "while I'm in there"...

Also, I'm in California, so it has to smog.

[snbush67]

A lot depends on the wear of your current engine, you wont know until tear down what condition the rockers, valves, cams, pistons cylinders etc. are in. They are all wear items that cold be reused if in tolerance, to requiring machining or replacement. You may not be able to reuse your cams/rockers etc.

Machining/resurfacing parts is usually less costly then replacement.

You may want to keep an eye in the calssifieds, there are often rebuilt engines with quality parts in the pelican parts for sale that are cheaper than the sum of the labor you will pay to rebuild yours.

[wannaporsche]

Thx Shane -- FYI, after teardown, I'm told rockers and valves are showing wear and should be new -- cylinders, pistons, and heads all are good and re-usable. Shop also wants to open the bottom case and do all 24 studs new with performance grade studs... can't remember the brand...ACS I think.

[snbush67]

It sounds like you have a decent shop. You really cant go wrong putting it back to stock, a fresh 3.0 will be night and day compared to a tired one. I am not sure how much can be gained with just a different cam grind, I think to get the most out of it you should maybe go to the larger ports and larger CIS (78-79). Ask your mechanic if they have the larger ported heads or if they would recommend machining yours to accommodate the earlier intakes. I have a complete fresh working system if you are interested.

[flat6s]

I just finished having my 1980 3.0 litre top ended due to a broken head stud. Went with ARP head bolts. Heads were fully redone. The hp mod i did was backdate exhaust and heater boxes. Removed O2 sensor . Plugged vaccuum advance and set timing at full advance. First test drive was today. The hp and torque gain from the backdate are impressive. The only other mod i wanted to make but did not was to re-time cams to Euro specs. I prefer stock, to modified, in most cases.
Best of luck.

[CEO]

Joe,

What does plugging the dist and setting at full advance accomplish. I have a 3.0 with 964cams set at 1.9 degrees with an exhaust as well.

Kenneth

[flat6s]

Kenneth
Pm sent

[CEO]

Joe, I never received your PM. try kenneth@aurynindustries.com

[snbush67]

Originally Posted by CEO

Joe,

What does plugging the dist and setting at full advance accomplish. I have a 3.0 with 964cams set at 1.9 degrees with an exhaust as well.

Kenneth

As in anything else,it is wise to know where you are starting from before heading in a new direction.

Before modifying or servicing your distributor you should determine its current condition by setting it at factory advance and then check the advance in increments until it stops advancing.

Typically this means setting the advance at 7 degrees +/- 2 while at 1000 rpms.


First you just want to warm the engine to operating temperature, then while watching the timing mark slowly rev the engine to 3000 rpms, you are watching to see if the mark advances smoothly, this will verify that the distributor advance is not getting hung up?

Then using a digital advance timing light check advance at 1200 then 1500 then 1800 then 2000 etc. total advance will likely be around 2700-3000rpms and should be in the neighborhood of 30 degrees advanced. If you are getting that then you are likely as good as you are going to get. If not then tear it apart and clean it, check for broken and worn parts.

Setting your distributor at max advance is great for wide open running, but will likely give you a rough idle. Consider the cars purpose and wether you want smooth street performance or if you simply don't plan on stopping for red lights and pedestrians.