Replace cams with partial engine drop?
 

Well, after 270,000 miles, my cam towers have started to leak like sieves (see bumper oil spray on pix below) Will be replacing the gaskets/seals next month and have started thinking about upgrading my cams to something hotter 'while i'm in there' after reading a recent thread. I will be rebuilding the engine next year, (simply don't have the time now) and am finally enjoying car again after sorting it out over last year. Have a couple of questions for you guys:

1) Can i replace the cams with only a partial engine drop while resealing the cam towers?

2) After a year of projects including ditching the CIS and going with EFI, i have finally got the old SC dialed in... runs better than it ever did, pulls strong up to 130mph, handles great. The compression is good all around (the longevity of these engines is amazing). Should i mess with the cams at all? (ie, like everyone, would love more grunt, but any issues on replacing cams on a 270,000 mile engine?)

3) With a 80 SC stock engine (8.5:1?) stock exhaust (except catbypass and GHL muff), and tbitz EFI, which cam should i go with.... 964, 20/21 or the DC13 camgrinder talks about? With a stock exhaust will there be much of a difference?

Finally 4)What hardware (rockers, etc) should i replace if i replace the cams?

Thanks guys
http://forums.pelicanparts.com/uploa...1142689700.jpg

Drop the engine to change the cams.

You need the dial indicator and mount to set each bank.

You'll need the crows foot wrench and cam holder with a large torque wrench. Check your car because they changed the cam mounting nuts during the 80's. I think yours is like my '78 though.

Get new rocker arms.

Replace any adjusters that are galled.

Use the rocker arm shaft seals.

Use Walt's tightening specs for the shaft seals.

I used Curil-t for the camhouse to chain cover seal (with the gasket and o-ring.) No leaks 25K.

Get Wayne's rebuild book. There's nothing better for the cam setting sequence. That includes Bently,the factory manuals (I have the fische), Bruce Anderson's book (2nd best) and Haynes.

You're not far from a top end at the point of removing the chain covers and cams.

I run a Elgin (cheatercam) and have it set to the top range of timing which gives me the pull from 4500 to redline. I also have stiffer valve springs installed.

I can only imagine if you have efi that you'd like it a lot more with a hotter cam. (I want the t-bitz)

I run a stock exhaust with a pre-muffler (old euro). I have nothing to compare it to. I like it better than the cat.

Ok, so can't avoid engine drop. Any real (noticeable) difference between the 964 and 20/21 for my (relatively) stock engine?

With 270k just replacing the cams doesn't make much sense; a rebuild/re-ring/top end rebuild is in order.
A 1980 SC 3.0 stock engine has 9.3 CR and may have Alusil, or Nikasil P/C's and has smaller intakes than the '78-'79's.
I plan to use 964-profile cams on my SS 3.2 with CIS but you can ask Camgrinder John what's best for you.
A really good HP increase comes from SSI's.
Figure on ~$5-6000 for the rebuild.

Superman installed the 20/21 cams in his SC and gives it a big heads up.

Depends on what is considered a "good" increase. 10 HP, maybe 15. A lot of $$$ for a small return by itself. Combined with cams and EFI, then that will make for a fun motor.

Your engine should be 9.3-1 compression ratio. I would normally choose the 964 profile if you were keeping the cis. Since you have EFI I would jump up to the DC20 profile.
This is a common step up from the 964 profile and fits as a regrind on the SC cores. You will also need to swap out the rocker arms for new or rebuilt ones.
If you plan on running the engine up to 7000 rpms, an aftermarket valve spring is good insurance.
The SSI suggestion is valid. This will help you get the most from your combination.

Thanks John, everyone. John, i will email you for more info.

You can do cam towers with a partial engine drop?? Did you mean chain covers? To get the Cam towers you have to have complete access I would think.

Do the whole thing and seal everything and clean everything. It will be worth it.

After practice an engine drop can be done by us rookies in 1 hour ....more or less...... :eek:

Why new, or rebuild?
What is meant by this? Replace the bushing? Regrind/polish the bearing surface?
I am looking at rocker arms/shafts from a 3.0 liter with 140k miles and the there is no play between bushings and shaft.

Why not re-use? :confused:

Because it easier to do it right the first time......than redoing it the second.....

Why not have your old ones refurbished or upgraded to 964 specs?

Other than replacing the bushing, what else?
Are you saying that the curve on the rockers has to be changed for a 964-profile?

Nope....but if one side of a wear item is replaced/refurbished you should do the other as well. The parts are not the expensive part of the job, it's the labor.....

What exactly do you mean by: Refurbish??

Regrind on the cam....on the followers there are services that do that as well if they are not to bad.

Here is an old post I did on rocker arms.
http://forums.pelicanparts.com/911-engine-rebuilding-forum/221408-rocker-arms.html