I'm in a tight spot...
 

So a 2.2 T is getting rebuilt with a 70.4 crank/rods and E cams. No radical machining was done anywhere....just a standard valve job. Long block is together. I just checked the piston to valve clearance which should be 1.5mm Intake and 2.0mm Exhaust. Unfortunately I have 1mm Intake or less...and exhaust doesn't appear to be a problem. With the increased compression of the stroked 2.2 T pistons using the 70.4 crank, the profile on the E cam looked right. Am I now to assume that the lobes are too tall on the E cam? And that they are causing the valves to go too far into the cylinder heads? Should I go back to the T cams, or am I still going to have problems? I am using the same pistons and cylinders, same heads, same everything except crank and rods. What am I missing?

Speedo

I had the same situation earlier this year with the same engine 2.2E/70.4 crank. The engine had E cams that I replaced with DC40's during the repair.

I rechecked my cam timing and it was a bit off, this solved the clearance issue.

During my searching on the site for similar posts I found that the minimum distance valve to piston in the manual (Page E68) is 0.8mm, after I checked and rechecked my timing I was right at 1mm but was happy to have found the reference in the manual.



W

cam timing off...hmmm
 

I had just timed the cams again to make sure they were dead on. In my case max lift intake at TDC is 2.9mm or .116 in. I was worried that maybe valve length was different, but the valves are all the same length. I then checked the height of the lobes and the E and S are taller, but not by much. Is the DC 40 closer to a T cam than an S? Waynes book specifies 2mm I and 1.5mm E. You say the manual is ok with .8mm? Damn...that is close. As I think the timing is dead on...I suppose I could adjust the valves again for 1 and 4 and then plus or minus 15 degrees from TDC screw the valves in to see what additional clearance I have. It's not very much. Thanks

Speedo

Wade is correct about the .8mm reference. I'd try to get at least 1mm. I think the closest approach is around 5 to 10 degrees BTDC for the exhaust valve and 5-10 degrees afterward for the intake valve. You might retard your timing a little to get more clearance.

-Andy

Don't be too concerned with what Wayne's book says...., it is full of interesting info.... :)

Your cams are closer to "S" than "T".

If you have more than 1mm clearance you should be OK.

cheers

I had a bit of trouble putting E cams into a 2.0. My valve clearance also was too tight. I ended up putting a thicker jug base gasket to get the clearance. Didn' t take much, seems I remember it to be 0.030 inch thick.

+1

why not just add an additional, or single thicker base
gasket? I think at this point on this build, you deserve to take the easy way out ;)

Its not getting any better
 

Went back out this morning to take a fresh look. Reviewed my timing, that all looks good. On both 1 and 4, if I turn the valve adjustment screw in to where it just contacts the valve, and rotate the engine, I get contact with the piston on the intake valves at about TDC. I am wondering what my options are...I have timed the cams per 2.4 E specs because I have E cams. I am thinking I should both replace the cams back to the T cams, and then re-time those cams to T specs (although there isn't much difference between the intake valve overlap on the 2.2 T at 2.5 and the 2.4 T at 2.6). I just need more room...bottom line. The intake valve overlap for the 2.4 E is 2.9 so I will gain something there. The cam lift on the 2.4 E is 36.58 vs 2.2 T at 36.25, so I should gain something there also. I would rather swap the cams out than add a cylinder base gasket at this point. Any suggestions?

Speedo

it depends on what you want to do with the engine

cams are at the heart of engine performance for a given rpm range -

you should look at the performance profiles for T vs E cams and decide which best suits your intended driving

givern the list of other porsches you own,
1976 911S targa 3.0 "Esco"
1974 911 coupe 2.7 "Ernie"
1971T-ST coupe 2.2 S "Gonzo"
1971 911 T targa 2.2T-2.4E "Helga"
1966 R clone coupe 2.7 RS "Axel"

you must have some goal for this motor that the other cars don't fulfill ??

imho - just put in thicker base rings - yes, it's more work, it makes infinitesmal difference in CR, but you get the E performance curve

.

LarryM...good point
 

The engine is the correct numbers matching engine for a 71 softie that I am restoring. I decided to step it up a notch by stroking it. I talked to John Dogherty today and he suggested backing down the overlap from 2.9 mm at TDC to 2mm. I did that today and it appears clearance was not an issue. I went ahead and screwed in the valve adjustment screw an additional 2mm (2 full turns) and clearance was not an issue. I am going to step back, loosen all my valve adjustment screws and time the cams once more. I can't see how I might have screwed up the timing...I guess it is possible. Once more with feeling. If I don't get the clearance I need, I will swap the E cams for the milder T profile. I always knew that timing the cams was my favorite part of engine building ;)

Speedo

tonight...started over
 

I have 1mm intake clearance, and 1.5 exhaust clearance. Numbers don't lie. I am just .5 mm off (too close ) on both valves. This weekend I will swap at the E cams for T cams and start over. Major PIA but better than pulling everything and installing bigger cylinder base gaskets and losing my compression. Good news is that I have all the parts I need and it is only a couple hours of work. I will report back.:p

Speedo

Another option would be to keep the "E" cams and just increase the valve pocket.
It relatively inexpensive and cures all of your problem.
Send us your pistons and we'll do it cheap. Call or PM me for a price.

I am contemplating the exact same engine build, i.e.; a 2.2 T with a 70.4 crankshaft and connecting rods and E camshafts. I am also interested in increasing the size of the valve pocket to eliminate the same problem Speedo found. I assume I would have the same problem.

Henry

E-cams - ????

you did not post the specs on your "E" cams- so we all don't really know which set you are working with

I picked up a set of E regrinds from DRC yesterday - he uses the "105" spec for the 2.4 engines ("late" style per BruceA)

the "late-E" 2.4 specs are significantly different than the 2.0 & 2.2-C specs in the factory white books

- John says that he has never seen any so-called "early E" cams and that the P0rsche factory "white books" and Bruce's book are all wrong

- i once had a set of "E cams" done by webcam back in 1976 in a 2.8 engine (10.5 CR) built on a 2.4T oem - (it pulled from 1800 and ran out of breath (torq) at 5800) - dunno anymore what specs those grinds were

so my question is - are you installing a set of DRC "late E" grinds, or do you happen to have a set of those mysterious oem 2.0/2.2 cams in your engine ??????????

.