[r-mm]

Hello all. I have the head off my 2 L for a few reasons. One of them is installing new cams with higher lift that required me to relieve the follower bores. After doing that I gave the head and all valve components a thorough clean. On reassembly I now have the ability to take a close look at all of the aluminum parts. So far I have two questions:


I noticed some scoring at the front of the frontmost exhaust cam shaft bearing. Any advice on this? The rest look good as do the caps.

When I rebuilt the head i used the guides which are cut for the white Teflon seals. The head has only approximately 3000 miles on it and the seals and valve stems look good. I presume there is no problem leaving the seals in place?

 

[Gordon Raymond]

Your timing chain was at some time too tight. Look at the upper cap of the rear journal on the same cam. Scoring? If not, polish the front journal, and ideally install the cam without valves/springs on that side, and plastigauge clearances. Can't do that? Check the cam in a lathe for run-out on the front journal. Plastigauge without lash caps or followers. If scoring is only on the head cradle, not the cap, it's likely it was a chain too tight issue.
Todays seals are too easy and inexpensive not to replace with new if the head is apart.

 

[Alfar7]

DO NOT polish the front journal. You will increase clearance. Clearance for can journals is .0008-.0015'.
Leave then alone.
I`ve suggested to deaf ears to get rid of the long guides and teflon seals.

I sent you an email that you do not have clearance for the cams with that stuff in the spring bore. Use the short guides and green Reintz seals. Centerlinealfa.com Part #s: Guides VG245, Seals VG191.
Guide should be set to a total height above the floor of 11mm.

 

[r-mm]

Thank you both. I found an older thread where this was discussed and plastigauged the exhaust cam. Torquing the caps to 15 ft lbs. I did this with no other valvetrain installed. I saw approx

.001"+ Front (just over .001 mark)
.0015" Middle
.0015" Rear

Thank you I received your email Richard. Did you type the wrong CL part number? VG245 says "These guides are cut to accept Centerline Teflon valve guide seals (VG129). Not for use with original Alfa valve guide seals. "

Valve Guide Ex V/6 | Centerline International

Centerline International is the leading supplier of restoration, performance, and maintenance parts for all Alfa Romeo models fr

centerlinealfa.com

Am I looking for factory 2 liter valve guides? Or factory V6 valve guides?

 

[Andrew]

Lots of engines have galling etc. on the front exhaust journal from too tight a timing chain. That's the one that take the brunt of the pulling from the crankshaft. I wouldn't worry too much. I've seen worse. To tighten the chain, I "help" it a small amount with a medium size screwdriver, then tighten down the pinch bolt while holding that. Not too much pressure, just more than the spring will give it, which isn't enough.
Have your cam cap studs been changed? Original ones are 1.25 threads in the head and 1.00 threads at the top for the nut. Yours look 1.25 on top. As long as they torque up OK.
Andrew

 

[r-mm]

Richard

From reading other threads I think you are recommending V6 12valve EXHAUST guides, cut for the original green seals. I'd have to call to see if these are so cut: Exhaust Valve Guide V6 - (SKU 14-4856) [14-4856] - $5.96 : Vick Autosports, The Premier Fiat and Alfa Parts Source

Otherwise - will the white seal (Centerline part you linked to) foul the valvetrain above it ?

Andrew that is one heck of a good eye. Yes I changed the cam cap studs and its far easier to find 1.25mm both ends than the ones alfa used which are 1.0/1.25 as you point out.

 

[Alfar7]

Months ago I had the same question about the "Teflon Guide" situation and talked with Joe (Centerline owner) about their statement.
He was going to make a change on the website and internal computer system. I and many others have been using these guides (VG245) and green Reintz seals (VG 191) the only ones used in ANY of my engine builds that use 9mm valves, over the last several years..

The green seals fit. I install them using a valve to center them and drive them on with a seal installer which is nothing but a steel tube that fits around the "seal lip & spring" with a flat bottom that contacts the seal base.
Be sure the steel spring pan is installed before you install the seals.

 

[r-mm]

Thanks Richard I'll order these and bring them and the head to my machine shop, who are familiar with Alfa twin cams. Is there an installed depth for the guides you recommend?

 

[r-mm]

Do you all replace springs as a matter of course? I measured the free length as best I could and found following.

Outers: 49.5 - 50.6mm (spec 51.3)
Inners: 46.3 - 47mm (spec 46.5)

This puts all the outers below the specs attached.

 

[Gordon Raymond]

You answered your own question. Yours are out of spec. replace all.

 

[Alfar7]

Total guide above the seat including the seal mount area of the guide is 11mm. I suggest using Isky 455/626 springs (Summit racing. The "Performance" springs from Centerline are inadequate for any lifts above 10mm and RPM over 6000. The same ones are sold for the V6 and 4 cyl.
The V6 uses a short spring with slightly smaller OD. Wire diameter is .130 outer and .90 inside. Proper springs for any true performance springs have fewer coils, and larger wire diameters.

 

[r-mm]

Not a big cost difference
Centerline: Valve Springs 1300-2000 | Centerline International
Isky @ Summit: Isky Valve Springs 455-626

Richard the cams you sent me are 10.8mm so I presume you recommend the Isky. The bottom end is stock so I don't anticipate revving past 6k, unless the engine gurus on this discussion believe the stock 2L bottom end can take a higher redline.

 

[Gordon Raymond]

BIG 3 spring Alfa Isky springs for Richard...

(Actually Donovan Hemi springs)

 

[r-mm]

I did the following test to see how much travel the valves have before the bottom of the collet makes contact with the current teflon seal.

I installed only the valve, collet and keeper then indicated of the top of the valve stem. I am seeing
.335" travel exhaust
.367" travel intake

Forgive the maybe naive question but does this measurement correspond directly to valve lift, or must lash or some other number be taken out of a cam's valve lift?

If my test is valid, I now see empirically what Richard has been trying to get into my skull with regards to why the existing tall guides and teflon seals won't work with the intake (.42626" lift) and exhaust (.41547" lift) cams he sent me.

 

[r-mm]

Richard: are the Isky springs a drop-in replacement, compatible with the factory collets / keepers?

 

[Alfar7]

Yes.

 

[r-mm]

Thanks. I ordered a set from Sumit to my machine shop.

 

[4sfed]

To tighten the chain, I "help" it a small amount with a medium size screwdriver, then tighten down the pinch bolt while holding that.

NEVER help the tensioner spring! Just roll the engine forward while tightening the clamp. The chain and block have different expansion coefficients and the chain gets tighter when the engine warms up. The difference is enough to remove a 5mm sag between the cams.

You don't want the chain that loose (sag) because the chain tension in a running engine stretches the chain (takes up a the clearance in all of the links) and the camshafts deflect.