7A cams, any known probs?

[audiman]

Gonna fit both 7A cams soon, and i was just gonna ask if anyone has already done this, and if so do you need to alter the valve springs as the lift is higher?

Is there anything needed at all to fit these, apart from tools!, ie special cam pulley, blah, blah,blah

[RSCoupe]

People here in the States with S4-S6s use the 7A exhaust cam as a cheaper alternative to the RS2 exh. cam. Some say that running both 7A cams may create problems due to excessive overlap. But if you use adjustable cam gears, you can adjust out some of the overlap. I will be running the 7A cams in my motor. But it will be far from stock.

[Mihnea]

I know of someone with a K26/27 running both cams and 420 crank HP with no problems whatsoever. I guess with no special remapping this wouldn't be as good as with proper remapping but time will tell us, right Tom?

[Mark Halligan]

Tom,
I think that they will be OK with the standard springs/retainers etc, at least I am going to use both cams in my rebuild, I'll just be careful to check for valve to piston clearance as I had a lot taken off of my head to get it straight, but I will ask for that to be taken into acount when I order my pistons.
I did read over on Kruemmer that there may be a loss of some low down torque, but you will probably not care too much about that once you get on boost .
It might matter though, what cam pulley you use, I had a look on ETKA a little while ago and the part #'s for the pulleys are different NM,7A and3B engines use the same pulleys, and the ABY and ADU engines both use different pulleys.
Will the 'wrong' pulley make a difference to cam timing?
As for the 'overlap', Marco posted the calcultions not long ago and there is no overlap, its close ,only to within a few degrees though, thats if you use the right cam pulley, assuming they make a difference .

Cheers,

Mark.

[newsh]

Aren't the different pulleys due to the hall sensor reading the cam posn. on the ABY / ADU rather than it being in the dizzy on the 3B etc.?

[newsh]

Marco's thread.

http://www.s2forum.com/forum/showthread.php?s=&threadid=1649&highlight=overlap+cams

[Mark Halligan]

Aren't the different pulleys due to the hall sensor reading the cam posn. on the ABY / ADU rather than it being in the dizzy on the 3B etc.?

John, I did'nt think of that, but why then do the ABY (034 109 105) and ADU (034 109 105B) have different P#'s, they both use the hall sensor? Maybe someone here knows for definate, hope so cos I need to know what pulley to use.

Mark.

[sal_s2]

I've counted the teeth on both adu and aby pulleys and they both have 52 teeth.

[Greg_S]

that seems fair. by the look of the part no on the ABY and ADU pulleys the ADU one has just superceeded the ABY one.

Greg

[Mark Halligan]

They'll all have the same number of teeth as they all use the same toothed crank pulley, (if I remember right the cam runs at half engine speed?), its the woodruff key position that determines the cam timing, need to know if the key notch in the 7A cam pulley is in the same position as the ABY or ADU pulleys (which themselves have different P#'s), as if they are different and I use one of them, the cam timing might be off, if used with the 7A cams.

Tom won't have a problem as the 3B uses the same pulley as the 7A, but I am rebuilding an ADU block with the 7A cams and what makes me 'suspicious' is the different P#'s, as John said this could be cos of the hall sensor, but why are the ABY and ADU P#'s different, is it cos of timing??

I checked in the 1995 section of ETKA and the ABY pulley P# is still different to the ADU, maybe Paul (Vagparts) will know, other than that I supose the only way to know will be to physically check a 7A,3B pulley against a ABY or ADU pulley for the notch position.

Sorry for hijacking the thread Tom .

Mark

[s2avant]

Looking at the part numbers, I'd have to say the difference must be the key position.

NM, 7A and 3B are more than likely a different number because of the hall sensor being on the dizzy.

ABY and ADU pulleys must have different key positions hence the similar part numbers.

The last three digits of a part number indicate the part itself. Looking at various engines on ETKA it would appear that the following is the case:

numbers ending 111 are used when the hall sender is not on the cam pulley.

numbers ending 105 are used when the hall sender is on the cam pulley.

The letters on the end are a version and/or supersession digit. As these pulley don't supercede then it must be a different woodruff key position (hence different cam timing).

I don't have any engine data for ABY/ADU engines so can't say whether the cam timing is different.

@Mark H,

Did you ever get to the bottom of the differences between ABY/ADU water pumps?

Ben

[Mark Halligan]

Ben,

thanks for that, what I will probably have to do then, if they are different, is get a 7A pulley and match it up against a hall sensor type pulley, either a ABY or ADU and have another key notch machined into it to match the 7A cam timing. Or use an aftermarket adjustable cam pulley assuming that these work with the hall sensor?

Never did get to the bottom of the ABY/ADU water pump differences, but I'm using the ADU block in my rebuild so I'll just use the ADU water pump on it.

Cheers,

Mark.

[Mihnea]

the ADU water pump has one more tooth than an ABY AFAIK...

[audiman]

Ah, the beauty of the 3B. Just bolt it in place and turn the key. Sod all this wrong pulley crap!!! LMAO

Mark if you want a 7A pulley I have one in stock. Going back to the pulleys for ADU and ABY, you will have to have a look at the two next to each other.

PS. Hope you had a good holiday Mark!

[Mark Halligan]

PS. Hope you had a good holiday Mark!

Cheers, had a great time .

Mark if you want a 7A pulley I have one in stock.

That'll save me searching if I need one, I should know soon.

Thanks Tom,

Mark.