NEWB Here, Needing Expert Advice

[TRH]

Hi all,
I'm building a 1835cc motor for a friend. The short story is; He obtained it, in pieces, from the widow of a guy that was just about to start his build.
Everything came to me in boxes and after sorting through all of it, I'm sure it's all new stuff including the cases. Here's what I have: 92mm Cyls., 69mm crank, 120 cam (.435 valve/.397 gross.) 1-1 rockers on solid shafts and two sets of heads. I opted for the heads that have smaller valves (Not sure of the exact size) and 53cc Combustion chambers with single valve springs over the set that has larger valves and dual springs. I believe the compression ratio with this combination is 8.2-1.
Here's my concerns: The guy I'm putting this thing together for does not want Hi Performance. He wants it reliable and most of all, he wants to run regular (87 octane) gas.
I talked with a VW mechanic in my area with my reliability/87 octane concerns and he told me to drop the compression to 7.2-1 and replace the 120 cam with a 110 (.430 valve/ .392).
Also, after I dropped the valves in, I noticed that the intake stems are Approx. .040 longer than the exhaust stems.
Questions:
What do you guys think about 7.2-1 with a 110 cam and 1-1 rockers for reliability and 87 octane?
Should I grind the intake valve stems so I can obtain a good swipe?
Thanks

[66brm]

Even with the W110 cam I would bump the compression up above 8.0:1, and if you have the right tools to grind valve tips then yeah even them up, but only after all the valve work is done, IE cutting seats etc.

Make sure the valve springs are HD singles if going down that route as stockers won't give the control required for the 110

[Leatherneck]

What case are you going to be using?

[Marc]

He said it was "new" so I assumed a BZ dual-relief piece. I'm a little more interested in finding out what kind of 92 cylinders they are...there are three styles available these days (98/96, 101.1/97.25, and 101.1/96). IMO the "classic" 98/96 version are doomed to a short life and shouldn't be used for any build expected to last more than ~20K miles...the other two are fine, but I see no need to whack the case out to 97.25mm for a 92 bore so the 101.1/96s are my first choice.

If it's going to be fed Regular gas, the C.R. should be held to a sensible point - although 7.2:1 is overly conservative IMO, that could be bumped up ~half a point with the W-110 and a bit more with the W-120. How heavy is the vehicle?
Here's another place where the cylinderwall thickness is relevant, if you run big piston deck (to drop the C.R.) on the classic 92s they're prone to splitting if there's any detonation. The thickwall jugs are more forgiving.

[TRH]

Even with the W110 cam I would bump the compression up above 8.0:1, and if you have the right tools to grind valve tips then yeah even them up, but only after all the valve work is done, IE cutting seats etc.

Make sure the valve springs are HD singles if going down that route as stockers won't give the control required for the 110

Thanks.
I went and bumped the compression to 8.2:1.
I'm not sure what springs I have but when I tested them (Singles), they

What case are you going to be using?

had 110 lbs at open height. Enough??

[TRH]

He said it was "new" so I assumed a BZ dual-relief piece. I'm a little more interested in finding out what kind of 92 cylinders they are...there are three styles available these days (98/96, 101.1/97.25, and 101.1/96). IMO the "classic" 98/96 version are doomed to a short life and shouldn't be used for any build expected to last more than ~20K miles...the other two are fine, but I see no need to whack the case out to 97.25mm for a 92 bore so the 101.1/96s are my first choice.

If it's going to be fed Regular gas, the C.R. should be held to a sensible point - although 7.2:1 is overly conservative IMO, that could be bumped up ~half a point with the W-110 and a bit more with the W-120. How heavy is the vehicle?
Here's another place where the cylinderwall thickness is relevant, if you run big piston deck (to drop the C.R.) on the classic 92s they're prone to splitting if there's any detonation. The thickwall jugs are more forgiving.

I'm not sure about the vehicle weight, but it's going to be a Baja.
All I know about the cylinders is that they are Mahle brand. The cases are new but I don't know who made them. I got all of the parts in a box and it has been like putting a puzzle togehter.

[Marc]

So far as I know, the only 92s Mahle's ever made have been the "classic" (thinwall) variety. More than likely he'll need to run midgrade gas to avoid pinging at 8.2:1 with an Engle W-110.

With a W-110 and HD single springs I'd be shooting for ~100lbs seat pressure and 175-200lbs at the nose. This grind is OK with HD singles for most combinations, assuming the valvetrain weight isn't too much. With steel pushrods, captive-ball swivelfeet and heavy retainers, dual springs will give better control without having to jack up the seat pressure.

If it's a "stock" case you should find the country of origin cast into the case halves below the pushrod holes (Germany, Mexico, Brazil) along with the alloy (AS41 or AS21). Generally speaking, dual-relief/large-passage has been the norm since 1970. "Dual-relief" refers to the oil-pressure plungers; single-relief cases didn't have the one at the flywheel end.