Aluminum VL.

[JoJo357]

Howdy, just spotted these VL Aluminum Heads by: *Speed-Machine M/C., in Minnesota. Looks like top shelf.

https://www.instagram.com/speedmachinemc

*M.A.D.*

[Steve Slocombe]

Nice work. I have the 7 bolt aluminium heads on my 35VLDD and my 34 racer. You can feel the extra compression when kickstarting, and they make for a good weight saving on a bobber or racer.

[kitabel]

Haven't seen those, what is the static CR?
Looks like they duplicated the iron casting (rather than increase the deck thickness or fin height), counting on semi-original appearance as a selling point.

[JoJo357]

Welcome Jeffrey, been on your Victory site many times & bought some books over the years. A shame there isn't a lot of material written in regard to the H-D J/JD's. Maybe Mark Masa will finally finish his J/JD debut one of these days.

*M.A.D.*

[Steve Slocombe]

They're not cast from the iron heads but modified from the early aftermarket aluminium heads you occasionally see at the swap meets. The fins are thicker than the iron heads and there are not so many.

[kitabel]

From an older post, it appears that a factory high compression 7 bolt VL head was only 7.3" volume, smaller than any 9 bolt head and giving 6.4:1 static CR in an 80" engine. The math:
1 cylinder 39.37" (using ULH data) + 7.3" = 46.67" total, ÷ 7.3 = 6.39:1
Did they duplicate this volume?

Note: to estimate the chamber volume needed for a specific ratio, divide the cylinder volume by the desired compression ratio - 1.
E.g. to get the chamber size for 7:1 CR in the same engine, 39.37 ÷ 6 = 6.56".
Important: the factory marking and ID ("8.2", etc.) are probably the volume of the entire chamber, not just the head itself. This includes deck clearance and valve relief pocket volumes, and is increased slightly by relieving and every valve job.

By comparison, 45 heads are marked with the approximate static CR (5, 6, etc.), not the chamber volume.
Using std. bore and stroke:
5:1 chamber volume 5.64"
6:1 chamber volume 4.51"

To get cubic centimeters from inches: multiply by 16.387.

[Steve Slocombe]

The regular VL 7-bolt high compression head was a 9.3, with 10.5 as medium compression and 12.5 as low compression. Harley experimented in 1935 with 8.6, 8.2 and 7.3 7-bolt heads for the domestic market, which are rarely seen. Aluminium heads were also tested in 1935 but did not make it into production. I'm guessing this was associated with the rare 1935 VLDD 80 inch models, and the very rare VLDJ 74 cubic inch competition bikes. This was the year Harley announced the 'hook cams' as a $9 option for the late season VLDD. The whole thing was superseded with the change to 9 bolt heads in 1936. This time 8.2 was high compression, 9.3 was medium and 10.5 was low. A few 7.3 extra high compression 9 bolt heads were made for the domestic market, with three cast ribs underneath. Again these are rarely seen today.

[duffeycycles]

By comparison, 45 heads are marked with the approximate static CR (5, 6, etc.), not the chamber volume.
Using std. bore and stroke:
5:1 chamber volume 5.64"
6:1 chamber volume 4.51"
This is true on '41 & later aluminium 45" heads but not the earlier heads.

[kitabel]

Which are marked...?

[duffeycycles]

marked like VL with 6.8 low compression,smaller numbers are higher comp..some are marked with casting bars

[wz507]

The subject of 7-bolt aluminum heads for VL engines certainly interests me. In a recent communication from Steve Slocombe he informed of purchasing a set of the subject heads at a swap meet a decade ago that were made by the W N Smith Company in Portland Oregon. Steve had patterns of these heads made and several sets cast, but long ago disposed of them, with the exception of 1 set on his own machine.

The patterns were evidently purchased from Steve by someone in the US and are alleged to reside somewhere in Iowa. However, Steve has lost any contact information he had in the matter and has no recollection of who he sold the patterns to. By any chance might someone here have any current knowledge regarding the whereabouts of these patterns? Thanks in advance for any assistance you may be able to provide.

[Steve Slocombe]

Dear All, I'm recasting a few 7 bolt VL aluminium heads for a customer race bike and should have an extra set.