• Ciao Guest - You’ve landed at the ultimate Guzzi site. NEW FORUM REGISTRATIONS REQUIRE EMAIL ACTIVATION - CHECK YOUR SPAM FOLDER - Use the CONTACT above if you need help. New to the forum? For all new members, we require ONE post in the Introductions section at the bottom, in order to post in most of the other sections. ALWAYS TRY A SEARCH BEFORE STARTING A NEW TOPIC - Most questions you may have, have likely been already answered. DON'T BE A DRIVE-BY POSTER: As a common courtesy, check back in and reply within 24 hours, or your post will be deleted. Note there's decades of heavily experienced Guzzi professionals on this site, all whom happily give endless amounts of their VALUABLE time for free; BE COURTEOUS AND RESPECTFUL!
  • There is ZERO tolerance on personal attacks and ANY HYPERLINKS to PRODUCT(S) or other competing website(s), including personal pages, social media or other Forums. This ALSO INCLUDES ECU DIAGnostic software, questions and mapping. We work very hard to offer commercially supported products and to keep info relevant here. First offense is a note, second is a warning, third time will get you banned from the site. We don't have the time to chase repeat (and ignorant) offenders. This is NOT a social media platform; It's an ad-free, privately funded website, in small help with user donations. Be sure to see the GTM STORE link above; ALL product purchases help support the site, or you can upgrade your Forum profile or DONATE via the link above.
  • Be sure to see the GTM STORE link also above for our 700+ product inventory, including OEM parts and many of our 100% Made-in-SoCal-USA GTM products and engine kits. In SoCal? Click the SERVICE tab above for the best in service, tires, tuning and installation of our products or custom work, and don't miss our GT MotoCycles® (not) art on the BUILDS tab above. WE'RE HERE ONLINE ONLY - NO PHONE CALLS MADE OR RECEIVED - DO NOT EMAIL AND ASK QUESTIONS OR ASK TO CALL YOU.
  • Like the new V100, GuzziTech is full throttle into the future! We're now running on an all-new server and we've updated our Forum software. The visual differences are obvious, but hopefully you'll notice the super-fast speed. If you notice any glitches or have any issues, please post on the Site Support section at the bottom. If you haven't yet, please upgrade your account which is covered in the Site Support section or via the DONATE tab above, which gives you full site access including the DOWNLOADS section. We really appreciate every $ and your support to keep this site ad-free. Create an account, sign in, upgrade your account, and enjoy. See you on the road in 2024.

1973 V7 Sport Stock Cam Spec

Tonerjockey

Tonerjockey

High Miler
GT Contributor
Joined
Oct 28, 2008
Messages
788
Location
San Jose
Working with a piston manufacturer and need the lift of the stock V7 Sport cam. I know I had it but can't seem to find it.

Does anyone have the lift of the stock cam on the V7 Sport? The maint manual lists the duration but not the lift.

Thanks,

Tonerjockey
 
Hello Toner

According my measurementes on my own V7 Sport, valve lift on the intake was 10.4 mm, on the exhaust 9.4 mm.
Valve gap has to be subtracted from this figure. But max lift has no influence on the piston design. More important is the following:

When the cam is timed in straight 106/106° in/ex, the valve lift in TDC is 4 mm on the intake and 3 mm exhaust. When timing in slightly advanced which is often benefical for power, the situation worsens and the intake valve is likely to contact the piston. A win/loose situation concerning piston cutouts and CR. Be careful, a valve is bent easily.
 
Thanks for the data mgnx.

I got off the couch and measured from the pushrod. I get:


Exh .237" or 6.02mm
Int .305" or 7.747 mm

At the valve :

indicatevalve.jpg



Exh .349" or 8.86mm
Int .387" or 9.83mm

Note the prescision dead blow hammer

I am interested in the maximum compression ratio I can get. The pistons will need to be relieved for the valves of course. This will affect the CR... and around we go.

Currently the cam is in stock timing. Once I wring all I can from this config I'll move on to a more radical cam ... and pistons ...

Tonerjockey
 
I just stumbled across this topic. According to Guzziology, the stock V7 Sport (and 750S) cam is part # 14053300 with lift of 0.272 inch on both intake and exhaust. According to the fine print with the table, this is measured lobe height of the cam itself. For possible comparison with your manual, timing is given as intake 40 BTDC - 70 ATDC and exhaust 63 BTDC - 29 ATDC.

Hope this is useful.

Howard
 
Hey Howard,

Tanx for bringing up Guzziology. I completely forgot about that. Indeed it is as you quoted.

Now the question is what the heck is in my V7 Sport? I know I can be off by a dozen or so thous, in spite of my "precision" set up, but looking at The Book I can't really get a clue. It has the late dist drive and a tack drive.

Uncle Dave:
.272 ex & int
Tj .237 and .305

almost .035 off on both my readings... both ways... this is leading me to think the difference is in my work.

Since I didn't buy the bike new I can't say that someone didn't stick something else in there. I did dissasemble the engine but who knows what happened before I got it. Even Guzzi could have built it in an unusual manner I spoze.

Hmmm something of a canundrum.

One way to resolve this would be to R&R the cam for thorough inspection. Something of a drag as I just re-installed it a couple months ago.

hhhmmmmmmmmm maybe a measurement with rigorous attention to detail is in order.


Tonerjockey
 
Tonerjockey, looking at your pic I see you took your readings on the valve side of the rocker, but say off the pushrod?, and Howards info is off the cam lobe or in your case you could measure it right off the top of the pushrod, Unless of course the rockers have a 1:1 ratio then it would not matter which side you got your measurement I suppose :dry:
 
Hello Toner

There must be something wrong with your measurements:
The intake lobe seems to be correct - if you multiply the measured cam lobe of 7,747 mm by the rocker ratio of 1.35 you get 10,46 mm valve lift which is very similar to my 10.4 mm see on the graph below.
The exhaust does not correlate: 6.02 x 1,35 =8,13 mm lift. This corresponds neither to my measurement nor to your valve lift figure. Maybe your measured exhaust lobe is severely worn or the measurement is faulty. A worn lobe could explain the low top speed of the engine.

Did you set the valve gap to zero for the measurement? You should take the measurements at the valve spring retainer, or did you? The picture does not show it clearly to me.

Here is a graph with my B10 cam - note the crossing of the curves is left (prior) of TDC even though the lobe centrelines are timed symmetrically to TDC. This is because of the different lobe shapes of in and ex.
 
You must log in or register to reply here.
Back
Top