1st Gen Service Manual missing cam specs

[GaryZ]

I downloaded the 1st Gen Service Manual (8385servicemanual.pdf) and found the cam specs, page 403, missing.

 

Does anyone know why this page is corrupt?

Can someone send me this page?

[mini-muffin]

I'll look for our service manual and find the info for you. Then I'll send a copy to Don to see if it can be stuck back in.

 

Margaret

[GaryZ]

Thanks!

[mini-muffin]

I'm having a fight with the scanner at the moment so I'll post what I found here for now. Hope this is the right info for you.

Note

Do not turn the camshaft when measuring clearance with Plastigage.

 

Camshaft to cap cleareance

Standard: 0.020 ~0.054 mm

(0.0008 ~0.0021 in)

 

Maximum: 0.160mm (0.006 in)

 

If the camshaft to cap clearance exceeds specification, measure the camshaft bearing surface diameter

 

Bearing surface diameter:

Standard: 24.967 ~ 24.980mm

(0.9830 ~ 0.9835 in)

 

If the camshaft diameter is less then specification, causing excessive clearance, replace camshaft

 

If the camshaft is within specification and camshaft to cap clearance is excessive, replace the cylinder

 

 

If you need anything else let me know.

 

Margaret

[GaryZ]

The specs that I am looking for are . . .

 

Cam Dimensions

Intake "A"

Intake "B"

Exhaust "A"

Exhaust "B"

 

Thanks!

[mini-muffin]

I finally got the scanner to work somewhat, but I can't seem to get it saved in the right direction. You'll have to rotate it to view it. Hope this is what you wanted.

 

Margaret

[GaryZ]

Thank You!

 

I was hoping to answer a few questions about the differences in a Venture vs Vmax cam. Instead, I am confused at how much they are alike. The difference seems to be in the springs and the valve size . . . ?

 

		Vmax VMX12N		Venture XVZ12TK
cylinder bore		75.07 ~ 76.02 mm
comp. ratio		10.5:1		10.5:1
cylinder pressure		206 psi		171 psi
camshaft
intake A (lift)		36.25 ~ 36.35 mm		36.25 ~ 36.35 mm
intake B		28.02 ~ 28.12 mm		28.18 ~ 28.28 mm
exhaust A (lift)		36.25 ~ 36.35 mm		36.25 ~ 36.35 mm
exhaust B		28.02 ~ 28.12 mm		28.18 ~ 28.28 mm
intake valves
head diameter		30.4 ~ 30.6 mm		28.9 ~ 29.1 mm
stem outside dia.		5.475 ~ 5.490 mm		5.975 ~ 5.990 mm
guide inside dia.		5.500 ~ 5.512 mm		6.00 ~ 6.012 mm
exhaust valves
head diameter		24.9 ~ 25.1 mm		23.9 ~ 24.1 mm
stem outside dia.		5.460 ~ 5.475 mm		5.560 ~ 5.975 mm
guide inside dia.		5.500 ~ 5.512 mm		6.00 ~ 6.012 mm
inner valve spring
free length		37.45 ~ 39.65 mm		35.3 ~ 37.3 mm
closed length		31.8 mm		31.8 mm
comp. pressure		13.9 ~ 16.3 lb.		10.08 ~ 11.84 lb.
outer valve spring
free length		38.90 ~ 41.10 mm		37.25 ~ 39.45 mm
closed length		33.8 mm		33.8 mm
comp. pressure		29.3 ~ 34.6 lb.		22.27 ~ 26.24 lb.

[mini-muffin]

I can't help you with that, but if you really want to know anything about the differences and the same stuff in the 1st gen (particularly the MK I) You're best bet is to PM Squeeze. He knows everything pretty much that there is to know. As far as I understand the 1st Venture was pretty much just a VMax with bags. At least that's what I've picked up from the guys.

 

Margaret

[Squeeze]

You can't tell the Cam Differences by just using the Specs.

 

If you want to know the real Differences, you'll need to put both Cams on the Bench, mount a Angle Scale and take Measurements about the Elevation above the Base Circle every two Degrees Turn Angle at least. Mark this on a Sheet of Paper or Excel (where x-Axis is Turn Angle in Degrees and y-Axis is Elevation on 1:4 or 1:5 scaled Dimension) and you'll see the Differences in the Sinus Waves you'll create. You might proceed this with the EX Cams also. You'll need to look at the Mounting Holes as well, because these fixed Holes can cause Differences in the IN/EX Valve Overlap. It's not that easy, but you could do it with some Measuring Devices.

 

Basically, Vmax Cams have a different Profiles, they open earlier and close later than the VR Cams. It's not that much of Difference but it's there. Even those Vmax vary by Years, the newer they are, the tamer they went.

 

You right about the Valve Diameter and the Springs. The Vmax Springs are good for 1kRpM more than the VR Springs. The Valve Diameter and the Valve Stem Difference give the Vmax more Filling per Stroke.

 

Filling is one Key to create Power. More Filling, more Power.

[GaryZ]

Excellent info, thanks Squeeze.

I bought Vmax cams on ebay and I can compare them to the cams in the 1987 VR engine where they are going to reside.

[Venturous Randy]

Great answer Squeeze.

In laymens terms on cams, the difference is lift and duration. Two cams can have the same lift, but when you start lifting the valve earlier and holding it open longer, as in duration, that makes a big difference in power and streetability. Extended duration is where you get much of the lope on high performance cams. Too much duration and bottom end torque will suffer and can make a vehicle almost unstreetable.

RandyA

[Squeeze]

Thanks Guys, but i just tell it like i know it. No Rocket Scientist here.

 

Another Aspect to keep in Mind is not only Lift and Duration, but also the Overlap of IN and EX Cams. If the Borings in the Cams would be milled to be adjustable you basically could change the Characteristics of the Motor from torquier to red line Champ. Of Course, that's all within basic Limits, but the Overlap is not to belittle.