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tips, technology, tools and techniques related to vehicle driveline components

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mabie1978
Michelle Pierce
Elyria, OH
(111 posts)

Registered:
08/25/2008 07:47PM

Main British Car:
1978 MGB 3.5 Rover V8

Question for you Rover guys
Posted by: mabie1978
Date: August 12, 2009 02:03PM

I am going to use the cam that Kurt included when I bought his parts, it is by Crower, part number 50232. Bernie Posey and I discussed it and he thinks if my heads were built to stock specs (which they were when I bought them) the valve seats will need to be cut larger. But he wasn't sure, does anyone know if you use that cam if the valve seats need to be enlarged?? Many thanks!!


NixVegaGT
Nicolas Wiederhold
Minneapolis, MN
(659 posts)

Registered:
10/16/2007 05:30AM

Main British Car:
'73 Vega GT 4.9L Rover/Buick Stroker

authors avatar
Re: Question for you Rover guys
Posted by: NixVegaGT
Date: August 12, 2009 03:00PM

I don't think so. I can't think of a reason to do so. Worried about piston interference maybe? Like get the valve to sit a few thou deeper?


Dan Jones
Dan Jones
St. Louis, Missouri
(280 posts)

Registered:
07/21/2008 03:32PM

Main British Car:
1980 Triumph TR8 3.5L Rover V8

Re: Question for you Rover guys
Posted by: Dan Jones
Date: August 12, 2009 06:13PM

> Bernie Posey and I discussed it and he thinks if my heads were
> built to stock specs (which they were when I bought them) the
> valve seats will need to be cut larger.

Valve seats or the spring seats? You enlarge the valve seats
when you install larger diameter valves or to sink the valves
deeper (not recommended if you don't have to). When you install
a higher performance cam, you typically check:

piston to valve clearance
valve spring retainer to valve guide/seals clearance
coil spring bind

Perhaps he meant spring seats to run a larger diameter spring?
Coil spring bind might be a problem with that cam and stock
springs. You might be able to get away with stock springs but
that cam really needs a better spring. D&D sells drop-in TRW
valve springs that are stiffer and are good to 6500 RPM with the
Crower 50232 cam. I previously ran a Crane H-216/285-2S-12 with
specs:

266/278 degrees duration (advertised)
0.456/0.480" lift
112 LSA

It was installed by the previous owner along with new stock
replacement TR8 valve springs. The lifters on that cam went
flat so I switched to an Erson RV10/RV15 (Wedge Shop custom grind):

280/288 degrees advertised duration (208/214 @ 0.050")
0.448"/0.460" lift
111 lobe separation angle
4 degrees advanced when installed straight up

which seems to work better with the stock springs (revs better).
Any bigger cam and Woody recommends a spring upgrade. If I recall
correctly, the Federal-Mogul (Speed Pro) VS1615 (aka TRW VS966)
is what D&D sell for the 50232 Crower. Specs are: 1.23" OD with
85 lbs on the seat and 230 pounds open (295 lbs/in rate). They
have a yellow paint stripe and damper. When I was looking into
the cam, I checked some other springs:

Part # OD (in.) Closed # Open # Rate(#/in.) Approx price
-------------------------------------------------------------
FM VS677 1.20 80 200 267 $1.5 each
FM VS739R 1.264 105 277 350 $2.5
FM VS1615 1.23 85 230 295 $5.0
CC 979 1.24 80 200 267 $4.0
CC 980 1.23 85 230 325 $5.0

The Fed-Mog/Speed-Pro/Sealed-Power books lists specs for:

VS-677: 1.238" OD, 2.03" free length, .177" wire diameter, 6.8 coils,
80# @ 1.7", 200# @ 1.25", coil bind 1.15", 267#/in spring rate.
With damper.

VS-744: 1.225" OD, 2.02" free length, .175" wire diameter, 6.6 coils,
80# @ 1.7", 200# @ 1.25", coil bind 1.15", 267#/in spring rate.
No damper.

CC = Comp Cams

Dan Jones


mabie1978
Michelle Pierce
Elyria, OH
(111 posts)

Registered:
08/25/2008 07:47PM

Main British Car:
1978 MGB 3.5 Rover V8

Re: Question for you Rover guys
Posted by: mabie1978
Date: August 12, 2009 09:12PM

Spring seats it was, so much info the last few days it is all running together. I know Bernie runs the same cam in his car that I have and he could remember if the spring seats need to be cut larger or not, I think his swap was like 10 years ago. Personally, I didn't plan on doing an entire engine rebuild but that is where I ended up at rather than look for yet another block. The heads have already been through the machine shop and rebuilt back to stock specs so I hate to have to rebuild them yet again. So I am trying to figure out which way is more cost effective, change to a different cam or cut the seats if that is the way it needs to happen.


castlesid
Kevin Jackson
Sidcup UK
(361 posts)

Registered:
11/18/2007 10:38AM

Main British Car:
1975 MGB GT Rover V8 4.35L

Re: Question for you Rover guys
Posted by: castlesid
Date: August 13, 2009 06:01AM

Michelle,

I am running the crower 50232 cam and am very pleased with it, bear in mind that my engine is 4.35L and I have Buick 300 heads with 1.63" In. and 1.4" Ex. waisted stem valves with the usual mods the the seat and throat areas to make the most of the cams potential.

The only basic mods required to run that cam are to have the tops of the valve guides machined down 100 thou. and to use a valve spring that has enough clearance and rating for the lift of the cam, and the valve spring installed height should be set to the correct height.

Bear in mind that with standard Rover heads you will be strangling the engine and the 50232 cam will not be able give it's full potential, effectively one component working against another, as you will also lose a little performance at lower RPM especially in a 3.5l engine.

With the Rover heads you can pick up 30+ BHP by having the seats cut to actual seat size and the throats opened up and blended into the bowls, it the about the cheapest 30 + BHP you can buy on a rover engine and you will get a lot more benefit from that cam. Also get the bottom end of the guides machined down to approx 1/4" from the cast support area in the port.

These simple mods will give you a nice free revving 3.5 engine but still maintain good drivability on the road.

Kevin.





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Edited 1 time(s). Last edit at 08/13/2009 06:10AM by castlesid.


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