MG MGB and MGB GT Tech Talk
Doing a bit of work on the B and will be removing the timing chain and inspecting things in there and am kind of thinking of installing a bit more of a cam in the engine.
I was looking on V.B.and they have a Kent cam available in three different grinds so I am wondering if anyone on this forum has had any experiences with them and also if there are any other cams available for an upgrade.
Thank You
Martin
I'm sure others will know more but I think Crane may be available again.
APT
Delta
Kent
Check with Basil and maybe Hap.
Martin, aside from all of the responses and suggestions that you are going to get on this one, I would suggest that you do some big time research on what to expect from the different makes and grinds and read a couple of the "SpeedPro" books on the subject. Money and time WELL spent.
Going further with your research than what is MG and MGB specific would be enriching too.
Committing to a particular cam is IMHO THE biggest step in planning a motor. A cam is "the brains of the outfit" and just about everything else is subservient to it's intended purpose and directions.
Jack
I am real pleased with the Crane cam thatwas available before their collapse. As mentioned above, Crane is coming back.
I would talk to Delta Camshaft, In Tacoma Washington, They likey can regrind your shaft for a lot less than a new one, and make it to do what you want out of it. They did a sunbeam camshaft for me, it came back looking new. They can also redo your rocker arms.
http://www.deltacam.com/index.php
I'm quite pleased with my Kent 17-155 Road cam kit from VB after 1,6000 miles. I seem to remember them suggesting Crane push rods and I used them too. Nearly everybody changes up from a single row timing chain to a double row then they have to worry about am timing, usually buying an adjustable cam sprocket. I stuck with the single row setup because changing to the double row throws the cam timing off. I'll probably catch a bunch of flack for telling you that but I don't think anybody else has ever checked that aspect of it. Everything works great together, I have a header pipe and DGV Weber carb.
Might be good to discuss your use/performance goals with the engine folks here (I'm not one). Some of the folks above and on the site have the real first-hand experience.
The 17-155 is the cam I am thinking of getting as I am not a racer but do enjoy sticking My foot into it and feeling them ponies run,this cam has a range of 2000 to 6000 rpms and I very seldom run it past 4500 so I would think that it would do real good for torque and horsepower at those rpms.
I am also putting together an Extrudabody injection kit but I want to do it one component at a time so i am planning on running with the 70s intake and cast exhaust header and tubing the carbs to get the engine running to peak then installing the injection kit then removing and grooving the combustion chambers in the head and seeing what difference that makes and then the cam who knows,after that I may get into adding a supercharger to it too.:thumbsup:
Martin, IMHO a rebuild done one part at a time is not cost effective and you may not like the
results when the next part is done. The entire package needs to be well planned including the exhaust.
What good is it if the engine doesnt breathe well? What is the intended compression ratio? Super chargers dont like
high compression, etc., etc.
RS
X2 on Delta cams.
Also X2 on a well planned program for your mods so you get a positive synergy. These engines love compression ratio but that's not good with a supercharger. Consider an 80/20 head with prepped carbs and an appropriate cam as this will give you good bang for the buck. Feel free to contact me for specifics. 970 564 5822.
The first thing I ask people is how high they rev their engine regularly. In reality, We don't usually get over 5K and something like 80% of the time, we're under 4,000 RPM on the street.
Now keep in mind that the duration of the stock cam is well suited to this RPM range.
So what can an aftermarket cam manufacture supply that the stock cam doesn't?
They can either increase the duration of the cam (which will move the RPM range upwards), or they can increase the lift (opening and closing rates) of the lobe to provide more valve open area in the same amount of time. They can also do both of those things.
So let's say we want to continue driving our car the same way we do now, but when we put our foot to the floor at 3,000 RPM, we want the car to accelerate harder. How are we going to alter the camshaft to make this happen? Well, we aren't going to increase the duration because we've already got a good situation going on there (plenty of time for the gasses to make it in and out of the engine). What we can do however, is increase the lift of the valves, which will allow the engine to breathe more freely at all times, but not significantly alter the RPM range over which the cam works. The stock cam is 260 advertised duration (215 @ .050" and .365" lift)
So if we know that, then we will be able to look at cam company specs and see that an aftermarket cam with a 280 advertised duration (say 240 @ .050") but with only .380 lift is going to be a high RPM cam. Usually you gain a little up top (over 5,000 RPM) and lose out before 4,000 RPM, so the average person is not gaining anything by using this cam.
On the other hand, a cam like the VP-11 from APT has a.400" lift and only .260* advertised duration (224 @ .050") which means it's going to be a much torquier grind than the previous cam. I have lots of customers who use this cam and love it. The VP-12 that Hap likes is very similar with just a few more degrees of duration, so it likes a slightly higher RPM band, but they are both good street cams.
Somebody mentioned timing as well. It's very important that your cam be timed properly! A retarded cam can cost a lot of torque without gaining any HP and that's usually how they end up being installed. This is especially true when the dual row timing chain is installed without an offset key, as mentioned above.
Watch out for camshaft sales blurb, it's usually wrong.
Sean
I very seldom hit 5000 RPMs so it sounds like the VP11 would work very well.
I know nothing about timing a cam other thn lining up the marks and put them together.When the time comes I will be looking for a lot of help on this.
I was thinking the purpose of installing components one at a time would give Me a seat of the pants dynomemeter feeling of improvement in performance with each change.
I like the stock cast manifold as I had a car once with headers and it seemed like I was always having to replace the gaskets to stop them from leaking.