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Valve Spring Help.

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vping

vping

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Good moring everybody and Happy Saturday!

So I had my head done, Boiled, Magnafluxed, new seats, cut valves, ported, polished..... and all looks really good. I found a cam, a Crane 342-0010 and it also came with Larger valve springs. In fact they are double springs - Springs inside of springs. I took off one of the springs from my newly re-done head and the new spings I got with the Crane Cam do not fit. The smaller inner spring does not fit over the lower spring pan and for that matter neither does the valve spring cap. If I do not use the inner spring, then the outer spring is too loose/large. These springs were in a Piper package and obviously are not part of a Crane package I thought I was getting or might not be for the MGB head. I spoke to the guy who sold them to me and he is going to make good if I want him to.

I'm curious, are the stock springs fine for this cam? Are there other manufacturers that will make compatible springs. He asked that I send a stock spring cap and lower spring pan so he could find something that matches - Kent, piper etc.... I am not sure how important it is to have more or less spring pressure or I should not even bother and leave well enough alone. If there is no need for me to send him back the springs or try and have him match something for me, I won't.

Vince
 
Sorry, can't speak for MG's but with SB Chevys it is not unusual when using after market valve springs to have to do additional machining to the cylinder head. Often the valve guides have to be turned undersize to fit small dia inner springs and the valve spring seat has to be machined flat or counter sunk to accomodate larger dia outer springs. Usually a stainless washer is used under the spring to protect the cast iron. Bob
 
Springs should always be specifically chosen to work with a given cam and sourcing from two different suppliers can often result in disaster (coil bind etc.)

You apparently own one of the late model MGBs with what is basically a low compression Marina engine. Of course the bottom spring collars are wrong. The cam and springs are for the early dual spring model. You'll have to buy the correct bottom washers and also the top retainer for an early engine.

If you still have the low compression pistons in it, and haven't done anything to improve the head, don't expect miracles from the cam, although some difference should at least be detectable.
 
I am actually using a 1968 Block and an 1974 Head. The pistons still need to be purchased. The best thing I can do now is to send the stock top retainer, stock spring and stock bottom washer to my vendor and have him give me a better set to match my application. He is totally fine with this. My only other concern with this is that the head is already done and I did not want to take it apart. I do not want to damage the seals while taking them off to get to the bottom washers.
 
Another point to consider is the valve pressure. Not only must you find springs that physically fit but they have to have the correct "tension". Too weak and they could possibly limit your revs due to valve float. Too strong and excess wear on the valve train and cam lobes is a distinct possibility. Bob
 
How do I find what pressure is needed?
 
If the springs came with the cam, and are meant to fit the cam and work with it, simply order up some stock early valve train parts and swap them out.

You are going to have to have a shop do this anyway in order to have them check and shim the springs. Unless your vendor deals with MGs, he won't be able to supply the needed parts unless he sources from the same places you could.

A cheaper solution is to find stock good used bits from an early dual spring head. If these springs are intended to work with a street grind, they probably won't be close to coil bind.

The number doesn't show up on the Crane site. What are the specs on the cam?

BTW, glad to hear you have the early pistons and compression.
 
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