WARNING, FAKE BIG VALVE HEAD?

[512BB]

Gentlemen... and Ladies,

Be careful all who would be thinking about bidding on item no 150500701633. I have checked all my Big Valve heads, and the N on the boss faces the wrong way on the one listed. The Ns all go at 90 degrees to the cam cover on the heads I have, and thats on a lot of heads! Remember that on one head there is no letter stamped, cant remember which one, so with a chisel you can make your own Big Valve! You bin warned.

And no, I am not bidding!

Leslie

[elansprint71]

Gentlemen... and Ladies,

Be careful all who would be thinking about bidding on item no 150500701633. I have checked all my Big Valve heads, and the N on the boss faces the wrong way on the one listed. The Ns all go at 90 degrees to the cam cover on the heads I have, and thats on a lot of heads! Remember that on one head there is no letter stamped, cant remember which one, so with a chisel you can make your own Big Valve! You bin warned.

And no, I am not bidding!

Leslie

I was seriously considering a bid on this item, as I could use a rebuilt head right now.

Apart from the slightly increased diameter of the inlet valves, what other differences are there to the casting? Surely fitting larger valve seats turns any head into a big valve head?

I asked the vendor yesterday why one Sprint camshaft and one SE camshaft were fitted and I have not had a response.

Vendor has good feedback from previous customers, although many of the items are just bits and pieces.

I was prepared to have a punt on the Ed Winter head which failed to sell yesterday, until I realised that when it was built, before it was put into lengthy storage, unleaded petrol was not available; so it would really need to have new seats.

[billwill]

Certainly the head that I have (now cracked) was 105 BHP but was converted to Big Valve by Vegantune Spalding back in 1983.

And before anyone says, "yeah but it cracked", it has done 190,000 miles now. !

[john.p.clegg]

Pete

I think it is to do with tuning,gas flow etc...(here we open another can of worms),the larger your valves are the more lift it will take,hence not fitting the same profiles in both inlet and exhaust...I've got different profiles in mine 1.625 Inlet with .420 lift ,1.4 exhaust with .360 lift (if I remember correctly).

John

[elansprint71]

Hmmmmm, anybody (UK-based) on here got a built up Big-Valve head which is surplus to requirements?

What is considered to be the "going rate" for these?

[theelanman]

I parted with my std weber head to a member on here for ?400.....it was not cracked and had never been welded........erm....very good condition and servicable....
that was everything except the cam cover and the carbs......basically as youd take it off

hope that helps

[billwill]

On the Big Valve head are the exhaust valves bigger than on a 'standard' head or is it only the inlet valves that are bigger?

[paddy]

What is considered to be the "going rate" for these?

I haven't seen a weber head sell on UK ebay for less than ?1000 for a long time, and the prices go up to double that for a complete rebuilt one from a specialist engine seller.

Having said that, the "Ed Winter" head discussed on another thread failed to make its reserve a couple of days ago; the bidding went up to about ?1600.

Paddy

[billwill]

The Ed Winter one may re-emerge of course if the seller realises he set his reserve too high.

[billwill]

The difficulty with the 150500701633 ebay head is that from the wording it appears to have been machined by someone who knows how to machine heads, but does not seem to be expert on Twin Cams. Else surely he would refer to it as Big Valve and not continual use of the word Sprint.

Also losing the cam caps?? Where does this head come from How long was it kicking about in the workshop for bits to get lost? From the photos he seems to have done a good job, but what was the state of the head before he started? Was it one of those really grotty heads sold on eBay earlier this year?

Ploughing through the comments from earlier buyers I see the seller sold a twin cam head back in 2007 for only around the ?250 mark.

I wonder where s/he seems to be getting an endless supply of aluminium water pump pulleys and high-pressure oil pumps? Perhaps s/he makes them?

[billwill]

It has sold at ?1041

[elansprint71]

Well the vendor did not not respond to my question asking why a non-matched "pair" of cams had been used, so I did not bid. Sold for ?1040 to some happy person?

I suspect that this was just made up from a collection of odd bits and pieces. Might be OK, but who knows.

Now..... any suggestions where | should look for a spare head, so that I can rebuild mine at my leisure?

[elans3]

Most competition engines use a different cams inlet and exhaust, very often from different manufacturers, depends entirely on the performance characteristics that you are looking for, eg a rally engine will need different attributes to a race engine.
My Hillclimb car had two Kent special grinds to suit the 1820cc, big valve engine for torque and wide power band, both very different profiles.
My last spare engine was fitted with a Piper 8FY inlet, and an L1 exhaust, there's absolutely nothing wrong with it, (a very popular combination) and in fact is probably more prevalent in competition engines than fitting two matching cams nowadays. It also started off as a std 105bhp head, and was modified with bigger than "Big Valve" valves.

So only be scared of a "big valve" head if you're into originality, there's absolutely nothing wrong with a modified one, although I personally wouldn't go to the trouble of stamping an "N" on it !

elans3

[bcmc33]

I asked the vendor yesterday why one Sprint camshaft and one SE camshaft were fitted and I have not had a response.

The original head on my car had the exhaust cam changed for the SE cam plus an off-set dowel. This had been done by a well know London 'independent' seller, and when asked the question why was told that the big-valve exhaust cam was not fit for purpose and that a dowelled SE cam was better.
I took his word for it and had no complaints as it was an unflowed head giving 129bhp (99bhp at the rear wheels) when run on a rolling road.

[512BB]

Hmm, you are getting a little muddled again Brian, as I dont believe you have taken the words out of MY mouth.

Leslie