Denis Welch Aluminum Head on a 100M

[AlanT]

I know this may be hard to believe , but the cylinder head on a 100M in the shop is cracked. So I just wanted to know if anyone on the forum has installed an aluminum head or is currently running one or has an opinion.
Thanks,
Alan T

 

[Healeysince59]

I have one on the BN1 1/2 I am restoring but I haven't fired it up yet so all I can say is it looks good.

Marv J

 

[zblu]

Is it the cast iron original head that is cracked, or the ali head?

 

[Randy Forbes]

Is it the cast iron original head that is cracked, or the ali head?

The original cast-iron heads were prone to cracking between the 2-3 exhaust seats. Just like the B-Series heads that followed (MGA-MGB).

Unless I'm mistaken (been known to happen) Dave Russell has been running an aluminum head for years. But if you know Dave, he could probably crumple up a bag of beer cans and get them to support combustion without leaking :wink:

 

[GregW]

I'll back you up on that Randy. Dave has the Denis Welsh head. From what I remember, he preferred the DW head over the SC parts head.

 

[Tadek]

I am planning a rebuild on my angine as well, and have investigated the 100 engine upgrade. There was a dicussion on it last week no the healeys@autox.team.net list.

It seems that the DW head is a further development of the SC head, although the SC head is already a major improvement over the iron one.

If I get it right, the way to go with the engine is to:
- start with the head
- it's wise to change the studs, nuts, washers a well as the gasket
- continue with the LeManst upgrades with a modern cam simmilar to LaMans one
- change the manifold and exhaust to enable better breathing of the engine
- lighten the flywheel
.....

I have not found though any dyno test results for any of the above combinations...

There is always another way to go, and that is to port the original head. One Volvo nut has taken to an extreme level here: https://forums.turbobricks.com/showthread.php?t=126569
(scroll to further pages, there is some extreme porting)

Tadek
AH 100 BN2 '56
Volvo 1800S '68
VW Beetle 1200 '73

 

[DEVOREBN2]

Alan, I have a DW aluminum head on my BN2. Had the same problem you appear to have (cracked head/not repairable). I purchased the head two years ago and have had no problems, just expensive. This winter I will be replacing the rockers with a roller setup.

 

[Michael Oritt]

Alan--

This topic was recently discussed on the Team Autox Healey list email newsgroup, another useful info tool.

I have had a DW AL head on my BN1 for about seven years now. I bought it after blowing a head gasket and finding the small bridge between cylinders one and two had been eroded away, probably by detonation. This is not the normal failure mode which is usually cracking and weeping between two and three but it was enough for me. I have never had any problems with the head, in fact I am not even sure I have retorqued it since the initial running in. I have put about 55K miles on the car since the new head, about half on long highway trips.

I installed the DW head with stage two "Fast Rallye" porting configuration along with the DW tubular headers, steel head gasket, hardened head studs, etc. I don't know what if any changes and developments have taken place in the last five years but at that time the DW unit was recommended over the aluminum head marketed by Southern Carburettors, another UK company.

I think it is quite telling that more than one company has gone to the expense and trouble of designing and tooling up a replacement part for an engine with a relatively low production run. There were approximately 15K 100's built plus others installed in A 90's and maybe other applications but I guess this lends truth to the saying that there are two kinds of 100 cylinder heads: Those that are cracked and those that are going to.

 

[zblu]

Looked into this a few years ago, would need about 10 or so orders to make the recasting of the cast iron heads even approach the cost of the current ali heads available, but such is the price of originality!

 

[healeynut]

My problem with all of this is I absolutely fear blowing out my A90 gearbox if I start uprating the engine. There isn't a Smitty kit for the Blue Turtle, let me tell yah!