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The 100 Forum

BN2 engine block passages

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dfaust doug faust
webster, NY, USA   USA
Hello, I currently have the head off my dad's 100 and I am curious about the varying hole sizes in the passages on the top of the block. There is some corrosion around them and it looks like a brass insert has been installed in one of them. I attached a picture to illustrate what I'm talking about. Are these passage holes the correct sizes and is the corrosion around these passages a common condition? I was hoping to avoid tearing down the whole engine but I'm not sure if it should go back together in this condition.

Thanks
Doug Faust

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Attachments:
IMG_2484.JPG    48.6 KB
IMG_2484.JPG

Hi,
here's a photo of a 100-4 Block I have sitting around, with the similar inserts


Attachments:
Healey 100-4 Bare Engine Block 008.jpg    51.6 KB
Healey 100-4 Bare Engine Block 008.jpg

DTDuck Avatar
DTDuck Dan Marshall
Redwood City, CA, USA   USA
In reply to # 200228 by dfaust Hello, I currently have the head off my dad's 100 and I am curious about the varying hole sizes in the passages on the top of the block. There is some corrosion around them and it looks like a brass insert has been installed in one of them. I attached a picture to illustrate what I'm talking about. Are these passage holes the correct sizes and is the corrosion around these passages a common condition? I was hoping to avoid tearing down the whole engine but I'm not sure if it should go back together in this condition.

Thanks
Doug Faust
Looks perfectly normal to me. I would certainly clean it well and it's always prudent to have the block checked with a quality straight edge to be sure it is flat and true. If not it I think it can be decked slightly but I am not sure just how much.

Cheers,
Dan M.

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simon1966 Avatar
simon1966 Silver Member Simon Griffin
.Madison County, IL, USA   USA
1953 MG TD
1954 Austin-Healey 100 "BEV"
1977 MG MGB
Looks a lot better than mine did :-) Note, it also has the same brass inserts.


Attachments:
IMG_9705.jpg    45.5 KB
IMG_9705.jpg

IMG_9243.jpg    36.4 KB
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dfaust doug faust
webster, NY, USA   USA
Thanks for the replies everyone. I did the straight edge check and I'm thinking the block will be OK with a good cleaning. The head is not looking so good. The engine was taken apart due to a coolant leak near the serial number plate and a pressure test showed a leak along a previously welded crack. I think I will be pursuing an aluminum replacement.

Doug Faust

Graham3647 Avatar
Graham3647 Graham Carpenter
Hereford, Herefordshire, UK   GBR
Hello Doug

Definitely go for the alluminium head, it’s a no brainer. Your engine will run cooler too!
Best of luck
Graham.

BobAH100 Bob Markovich
Patterson, NY, USA   USA
ABSOLUTELY go for the alloy head. Unlike the six-cylinder heads, the original 100 heads are known to crack between cylinders 2 and 3. My head gasket ('53 BN1) blew in that spot—a common occurence on these engines. Decades of heating/cooling cycles and, often, multiple head millings only make replacement more mandatory.

I got hold of the Dennis Welch head, considered the best out there, through Moss. Cost: a heart-stopping $4K American. But I realized that if the original head isn't cracked (mine wasn't yet), it eventually would be. The former owner had installed hardened valve seats, which only increase the cracking risk! So I bit the bullet. Also a must: hardened ARP head studs, nuts, and washers as well as a modern sandwich-style head gasket that goes on WITH NO SEALENT and is tightened to 75 lbs. ft. and is NOT retightened thereafter. Got that advice from Dave Nock at British Cars in Stockton, CA, who has done lots of these conversions. I consider Mr. Healey.

Result: a nice, reliable 100 engine. Added a Wizard radiator and high-flow water pump to bolster that reliability. Also strongly suggest a much lighter flywheel to counter the torsional vibration these long-stroke engines can suffer at prolonged fast road speeds; did that as part of a Toyota 5-speed conversion, also highly recommended for those who actually drive these cars. If the bottom end ever goes, in goes a steel crank and the best con rods I can get my hands on. Good luck!

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dfaust doug faust
webster, NY, USA   USA
Thanks for the replies, I plan on getting the head, stud set and gasket set on order from Dennis Welch in the near future. Fortunately Brexit has helped a bit with the cost of importing British parts recently.

Doug

San Jose, CA, USA   USA
In reply to # 200708 by dfaust .... Fortunately Brexit has helped a bit with the cost of importing British parts recently.

Unfortunately, the 'Brexit Effect' has subsided in the last year or so. I bought parts from DWR winter 2016, and it was $1.24/£; today it's $1.43/£.

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