Block Head Modifications- Dose it run too Hot or is that just a Myth

Wrench

Member
Joined
Nov 14, 2018
Messages
54
Howzit Everyone,
I would like to share with ya'all my experiences and opinion of the Block Head.

When the Block head first came out I heard some bad reports.
That the Block Head was too thick the cooling fins were too short and it ran too Hot.
It was suggested by a respected member to have the cooling fins milled taller. So I sent one out to have the cooling fins milled taller.
I paid $45 + shipping. I noticed some casting voids the milling uncovered. I Shaved the Head .150"th to make it High Compression.
This uncovered more casting voids in the combustion area. I prayed they didn't go all the way through.
I ran the Head and yes the voids were leaking combustion gasses. The Head was now a paper weight.
I decided not to try and weld the all the leaking voids there were too many voids to chase.
My Block Head would have been fine if I didn't have it milled.

I suggest not to mill the Block Head cooling fins taller.
I suggest to Shave the Block Head .150"th and make it a High Compression Head. Make some Power.

I ordered a new Block Head. I did not have the cooling fins milled taller. I shaved .150"th off and made it High Compression.
I ran the Head in 100* heat all summer. I was expecting the Block Head to melt down. Nope it performed great.
Sure the Block Head runs a little hotter but not too hot. It's a MYTH the Block Head dose not run too Hot.

Block Heads weak spot
When the Block Head was new I inspected it. I noticed a weak spot by the left rear bolt hole. It's thin there around .040'th.
I ran the Block Head for around 5,000 miles and then it cracked at the weak spot the left rear bolt hole.
I welded it. No fear of that spot ever cracking again. I also raised the left rear bolt hole height. I trust in the Block Head now.
I'll never understand why Taiwan Minds designed the Block Head the way they did. Taiwan Specs - Close Enough is Good Enough

Reproduction High Fin High Compression Heads for the NE-5
The Block Head looks kinda modern. It's not as cool looking as the Reproduction High Fin High Compression Heads.
I bought 3 Reproduction High Fin High Compression Heads from 2 different people. I paid $175 each and all 3 Heads were different.
All 3 Heads cracked within 2,000 to 3,000 miles. All 3 Heads cracked in the same spot. By the spark plug hole.
I welded each Head and within 1,000 miles all 3 Heads cracked again right next to the weld.
It's not worth it to try and weld them a third time. I now have 3 very expensive paper weights.

Stock Block Head Combustion Chamber Depth is .465"th Shave Block Head .150"th = .315"th Now High Compression Head.
Must burn 91+ Octane Fuel. or will have Knock and Ping - Air fuel mixture igniting before spark on compression stroke.

Pictures are of the Milled Block Head and casting voids, Block Heads weak spot, Welding repairs and combustion chamber depths.

I hope this info can help someone
ALOHA Wrench
 

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Wrench

Member
Joined
Nov 14, 2018
Messages
54
Howzit Everyone,
Review - Mill and Shave the Block Head $45+ shipping

In my opinion it was a waste of $45+ shipping
My opinion is based on the Block Head I received from the service provider.

The service provided - Milling the Block Head cooling fins taller and Shaving the Head.

After talking with the service provider.
I was under the impression that the Block Head would be machined into a Taller Fin High Compression Head.

How was the Quality of the mill work?
The milling was very rough. there are areas where the milling is very uneven. Makes the Head look like a prototype.
I used a Dremel tool a file and sandpaper to clean up as much of the rough milling work as I could. I was not happy.

Did the Shaved Block Head make a difference?
The Block head was only shaved .040"th
To Shave only .040"th off the Block Head dose hardly anything for performance of the Block Head.
To Shave only .040"th off the Block Head. Makes it perform like it has only been resurfaced.
The Stock Block Heads combustion chamber is .465"th deep. Ya need to Shave a lot more than .040"th to make any difference.

Did the taller cooling fins make a difference?
If the Block Head ran any cooler than before it was milled I didn't notice any difference.
No I didn't compare Thermal Temperature Readings from a Thermal Temperature Gun.
The Whizzer Motor is air cooled. Get in the wind. Now try and take Temperature Readings with a Thermal Temperature Gun.
It's only a MYTH that the Stock Block Head runs too hot.

I was very disappointed in the work preformed on my Block Head. I do not recommend having this work done.
Return delivery was reasonable 2 weeks

BEWARE - The milling uncovers hidden casting voids in the Head.
The voids materialized while the Head was being cast. The Block Head is Made in Taiwan.
Notice the voids in the pictures. They went all the way through to the combustion area and leaked combustion gasses.
It's not worth it, to mill the Block Head cooling fins taller and risk the chance of uncovering hidden casting voids.
It's not the fault of the service provider that there were voids in the Head casting.
You might end up with a paper weight.

My Block Head would have been fine if I didn't have it milled. The Head is now a paper weight
ALOHA Wrench
 

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Wrench

Member
Joined
Nov 14, 2018
Messages
54
Howzit Everyone,
I would like to share some more info about Block Head Modifications.

The Block Head was designed to be used with the OEM Whizzer NE-5 Cylinder.

What to do if ya want to use the Block Head with a Westman NE-5 Cast Iron Cylinder?
All Westman Cylinder bolt hole threads are 8mm x 1.25
The Block Head has two 10mm bolt holes.

Use Shoulder Bolts

10mm shoulder x 14mm x 8mm x 1.25 threads. Use with Block Head shaved .150"th or to Da Max .165"th
10mm shoulder x 16mm x 8mm x 1.25 threads, Use with Stock Block Head or only shaved .040"th

Shoulder Bolts and Hardened 10mm Washers can be bought or ordered at Ace Hardware.
They can also be ordered from Bolt Depot on line

I use the Westman NE-5 Cast Iron Cylinder with Stock Valves and a Shaved to Da Max Block Head
The Shoulder Bolts did the trick. I always have good compression.
With a slight tail wind I see the Speedo hit 50 MPH all the time. Slight downhill 50 MPH+
Routine maintenance for my Whizzer is to resurface the Head and clean or replace the Copper Head Gasket every 1,000 miles.
I've been using the same Westman Cylinder for over 25,000 miles
I've been using the Shoulder Bolts with the same Block Head For over 5,000 miles

Here's a Tip,
Custom make your own Copper Head Gaskets.
Match the combustion chamber exact.
Make all the bolt holes 8mm and have more sealing surface on the Copper Gasket.

I hope this info can help someone

ALOHA Wrench
 

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Wrench

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Nov 14, 2018
Messages
54
Howzit Everyone,
Washers, which ones to use?
Taiwan uses Unhardened Washers on all Repop Whizzer heads.
Regular Unhardened Washers are no good. They get crushed by the heads bolts and the head bolts loose their torque.
Must use Hardened Washers on Whizzer Heads. Some people suggest to use Extra Thick Hardened Washers.
The reason Washers are made Extra Thick Is so ya can use one Extra Thick Washer instead of 2 Normal Washers.
The only reason I can think of to use an Extra thick washer is if the head bolt threads are bottoming out in the bolt hole.
Both types of Hardened Washers perform the same. The Extra Thick ones cost 3 times as much. Your choice.
ALOHA Wrench
 

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Wrench

Member
Joined
Nov 14, 2018
Messages
54
Howzit Everyone,
One more thing I would like to share about the Blochk Head.
When shaving the Block Head to Da Max .165"
Check the Spark Plug depth.
To see if it needs a 1mm Thick 10mm Aluminum Washer.
When your dealing with - Taiwan Specifications - Close Enough is Good Enough.
Ya have to Check Everything Twice.
ALOHA Wrench
 

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