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Worth $1000?

  • Yes

    Votes: 0 0.0%
  • No

    Votes: 1 33.3%
  • Maybe, need to inspect

    Votes: 2 66.7%
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Discussion Starter · #1 ·
This head was listed as new at Classic British Spares. When I pulled the trigger and ordered it, prior to shipping they sent these photos to get my "ok" before shipping. I hit the brakes on shipping and asked my machinist/tech what he thought. What do you think?

757019

757024
 

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Not very well finished is it ? The chamfer around the combustion area is a gentle curve on my head. I think i would look for a good used one instead.
 

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That chamfer is good, it will give some effective squish. That said, I have generally found used T140 heads have very little valve seat recession, so need little work to be good. The head you're looking at has the late parallel inlet ports if that's what you want, and it has the threaded exhaust ports, a desirable mod on early heads (but expensive). Your choice!
 

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Hi Rafterman,
You might get in a heap of trouble with this head.
It looks to be parallel port as Mick pointed out, this was a 78/9 on head cast for the mk2 Amal carburettor. When we have been talking about your bike previously, you have always stated it is a 1976 model. These had splayed inlet tracts to accommodate the Mk1 Amal carburettor.
there are other changes also, the screw threads were installed on the T140D Specials, to fit a screw in retaining collar ( Norton Commando style, if that means anything to you). Threads were also added post 1980 to fit an exhaust stub, so the exhaust pushes over it and clamps on, pre stub and post stub exhaust downpipes are not interchangeable.
The earlier head is fitted with a different type of pushrod tube to the late ones, I am uncertain if the head is machined differently where the pushrod tube sits, but this would need investigation, I am pretty certain the tappet blocks would need changing.

Apart from the fact that it is the wrong year head (if we are still talking about the 1976 T1400, and fitting it will require awkward conversions of , carbs, pushrod tubes and exhausts, there are som other strange things in the photos.

The squish bands look too heavily machined, the valve seats are something very odd, by the way the seats are cut it looks like 3 of the seats are not fitted anywhere near concentric to the valve guides. The timing side plug hole does not look central between the valves (this could be a trick caused by the photo angle though) . The ouside finish looks like somebody has tried to remove paint with a rotary wire brush.

Regards
Peg.
 

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As far as I can see its the same head. ie for a later Bonneville, they are using the parallel port design to say it can be used as a Tiger single carb.. anything can fit anything given enough work and time, shops like the one selling it should be rapped over the knuckles for how they word their description. Its not a direct replacement for your head.
 

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Hi
You can fit a single carb, but you will need the manifold, then you will need to remove or replace the air filter boxes, you still have the uncertainty of the pushrod tube fitment. You will need to change the exhaust downpipes.

Why do you need a new cylinder head?

$1000.00 will buy you the best cylinder head refurbishment. Ultimately it will be better than new with top quality valves and guides with a proper concentric valve seat cutting. This will be better than new.

regards
Peg
 

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Discussion Starter · #8 ·
As far as I can see its the same head. ie for a later Bonneville, they are using the parallel port design to say it can be used as a Tiger single carb.. anything can fit anything given enough work and time, shops like the one selling it should be rapped over the knuckles for how they word their description. Its not a direct replacement for your head.
That's what I see too. Same port design. I'll see what my mechanic thinks.
 

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The threads (if they are present) for the carb stubs would not do wonders for the flow and the holes for the studs to take the single carb manifold would have to be drilled and tapped. As Peg said, you can can get a head re-furbished to far better than original Triumph spec for way less.
 

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Late model parallel port heads are said to have higher velocity intake ports, not a bad thing. The head the OP shows does look like crap. Classic British Spares is a honest vendor and that's why he sent photos for the buyers approval...
Replacing Triumph valve seats can messy because the original seat inserts are often off center. They must be machined away, the area welded and then machined for new seats and clean up..But often as mentioned the seats are not badly worn.
It's my experience the badly recessed seats even with a decent valve job has a negative effect on performance.
 

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Hi Rafterman191, What is the condition of your head now? Please refresh my memory.

Engine Dynamics, in Petaluma CA can pretty much fix anything with heads. $1000 will go a long ways to have old head repaired. They do everything in house from welding, seats, surfacing, machining of every kind. Serdi valve seat cutter. I've visited the shop. The real deal. My head is there as we speak. Expect it to be done around end of month. They bored my cyl. as well. Full report will follow. I'd give them a call. Send detailed photos of your old head. See what they have to say. A smaller shop, very well equipped, clean, neat & tidy place. Michael the owner has been involved with Triumphs since the Meriden days. He worked on Triumphs in England. This shop is the real deal.

The Bonnie shop head is naked so will need valves, springs etc. None of this stuff is cheap that's for sure.

Too bad the repro head didn't work out. There is a need for new heads for sure.

Good used heads very hard to find these days.
Don
 
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