Start of another new project

[tony g]

When are you going to do a Stag engine to this spec?[/quote]


When the sprint heads fit

Tony

[soe8m]

Two questions:
Don't you think that headed note paper is showing off a tad?
When are you going to do a Stag engine to this spec?

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When are you going to do a Stag engine to this spec?

When the sprint heads fit

Tony[/quote]

No need when you have a few of these in stock:

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[tony g]

Should sound nice

Tony

[soe8m]

Finished the head tonight. Made some dowels on the inlet side and m10 helicoils on the outlet side. I'm using m10 studs with copper locknuts on the manifold. This way you can tighten and retighten the manifold easy without the threads damaged in the alu head.

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Valves do not need to be lapped when they are new or machined and put in new or machined seats. But you can lap them to check the contact area of the valve. For LPG i use a slightly bigger area because of the better valve cooling. LPG burns hotter and this way the valve can dispense the heat more.

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These pics are of the original head of this engine. This was the LPG injected head after about 300.000km. I did run it for a while on 3 cilinders but at once it was within 20km 2, 1, none.

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[soe8m]

Assembling some shiny new parts. As the collets are very inexpensive you can replace them. They do wear. You can test them by pulling lightly on the springseat and it has to clamp. When it falls down most of the time the collets are worn.

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[soe8m]

I de-tr7nized the manifold because i do not have egr.

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I have to get used by the sight of one carb on a slant. This is a HS8 carb. The tr7 had originally a stromberg fitted.

Jeroen

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[straylight]

this is beautiful info Jeroen, thanks for taking the time to document how it all goes together and the reasons why.

stu

[Edin Dundee]

Jeroen, is that rubber between the carb and the manifold?

[soe8m]

It is tryfitting. There are no pistons in the engine yet. I did order a club alloy one. This is the std rubber one for the hs6 type.

Jeroen

[trackerjack]

Does your lovely wife (I know she is as we met the poor lass ) mind you building engines in the family kitchen?

[soe8m]

That isn't such a good idea because the backdoor of the house is locating in the kitchen

Jeroen

[soe8m]

Tonight was cranckshaft night. It all started with a freshly balanced combi of a cranckshaft of another engine, my "old" lightened flywheel and a new saab clutch cover. I wanted to re use the cranckshaft what was originally in the engine so i didn't need to have all balanced but there was too much wear on that one.

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I like to use std size cranckshafts because the hardening is deeper, it is cheaper, no grinding and 70% of my vandervell stock is std size. I took this one out of a very original engine and it was on size. The marks on the journals are just optical marks. This engine did not run for a very long time and then you can get these marks/discolourisation.

First you use some scotts brite to remove all the marks and residu's of old baked oil. Then you have to lap the journals to have the smooth shiny surface. That is with a sort of canvas grinding band but very fine. You can tear it of a roll to journal width.

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Then it is cleaning. I use a riffle barrel cleaner stick with different diameter brushes and that goes fine. It is a copper brush. For alloy parts i have nylon brushes.

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[soe8m]

Fitting the ARP main bearing studs. Not all engines but a few have the bearingcap bolt bores not inline with the threaded hole in the engineblock. Using original bolts which are a bit thinner and have still a threaded in the lower area of the cap all is well but the ARP studs are slightly thicker and have a non threaded part in the lower area of the bearingcap is does matter.

Cap number 4 and 5 you had to tap with a plastic hammer to fit, the rest did just slide over. In the picture you can see that the bore on one side is not inline and that there is a marginal gap between the side of the cap and the engineblock. The cap is on one side pushed to the inside. If the cranckshaft was fitted in this engine it would not have turned by hand. The same happenend at the other (blue) sprint engine of the "new project". From then by every engine i do drill the holes of all the caps 0,5mm bigger and the problem is solved. All the caps because the ones who feel ok you cannot check if the stud is free in the hole or is slightly toughing the edge.

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When fitting the studs permanently i do loctite them. There's no need but i have a better feeling glueing them. I use studs because the holes where the caps are bolted in are a weak point of a slant four so studs are much better and less stress when tightening the caps. But filling the threads with locktite also can't harm. When installing the studs with loctite you have to fit the cap and tighten it direcly. You want to have the thread coils toughing and the loctite filling up the non toughing gaps. Otherwise it can happen when tightening there's loctite between the stresses thread coils of the stud and engineblock and that is not a good fit.

[soe8m]

Measuring the bearing play is easy. For the journals i use a micrometer to start with but when all is fitted plastigauge is ok. It is a soft plastic strip what you do fit between the journal and bearing. Tighten ands it's compressed. How much it is compressed you can read waht the play is. Journal number 5 has the most play and is about 0,04-0,045mm. Triumph has a line somewhere in the big book that say's that the play should be 0,02 till 0,06mm. New ones did have around 0,03 so this cranckshaft is a good one.

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Jeroen

[Howard81]

Oh so that's how plastigauge works!

Excellent write up, very interesting indeed