RE: V8 Rebuild

[andymadmak]

wedg1e said:

I can't believe he went to such lengths and then reused the head bolts. I calculated my engine CR to be 9.2:1, that's at 3948cc which a standard 400SE should be, using Rover pistons (with dished crowns) and valve pockets machined in. Standard CR would be 9.35:1. As far as I know, TVR only claimed that for the 400SE, with 10.5:1 reserved for the original 390SE (flat-topped pistons). If they claimed 10.5, it was a lie. What a surprise.... Ian

I had to make some savings somewhere!!

Yup, TVR lied , I've got the sales brochure for my car and it says it should be 10.5:1!! It's not so much the rise in compression ratio that Mike was looking for (although thats a useful side effect), it was more a question of improving the squish. The pistons were running so far down the bores it's unlikely there was any squish effect going on at all..
They look to be standard rangie pistons, dished top, valve cut outs etc. Even so, 8.8:1 was pretty low.

I'm still thinking about the rolling road tune up thing. One effect of the gapless rings is that the inlet vacuum is MUCH better and this is clearly having it's effect on the Fuel pressure regulator. In fact, it's gone from running quite lean, to running a little rich, and the induction note is much more agressive.
It starts first time, and idles reasonably well (only a tiny suggestion of a slow hunt when hot.)
I'm thinking to let it bed in over a few thousand miles and then think about a tune up.

Andy

[jvaughan]

jmorgan said:

Plenum insulator next. You won't regret it.

Whats one of those ?

[adam quantrill]

You could get a rising rate regulator, they are adjustable and you can dial in the pressure compensation w.r.t. plenum vacuum.

Incidentally, what gearbox oil did you get and how much was it? I want to replate mine and looked in unipart for some EP80 but you can only buy it in 1L bottles. I heard there was a Castrol one some people use?

[350matt]

A plenum insulator is a gasket / spacer affair which is sandwiched in-between the plenum and trumpet base. As its made of a low conductivity material the plenum doesn't get so hot and the incoming air is cooler so more power

as for gearbox oil use a semi-synthetic 75-90W oil catrol do one - snythrex or summat?

Matt

[jmorgan]

jvaughan said:

jmorgan said: Plenum insulator next. You won't regret it. Whats one of those ?

Here you go piccy

In place piccy 2

Works as Matthew says. Usually the plenum is very cool after a long drive, even in the summer.

[HarryW]

Looks about 25mm and a straight forward fit, are they soft(ish) or do you need to use a sealing compond when fitting as well. Where do you get them .
I take it the additonal 25mm on the intake length would produce a slight change to the engine characteristic, but probably not much, anyone know for sure Rob?

Harry

[jmorgan]

HarryW said:

Looks about 25mm and a straight forward fit, are they soft(ish) or do you need to use a sealing compond when fitting as well. Where do you get them . I take it the additonal 25mm on the intake length would produce a slight change to the engine characteristic, but probably not much, anyone know for sure Rob? Harry

Hard material so a sealing compound was used. Got it fitted on a service at DJE. He had them made up. As he builds V8's (and rebuilt mine) I assume its all OK. I think he does 2 thicknesses. Was £60 (excluding fitting) but best speak to him if you are interested to check.


DJE

>> Edited by jmorgan on Monday 1st March 08:59

[rev-erend]

Does it fit without the plenum hitting (rubbing) the bonnet ?

[jmorgan]

rev-erend said:

Does it fit without the plenum hitting (rubbing) the bonnet ?

Opps, forgot that. Try a bit of kiddies play putty to the rquired thickness on the plenum top then shut the bonnet. See if it hits. My bonnet lining has gone so an extra bit of space.