TVR Griffith engine rebuild

dnb · Post by **dnb** » Sun Jan 12, 2014 10:32 pm

The original 19 year old engine had 150k miles on it, so was "a little tired".

My goal for the rebuild is to get a reliable 350bhp Rover engine without spending a fortune. (Starting point is the remains of a 320bhp engine). Capacity will remain 5 litre unless the existing pistons are scrap.

The extraction and strip down took most of my free time at the weekend.

Engine turned in to a pile of parts:

Lots of cleaning and checking to do now. Will get better pictures of the heads because I'd like to see where things might be improved and why they made decent power with a hydraulic cam.

First discovery is 2 dropped liners - one on each bank. Top hatting will commence ASAP.

Big end bearing shells:

Only a bit worn!

More to follow when I am allowed back in the garage.[/img]

Post by **Coops** » Sun Jan 12, 2014 10:35 pm

keep us posted mate

DEVONMAN · Post by **DEVONMAN** » Mon Jan 13, 2014 8:48 am

I note from your other thread that you are planning to cross bolt the block.
I have done three and have discovered the following.

Some blocks have blank bosses but do NOT have full height main bearing caps. The block needs full height caps to facilitate crossbolting.

You will find that there is a very minute gap between the caps and the block (starter side of the engine usually) for part of their height.
This gap is only 4-6 thou but if not shimmed will close when the cross bolts are torqued up and may pull the main bearing tunnel out of line.
The solution is to fit shims of the correct snug fit with the cross bolt running through them.

When I had my 500 crank balanced it need some Mallory metal added to the counterweights so the cost went up by £40 over the quote.

Good luck with the rebuild

Rgards Denis

ChrisJC · Post by **ChrisJC** » Mon Jan 13, 2014 9:15 pm

You should line-bore the engine with the new crossbolts and mains all torqued up.

I got my top-hats from Turners. As far as I can tell, they do a more thorough job (i.e. o-rings rather than instant gasket) than other vendors.

Chris.

dnb · Post by **dnb** » Tue Jan 14, 2014 12:40 am

I'm getting that impression... They're significantly more expensive than other options but it might be worth it to have the job done right. Didn't get much done tonight other than getting the kitchen parts washer ready

I had a look at a couple of pistons. There's a bit of skirt wear, as you'd expect, and some odd damage to the crown on one piston. It must have been like that for a while, but there's no evidence as to why. It's possible something fell on the engine while I had the heads off a few years ago, or it could have been there all along.

What looks like mild skirt wear. They all look like this, one side slightly worse than the other.
.

The odd damage. Not too happy about this.

Since it's the first time I've concerned myself with blocks, pistons and the like (I usually stick to heads, manifolds and ECUs), I'd be keen for some advice on what is acceptable wear.

DEVONMAN · Post by **DEVONMAN** » Tue Jan 14, 2014 9:19 am

These TVR pistons are Rover 4.2 items with part of the skirt removed and valve cut outs added.
You really need to mic up the pistons to see what amount of wear is present. Tvr 500 pistons poke out of the bore at BDC and there is sometimes a slight mark/ridge at about 15mm from the bottom of the skirt so have a close look. I can see a slight mark in your photo.

Regards Denis

kiwicar · Post by **kiwicar** » Tue Jan 14, 2014 9:20 am

Hi
they look brand spanky new to me, have they realy dome 150k miles? You have some very fine scratches on the skirts, probably from when they were pushed through the piston ring compressor when the engine was first assembled. I can see every machining mark on the walls of the pistons. the marks on the top of that piston are I suspect where the piston was clamped down for machining they were made before the bowl and valve cut outs were made, both these cut through the indentations I suspect if you look from the side they will be cut by the the lathe that cut the pistons to size, re-ring re-use.
best regards
Mike

ChrisJC · Post by **ChrisJC** » Tue Jan 14, 2014 6:21 pm

dnb wrote:I'm getting that impression... They're significantly more expensive than other options but it might be worth it to have the job done right.

I also purchased all the gaskets / bolts / etc etc. that I needed from Turners. That way I could be sure it was all good quality stuff.

Chris.

dnb · Post by **dnb** » Tue Jan 14, 2014 9:13 pm

No pictures today, but managed to find time between work to get the crank taken for examination. I await his pronouncement. I checked the cam and followers too - all lobes are within 0.02mm (within my measurement error) so should give me 12.65 inlet and 12.7mm exhaust (assuming I remember which is which

) valve lift - close enough to the cam spec for government work as they say.

Yes, it's really 150k miles, but it's been pampered for most of the last 19 years. I bought the car with 85k on it (the previous owner clocked up 30k a year in it!) and used it as a daily driver for the first 3 years of ownership and for the next 3 as a spring and summer daily driver as much as daughter would let me (she loves the "noisy black car"). It's not been used in the last 2 years much at all.

Averaging 10k a year is easily done.

Just got to wait for things to happen now. Maybe I should take the gearbox apart...?

mgbv8 · Post by **mgbv8** » Tue Jan 14, 2014 9:42 pm

I cant see that those pistons are worn at all ???

They look really good to me ?

If you decide to fit new pistons and chuck these out, give me a shout and I'll pay the postage to my house

dnb · Post by **dnb** » Tue Jan 14, 2014 9:59 pm

Not got around to looking at the pistons yet other than the exhibit A with the odd marks in. The "parts washer" is currently occupied with its day job - I only dare use it on the night shift!

There's a big part of me that says I've gone to the trouble of new bores, so why risk compromising the build for what amounts to a small part of the total cost. But then where do you stop? I'll remember you asked about the pistons should they be going spare.

dnb · Post by **dnb** » Wed Jan 15, 2014 10:53 pm

I love my wife. She's told me to get the new pistons and stop messing about trying to save money on the build.

(With the small caveat that she gets to watch as I get fed to the sharks if the engine doesn't last at least another 100k miles...

)

With that in mind, I am looking at these http://www.v8tuner.co.uk/product.php?id=874 on the grounds that they are available and it's an easy solution. I can get new standard pistons or new standard size forged pistons, but it looks like that by the time I've got them, new rings and then got them assembled with the existing rods (it's an odd pressed in floating gudgeon pin with no circlips which apparently requires special tools to dismantle and assemble? ) the price isn't that different. And I can design out the short skirt (not desired in engines, but appreciated elsewhere

) get a better rod/stroke ratio and get a moped's worth capacity increase.

I've used Paul before as a supplier and been very happy, but wondered if anyone had gone down this route and had useful pointers?

kiwicar · Post by **kiwicar** » Thu Jan 16, 2014 7:16 am

Hi
" And I can design out the short skirt (not desired in engines,)"

I would disagree here, in a performance engine you want to get the skirt as short and reduced as possible, in a high performance design the skirt will probably end at the bottom of the gudgeon pin at 90 degrees to the crank and be cut away completely in line with the pin so it ends at or above the oil control ring. Anything else just adds weight and friction. These are in my engine, http://www.ebay.co.uk/itm/Mahle-Pro-Ser ... 3cdb0d695d they are typical of a modern performance piston anything of an older design is just dead weight that you then have to add metal for when you balance it.
These are even better http://www.ebay.co.uk/itm/NEW-NASCAR-CH ... 5af8a2752d the pin length is reduced so that the piston can be reduced further around that area and cut the skirt even further at 90 degrees to the pin.
best regards
Mike

dnb · Post by **dnb** » Thu Jan 16, 2014 9:20 am

I take your point. I explained myself badly really - I meant not having a short & fat skirt. The sides (apart from holding the piston together) don't contribute to stopping the rocking motion and would seem to add considerable friction. So wouldn't it be best (assuming no intersection with the crank or rods) to support the piston at 2 points, made as small as possible, such that it is supported in the bore with the pin located as close as possible to the centre of mass?

Looking at the design of the V8 tuner piston and the others in the Ebay links (from the little you can see in the picture ) they look to be trying to achieve what I said above, although presumably compromised by things getting in the way.

Are there any other options open to me I might have not looked at? I know the TVR 5 litre engine is a bit of a pain to get matching parts for.

BTW I assume you haven't found a way to get a 100mm piston in a Rover?

Do I need a bigger mallet?

kiwicar · Post by **kiwicar** » Thu Jan 16, 2014 11:05 am

Hi
If you are prepared to go wet liner then you can go to 4 inches, it has been done in the states, I would debate what is actually gained apart from bragging rights.
What do you want to achieve by going to a custom big bore?
If you are replacing the liners then you just bore the holes in bigger and fit larger diameter liners, then you have to find pistons. . . . you can go up to 3.736 inch bore on stock liners, that is a chevy 305 piston and you can go +20,+30 and +40 on that with aftermarket liners, ford Mod pistons come as a 3.7 and you can go +20 on them (stock liners).
have a look at Ebay or piston catalogs for pistons, 305 307 chevy pistons give you some choices, ducati motorcycle pistons are in the 96mm to 104mm range and have been used (by those with big wallets!) and JE and others will go you full custom pistons, to me though this is just a way of spending money. Choosing a bore like 3.736 is a good idea because you can buy cheep high quality pistons with decent rods and drop them in the rover for minimal money but going 100mm I can't see a reason to do it if you need to buy expensive custom pistons, it is also why I like the 3.7" ford mod piston, relatively cheap forged light weight piston that has a sensible deck height and can be easily bushed for chevy or rover rods all on a stock liner that will be reasonably reliable.
If you are going normally aspirated you can take the liner wall thickness down to about 200 thou at the sides and 300 between pairs of cylinders if the liners are touching and 250 thou on Siamesed liners but you would need top hat liners and be confident you could clamp up the heads of a partially floating liner block. You will be lucky to get 30k miles between rebuilds on a semi floating liner block.