The V8 Owners Forum -

I have a 3.5L V8 on which I have installed RR 3.9 heads. The heads are the intermediate type which have the rubber washers as valve seals and not the push on neoprene items.

I had the heads skimmed to keep CR so that I could use composite gaskets. I am getting a rattle on start up (about 10 - 20 secs) as the tappets fill and if I give it the loud pedal she will also give a rattle. She idles smoothly and seems be quiet at cruise. This makes me think that the tappet preloads are incorrect. I have already tried the shimming route but the vale stems have sufficiant variance to make the shims of dubious benefit. I am now biting the bullet and looking at adjustable push rods and doing things properly.

The question is will these items fit the push rod guides on stock heads without machining?

http://v8tuner.co.uk/product.php?id=81


Cheers
Gregor
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Not a chance.

The heads will defo need drilled for 3/8" pushrods.


Even when I had the 5/16" adj pushrods, the holes should have been enlarged...not much, but they did need it.

Thanks.
I don't want to take the heads off again so that could have been an expensive lesson.

They look like the ones I have just fitted to my new engine. They are the same size as the Real Steel Rover V8 standard heavy rods at 8mm diameter.
I drilled my holes out to 12mm to make sure I have enough clearance.
It took me 2 hours to set all the pre-loads in the end, as they are fiddly to hold in place while you clamp the lock nut down. Also they do open up a bit as you clamp the nut down.
Dont forget, if you are using Rhoades lifters, you need to fit the smaller radius ball ends on the bottom of the rods.

http://s205.photobucket.com/albums/bb27 ... ics003.jpg

I forgot to mention, there is definatley a variance on the pre load adjustments on my engine now. If I measure the gaps on between the adjuster nuts as they are fitted now. I can see + or - 10 thou across all 16 adjusters. A bit fiddly to do, but it seems a more accurate way of getting the clearances even. FWIW.
Perry

greenmeanie wrote:Thanks.
I don't want to take the heads off again so that could have been an expensive lesson.

I've been pondering whether I should fit adjustable pushrods as with the shim method my pre-load measurements are all over the place!

Most people on the Cobra forum don't reckon that the pre-load is very critical but in my opinion if you spend ages setting the motor it seems a shame to just say "that will do" for the pre-load.

Does anyone think that its a "bodge too far" to drill the holes whilst the heads are still fitted if you block off all the holes in the valley area and hoover out all the swarf?

Regards,

Pete

mgbv8 wrote: They are the same size as the Real Steel Rover V8 standard heavy rods at 8mm diameter.

The link says 3/8" pushrods, which is 9.8mm give or take.

5/16" which are the small ones, that some used to claim will fit standard heads, are 7.9mm....but they didnt fit my heads.

I did open the holes a little, but problem is, they need opened in an offset manner, so even drilling them manually isnt that easy.

That said....they will work at a push, although they will rub on the head a little ( 5/16" ones ), which obviously is FAR from ideal...but I admit I ran mine like this for a while, and they were fine. Only very light rubbing on some of them though.

If you have the valley open Pete. I would stick some fine cotton rags under the holes, and have the hoover on the go as you drill. I get my Henry and tape some 15mm copper tube into the metal tip and get my sone to hold it next to where I drill. I soak the rag in oil so any swarf sticks to it. It may not be perfect, but it works for me mate.

The exact preload measurement isn't that critical. It has to be done but doesn't have to be for example 60 thou on every one like mechanical tapit clearance has to be. Just so long as it isn't too small or too large which causes problems. This is the whole point of hydraulic lifters - fit it and forget with no maintenance as they self compensate.

So long as you make sure the swarf is completely removed there isnt any reason why you cant do it in place. Try a dolop of grease where your drilling so the swarf sticks to that and makes it easy to remove, a slow drill would be good too so you don't get bits flying all over the place. Obviously there is a risk involved but if your willing to live with that and be careful its easy doable.

I think too little pre-load is worse than too much...if you do stick with that method.

Problem with drilling, is that more material needs to come away from the valve side of the head, than the open/pushrod side...which is where the drill bit will tend to walk.

Some sort of die grinder might be better, but thats major swarf....or a drill stand, which you can secure the head so you drill where is needed exactly.

Thanks for the advice guys, I reckon it's a job for the winter using a flexi-drive, burr tool, and plenty of rags. Sounds like it will take a good few hours!

(A set of group A rods and rockers have just gone on ebay but as the seller didn't answer any of my qustions I thought that I'd give them a miss. Plus they went for more than a brand new set of adjustable rods)

Regards,

Pete

If your installed valve heights are all similar, Id just stick with shimming. Its so much less hassle !!