20 replies to this topic

[haz]

Right. Bit of an odd question, as its not something you can measure.... but if anyone knows from past experiences perhaps? I'll get to the point...

The problem I have is my rod bolts are fouling on a windage tray in my gearbox... nothing too shocking, a slight score as it brushes past. Now I've taken the windage tray out & tried it with a dry gasket, no clearence issues. I've then ground out areas of the tray where the scoring was, giving me around 1mm of clearence. My worry is that when the engine is rotating at 6-7000revs that there will be some deflection & thermal expansion in the rotating assembly which will casue it to foul... can anyone offer their advice on how much clearence is needed?

I'd rather not grind the rod bolts or gearbox casing (as its built up - cam timed, head on & rockers set). I'd rather not change the rod bolts. I could run without the tray but I'd rather run with it in. As I'm sure that these suggestions will pop up.

[mini93]

this one of the trays from paul? he states there hand bent, as such not accurate shaped. Iv also had a clearance problem, was solved by a bit of shaping and using a hammer to knock a recess, not through the plate but a clearence "swage" kinda thing, still clears the gears but also has clearance for the rotating assembly...sorry no pictures though

[haz]

Its a guessworks mutts box

ahh yea, iv done that in the middle, but the main score is at the edges where it bolts to the box, so no bending possible. The reason this is happening is apparently some odd ball S-rods.

[mini93]

im thinking paul supplies GW but i could be wrong.

do you have any pictures of the markings and clearances?

i take it the plates all drilled n bolted to your 'box now too? because mine would sit in the box fine but was still able to move down and change the hights at which the sides sat.


also...i just remembered, i didnt have to knock the pannel for my engine to clear but in fact the gear (so i just told you the info the wrong way round) weather my problem was because my plates further pushed down into the box meaning it was fouling a gear but clearing the engine im unsure

[Paul Wiginton]

What exactly are your rods? Do you have a longer stroke?

The trays are made to a compromised shape that WILL need altering to suit your particular casing as there are so many variances between casings.

Ive bever heard of rods fowling where the tray bolts on, have you fitted the dowels to ensure correct block positioning?

Can you show a picture?

Paul

[haz]

I will confirm rod type & post pictures of the scoring and my 'fix' when i get home tonight.

I am told that the stroke is standard, although i did specify a 1430 offset when getting the work done, however the engineer managed to forget to offset the grind. I did get it very cheap as a result though so i wasnt too fussed. I've never measured it as I was of the opinion that 'it is what it is'.

GW suggested that I may have standard 1275 ARP bolts rather than S-bolts too, but looking back through recipts, they say I have S-bolts. - not that recipts are gospel... anyone know the spec for lengths?

[Guess-Works.com]

I have the lengths for ARP rod bolts, which is 54mm from the base of the head ( which buts against the conrod ) to the end, 1275 rod bolts are 58mm.

However, if you have AEG177 rods and not the later 521's or 625's then they use a shorter rod bolt which I'm afraid I don't have measurements for.. You have also mentioned that the rods have been modified/lightened. There are also important measurements which need to be made in relation to the rods... Hopefully a picture will explain... I'll be back with that in a mo....

[Guess-Works.com]

Picture...



The measurements on the rod A and B will also affect how much of the bolt protrudes from the bottom of the rod and hence crank when rotating..

On a 625 rod A is 43.5mm and B is 22.5mm

so an ARP rod bolt should protrude no more than 10.5 mm from the lower face of the cap.

Edited by GuessWorks.co.uk, 10 August 2009 - 04:18 PM.

[haz]

thanks for that, I'll take some measurements in the next couple hours

as I said in a PM to you though, the bolts protrude around 16mm (oddly there is enough thread to accomodate this - unusual?)

[haz]

ok A is 40mm and B is 21mm, the rod protrudes a little less than 16mm (around 15.5-15.75mm)

Pics to follow shortly

[haz]

 Photo0032.jpg   1.34MB   13 downloads

 Photo0040.jpg   1.41MB   6 downloads

[Paul Wiginton]

Need pics of the rods and stroke confirmed. They shouldnt be anywhere near there.

Paul

[haz]

Will have to wait till tomorrow for an accurate stroke measurement, I'll borrow a vernier.

If you follow the link in my sig there is some pics of the build in there, do these help at all?

Cheers for your help by the way peoples

[Paul Wiginton]

Just looked at your build thread, they are S rods but Im certain the bolts are wrong.

When I developed these trays I tested them on my friends 1400 which is a 73.5mm bore with a 1mm extended stroke with S rods, there were no clearance problems at all, if your stroke is std you will definately have no problems unless something else is wrong. The rod bolt should only protrude from the nut by a few mm.

Paul

Edited by Paul Wiginton, 10 August 2009 - 06:37 PM.

[haz]

Ok Thanks Paul, it seems I have been issued the wrong bolts then. Dissassemble number 6 it is :\

Im half tempted to not bother sending them back as I cant be bothered with the hassle as I bought them probably 18 months ago. If i were to grind them, how much clearence would you recommend I aim for?