Please explain

need4speed · Post by **need4speed** » Tue Jun 17, 2008 8:45 pm

Reading Des Hammills book with interest. However im a little confused about the explanation re fitting the mains caps. I understand that they should be fitted into the registers at an angle to avoid damaging the aluminium of the block. Given that i have a spanking new block the fit between the caps/block is VERY tight. This is obviously a good thing. However what way should the caps be angled when 'snapping' them in? I was expecting a better explanation in the book, but it just refers you to another book for a full explanation - very sneaky plug for the publishers there (Veloce).
Could someone show the correct way to do this. I do not want to risk damage to a brand new block!

need4speed · Post by **need4speed** » Wed Jun 18, 2008 10:54 am

anyone?

Seight-V8 · Post by **Seight-V8** » Sat Jun 21, 2008 2:41 pm

hiya,

have a look at this RPI utube video, might help you alot.

I know i watched it and learned...more from this than reading the book.

Hope it helps

scott richmond

http://www.youtube.com/watch?v=wYyBK960GRU

need4speed · Post by **need4speed** » Mon Jun 23, 2008 9:48 am

thanks for that mate. thats a good video. the only thing that still concerns me a little is this - in des hammills book he clearly states that if the main caps more or less fall into place (without this so-called 'snap-fit') then the block is useless and should be confined to scrap as it has obviously succumbed to fretting. now it maybe because the block in the vid is cross-bolted but it looks to me like they fell in without any interference at all.
my main caps will defo not go into place like that. hhmmmmm

TVRleigh · Post by **TVRleigh** » Mon Jun 23, 2008 3:37 pm

Umm I have a few issuses with the video also.
1. as stated the caps shold be tighter, my was, they did slot in easy but the last 10mm was very tight.
2. side bolts should be put in before torqing mains. plus there order for sides and mains differ from the rover manual.
3. I though you put some silicone on the bottom ridge of the maincap no where the cross seal goes.

need4speed · Post by **need4speed** » Fri Jun 27, 2008 11:37 am

im surprised no-one else has an opinion on this as it probably affects most of us on this forum...especially the guys with non-crossbolt mills...

Paul B · Post by **Paul B** » Fri Jun 27, 2008 1:40 pm

need4speed wrote:im surprised no-one else has an opinion on this as it probably affects most of us on this forum...especially the guys with non-crossbolt mills...

I've never worked on a Rover bottom end, but the difference between interference (a tight fit) and dropping in, can be mere couple of thousandths of an inch.

So it does seem a rather broad statement saying "if the main caps more or less fall into place (without this so-called 'snap-fit') then the block is useless and should be confined to scrap as it has obviously succumbed to fretting"

Putting the main caps in a fridge for an hour will shrink them enough to make them literally drop in, as the coefficient of expansion of ally is very high. As opposed to the block being warmed in the sun, will also make it expand enough to make the caps drop in. Obviously they will both be the same temp in a garage, before assembly, but a couple of thou shouldn't equate as scrap.

Or am I talking cobblers

need4speed · Post by **need4speed** » Fri Jun 27, 2008 4:01 pm

well i would agree with you and to be honest ive built an RV8 before where the mains more or less fell in. however after reading mr hammills book (which is very highly regarded in RV8 tuning circles) it has me slightly concerned.
im just trying to guage how important it is but im not getting many takers.
due to the infamous RV8 fretting problem i think what mr hammill is trying to stress is that if the mains fall in when the engine is cold, then they will be hellish loose when the engine is hot and therefore leave you open for potential fretting issues. im using arp studs/nuts but even this is not reported to stop the problem...
i know there are some very knowledgable people on here and was just looking for some opinions on the subject.

I dont think youre talking cobblers at all...

kiwicar · Post by **kiwicar** » Sat Jun 28, 2008 2:44 pm

Why not just tighten the cap to block fit up a bit ? seems silly to scrap a perfectly good block when you can close the gap up by using a cold chissel about 3/16 outside the joint line and with a whack of a hammer it will tighten the gap for you.
You could also dowel the block and caps and use bolts or use tube dowels around studs, either would hold things nice and rigid.
This will probably be treated as heresy but personally I would read a little wider than take everything one author says at face value (yes I've read said book and it has some good info in it but there are other equally good books on engine building out there that have different ideas on what can be done that are equally valid).

Mike

Post by **katanaman** » Sat Jun 28, 2008 3:07 pm

kiwicar wrote:Why not just tighten the cap to block fit up a bit ? seems silly to scrap a perfectly good block when you can close the gap up by using a cold chissel about 3/16 outside the joint line and with a whack of a hammer it will tighten the gap for you.
You could also dowel the block and caps and use bolts or use tube dowels around studs, either would hold things nice and rigid.
This will probably be treated as heresy but personally I would read a little wider than take everything one author says at face value (yes I've read said book and it has some good info in it but there are other equally good books on engine building out there that have different ideas on what can be done that are equally valid).
Mike