That is a very interesting sealant Peter---does it have a reasonable shelf-life? Some of these sealants, especially the ones on 'pressurised' containers seem to have quite a short shelf-life, which can be a real(and expensive) pain in the bum; As you know, if all goes to plan during a build-up, you amay not have use of the sealant for quite a long 'between jobs' period of time

the hobbler said:

That is a very interesting sealant Peter---does it have a reasonable shelf-life? Some of these sealants, especially the ones on 'pressurised' containers seem to have quite a short shelf-life, which can be a real(and expensive) pain in the bum; As you know, if all goes to plan during a build-up, you amay not have use of the sealant for quite a long 'between jobs' period of time

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The sealant is in a tube and I think it comes with a "key" so you can squeeze the last drop. It keeps very well despite me not always being rigorous in keeping it away from frost or an overheating shed in summer.

As I must have said before, it came to my attention when I was rebuilding a Husqvarna chainsaw and found that no gasket was specified for the crankcase...and this is a two-stroke going at maybe 12,000rpm. Somewhere on the internet I read that the manufacturer uses this stuff in assembly. It doesn't go stringy, sets to a slightly harder consistency than some older sealants and peels away easily when dismantling.

My modern Citroen gearbox is factory assembled with a similar grey mastic and our modern Fiat 500 uses sealant on the flimsy, pressed-steel sump, which I recently replaced like for like.

So convinced am I of its efficacy that on my recent engine rebuild, I hardly needed have bothered with the full gasket kit and in future I will just buy the ones which can't be replaced with sealant.

I'm not advocating its use because it's more economical or quicker but because it seems to be completely leakproof. I've noticed that you can get a slight seepage on many paper gaskets whether or not belted and braced with sealant, even when they are so thin as to be almost negligible.

Greetings, I've not been out in the car much so little to report, however, made an effort to rack up a few more running-in miles today and had a spin around the local country. The car remains easy to start and runs well, the noise of the straight cut timing gears is something I am getting used to and short of taking the gears off and replacing them with the original gear and chain set up there is nothing I can do to stop the gear whine!!! They do have the advantage of giving an exact timing set up though, so it's a bit of give and take.
When I press on the exhaust noise drowns out everything
anyway!! More later.
Ian.

Hi Ian,

I’ve read your thread with great interest- thanks for all the detailed information.

I’m in the process of building a very similar spec 700cc engine and am just in the process of getting the rocker geometry sorted. I need to cut down my pushrods by about 4mm and wondered if you had any tips for doing this, or did you get it done by a machine shop?

Best wishes
Lori

Lori, before you do cut your pushrods (which really need to be done by somebody with a lathe), I have a very interesting technical article regarding rocker angles and push-rod lengths. You have my direct e-mail address; if you let me have your address i will put a copy of the article into the post to you. Ian has a copy and found it most interesting.

Mcflozza said:

Hi Ian,

I’ve read your thread with great interest- thanks for all the detailed information.

I’m in the process of building a very similar spec 700cc engine and am just in the process of getting the rocker geometry sorted. I need to cut down my pushrods by about 4mm and wondered if you had any tips for doing this, or did you get it done by a machine shop?

Best wishes
Lori

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Hi Lori, Tom is correct, his article covers this subject in detail. As you will no doubt know it's not just a simple case of hacking the end off of the pushrod. My rods were all shortened (at the top) on a lathe using a parting off tool, whoever does the job must be careful as the contact cap that the valve adjuster sits in has a long tail fitting down into the (Hollow) pushrod. The amount you require removing should be conservative - you cannot put it back!!!! It depends on the rocker angle and how much is needed to get the horizontal rocker at half of cam lift. I would ask Tom for a copy of the article before you go any further - reading it will help you understand what is required before any cutting
Ian

Thanks to you both for your replies. Tom- I’ve emailed you.

I know it’s difficult to achieve the requisite accuracy when shortening pushrods without a lathe, Which is why I was wondering how Ian had his done, so thanks for confirming this.