4 replies to this topic

[Minigirl]

1. What gasket should i get to fit a 940 head to my 998?

And Whats the thickest gasket I can get to increase my chance of valve clearance?

2. Is it a 1275 water pump pulley I need?

3. I have a spi head with the heater tap blanked off but the hole is there with the threaded bolt holes, do I just drill the blanking part out?

4. Will my 998 radiator take off bit fit on the 1275 head?

5. What's the best way to check the valves are clearing the block?

Thanks

[Turbo Phil]

You need to use a 1275 gasket.
On a stock 998 cam and unskimmed 940 head you'll often find the valves are clear of the block face at full lift. If you need a little clearance you can cut the ex seats to recess the valves slightly, though not ideal, this is a budget option.
You need to use the small waterpump pulley.
You can just drill the head for the heater take off, yes.
You'll need the 1275 radiator bracket.
To check clearance you can put a small blob of plastecine on the block face, and turn the engine gently by hand, if you get a full rotation with no issues then check the plastecine to see how much clearance you had.

Phil.

[Minigirl]

Thanks for the reply

yes I will be using the stock cam

Its had a very light skim but I will measure it, is there a thicker hg I can get to compensate that?

So things I need are

1275 rad bracket
1275 water pump pulley
1275 headgasket

Do I need to do anything else with the heater take off after drilling it (except clean the iron fillings out)

Also what diameter is the smaller 1275 pulley incase the previous owner has already fitted one?

Thanks

[Stiggytoo]

Calculate the compression ratio.

Edited by Stiggytoo, 09 November 2016 - 08:51 AM.

[Spider]

Sorry here, maybe a little OT.

 

I've not done one of these conversions, but have looked at them.

 

Are they really worthwhile?   There's quite a bit of shrouding of the exhaust valves and that's made worse if pockets need to be cut.

 

A mate of mine did flow bench tests years ago, with a 1275 head on a small bore block and various valve openings. I recall, in overall terms, he found that in the Inlet side, there was some improvements, but on consideration of the exhaust he found a stock 202 head better.