Engine rebuild questions

[CaliTrav]

Hi folks. I'm in the midst of rebuilding an engine for fun (strange idea of fun but it takes all sorts!)

The engine came from a scrap car. It seems OK - looks like the bores had been redone to 20thou at some point, but to eliminate wear I'm having those put out to 40thou and will get some oversize pistons. The crank was very worn but managed to pick up a 10 thou reground crank on ebay to replace for peanuts, so very happy with that.

What has also become clear is that the block was pocketed and paired up with a 940 head (possibly a gold seal head, or maybe just wishful thinking paint!)

Now looking at longer term reassembly, the 940 head was used with a standard HS2 carb and manifold which reading around is a bit restrictive.

So questions are...

1. With a HS2 and standard exhaust, would the 940 head and rebore make much of a difference? Or do carb/exhaust need doing too?

2. If I changed up to a HS4 using a standard 998 mini manifold to fit it, and again standard exhaust, is that likely to be noticeable vs a HS2 set up?

3. Does the "hot spot" really make that much difference? (So would be better to have a HS4 with a separated manifold eg Metro or homemade)

4. Is there much difference in fitting a HS4 vs HIF38?

If we're talking small gains in the above areas I might leave it stock on the carb/manifold/exhaust side.

And last question... I'm assuming the stock con-rods will be fine with the rebore, unless anyone says differently here!

[kevin s]

I am assuming it's a 950 Engine?

Stock con rods will be fine with a mildly tuned engine and any standard overbore.

With the larger valves in the head you should see some gain a HIF38 would be fine for your needs, deleting the hotspot will certainly help, almost all tuning focuses on getting the most air through the engine, the colder the air the denser it is purposely heating it is good for cold emissions and poor quality fuel but should not be necessary on modern fuels, on the exhaust side the standard set up is quite restrictive but it's not as critical as the inlet.