19 replies to this topic

[timmy850]

There’s a calculator here, of course you’ll want to double check all the calculations & measurements on your own head and parts to confirm

https://www.classicm...cal/compression

[Turbo Phil]

By my quick calculations the 295 won’t need much skimming with flat top pistons, with the overbore to 1060cc I’ve got above 9.5:1 with a stock unskimmed head.

Without sounding to much like a school teacher could you please show your workings?

It will help ensure I’m doing it correctly

Blakie

I did a video covering how to calculate and measure for this. It’s pretty simple.

Phil.
https://youtu.be/9Lp-1Rbb4Yo

[humph]

Quick question. For the spec the OP has described, similar to mine, what temp of spark plugs would people use?

And what gap would you set. I’ve been told that this state of tune and elec ignition needs a larger than standard gap. Thoughts?

Edited by humph, 22 January 2022 - 11:02 AM.

[Hpal]

By my quick calculations the 295 won’t need much skimming with flat top pistons, with the overbore to 1060cc I’ve got above 9.5:1 with a stock unskimmed head.

Yep I reckon don't skim it at all, or just a clean-up cut, they're not making them anymore....

[josheastaugh]

I would suggest using an electric fuel pump as the mechanical pump will otherwise be close to your exhaust manifold. A standard SU or Hardi pump on the rear subframe would do the job.

You'll also need to be careful with fitting the HIF 38 as it will be perilously close to the bulkhead. I needed to cut down the carb spacer on mine so that the accelerator quadrant barely cleared the manifold.

Otherwise all looks good to me although a CR of 9.5:1 may be a safer bet for 95 RON unleaded. 

 

Not meaning to jump in to much but like a few others have said, My engine is a similar spec.  Regarding the HIF38 hitting the bulkhead, I too had to fit a very thin carb spacer to my manifold and then bought a Retrosport adjustable upper engine steady to just push the top of the engine forward slightly. Hasn't hit the bulkhead yet. 

 

I also used a MD266 cam and it is great. You do have to rev the engine though, sounds great at the higher revs.