Will most Pre 1980 V4s Benefit from High Comp Heads

[spybot]

As the title says.
Will pre 1980 V4a benefit from having High/Comp Heads or is there a limit to how much an old engine can take ?

 

[Joe Reeves]

Usually ends up causing pre-ignition, melted aluminum pistons, that sort of thing.

 

[F_R]

If you do try it, use the highest octane gas you can get.

 

[spybot]

Here in UK we have unleaded at 95 octane or Super unleaded at 98 octane
Will these do running a 50/1 premix ?

 

[V153]

95 octane oughta be just fine. I would run a synthetic blend.

Btw only '78 and up have the coil mount lugs.

 

[ondarvr]

Here in UK we have unleaded at 95 octane or Super unleaded at 98 octane
Will these do running a 50/1 premix ?

​Your octane ratings are different than here in the US, so the numbers don't line up the same.

 

[V153]

​Your octane ratings are different than here in the US, so the numbers don't line up the same.

Didn't know that.Well in that case run the 98?

 

[jimmbo]

I thought it was the pre 1980 engines that had the higher compression heads

 

[V153]

I thought it was the pre 1980 engines that had the higher compression heads

'76 135 were the tightest. Then they kinda wussed out. Believe after '79 or '80 they were all the same.

So yes, you are correct.

 

[Faztbullet]

Yes most engines will pick up some low/midrange torque with tighter heads...

 

[jimmbo]

'76 135 were the tightest. Then they kinda wussed out. Believe after '79 or '80 they were all the same.

So yes, you are correct.

The 73 135 had the highest compression head. In the 80s the crossflow 140s, prop rated 110/112/115s had higher compression heads than the 90/88 hp and the crank rated 115s