<VV> Re: 62 Turbo Knock Issues

[Garth Stapon]

Hi:

I have a 65 Monza with a 62 Turbo Motor with a 1 1/2 inch SU carb and a very 
large fan pulley. The previous owner raced this car and switched the pulley 
to prevent the belt from coming off. I know that I have reduced cooling 
effect due to reduced fan speed and will switch it back.

He milled the heads to increase compression and the problem I face right now 
is that there is THUNDERING engine knock at anything below 4,000 rpm. Above 
4,000 rpm (with 94 octane), things quiet right down. He told me to use 
aviation gas to eliminate the knock. The car had av gas when I test drove it 
and oddly enough did not knock.

I had Grant redo a factory 62 carb, so I can put the original carb back on 
if it makes sense.  I have been following the threads on 95 heads being the 
best for turbo - even better than a stock turbo head from what I saw. I 
asked Grant to equip it with fat jets.

Here are my questions.

1) Can I make the car run without knock with the SU carb with the milled 
head at normal RPM's? (Fatter jets maybe?) The use of aviation gas is not a 
practical solution for me.

2) Am I better off to put the factory carb back on? What are the advantages 
of keeping the SU carb? The previous owner seemed pretty hot on it as 
suggested that it was worth some money. I just want a car that runs well at 
less than 3/4 throttle.

3) Can I just simply lower the compression ratio reliably with a gasket kit 
from a vendor or am I better off to buy a new (to my car) set of heads?

4) Has anyone seen some real world advantages in replacing the stock turbo 
heads with the 95 specially prepared heads?

5) Would there be any advantages to installing a set of truck heads that 
have the valve rotators? Is this practical on this motor? Are these still 
available?

Do I need to consider anything special with the 145 cubic inch motor that 
would not apply to any other Corvair motor that will control the engine 
knock? (I already tried to retard timing and took it down to six degrees and 
it still knocked)

I suspect my compression ratio is around 10 to 1, but I am not sure.

Please e mail me off line.

Regards, Garth

(Late Power Glide Sedans Rule) - because 110 HP motors are simple.