Engine Idle Quality After Installation Of Aluminium Head

Very courious if the installation of the head with the long intake runners changed the idle quality, compared to the same camshaft using the log head??
I just wondered if the isolated intake runners resulted in less intake contamination during the valve overlap area compared to the log where the intake of one cylinder is just inches away from another cylinder????
What i'm looking at is the idle quality of say the 274 cam with a 112 l/c on the log head equal to the same cam with a 110 l/c with the new head with respect to idle quality. Bill

Bill, Here is a sound clip of my 250 with a 274/110 Cam. I wish I would of made a clip with the log head, but didn't even think of it.

Hope this helps.

Bill

Bill, thanks for the reply.
Your engine sounds great.
The X factor is the new head has larger valves & that will expose more valve opening area during the overlap period.
Just trying to see if any owners found the curb idle rougher with the new head vs the old log head with the same camshaft.
Yes this an off the wall question, but just trying to see if there is a difference in the curb idle between the two heads. V/R Bill

wsa111":27l95wfh said:

Bill, thanks for the reply.
Your engine sounds great.
The X factor is the new head has larger valves & that will expose more valve opening area during the overlap period.
Just trying to see if any owners found the curb idle rougher with the new head vs the old log head with the same camshaft.
Yes this an off the wall question, but just trying to see if there is a difference in the curb idle between the two heads. V/R Bill

Click to expand...

I haven't noticed much difference in idle, BUT the tone of the exhaust has changed, the tone of the exhaust has a deeper sound.

Bill

Remember that the Aluminum head is based on the Aussie 250 2V and port matched to it. The idle , therefore, should not be that much different.

Just my $0.02.

rocklord":2vwhv1fc said:

Remember that the Aluminum head is based on the Aussie 250 2V and port matched to it. The idle , therefore, should not be that much different.

Just my $0.02.

Click to expand...

It's not really port matched to it. It is close, but different enough that Aussie intakes need some serious porting to make them fit, according to what I've heard here.

Just sayin'.

Bill,

My new motor cams harder at idle now!

Maybe the jump in PSI per cylinder now vs last summer? New Bigger valves? Cam advanced 4 degrees?

All of the above?

I do need to throw the vacuum gauge back on it and see if the vacuum has risen from the 7-8" its been for the past couple of years.

Later,

Doug