More similar than just cams...
alsoThat would make the intake ports about 24thou closer to the crank, and therefore (if my maths still stands up) about 18thou less space for the induction module to fit between the intake ports.

In regard to the breather bolts; they move down with the heads so no problem there, but also 18 thou closer together ...but the size of the holes in the air filter backing plate should probably handle that.

I might have thought a compression type rubber seal would be able to cater for that kind of difference ...I've never come across another thread where anyone is trimming down the induction unit to fit ??

 

Trimming happens quite a bit. And the 124 guys go with longer manifolds for the increase in height

 

I've trimmed a few. Even stock ones... Also had to trim intake manifolds for carbs. Depending on the amount milled and running a thinner headgasket, each side will be about 40% of head height change. Take 10 off the heads, go from a 55 to 30 thou head gasket and you might need to cut 0.012 off each side. Last head change I did was from a set of 99 heads that were cut 0.060/ 0.040 head gasket and 5 off the cylinders to a set of 06 cut 0.010, 0.030 HG and stock length cylinders. I still had to clean up the ends of the TB.. Since the bolt hole locations changed I also had to cut clearance in the TB for the screws..

 

Good info. So too tight can be one possible reason for air leaks

 

For what it's worth, I went at mine with isopropyl alcohol around the flanges, injectors, MAP sensor, and IAC and could not get the general un smooth idle to change at all.

Then I attacked it with a can of butane with a rubber pipe on the end so I could point it at stuff, that didn't change anything either

Mind you, I aimed the butane at the air filter for a few seconds at a time and that didn't change anything either ...maybe mine is so lumpy you couldn't see the change.

Just wondering if you do have a leak or not, looking at your logs mine is as bad as yours. Just a thought.

 

At this point , it would seem to me that it's either a tuning issue or simply just the way it is...

 

Yea, I'm just getting on with mine, was just in case a comparison helped Jason at all

 

Mine did not show a leak with butane when the intake flanges crowd the manifold. But it binded and leaked when I put it on. I had a machine shop take .040 off of the backside of the flanges and that gave me room to move them back toward the steps of the manifold to get it one. Then when sprayed it was obvious where the leak was

 

Haven't done **** due to a stupid hurricane. No roof damage this time. Maybe this weekend

 

Well I think I may have located the issue thanks to help.

The Hpi plate looked like it was centering the manifold. It was a big difference between where the oem backing plate puts it. Now, from trimming the manifold spigots, there is waay to much of a gap. I will have to find a new to me 06-up dyna manifold to start over. Anyone holding