my90bird

I have 14101081 heads on my 305.stock heads.whats the cam lift on these heads with aftermarket springs of a max lift of .600?are they the 416 heads?

Saculia

iTrader: (1)

Yes, they are center bolt version of the 416. I don't think that a .6 lift on those heads is going to help you. First, there is no way those heads will take that kind of lift without machine work, 2nd .6 lift I think is well beyond the lift at which these heads have maximum flow. I think they peter out around 0.5" lift.

my90bird

so a .500 lift is pretty much the limit with out mods?

my90bird

do you have any mods on your head with the xr258hr12cam your running?do you have any sound clips?

Saculia

iTrader: (1)

What do you mean by "without mods"? Any aftermarket cam you put in there is going to require something better than the existing stock valve springs. Also, once you start exceeding let's say .47 lift, you may end up running into clearance issues which may require grinding down the valve guide bosses. But I would say that with the stock port size and valves on those heads, you don't want to go any bigger than 0.5". Beyond that you will likely start losing power. Also, when you start approaching lift near the .5" mark, you may want to also consider machining the heads for screw in studs. Probably the biggest you may want to go as far as lift is concerned would be a cam like the comp xr264hr12 without major head work, but with some head work.

my90bird

well the springs I am going to be running have a max .6 lift,have a set that comes will the keepers,seals and all thats needed for a new spring install

Saculia

iTrader: (1)

I went with better springs (don't remember what the comp part number for them was). My heads were fully rebuilt (same heads as you have). Also things were measured to make sure that all clearances were met. I had a reputable machine shop do all of this. Also as I recall I don't think it was necessary to get screw in studs for that cam.
As far as the sound is concerned, it is definitely more aggressive than stock. Try this link, it may give you an idea of what the car sounds like: http://www.youtube.com/watch?v=P3dpbnLcP4Y. This was taken about 1200 miles after the rebuild, with the sock computer tune, stock catalytic converters, and no muffler, just a muffler eliminator and tail pipes. The car sounds much better now after the tune and with the 3" magnaflow exhaust. The link however should give you somewhat of an idea of how choppy the idle is, but is not as refined as it is now.

my90bird

okay cause the cam I want is either the XR264HR-12 or XR258HR-12.

my90bird

this is the spring kit I have now that I will be installing.got it from summit.http://store.summitracing.com/partde...5&autoview=sku

Saculia

iTrader: (1)

I went with the 258 instead of the 264 because wasn't sure how well the speed density computer would like the bigger cam, thus I desided to err on the side of the smaller cam. Some people have had no problems with the 264 and perhaps with a MAF car you would not have as much of an issue. But I must say, that even with the 258 my car was badly out of tune. Fuel economy was horible, and the power was not what I expected to get. There were numerous flat spots in the power curve. It ran too rich at some spots and too lean at others. Tunning it made a tremendous amount of difference in performance. I don't think that I can over emphasise that. A computer compatible cam does not mean that will not require tuning. I ran my car for 12000 mile with the stock tune before I got a full wide band tune and a set of new injectors. Needles to say, my brand new park plugs were shot by then and so were my stock catalytic converters. Just my .