any reason not to swap cams?

[falcon fanatic]

I'll be getting my head back from the machine shop this week, so I'm gearing up for that swap. I'm going with the full roller ratio rockers at 1.65:1. The head is pretty heavily modded with 2v direct mount, porting, and 1.75" and 1.5" valves & 50cc chambers.

I'm thinking that since I've got to go as far as replacing the lifters, shouldn't I just go ahead and swap the cam while I'm at it? That gives me an opportunity to get a fresh water pump and a new timing chain and swap in the dual pulley harmonic balancer I need for my upcoming R&P conversion. Aside from the added expense and time and effort, is there a downside to doing the cam swap? I plan on just slipping out the old cam and slipping the new one in. Am I in store for an unpleasant surprise of some kind?

while your'e at it, cam recommendations are welcome. I have a stock c-4 with a stock TC and 3.25 rear end ratio.

 

[addo]

Hardened distributor gear is pretty much compulsory unless you're using a reground cam. For specs, I'd look at a split pattern cam (thinking you have a standard manifold) in the higher 260's.

More than that, and you risk having too low a static compression. Also there would be possible issues with idle quality/speed and TC stall.

 

[falcon fanatic]

Addo,
I have the M head which I think is the highest volume log manifold available. I'm direct mounting a weber 38/38. I'm using a DUI distributor, so I think I'm good to go on the drive gear.

My idea was to use one of the three tamest cams that Mike offers; the ones that are described as "designed to take advantage of modifications to the log head". I believe that will resolve the idle quality and stall speed issues. Also, I've milled the head for a moderate boost in static compression so hopefully I won't loose too much bottom end power with the larger manifold.

At the heart of it, my questions where really about whether I'll be cool reusing the same cam bearings. I can always wait for a total bottom end rebuild if there are any doubts as Idon't want to disable my car just as the very brief convertible season is kicking in here in Washington DC. Soon it will be 95* and 90% humidity and my air conditioned volvo will start to seem like the rational choice again.

 

[addo]

Your cam tunnel should be fine. If you inspect the journals carefully on pulling the old cam, it'll be the final determinant.

 

[rbohm]

8) this is the cam i recommend

Product ID: ARC-268-HDP-10
ARC-268/274 (110*) Hydraulic Dual Pattern Camshaft


Details

Adv Dur 268/274


@.050 208/218


Valve Lift .455/.480


L/C 110*


Range 1600-5400


We also have 109* lobe centers in stock.

for the street i like the 110 lobe centers. this cam is a good one for low and midrange torque.

 

[Bort62]

Thats a lot of difference between intake and exh duration.

Of course, I am used to SBC cam profiles so that really means nothing.

 

[falcon fanatic]

rbohm, thats the one I was looking at! seems perfect for acar like mine.

 

[rbohm]

8) that is the cam i plan on using in my 250 when i build it for my 64 falcon.

bort62, the reason for the added lift and duration on the exhaust profile is to aid in getting rid of the exhaust gasses due to the poor exhaust flow in the stock head. in fact most street engines with stock heads benefit from added exhaust lift and duration. if you plan on using mikes new cyliner head though, i would go with a single profile cam rather than the dual profile cam.

 

[Bort62]

I understand why it is split profile - and I generally like dual pattern cams.

I was just commenting that the difference duration between intake and exhaust is quite large. Altho since we know that the exhaust on these heads flows even worse than the anemic intake, it makes perfect sense.