How much overlap before a 88 starts to have problems idling?

 

The answer to that question is totally subjected to variables such as tuning, compression ratio, fuel octane rating, the type of exhaust (which usually doesn't matter if the tuning is good) and the quality of head porting.

Generally speaking, more over lap means longer duration cams and the more over lap that you have, the more you need to raise the compression ratio, in order for the engine to idle and perform well.

I didn't really answer your question but I would go with what the manufacters recommendations are.

 

Really need to look into this.

Look into the LCA, this is the angle between the intake centerline and the exhaust centerline.

Some cams that are extremely good torque cams have a very rough idle because the centerlines and the high lift are such that if you look at the lift curves there is some fair amount of overlap. These cams actually have intake closing around 40-42 degrees but---

This particular overlap is most apparant at idle.

Once above 1250-1500 RPM the engine doesn't care and above 1600 RPM pulls like a freigh train.
T-Man and Woods torque cams are perfect examples.

This are actually the best sounding idle one can get with the new FI engines. And at 1000RPM.

 

Just to try to add a bit to what the other (wiser) people have said. An LCA of around 100 degrees is where you get the high torque, rough idle cams. A 105 degree type cam is more common as it smooths out the idle so that should give a basic idea.

There are other considerations with choosing a cam - too "big" a cam on an engine will make it lose power nearly everywhere. On a stock 88" my guess (and it's only a guess) would be that anything over 250 degrees duration and/or after 45 degrees intake close might be where you'll notice some lower down losses but I'm sure someone else can offer a more educated view (and if it had a 100 degree LCA it might make up for it anyway).

 

I have a stock 02 Dyna stage 1.
I cheaply acquired a new crane 316. The cam and SE hybrid cam-plate kit, bearings, tools etc.. are setting on my work bench waiting.
Is this too much cam? I plan on riding with the stock top end till I get my money's worth, so higher compression will have to wait.
Everyone posts dyno graphs, but never a comment about what they had to give up in street ability to get those figures. Any opinions would be appreciated.

 

No! its very conservative and safe.

 

That cam closes the intake at 43 degrees, so you won't have any low end. You'll need to keep the revs up to make good power. What kind of cam is right for you depends on how you like to ride.

 

I think his low end torque will be fine. maybe not as nice as a 203.

 

I don't mind if the engine has less torque below 3000 rpm, I can always down shift. I don't want the engine to have bad habits. Such as fogging out the carb, unstable idle, Poor throttle response just off idle etc...
I ride every day, I want power, without the problems.
Does any one have any comments about the drive-ability of their cam of choice. I'm looking for information before I make a decision...

 

The overlap on my cams is 40 degrees. My intake lift is .580 with a shorter duration. The exhaust lift is .530 with a longer duration then the intake. It's considered a high torque and higher than average horsepower cam. My motor idles better at 960 then at 1000 when it gets up to temp and that's where I have my idle set. It has lot's of power out of the hole and lot's of power on the top end. But I have a stage 3 motor too.

This is what I believe; You can use any cam that will work with your stock compression ratio and any good tuner (person) can make your engine idle very well. Look up Dalton and Hog-doc on this forum and quote what I said. The will say the same thing.