v2racing

I would run a cam with something in the mid 230's @ .050" in a hydraulic roller. The exact numbers for split and lift would depend on the flow numbers from your heads. Did your engine builder give you a flow sheet on your heads after he ported them?

With a drop base air cleaner you should be able to get a Performer RPM under the hood. That would give you the best all around performance for the type of driving you mentioned above.

Mike

REELAV8R

It sounds like you may be suspecting, and rightly so, that the intake may be holding your current combo back.
With that much duration I would expect it to make power up to at least 6300 RPM. My guess is that something in you induction is holding that cam back.
Heads don't flow enough (this is a potential reason for the long duration) or the intake doesn't flow enough. I'm guessing they were using at least 1 3/4" headers on the dyno with no airbox assembly?

If I were to build a good street 383 that produces good power I would probably use a cam with about 230* @.050 on about a 108 LSA maybe a 107 LSA. The 110 is going to reduce your torque output and require a longer duration vs the 107 or 108.
The 110 will have better idle manners however given the same duration.

Valve lift at least .550" but no more than .600". with 1.6 ratio rockers.

I run a 108 LSA now on a 350 and find the idle nice. It has that lumpy sound that a lot of folks like.

Any flow numbers on the heads you have now?

Darinm

Unfortunately no, I honestly didnt even think about when i built the engine. I'll give him a call this week to see if he keeps a copy of his work.

Darinm

Correct, large headers with open airbox bell. And yes i do suspect the intake which is why i asked. With the stock 1980 hood being a bit lower than others and using a drop base filter, i have about 3/4-1" of hood clearance. Obviously changing the intake is much easier than swapping a cam, so it may be on the to-do list sooner than a cam. Also, i've been wanting an l-88 style hood which would open the possibilities for intakes.

Unfortunately no, but i plan to give my builder a call next week to see if he keeps a copy of what he did.

This all came down to using alot of what i already had (Heads and intake). The intake (Weiand Street Warrior) is very low profile and i've read not soo good reviews of it. Especially compared to what's available today.

REELAV8R

Are these heads the 195 cc runners or the 185cc runners?

Just about as important as flow in the heads is velocity. Too little velocity and you may suffer from sluggish bottom end and poor acceleration.
In addition, with a cam of suffecient duration you will suffer more intake reversion (google that) and exhaust contamination during the overlap period, both of these reduce torque below peak torque.

With the current cam I believe that these items would likely become worse if you changed your intake to something like an RPM intake. The RPM intake is rated from 1500 RPM to 6500 RPM vs the street warriors ildle to 5500 RPM. So the warrior may be helping you out a bit right now below peak torque.
One other thing that may help with what you got is a 4 hole spacer. If you got about an inch to work with, look for some 4 hole spacer(s) to take up that inch. These will help to accelerate the intake air during low RPM use and increase the vacuum signal to your carb. Use some clay on top of your air cleaner to measure how much room you actually have before hitting the hood to be sure.

It's the mismatch that is causing the problem, not any one component's failure to do it's job.

I mean a guy could drive it for the season with a 4 hole spacer and adjust the timing to something that works and then dive into it this winter, or some other time down the road to change the items that can make it a better street machine if desired. Or change it out now, depending on time and money constraints.

Darinm

They are the 195cc runner, 64cc chamber

The clay trick is exactly what i did to get my clearance. I will look into a spacer today to see availability and options.


I have learned more from these sessions than ever ! I honestly appreciate the good feedback. I've read and re-read to ensure i fully understand how lobe seperation, lift, duration etc, all work in relation to compression ratio. Driving this season is exactly what i hope to get out of this. Later, and as funds are available, i'll do the cam swap, new hood and intake. I really like the idea of the AFR composite intake. Also, i read good things about AFR heads. So again, future possibilities.

REELAV8R

If you want some really good info on cam selection and the SBC build in general I highly recommend this book by David Vizard. It is well worth the $18.


You can also google stuff like "cam selction david vizard" and get some pretty good hits.
He bases his cam selection on LSA, (LCA) he calls it, and displacement and not the duration of the cam. Also uses overlap period as a critical criteria for cam selction. The amount of overlap is going to directly effect the amount of vacuum the engine will generate and it's streetable performance.

Pretty much most of what I know and understand comes from his books and articles.

Another decent resource for info might be Speed Talk. Lots of folks with tons of engine build info over there. Not to say there isn't plenty here too, it's just you can get into a section there where engines is all they do.