Are these less sensity to cam changes? What are limts to go on cam?

 

Yes, SD systems are sensitive to things that change how much vacuum the motor pulls. A SD system relies entirly on whats programmed into the ecm to calculate how much fuel, spark, etc to give the motor since it can only measure the manifold pressure. If you put in a cam with lots of duration and a tight LSA, the computer will see the increase in manifold pressure at idle and low load and itll go to the locations in the tables that correspond to that pressure. One of the problems is that with the stock tune, the computer will add too much fuel since those locations correspond to the stock engine being under moderate load and not low load or idling. There is also the problem with erratic vacuum. For one thing, itll cause a flaky idle. Both of these things can be fixed by tuning but pretty much anything that alters the engines volumertric efficiencies or operation will require that at least small adjustments are made to the ecm's calibration to compensate for it.

 

my new cam is going in soon hopefully(still in box). that cam is not huge relatively speaking but for a SD car it may be at the upper end. anyway it is largest that comp cams offers for computer controlled cars and is larger that cranes line for same. i may run open loop idle and compare that with CL for drivability. i see all my idle cells are same spark timing so jumping cell to sell may not be affected by timing values. my VE fuel tables maybe should all read the same for idle cells not sure on that. comments?

 

there are alot of things that play into it, you lose resolution as the vacume drops at idle. the LSA and overlap also play a big role.

what sort of cam specs are you looking at running?

 

Would of like to run more, but a 114 LSA, 212-218 duration cam with a Turbo City modifed TBI, Edelbrock 6704 manifold, not sure on headers hedman maybe. Flow master, 3" pipe dual 2.5 out.

76 cc heads were shaved .020 and to get a 40 quench went to a Fel Pro 1094 gasket, .015. Changes things by .046/.0059 should be over 9:1:1 and under 9.5:1, using Fel Pro Hyp H345NP40 pistons, balanced, open air cleaner with K/N filter for now.

Smallest cam I used, but cars are so different from the 70's, thank for any and all help. Looking to get read out on ECM using winALDL or whatever will work on this year of ECM/Prom.

ECU is listed as: Service # 16168625 BBMW
86BBMWK330491987


MSD coil, Proform Distributor with 3:42 gears which I may go to a set of 3:73 with 4L60E transmission. Turbo City made a chip, but at time we expected to be running 2.02-1.60 heads but used SR 1.94-1.50s. 50 dollars they will redo chip, which I would like to learn myself and if I can get readout, maybe I can see what or where things go etc. With out trying, I have no idea what to is wrong. Sure to many stock settings not needed and issues set wrong for stock and motor is not stock, if a 6383, well it may been ok, larger motors more cam can be used.

 

thats just a baby cam in a 350, you'll have no problems, in a 305 it would be a pretty hot cam, but tunable, that is a little smaller than i am going to be running, and i was able to tune in a 206/216 on a 112 in about 2 hours, so it ran like a top better than most people would beleive (yes of course it still needed work, but it was def. driveable) if that cam is going in a 305, you will def. need to tune, but 212 on a 114 won't be too bad. i plan to run somewhere around 215-218 and on a 110 in the new combo.

 

I wanted to run more cam and bad advice is why this one is so small-444 Lift. I do get a little more lift with 1.6 Comp Rollers. I had wanted to learn chips and how things work before going further as I seen Comp Extreme 262 218-226 Duration 480 Lift with 112 LSA (462-110 LSA) Looked also at Crane's that Has a 216-228 Duration 450-480 Lift and told they may be to much, which I had questioned, but it's been a long tiime since I worked on HP cars, which were mainly big blocks at that time.

When I asked about High Energy Cams such as their 268H, I was always told 110 LSA and lopey idle would not work. As vehicle is customized a lot, we were not looking for a stock sounding cam why I had asked about HE and 270H Magnum Comp Cams.

See a couple cams with 112LSA with lifters for around 80.00, which had some nice profiles. Son used one in his 383 vehicle, lots of power and torque. 5.7 40 over, balanced, 4 bolt main with SR 1.94-1.50 heads, had torker 2.02-1.60 heads, but their bare heads and 67 cc/SR's are 76 cc which were shaved .020 and went to a Fel Pro 1094 gasket to get a 40 quench motor, later hope to go to a 383 setup once I get ECM etc learned and 350 to run well, thank you!

 

i really like the comp 274 for 350 build-ups, with practice you can run alot more cam than most cam-tech-help folks would recomend. i have one friend running a solid lifter 248 @ .050 with .570 lift, on a 112, in a HRS 355, and a another with a mini-ram 383, with a 242 .565 lift cam. granted it takes practice, and lots of hours to dial them in, but it can be done.

 

Cool, 212-218 cam specs are @ .050, I appreciate your advice and encouragement, Greatly!

 

no problem, i started in the same place you did.

my best advice, is to start computer work NOW, start small, and get some experiance, on how changes effect the engine. i was supprised at how many changes i ended up making, just for headers.

when i did the cam, i started by 'guessing' i knew it would need more inital timing, less initial fuel, more pump shot, more fuel up high, ect. and then i went from there.