Show off/tell about your ignition and cam set-ups

[Mrturner1]

Hey guys I've been reading a lot about distributors and timing, as well as cams and what all the specific numbers on a cam card mean. What I'm specifically wondering about is how you guys with good sized cams (.480"-.600" or bigger) set up your distributors as far as springs/weights/lock out. What have you found that your engine combo likes best as far as base (initial) timing, mechanical or centrifugal timing, and vacuum advance. How do you get a cam with big duration or LSA's in the 106-108 range to run decent on the street? How do you set them up on the street as opposed to when you get to the track? Feel free to make conversation about the topic because I've been reading ALOT but nothin beats the experience of guys who have been building/tuning motors as long as I've been alive.

My setup right now is a 355 with a comp 280H cam (230 duration @.50 on a 110lsa) and around 10-1. So far I haven't ordered the parts to customize my distributor but a mechanical advance lockout is in my near future. I noticed that it runs much better with about 16-18* initial but that puts my total way over 36*. My timing is all in by 3200 rpm so I'm going to stick with the springs I have.

[Grumpy old man]

Well....on my old 292 i jus figured I'd run what good old GM gave it when it was new back in 67 she'd hadn't run more than a lick in a coons age so iz figured she was good to go , iz pulled the batrey out in the tractor for daddy seen was iz was up to and all it took was some corn squeezings and a good bit of cussing for shown enuf she coughed over and started hitting a mean old lick liken some mean old NASCAR (all rednecks can spell NASCAR!) An wudya know half in the lights sparked on Woo hoo ! Well the seats been on the front porch for years so iz not gonna move sissys necking spot just to drive her down to the barn and drop that mean ol crackly blockked 350 iz got ,she's run good but iz got me some Argentina built heads for a racing buddy and he's gave me a good deal only run a few hundred times around a dirt track south of some border ,once I scraped the chickendropping offthemthey shined up like a new radiator (whoops that part comes later )

[hugger6933]

Too funny. No Matt really not a hit towards you or anything but I think you over think things. Now of course this is a big-block I'm about to tell you about but I would turn my timing light to 36 and have everything in by 3000 RPM.
Now IDK about others but I never did fool with the timing much and didn't change it between the track and the street. If the timing is best for the motor, it will be best for the street and track. I had some buddies that would talk about running someone then pop open the hood and twist on the dist. pulling it around to crank up the timing. I never thought that was real smart.Back to your timing get it set where you find it runs best and set it there. Some pull it up til it labor knocks[detonation] the backs it off a couple degrees. You go all in @32 by 3000? Try another degree or two and see how it does. You can limit the weights or block them off but I think the mech advance coming in right about where your converter flashes might help a little

[Mike C]

combustion chamber design is one of the biggest factors. My 492 heads on my Camaro's 355 run best with 42 degrees total. How fast it comes in depends on how heavy the vehicle is, how much compression it has, and how much gear is in it. There is no "right" answer for yours based on someone elses, you will just have to experiment.

But locking out the advance is not the right answer. It needs to operate in too wide of a range on the street for that to be effective IMO. You need to make sure everything is in good shape and then just work with it.

[Mrturner1]

Originally Posted by Mike C

combustion chamber design is one of the biggest factors.

Now that's something I hadn't considered OR read about yet. I think my RHS heads have a round(ish) chamber, but my next pair is definetly going to be AFR 180's and I think those are heart shaped chambers. I'm going to order those bare and try assembling the heads with nice parts and also according to a cam card.

[Grumpy old man]

Secretly squirrel hidden tricks ? Takes two guys one to adjust timing the other to powerbrake the truck ( one foot on the gas one on the brake ) have the driver slowly increase the rpm / load on the engine while the other adjusts the distributor until the engine starts to miss ,and then back it off some and try it again ,once you get it to pull as hard as possible without breaking up THATS your max total advance . Poor man's dyno no matter what numbers your reading in some book reality always wins . Have you ever seen a crew chief at the track pull out a book to setup their car for the track ? It's done by experience in the real world . They write books to sell .Nobody can go on here and tell you from Texas how to set up your truck to run in Northern California ,there are to many variables ,fuel type ,heat,air density etc,etc I've been trying to tell you all along this road your on your going to over think what you have and what it's doing ! Put some decent 20-50 oil in it and dump in a can of stp and put some NORMAL driving miles on it ,Stop revving it to 5,000 rims and just drive the dang thing ! Real world driving down the road miles not trying to twist it at every red light or corner ,the truck will reveal more information this way than sitting in your driveway ! NORMAL like driving a minivan miles ,let it all learn to live together before you tear it apart revving away like some mad man on a mission of destruction .

I'll go ahead and say it you don't have a race engine , the first stock mustang or camaro will blow your doors off in part because you have been ignoring the suspension ,and when you make it go you also have to make it Woah (brakes) Close the hood and start looking at the truck as a whole stop concentrating on just " how fast can it go " you'll be much happier in the end !

P.S. And once your done I have a nice little 292 M-22 4 speed posi short bed farm truck I'd like you to drive , automatics are fast 4 speeds are more fun to drive !

[Mike C]

Originally Posted by Mrturner1

Now that's something I hadn't considered OR read about yet. I think my RHS heads have a round(ish) chamber, but my next pair is definetly going to be AFR 180's and I think those are heart shaped chambers. I'm going to order those bare and try assembling the heads with nice parts and also according to a cam card.

One of the ways that aftermarket heads make more power is in the chamber design and not just flow. LS motors make max power lots of time with about 30 degrees total timing and aftermarket aluminum heads like the above described AFR's in the mid to low 30's. But early iron heads like my 492's like/need TONS of ignition lead.

My motor runs great at 42 on pump gas. No audible detonation and 110 mph in the quarter. Keeps gaining MPH as I turn it up but that's about where my comfort level ends.

Cam is 280/280 advertised with 236 @ .050 Comp Mechanical Street Roller with about .540 lift before lash which I run tight at .020.

[Mrturner1]

Originally Posted by hugger6933

Too funny. No Matt really not a hit towards you or anything but I think you over think things. Now of course this is a big-block I'm about to tell you about but I would turn my timing light to 36 and have everything in by 3000 RPM.
Now IDK about others but I never did fool with the timing much and didn't change it between the track and the street. If the timing is best for the motor, it will be best for the street and track. I had some buddies that would talk about running someone then pop open the hood and twist on the dist. pulling it around to crank up the timing. I never thought that was real smart.Back to your timing get it set where you find it runs best and set it there. Some pull it up til it labor knocks[detonation] the backs it off a couple degrees. You go all in @32 by 3000? Try another degree or two and see how it does. You can limit the weights or block them off but I think the mech advance coming in right about where your converter flashes might help a little

I'll be playing with mine a bit down the road to see what it really likes, but this is mostly to learn about what others prefer who run big cams or modify distributors to try and make a snotty engine streetable. I never did consider the converter flash in all my planning though. That's definetly a good one to consider

[davepl]

Originally Posted by hugger6933

Too funny. No Matt really not a hit towards you or anything but I think you over think things. Now of course this is a big-block I'm about to tell you about but I would turn my timing light to 36 and have everything in by 3000 RPM.

That's pretty funny because I didn't see that when I posted my data, which was a best run of 36 degrees all in by 3000. Pretty standard for a big block, but goes to show you that the cylinder head determines a lot of it, and its consistent from one big block to the next.

[Mrturner1]

Originally Posted by Grumpy old man

Well....on my old 292 i jus figured I'd run what good old GM gave it when it was new back in 67 she'd hadn't run more than a lick in a coons age so iz figured she was good to go , iz pulled the batrey out in the tractor for daddy seen was iz was up to and all it took was some corn squeezings and a good bit of cussing for shown enuf she coughed over and started hitting a mean old lick liken some mean old NASCAR (all rednecks can spell NASCAR!) An wudya know half in the lights sparked on Woo hoo ! Well the seats been on the front porch for years so iz not gonna move sissys necking spot just to drive her down to the barn and drop that mean ol crackly blockked 350 iz got ,she's run good but iz got me some Argentina built heads for a racing buddy and he's gave me a good deal only run a few hundred times around a dirt track south of some border ,once I scraped the chickendropping offthemthey shined up like a new radiator (whoops that part comes later )

I was hopin you'd show up and tell some of your tricks and track stories lol not tell me a backwoods swamp tale. You mean to tell me you never played with distributors and timing to tune big cams?! I don't buy it! not the grumpy I read about, now cough it up, I want super secret squirrel tuning material

[davepl]

May not be right, but here's what I do:

- Dyno it to figure out max timing at 3000+ (Let's say 35)
- Tune it to figure out how much initial it likes (Let's say 12)
- Recurve distributor to make up the difference (Call it 23 in by 3000)
- Don't mess with vacuum unless it pings at part throttle

In terms of how fast the mechanical should come in, I even know a guy with a distributor machine (he recurved mine as above) and all they cared was "all in by 3000" or a similar number.

Without a dyno, all you can really do is advance it until it pings! Well, you could follow the tuneup sticker, but they seem very conservative with today's gas.

It's really faint, but in looking at my dyno data the actual numbers are:

CAM - 214/218 @ 0.50 on 115 LSA, Intake Centerline 110, Life .476/.496
Main Jet - 78, Sec Rod .054
Specific Gravity: .750
Timing: (Best) 36

So that's in a big block (different chambers) and a different cam, so it's not applicable to yours, but gives you a very rough idea. I believe they put 12 degrees initial in it and recurved the Pertronix to 24 total mechanical.

[Possmguts]

Well, since I dont smoke anymore.. a Cigarette, a Beer and a 9/16" wrench aint gonna work no more. But I guess Im gonna be around 34 at something like 3000 rpm?... maybe... but I do know Im not going to the dyno to try and figure it out...

[Mrturner1]

Originally Posted by davepl

So that's in a big block (different chambers) and a different cam, so it's not applicable to yours, but gives you a very rough idea. I believe they put 12 degrees initial in it and recurved the Pertronix to 24 total mechanical.

Exactly what I was talking about and wanted to learn more about. They recurved your Petronix after figuring the initial so that the total would be spot on after it was all in. I hope to get mine on a dyno in the next couple months so I can try a few different things and see what it likes best. Most guys I've talked to with the same cam as me in a SBC say they run 16-18* initial, which is a lot, but their distributors are limited to about18* mechanical and they say it runs perfect. Maybe with the next build I'll have some things to compare to later when that ones done and dyno'ed

[Mrturner1]

I've also been eyeballin a couple Holley carbs to try out in place of my Edelbrock 650 AVS. I'm probably gonna have to build some shelves for all the parts I'm starting to acquire, not to mention my fiancé wants me to build her a 73-87 K-5 with 4x4, air conditioning and some 35 inch tires

[snj8198]

Takes two guys one to adjust timing the other to powerbrake the truck ( one foot on the gas one on the brake ) have the driver slowly increase the rpm / load on the engine while the other adjusts the distributor

"alright Jim, git up there and worky the distribter while i rev'r up."

vroooom....bump bump

"seems like the brakes are bleedn off Jim".. "Jim?"

"whatchya doin under there Jim, the distribter is under the hood"

[Mrturner1]

Grumpy for cryin out loud, my truck is running awesome and I haven't touched my tools in a week and I'm not revving the piss out of the truck, I don't even know where you got the idea that I do that (okay there was that one video I posted, but that was showing off my victory!) I just like learning about what other guys run and what works best for making snotty cammed engines really run great. I'm not over thinking it, just learning everything from mild to wild. I'm in the planning phase of my next SBC and this ones gonna be a stump pulling 400ft lbs of torque at 3500rpm beast.

Btw I'd love to drive that farm truck!