BBC Camshaft LSA question

[CharlieB53]

Need more data.

Do not change anything.

Install a GoPro and record both the Tach and the O2 gauge.

BBC generally do not like excessive timing. There has to be a reason for this and this needs more data to figure it out. Continuing to make changes keeps clouding your data.

Verify your timing mark (TDC) to make double damn sure it is correct. It very well may be something so basically simple that you keep missing it.

High speed timing retard may have advantages, as well as lower gearing, either rear end, lower first gear, or switching to the T400. But none of these changes should be done until you record the tach and O2 reading during a few passes.

[turdwilly]

It is not a LS motor with knock detection and computer
controled timing and efi.

It is a BbC with a carb.
At 11.50 on pump gas on the street, uou will have a good time but not a long time.

It is not a alumin um block engine.

I had a 11.0 to 1 BBC with 048 heads, 280m cam and a 850 holley in a 76 4x4. It had 3.73 gears, th350 w a 2200 stall and 36in tires. It could do 140mph, then tow the race car and all of the pit equipment over the pass at 80. On pump gas, in the early 90s..............?

My friend had a '70 Mach 1 with a 351C during that same era. It had the old speed pro forged domes & closed chamber 4v heads, somewhere around 13:0.1 CR iirc. Doug Nash 5 speed & the large port shelby aluminum dual plane with the carb centered & not offset like the factory iron manifold, & a moderate Lunati solid flat tappet. It ran fine with no audible detonation on the old Amoco Gold 93 octane pump gas. And it apparently had no inaudible detonation as it was still going strong when he sold it after many years of driving. But that was leaded fuel. I have my doubts as to whether it would run on today's unleaded 93.

That was a fun ass ride & pretty quick for that era, if you could shift it quickly enough, it would blow the tires off into 5th gear. Torquey SOB. But it was slow as hell if you weren't on it hard since the gear ratios were so close.

[Jeff Lee]

Spent an hour or two and read this front to back. I applaud you for your efforts but were you lost me was when you had it running 10-teen;s and then trough 4 or 5 new parts on it and slowed down to 10.80’s or so. Then, instead of going BACK to your 10-teen structure, you threw MORE new parts at it! I lost count on the amount of changes post 10-teens. Not trying to be disrespectful, but you need more discipline and learn A-B-A testing. Baseline run, new part, back to baseline parts. The second A should run the same as the first A and if B picks up or slows down, you know B was the cause; not something else.
One thing I did not see was trying different heat range on spark plugs. I went through hell on my 390 AMC once as NOTHING I did would change the ET or MPH. Most suggested valve springs or fuel delivery were the culprit. Finally an old racer asked about the heat range and determined I was way to hot. Put colder plugs in and instant fix to everything and then I could adjust timing, jetting, etc., for best HP.
I understand limited funds and not visiting a dyno but you seem to have enough funds to afford $500-$1000 to get this car thoroughly dialed in at one day at a dyno. It is money well spent. Heck, instead of working on the car at the track, you may focus on winning and make $500-$1000!
I would NOT suggest changing ONE more part unless it’s A-B-A tested on a dyno. Personally, I would put a 3-speed in it with a 2.75 low gear to better launch with your (barely) adequate 4.10’s. Then I would make better use of your rear suspension and shocks (all 4).

[prairiehotrodder]

thanks for taking the time.
Those backwards results you mentioned were just traction related issues racing on "street legal" friday nights with no track prep. Here is the true results over about 7 years :

First motor - 500 cadillac went 12.1 at 110
second motor - 500 cadillac lasted 10 miles
third motor - 489 BBC went 10.87 at 125 and 9.84 at 134 with a running out of nitrous 200 shot. Motor lasted 4 years
current motor - 540 BBC started in the mid 10's with 3.50 gears and a turbo 350, now running 10 flat with 4.10 gears and a glide. 3 years in. Has ran 9.94 at 135.8 last season without a cage, has ran 9.992 this season legally.

To put this in a financial perspective since you mentioned that, I was a welder building hopper bottoms for 10 years making really good money. One day the shop burned to the ground. My employer decided not to rebuild and i was happy to be done. That was about the time that i just started building the 540. Now i have my own little speed / repair shop, raise one cow, 2 pigs and 11 turkeys, homeschool 3 children and enjoy racing my car. My life has never been better even making a fraction of the money. This is more info that you needed to hear but might be an encouragement to others. I appreciate all the help and advice i have gotten from great people on this forum
Brian