T and D rockers coming loose?

You want to run a conventional head bbc at 22 degrees timing??!!!?? Won’t fall out of a tree.

 

Only time I’ve ever seen an engine detonate from being over rich is in a nitrous engine, and I have my own theories on why that occurs. I’ve never been able to play with a particular combo long to try it both ways timing and fuel vs bo timing and no fuel. Some people say less timing, less fuel and it will go quicker because it is more efficient. I’ve always liked timing, it seems to make the engine real responsive and the way I look at it, the fuel carries the BTU content. There are also those out there that believe you have to get the engine all hot and bothered through the middle, on the ragged edge of nuclear melt down and then throw a bunch of fuel at it that it normally wouldn’t burn.

 

To each their own. Of course it won’t get out of its own way if it’s dead fat (which it sounds like OP’s car is) which is why I said lean it out. You probably don’t think a hemi should be fast with 24* in it either then huh?

 

I’ve played with it both ways on blown alcohol hemi. And lean with lest timing is faster every time in my experience at the pro mod level.

 

I have no clue about a hemi. I do think I have been faster on a 110 pump than most. If you have real data on a conventional bbc (115-125cc) I’m all ears, but I’m going to be really surprised if you do.

 

I’ve tested it on a conventional 540 but only on gas as far as conventional heads go. Spread port stuff I tested it on alcohol. I have yet to find an application lean and less timing makes less power.

If you think about what timing actually is, having more timing in an engine isn’t necessarily a good thing. Creates more pumping losses than less timing. Not to mention I don’t think anybody has ever burnt anything up from having too little timing in it. Keeps your oil less contaminated, bearings are happier all around better option.

I’m ok with you not believing me, if you’ve had good luck doing what you’ve been doing then more power to you. But don’t be so afraid to try something. More than one way to skin a cat.

 

20-22 degrees on a blown alcohol spreadport Chevy is pretty standard. Just like on nitrous, a conventional bbc head wants between 6 and 10 degrees more than a spreadport.

 

I send my rockers back to T&D every year for a check. Usually about a 1/4 have out of tolerance bodies, bad bearings and sometimes an occasional adjuster. Part of running it. If you can, stay away from the 3/8" adjusters as the bigger ones are better and don't break as easily. BBC conventional, pretty close to yours with cam, rockers are 1.75. Run 35 degrees timing as it's always fastest at that number and that also puts the burn on the strap at that right spot. Usually pull some timing if the tires get into a overspeed condition but it's normally all in at about 1.5-1.7 seconds into the run. Titanium valves and 450 on the seat. Run it to around 8600 and somewhat fat burning around 1/4 to a half of the cad. No bearing issues ever, doesn't flood the oil and it has 117cc chambers, 10-1 compression with a C rotor at 115% over.

 

Read ground strap heat band for timing, base for fuel.

 

I think from everything I’ve always heard that a conventional headed bbc because of the large combustion chamber they require typically a lot more timing than a spread port head or a hemi such as a BAE and in fact a lot of the old timers such as bob bunker senior have claimed that the conv. Headed bbcs really come alive with 34-35 deg.of timing I just haven’t had the need to experiment at that level yet!

 

Pictures to prove it? I’ve seen a lot of plugs, never saw a ground strap on blown alcohol that actually responded to timing changes. The whole plug will respond, but the strap and the base don’t move independent of each other so you can’t tell the difference between fuel and timing.

 

Blownalky what bore and stroke is your bbc? And you say your cam specs are close to what I’m currently running? 280/290 @.050 with a 114lsa? 800 lift? And how much boost does that C rotor make @115% OD? Appreciate you sharing the info! Thanks!

 

Sure, the base and the strap move together. The strap would have to move independent of the base to say that the strap shows timing. It doesn’t. It’s just showing temperature which will move with either fuel or spark.

I will say, though, that I have never seen standard NGK show a blue line in the hundreds of sets of plugs I’ve looked at. Ngk has a very distinct color change pattern that you have to know from experience. I’ve moved them all the way from cold to eroding the end of the strap off on both nitrous and blown ally and never seen any blue. Autolites will turn blue but I would never tune off an Autolite. I don’t know 6061s so maybe that’s what you’re referring to?

 

It's a 4.446 bore and 4.25 stroke for a 533. I use 1.75 rockers and the cam specs out at .840 In and .813 Ex with 292 In and 296 Ex @ 115 LSA with a 4/7 swap. Boost with an Indy intake modified for a screw is around 52Lbs @118 degrees manifold temp at the end of a run.

 

Thanks blown alky for your response and sharing the information !

 

Blownalky I also am very curious as to what size fuel pump and how much fuel you are actually putting thru your motor at those boost levels???

 

I also don’t remember if you stated what cylinder head you are running ???