SBC timing

Message

Bowtiestang · #1 Post by **Bowtiestang** » Thu Jun 04, 2009 9:05 pm

Do you guys think 40 deg timing is to much for a 355 SBC. My car seems to run the best with 40. I dropped it to 36 lost .40 sec back up to 37 deg still .20 slower. I have never tried over 40 deg.

edit btw
13:1 comp
alum heads
cam= 631 lift 298int 306ex on a 106

jmarkaudio · #2 Post by **jmarkaudio** » Thu Jun 04, 2009 10:12 pm

My 427 with 11X heads runs best at 41˚. The 447 SB2 I put together last year ran best at 29˚. Sneak up 1/2˚ at a time and watch your plugs, you might still need a little more. Also, are you sure your balancer/pointer is correct?

Bowtiestang · #3 Post by **Bowtiestang** » Thu Jun 04, 2009 11:05 pm

jmarkaudio wrote:My 427 with 11X heads runs best at 41˚. The 447 SB2 I put together last year ran best at 29˚. Sneak up 1/2˚ at a time and watch your plugs, you might still need a little more. Also, are you sure your balancer/pointer is correct?

I will see how she runs friday... I have it back at 40 right now... think I will run it first there then bump it up a little.. I was mixing 110 race fuel and 91 pump 50-50. Now that it is 100 degrees out I think I should run all 110 fuel.. will report back

drummondracing · #4 Post by **drummondracing** » Fri Jun 05, 2009 6:13 am

I guess every motor is different my 355 runs best at 38*

Bowtiestang · #5 Post by **Bowtiestang** » Sat Jun 06, 2009 9:39 pm

40 deg put my et and mph right back where it was

Iguess she likes 40

Craig W. · #6 Post by **Craig W.** » Sun Jun 07, 2009 8:47 pm

Combustion chamber efficiency and octane are two big players in timing. Higher octane fuel burns slower, so you have to start the burn earlier. So if you go from a mixture of pump gas to straight 110, it'll want even more advance.

Domed pistons and poor chamber shape/size block flame travel and hurt mixture motion. This also will lead you to need a lot of timing.

I personally don't like mixing fuel. Its hard to get the same mix every time and your performance will vary.

40 degrees is not that uncommon for SBCs. Its on the high side, but if that's what it likes, that's what it likes.

dadnova · #7 Post by **dadnova** » Mon Aug 24, 2009 8:52 pm

Keep going up 2 degrees untill the MPH stops going up, then go back 2 degrees and lock it down.
Each and every engine is different, by doing this, its a safe way to go and let the engine tell you what IT want's.

My sons Nova stopped picking up MPH at 46 degrees, so now its set at 44 degrees and he has been running better then he ever has.

Simple but it works.

#8 Post by **John_Heard** » Tue Aug 25, 2009 5:36 am

Additional Note - Humidity will affect what timing it wants also, water vapor in the air will slow down the burn process.

fishman · #9 Post by **fishman** » Tue Aug 25, 2009 11:58 pm

I run my sbc at 41 degrees and the spark plug ground strap annnealing is in the middle went to 42 degrees and it went to the end of the ground strap so it is telling me that 41 degrees is right

SBC timing

SBC timing

Re: SBC timing

Re: SBC timing

Re: SBC timing

Re: SBC timing

Re: SBC timing

Re: SBC timing

Re: SBC timing

Re: SBC timing

Who is online