# Slight pinging or detonation?



## KowalskiCW (Jul 11, 2016)

So I've had this car(69 350 4barrel with big cam-PO installed-and rpm performer intake and edelbrock carb) for a couple months now and I notice a slight pinging or valve noise when under load. I've been running 91 octane and even octane boost to no real avail. What year were hardened valve seats normal? How do I know if mine has been done or not? I took it to a shop and the guy tinkered a little and tuned the carb and said it was running great at 30 degrees of timing. I've been in contact with a engine timing guy and he said that motor should be running 34-36 degrees but if its already pinging that would just make it worse right? Where do I start before this engine goes to s**t?


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## PontiacJim (Dec 29, 2012)

Read this: http://www.gtoforum.com/f170/1967-gto-engne-pinging-109585/

Do a search and you will find other threads that will also give you some ideas on Total Advance, Advance Curves, and selecting your advance springs. :thumbsup:


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## Pinion head (Jan 3, 2015)

Most likely a poor cam selection providing extra cyl pressure & thus detonation. Def sounds like a mismatch of parts. Want to run it as is, back out the timing a few degrees or run higher octane gasoline. GM really didn't get their induction hardening process down on the unleaded fuel engines till '74. Even then, take a set of late 4X heads, or 5C's, or 6X's, open the the exhaust seats up for 1.77's and the induction hardened area is gone. Not a big deal unless running quite a bit of valve spring pressure, then it would be a good idea to at least mix leaded race fuel to acquire some imbedded lead in the ex seats.


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## KowalskiCW (Jul 11, 2016)

PH-yea the cam selection is crap. I have no dang power til 2800 rpm. I don't know what the guy was thinking. I'll try backing off the timing when I get a chance. I tried some Napa octane booster but it barely helped. I'll fill with 92(best I can find around me) and maybe order some real octane booster that I read in the post from PJ above.
PJ-those posts were super in depth and I'm pretty savvy but I'm not that smart when it comes to all this. I know enough to fix most things but timing and carbs are still muddy for me. Now's time to really learn I guess. I'll keep reading and see what I come across.

So overall a new cam and getting a full tune would be a smarter route correct? This motor has about 115k on the lower but the upper from what I know was regasketed because of a blown head gasket at one point then the guy did the cam and lifters and intake and carb at that time.


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## Goat Roper (Oct 28, 2014)

I am still messing with my timing, I ordered the Mr. Gasket kit that came with dist springs and weights.
There are 3 different springs in the kit, black, silver and gold but it comes with no info at all on what the spring weights are.
All I can find on the net are conflicting posts, one say the black are the stiffest while another post claims the gold are the stiffest.
I guess the only way to find out is to rig up a small sandbag and use it to determine what is what.
The kit is basically useless since they provide no info on it.
:/

Any of you gurus on the group some enlightenment would be appreciated, engine is a 400 with a 2.93 rear end, what should it advance at what RPM for tall gears.


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## chuckha62 (Apr 5, 2010)

You're looking for 34-36 degrees and you want it all in @3000 RPMs. IIRC, the gold springs are the lightest ones. 

Remember at part throttle, you may see anywhere from 48-50 degrees. This is absolutely normal.


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## bigD (Jul 21, 2016)

"...I tried some Napa octane booster but it barely helped. I'll fill with 92(best I can find around me) and maybe order some real octane booster that I read in the post from PJ above..."


Torco Accelerator will work. Can order from Amazon or Ebay.

Torco unleaded accelerator, it is not just another octane booster

https://www.amazon.com/Torco-Accelerator-32oz-Best-Additive/dp/B004ZO3VN0

http://www.ebay.com/itm/The-Best-Fu...1815ab6&pid=100005&rk=1&rkt=6&sd=190494481830

http://www.ebay.com/itm/TORCO-UL-AC...1815ab6&pid=100005&rk=2&rkt=6&sd=190494481830

http://www.ebay.com/itm/The-Best-Fu...0d35e3f&pid=100005&rk=3&rkt=6&sd=221430344251


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## KowalskiCW (Jul 11, 2016)

So I found some 93 octane! I also dumped a small bottle of STP octane booster and I ran for 3hrs with no pinging. I guess for now I'll just make sure I find the highest octane I can until I can take a little timing out or until I rebuild the whole engine as its on my future plans. I ordered some of that Torco Octane booster to keep in the car incase I find myself not near 92 or higher octane so thanks bigD.


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