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Old 02-18-2006, 10:20 AM
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timing problem? 350 chevy

I probably don't have enough info here but here goes. I have a 350 .020 over flat top 4 valve relief pistons, stock 350 crank, 441 heads from a 400, older dual plane edelbrock (old enough to have the oil spout hole in the front), stock points distributor, camshaft is a 270 comp magnum cam. The motor runs great, no knock, no pings, it is in a 67 camaro with a m20 wide ratio 3:08 gears. It will run 10 flat in the 1/8th mile, (w/no traction bars, fair amount of wheel hop). The problem is I can't advance the timing far enough to get it to knock or start hard or anything. According to the timing light it is advanced off the timing marks on the stock 350 balancer. The vacuum advance can is up against the intake so I can't go any further. The motor runs nice, starts nice, power is ok, but with flat tops it seems like I should not be able to run this much timing w/o some knocking and pinging. It doesn't seem to matter what octane I run 88 or 91. I think I can get away with 85. Our elevation is 3500+. It doesn't burn any oil, it does'nt smoke. A freind put this cam in for me, could they have screwed up when they put it in? I would like to get this combination into the low 9's (1/8th) w/ this gear ratio if possible. I am running 255/60 bfg street t/a's. The rear suspension is stock except for the multi leafs from a 74 Nova.

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Old 02-18-2006, 12:08 PM
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Quote:
Originally Posted by 95th67cam
I probably don't have enough info here but here goes. I have a 350 .020 over flat top 4 valve relief pistons, stock 350 crank, 441 heads from a 400, older dual plane edelbrock (old enough to have the oil spout hole in the front), stock points distributor, camshaft is a 270 comp magnum cam. The motor runs great, no knock, no pings, it is in a 67 camaro with a m20 wide ratio 3:08 gears. It will run 10 flat in the 1/8th mile, (w/no traction bars, fair amount of wheel hop). The problem is I can't advance the timing far enough to get it to knock or start hard or anything. According to the timing light it is advanced off the timing marks on the stock 350 balancer. The vacuum advance can is up against the intake so I can't go any further. The motor runs nice, starts nice, power is ok, but with flat tops it seems like I should not be able to run this much timing w/o some knocking and pinging. It doesn't seem to matter what octane I run 88 or 91. I think I can get away with 85. Our elevation is 3500+. It doesn't burn any oil, it does'nt smoke. A freind put this cam in for me, could they have screwed up when they put it in? I would like to get this combination into the low 9's (1/8th) w/ this gear ratio if possible. I am running 255/60 bfg street t/a's. The rear suspension is stock except for the multi leafs from a 74 Nova.

Are you sure you got the correct harmonic balancer and timing tab that corresponds to it. They all are not the same.
You may have to pull dist. and advance it one tooth if it is hitting the intake.
What is the initial timing (vac advance unhooked and engine at idle)??
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Old 02-18-2006, 03:44 PM
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It sounds like your unsure of your spark timing, I would order Proforms balancer cover and install a chrome timing tab, then you`ll know where your timing is. Next I would at least install a pertronix conversion unit, points belong in the trash. You can run high timing because the engine doesn`t have much compression. If you used the common "rebuilder" flat tops, they have a 1.540 compression height instead of a stock 1.560 height, the piston will be .045 in the hole, add in the standard fel pro or almost any regular replacement gasket of .041, plus the overbore and the 76cc chambers on the 441 heads you have about 8:1 compression, possibly lower. To be honest, you really don`t have enough compression for the cam you have, if the pistons are true height of 1.560 then the ratio would still be on the low side, but not too low to run okay. What Edelbrock intake is it? what carb are you using? to get it into the low 9`s you need more compression and lower rear gears. Does the car have headers? if it don`t by all means add some.
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Old 02-19-2006, 11:48 AM
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Yes, pretty much stock replacement type pistons so this is very likey just a low compression motor. What is the thinnest gasket I can use, or do I have tear it down first. I hate to get into the shortblock as it has maybe 5000 miles on it and its balanced and bored with a torque plate. It seems that I can run any junk gas that's out there. I have wondered if the cam was a little much for my compression. (it sounds nice though) I will do a compression check when it gets warmer. I need to get some base lines and change some things. It's about -6 in the garage right now so I am waiting for warmer weather. I don't know what exact model the intake is other than it looks like a performer but it's old enough to have the oil filler spout in the front. I'm running a box stock 600 vacuum secondary holley. The only change is I have the lightest secondary spring in it. I have not touch the jets. (mileage stinks to). Distributor is box stock and old.
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Old 02-19-2006, 11:55 AM
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yes it has headers

yes, it has headers. I put this together probably 15 years ago so I can't remember where the balancer came from. I pretty sure it was from a 350. Which way would I move the rotor, clockwise or counter clockwise, if I want to advance it.
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Old 02-19-2006, 05:16 PM
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You want the rotor to move away from the intake manifold.

IMO you have a mis-matched combination. You should consider making some changes within your budget. Let us know how much $ you can spend.

Upping compression and a better cam should be tops on the list....
or you could just go to a 100+ nitrous hit. That should get you 9 flat.

With those large tires you will need at least 3.5-3.8 posi gear with the M20. You now have 25 % less torque than with 4.11 gears. (3.08 / 4.11= .75)

With that combination your gas mileage will be fair to poor even with the best tune up. If you get 13 highway now you are doing well.

NO matter what, you definitely have to make some rear suspension changes such as PROPER slapper bars with urethane bushings at a minimum, or even lift bars and defintiely urethane spring eye bushings. (most Camaros have poor too short slapper bars) Be sure to eliminate any rubber leaf spring isolators there might be between the spring and the axle pad. You will need stiffer rear shocks to slow body rise, and definitely work on the front suspension also. You must tune the frog-hop out of it.

BFG streets T/A tires (S rated) are minimal traction performers, especially after they get a year or two old and the rubber gets significantly harder. You will need fresh drag radials or sticky Mickey's, and VHT. Invest in a duromater.

"People worry too much about horsepower and not enough about getting down the track." Evan J. Smith, MM&FF magazine

Last edited by xntrik; 02-19-2006 at 05:23 PM.
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