Thread: 350 sbc wont start

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compression 35-40lbs in each cylinder! i have never seen one so low! believe i found my culprit of why she won't fire

Won't explain the back firing or hard start. Check your cam timing again and be sure your valves are adjusted correctly, with the correct push rods and rockers arms. After re-aligning your cam timing, check the valves on #1 cylinder to make sure they are both closed in the compression stroke. If the valves are not closed, check your crank key and cam pin to make sure they are not sheered and giving a false alignment.
And beware, if the cam timing was off, you could have bent valves and/or damaged pistons.

Originally Posted by 36 sedan

Won't explain the back firing or hard start. Check your cam timing again and be sure your valves are adjusted correctly, with the correct push rods and rockers arms. After re-aligning your cam timing, check the valves on #1 cylinder to make sure they are both closed in the compression stroke. If the valves are not closed, check your crank key and cam pin to make sure they are not sheered and giving a false alignment.
And beware, if the cam timing was off, you could have bent valves and/or damaged pistons.

I agree. With fuel, spark and correct timing, the engine will run with little compression. It just won't make power. It would help if you would tell us how your crank and cam gear aligned because there was some erroneous information posted above. With #1 cylinder at top of the compression stroke (as verified by your finger over #1 spark plug hole), were both of your timing marks at 12:00?

Originally Posted by Henry Rifle

I agree. With fuel, spark and correct timing, the engine will run with little compression. It just won't make power. It would help if you would tell us how your crank and cam gear aligned because there was some erroneous information posted above. With #1 cylinder at top of the compression stroke (as verified by your finger over #1 spark plug hole), were both of your timing marks at 12:00?

This is correct above ^^, with the 6 & 12 position of the timing marks, #1 & #6 are at TDC, however #1 is on the exhaust stroke and #6 is on the power stroke. If set up on #1 using the dots you'er 180 out.

The purpose of the 6 & 12 alignment (dots) is to make sure the cam, crank and chain are not one tooth off. Rotate the crank one turn, marks now 12 & 12, Set balancer to 10-20 degrees before TDC and stick distributor in on #1. Start the car. Timing should be close.

backfiring was due to two wires being crossed. the hard start is gone, now that the cam gear and crank gear are correct, yes on tic #1 they are at 12:00. has fuel has good spark, easily 1/4-1/2 arc onto metal. now im not 100% positive or anything, but with it only having such little compression would it not be hard for the compression to pull enough fuel down into the cylinders to fire it over?. i mean im sure if it was 80-90 lbs it would fire up and not make alot of power, but the compression being the whole way as low as 35-40 lbs?.

Adjust your valves, then measure the compression again. If it's still low you may have bent some valves when the cam to crank alignment was off. If you're not sure about adjusting the valves, read here - http://www.crankshaftcoalition.com/w...stment_SBC/BBC

Originally Posted by camaro8484

backfiring was due to two wires being crossed. the hard start is gone, now that the cam gear and crank gear are correct, yes on tic #1 they are at 12:00. has fuel has good spark, easily 1/4-1/2 arc onto metal. now im not 100% positive or anything, but with it only having such little compression would it not be hard for the compression to pull enough fuel down into the cylinders to fire it over?. i mean im sure if it was 80-90 lbs it would fire up and not make alot of power, but the compression being the whole way as low as 35-40 lbs?.

All the way around, every cylinder.....35-40? Has it got rings, head gaskets ?

cyl #3 has no compression dry and wet test, the rest of them were around 34-40 wet test jumped it up to 65-70, pulled intake and heads. number 3 cylinder has a chunk of the piston around the edge gone, im sure the rings are fried in the other cylinders. motor is out of car and time for 383 stroker build