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just bought a 86 camaro swapped tpi 305 for a carb 350, guy had it running so he says, had a cam swap it ran then shut off, cranks very very slow, so new battery was put in. i pulled the distributor put it on #1 tdc put it back in, still cranks slow pulled all plugs still slow, so app its something in the motor. any ideas on what it could be? bad bearing, cam, both who knows any info guys thanks!
You're on the right track... with no plugs in it, it isn't a question of compression. I'm thinking a bearing on the crank... can you drop the pan easily?
im not to sure, ill put the car up on some ramps today and get under there see if i cant get that pan off easily or if ill have to jack up the motor, are crank bearings hard to install? i know im not to sure on how to do cam bearings either. thanks for the help!
If you have bad crank bearings the crank will have to be pulled and checked. Depending on what you find by pulling the pan you may be looking at pulling the engine. Good luck
Before you tear in to the engine you might want to check all the grounds.
Ground was my first thought
heres the ground situation, guy has ground coming from battery to alternator bolt, the from battery to strut mount, (was thinking of moving this to the fender). Then he doesn't have one from the block to the firewall, that i can see and i looked pretty hard. Or from the intake to the firewall i should say. should i move the one from the strut mount to the fender? and then add one from the intake to the firewall?
Welcome to CHR!Quote:
Originally Posted by camaro8484
The main ground from the battery needs to be to a clean bolt on the block, not on the alternator and close to the starter is best. One of the starter bolts is an ideal place for it. The ground to the strut mount is to give things in the cabin a good ground, as would a strap from the firewall to the block.
Have somebody with an avr and check starter draw or put a tq wrench on the font of crank before you start tearing this thing apart....ted
Both the positive and negative battery cables need to be at least 6 gauge, preferably 4 gauge or larger, especially the positive since it has a longer run.
On the front of the block there are bosses drilled and tapped and the bottom one is a good place to hook up the ground. Clean it to bare metal and use a good washer and lock washer. The block needs to be grounded to the frame and yes the block should be grounded to the firewall.
while you still have the plugs out, check to see how much torque it takes to turn engine over from the from crank bolt
then check starter draw with a guage and/or the cranking volage drop
while cranking the motor use a timing lite to see where #1 is firing
one your past these three items reinstall plugs
The very best way to test the ground or positive circuits is a voltage drop test.
Set your multimeter to 12 volts DC. Connect one lead to your neg. battery post (not the battery cable terminal) connect the other end to a clean bolt or such on the engine block. Now have someone try to start the car while you watch the meter. Any reading of less than 10 percent of 12 volts or 1.2 volts is acceptable and tells you the tested circuit is good. This test works the same for the positive side also. So if your ground side tests good do the same test from positive battery post to starter lug. Just remember to hook your meter to the battery post and the starter cable bolt, not the battery terminal or terminal that hooks to starter and the circuit must be energized.
so pulled timing cover marks were way off, got it right. pulled plugs cranked strong. put plugs back in was still cranking good, checked distributor was still on pointing to #1 at tdc put wires on checked twice cranked slow and back fired through the exhaust. i mean louder then i ever heard? still timing or valves to tight?
Did you replace the timing chain, if not you'll have the problem again? Timing is still off.
timing chain was like new, i don't think the car ever ran after the kid had the cam put in even though he said it did. it didn't have much slop in it at all.
ill have to re check wires and distributor position again tomorrow
When you checked the distributor rotor "...still pointing at #1" did you pull your #1 plug and move it to TDC with your finger or thumb blocking the plug hole to verify you were on the compression stroke? It sounds to me like you may have the distributor in 180 out of phase, pointing at #1 when the piston is at TDC of the exhaust stroke.
was by myself but what i did was put a piece of paper towel in the hole, bumped it over when it blew the paper towel out of the hole assumed that was compression stroke?
:) I can see myself doing that, and in theory it should be OK but the problem is if you're using the key to bump it's hard to know for sure working alone, watching for the flying plug of paper. You really need to pull all of the plugs and put a breaker bar & socket on the dampner bolt so you can slowly bring the engine around to align the marks at TDC compression for #1. If you're in a hurry get a remote starter swicth and bump the engine until you get #1 compression on a thumb or finger, and then use the bar to align the marks exactly.Quote:
Originally Posted by camaro8484
Another possibility is that your harmonic dampner may have de-laminated, allowing the outer ring to shift relative to the keyed center ring that's tied to the crank. If it's still backfiring after you ensure the distributor is stabbed right you might want to verify your timing mark alignment. One way to do that is in this thread - http://www.clubhotrod.com/shop-talk/...nding-tdc.html Read the lead method, and then also read the one that Tech linked from the Crankshaft Coalition.
Let is know what you find.
im gunna get over there and im gunna put it up on tdc #1 again and check to make sure it was on compression ill pull the valve cover and watch the intake valve, and ill get this figured out. i was afraid it was a crank bearing or something downstairs. but with it cranking pretty good with the plugs out and backfiring last night kinda relieved the thought of it being bearings. thanks for the info!
It's also easier to stab the distributor if you align the oil pump with a large screwdriver.
Well here's what happened today pulled balancer again pulled chain cover put it on tdc 1 still lined up with the dots at 12 both of em so I redid the distributor. Pulled plugs out she cranked good put plugs in wirednip the wires and bam slow cranking no matter what way you turn the distributor. No idea kinda pissin me off thinking of just selling the dang car
Back to basics, have you gone back and re-checked your plug wiring per the firing order and clockwise distributor rotation? It's easy to be off one space, or for someone to wire it backwards...
I got the wires clockwise / cclockwise. Backwards once, thought I was going to wear out the starter figuring it out. Now, if I have any question, I'll watch the dizzy rotor while I bump the motor, and I know for sure the rotation.
I just saw something....
You say both cam gears have their " dots at 12 "
Someone chime in on this one, but as my feeble brain is telling me that Chevy says the dots point to each other- cam at 6, crank at 12
Times 2... SBC I think is like you say crank at 12 and cam at 6, put the dots together.Quote:
Originally Posted by firebird77clone
Here is how you want your timing marks
http://ww2.justanswer.com/uploads/Vi...3432_marks.jpg
Charlie & I were typing at the same time. The instructions I've seen for a Gen 1 SBC are install dot to dot to be sure of alignment, which puts #1 at TDC exhaust stroke, and #6 at TDC compression. When you're ready to drop the distributor in place rotate the crank 360 degrees, putting the crank dot back at 12, but the cam dot now at 6 (TYPO - SHOULD BE BOTH AT 12 - See below). #1 is now at TDC compression stroke. Use a big screw driver to set the oil pump slot just a bit early on rotation, and drop in the distributor ending with it pointing at #1 on the cap/body. Correct me if I'm wrong.Quote:
Originally Posted by 34_40
Ok, Roger . . . you asked for it. :) You were right except that the cam dot would now be at 12. Foolproof: Install dot-to-dot, and #6 will be at TDC on the compression stroke and #1 will be at TDC on the exhaust stroke. Rotate the crank one turn, both dots will be at 12:00 and cyl. #1 will be at TDC on the compression stroke. Put your thumb over the #1 spark plug hole to verify that it's coming up on compression.
Ooops! :o:o:o You got me, Jack!! I was 'thinking' 12 and typed 6 :(:( I guess I'm just a dumb ass after all.... :LOL::LOL::LOL:Quote:
Originally Posted by Henry Rifle
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.
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?Quote:
Originally Posted by 36 sedan
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.Quote:
Originally Posted by Henry Rifle
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
All the way around, every cylinder.....35-40? :eek: Has it got rings, head gaskets ?Quote:
Originally Posted by camaro8484
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