[evilbeef54]

I have a small block 350 4 bolt main, that we changed all the seals on and put a new Comp Cams cam and lifters. It also got a new cap, rotor, and wires. the old edelbrock preformer intake, Edelbrock 1406 600 4 barrel Carb went back on. The truck also is getting a whole new painless wiring harness

On first attempt to start up it didnt want to fire i removed the distributor and made sure it was inserted correctly with the #1 cylinder at TDC rotor pointing at the #1 cylinder, #1 wire on that post and double checked the wires were on in the right order. After that it fired right up, tried bringing up the rpm to 2k for the break in and i am getting some LOUD backfiring through the carb at about 2K rpm. I shut it down and reset the idle mixture screws to 1.5 turns out each and made sure the air filter was on tight. It started happier but still backfires through the carb at 2k rpm. Also after turning off the key one time it kept running, for a few seconds.

I would like to get some suggestions from you guys on what else to check/inspect/additional info you need. This is my first cam swap and want to get this thing broken in correctly. I'm not trying to tune for performance or anything right now, just want to be able to have it running at 2k rpm so i can break in the new cam

[mustang 671]

your timing has to be out . have you got the vacum hose onto the dizzy. have you timed it up with a light ? plugs ok ? no air leaks ? cheque with some carb cleaner when running. the engine will pick up quickly if there is a air gap and it will get sucked in and you will hear a different engine pitch sound for a secound or to.

bet its timed up wrong , all plug leads corrcetly fitted and to correct numbered plugs ?

i would start again with the timing light and double check everything before you start it again

[techinspector1]

Valve adjustment too tight. Use the "jiggle up and down" method instead of the "twist the pushrod" method.
http://www.crankshaftcoalition.com/w...stment_SBC/BBC

[evilbeef54]

Originally Posted by mustang 671

your timing has to be out . have you got the vacum hose onto the dizzy. have you timed it up with a light ? plugs ok ? no air leaks ? cheque with some carb cleaner when running. the engine will pick up quickly if there is a air gap and it will get sucked in and you will hear a different engine pitch sound for a secound or to.

bet its timed up wrong , all plug leads corrcetly fitted and to correct numbered plugs ?

i would start again with the timing light and double check everything before you start it again

I have triple checked the wires are all correct, brand new plugs, the timing should be at about 10* at idle with the vac advance line removed from the carb and plugged correct?

i will check for leaks

Originally Posted by techinspector1

Valve adjustment too tight. Use the "jiggle up and down" method instead of the "twist the pushrod" method.
http://www.crankshaftcoalition.com/w...stment_SBC/BBC

i will double check the valves before i start it up, thanks

[stea]

As Tech said jiggle the push rods for setup. I then always readjust while running at a low idle. Can make a mess but i always feel better about the adjustment when im done. I also dont do it enough to have the "feel" for it.

[evilbeef54]

Originally Posted by stea

As Tech said jiggle the push rods for setup. I then always readjust while running at a low idle. Can make a mess but i always feel better about the adjustment when im done. I also dont do it enough to have the "feel" for it.

ok, i used this method when i first set the valves

How to adjust valves on a chevy small block engine

i will try the other method, seems like the other method techinspector1 listed would have them set quite a bit looser which hopefully will help, i just brought the engine back around to line up with the timing mark on 10* before TDC and made sure the rotor is pointing at the #1 cylinder and the #1 plug wire on the cap and the wire order is correct on the cap... That should be a good starting point right?

with having to break in the new cam i dont want to sit at idle too long trying to set timing and adjust valves, is that correct, i pretty much need to fire it and get it up to 2000-2500 rpm right away?

[stea]

Didnt see that you put in new cam. Do Techs method then do break in. After break in if your worried they are not set right (like i always am). Then adjust while running.

[evilbeef54]

ok

I will be checking the valves in the AM


If the ignition is ok, and it turns out that the valves are alright the other thought i had was i moved the gas tank to the bed of the truck and the old hardline was pretty nasty i ran rubber line all the way forward temporarily, maybe it is not flowing enough at 2k and that is causing the backfires through the carb? I dunno I am just trying to figure out everything i need to double check before i start it up again

[66GMC]

Originally Posted by evilbeef54

ok, i used this method when i first set the valves

How to adjust valves on a chevy small block engine

i will try the other method, seems like the other method techinspector1 listed would have them set quite a bit looser which hopefully will help, i just brought the engine back around to line up with the timing mark on 10* before TDC and made sure the rotor is pointing at the #1 cylinder and the #1 plug wire on the cap and the wire order is correct on the cap... That should be a good starting point right?

with having to break in the new cam i dont want to sit at idle too long trying to set timing and adjust valves, is that correct, i pretty much need to fire it and get it up to 2000-2500 rpm right away?

I was going to give my $0.02 worth earlier, but IMO ... leave the timing light in your toolbox until after the break-in.

Just "static-time it" (I'd go at 8°) as you have described above. Turn the key on to the "run" position, stick a spark plug in lead #1 and ground it where you can see it. Rotate the distributor until the plug snaps, and tighten the dist clamp to the point where you can still adjust the dizzy with the engine running.

Well OK ... I suppose that you could use your timing light instead of the grounded spark plug.

Anyway, yes, you want to get that engine fired up on the first cranking attempt and get it up into that "splash oiling" RPM range and keep it there. You can always fiddle with the distributor if the engine is obviously laboring or getting too warm.

You'll want to vary that engine RPM occasionally to ensure that oil is getting splashed in all directions.

Good Luck. I can tell you first-hand that wiping out a cam during break-in is no fun at all.

[cobalt327]

Originally Posted by evilbeef54

ok

I will be checking the valves in the AM


If the ignition is ok, and it turns out that the valves are alright the other thought i had was i moved the gas tank to the bed of the truck and the old hardline was pretty nasty i ran rubber line all the way forward temporarily, maybe it is not flowing enough at 2k and that is causing the backfires through the carb? I dunno I am just trying to figure out everything i need to double check before i start it up again

If the mechanical advance springs are (God forbid) stock, or still aftermarket ones, 10 degrees initial is not going to be anywhere near enough timing.

If you don't have a dial back timing light, make a timing tape and use a timing light to see what the timing is at 2000 rpm. If it's not high enough, give it some more timing. I'd use at least 36 degrees w/the engine running at 2000 rpm.

Once the cam is broken in, set up the advance curve.

[evilbeef54]

Originally Posted by 66GMC

I was going to give my $0.02 worth earlier, but IMO ... leave the timing light in your toolbox until after the break-in.

Just "static-time it" (I'd go at 8°) as you have described above. Turn the key on to the "run" position, stick a spark plug in lead #1 and ground it where you can see it. Rotate the distributor until the plug snaps, and tighten the dist clamp to the point where you can still adjust the dizzy with the engine running.

Well OK ... I suppose that you could use your timing light instead of the grounded spark plug.

Anyway, yes, you want to get that engine fired up on the first cranking attempt and get it up into that "splash oiling" RPM range and keep it there. You can always fiddle with the distributor if the engine is obviously laboring or getting too warm.

You'll want to vary that engine RPM occasionally to ensure that oil is getting splashed in all directions.

Good Luck. I can tell you first-hand that wiping out a cam during break-in is no fun at all.

I have it static timed at 8* now thanks for the tip

Originally Posted by cobalt327

If the mechanical advance springs are (God forbid) stock, or still aftermarket ones, 10 degrees initial is not going to be anywhere near enough timing.

If you don't have a dial back timing light, make a timing tape and use a timing light to see what the timing is at 2000 rpm. If it's not high enough, give it some more timing. I'd use at least 36 degrees w/the engine running at 2000 rpm.

Once the cam is broken in, set up the advance curve.

I do have a dial back timing light and after i do the valves and try to fire it up again in the AM i will see what it is at at 2k if i can get it to run at 2k with out sounding like there is a shoot out in my garage.


Im not looking for performance right now just what ever it takes to get it running at 2k-2500 to break in the cam, once it is broken in i will be trying to get it running perfect

[evilbeef54]

ok so I checked all the valves, they were all pretty close, maybe 1/4 turn looser now, hopefully that will be the difference, still planning on getting the fuel pressure gauge before start up tomorrow so i can rule out the fuel line, also i have seen that i may need a seal plate for this carb with this intake and they are cheap so i may pick that up too... hopefully start up goes well in the morning I will report back in the afternoon, thanks for everyone's help and if anyone has any other thoughts i would love to hear it

[66GMC]

Just one or two.

If this is a flat-tappet cam, make sure that your engine is well-primed (i.e. oil coming from all rocker arms), and that you have added some ZDDP additive.
If you're running dual springs on your valves, you should remove the inner springs to reduce the spring seat pressure. (You won't need them at this comparatively low RPM range.)

[evilbeef54]

Originally Posted by 66GMC

Just one or two.

If this is a flat-tappet cam, make sure that your engine is well-primed (i.e. oil coming from all rocker arms), and that you have added some ZDDP additive.
If you're running dual springs on your valves, you should remove the inner springs to reduce the spring seat pressure. (You won't need them at this comparatively low RPM range.)

okay thanks I did use the break in additive. At this point since it already ran shouldn't it already be primed? Also i am not using dual springs

[tjet]

When you installed the cam, you lined up the 2 small dots on the timing gears - which is correct per the instructions.

If you installed the distributor after that, it will be off 180 deg.