What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

350 Hei Timing Question

U

UD0MEILLD0U

Registered Member
Joined
Oct 12, 2005
Posts
37
Reaction score
1
Location
Gainesville FLORIDA
Hello all,
I have a k5 with a stock 350 except for headers and a edelbrock performer intake and carb. I was told base timing without vac advance is ten degrees. I am getting hella valve clatter from like 4 degrees to maximum advance. I have friends telling me at 4 degrees it must still be too far advanced.. isnt that impossible? Please please help lol this clatter is killing my engine.
 
If your getting valve clatter than you should try adjusting the valves. as far as i know the ignition timing doesn't have anything to do with noisy valves but then again i don't know much either
 
The timing should be listed on the emissions label under the hood. If I remember correctly stock timeing is like 8 degrees. Yeah if your getting a clacking noise I cant see timing doing that. You should check the adjustment on all the rocker arms.
 
I always run my Chevy's with carb and HEI at 4 BTDC to start. No issues. May be a little low for timing, but I would start there and then go up. If it's truely pinging at 4, you've got something else wrong.
 
Hmmm

Well I found out that I had a bad mechanical advance on my distributor so i got a new 1. It wasnt till after I put the new 1 in and set the timing to 10 degrees btdc without vac advance that it started clattering. I am running it a 4 degrees btdc now and it seems the further down I go in timing the less it clatters... Lol. I am at a loss... So adjust the rockers huh... I just dont see why I never had any noise until I got the new distributor. I was told that too far advanced can cause ping/clatter but yall are sayin not really. I am just terrified about hurting my engine! Oops.. The engine is a 1 year old GM crate engine btw. Reason for the Hei was I got rid of all the computer controlled crap n went back to the basics! =)
 
check valves (just takes a minute). I had similar problem and turned out I had dizzy off by 1 tooth when I reinstalled it. :o
 
Ok gonna check the valves now. Was also told to put a new set of springs and weights on the distributor. I was told that can cause it also. Dunno lol but I'm tired of my 350 soundin like a powerstroke!! =)
 
Ok so I changed the springs and weights....no difference. Moved the distributor counterclockwise 1 tooth....no difference. I am gonna hafta assume that the rockers need adjusting. That really baffels me seeing as how b-4 the new distributor I had no problems but as soon as the new 1 went on I now have the clacking! On the old distributor the mechanical advance as well as the vac advance were both shot (no advance at all) so I am leaning towards this being the reason there was no clacking. So... I know of 2 ways to set the rockers. 1) running and adjusting by ear. 2) turning the crank by hand and adjusting the rockers to snug while on a flat spot on the cam. Are these ways right? which is better? I did the rockers in my 4.3 lil blazer using the flat spot method and all seems well on it. Are there torque specs on the rockers? I would assume there are...Everything in these motors has a torque spec =). Thanks for the responces and help, yall are the chiltons of forums =).
 
Timing that is too far advanced will cause predetonation (sp?). You shouldn't be getting predetonation at the settings you listed. If there wasn't a problem before the distributor work, then you should be able to narrow it down to something you just repaired.

I'd look at the firing order, check the wires for cross-induction, check the distributor cap for carbon tracks/cracks, etc. Also, and don't take this the wrong way, what cylinder are you hooking the light on? :D Should be the front/left cylinder as viewed from the driver's seat.

Where are you located in Florida? If it's close by, I might be able to lend a hand. I just picked up a Bear/Pace 400 and it's pretty slick for locating some of these problems.
 
last time mine ran like crap and had a chatter going on i did valve adj and noticed that 4-5 valves were only getting about 1/4 lift after being tightened down, so pulled out a completely wasted cam and lifters and replaced. :D
 
I am in gainesville. the distributor is clean of carbon marks. The rotor button shows some around the tang that presses against the coil button but thats it. I know my timing is right and I find it hard to beleive that having no advance on my old distributor kept the engine from clacking. I am just out of ideas. I have the timing light on the #1 cylinder, front right when looking from front of vehicle. I am rather good with engines and cars I did a complete rebuild on my 4.3. I have MANY years of shade tree lol. This time its just baffeling me. I just dont see the rockers being perfect and queit 1 day and the next sound like they are coming outta the hood. I also ran 3/4 a quart of ATF through it last night to break up any carbon and that was no help. The only thing left I know of is to retorque the rockers, or atleast check them for looseness. Royjones, Why do I need help? My question about adjusting the rockers by ear or on a flat spot on the cam is valid. The ear technique has been around a LONG time and the flat spot on the cam is in reference to the area that is not lobed when the valve is completely closed. =)
 
I do the valves by ear; I take them 1/2 turn past zero lash. I have a junk cover with a slot cut out of the middle to eliminate the oil mess. Just make sure you adjust slow so you don't wipe out a lobe.

When you say the valves are "clacking", are you hearing loose rockers or predetonation? If it's actually rockers, then in may have just been something else that happened when you messed with the distributor. Do you have oil pressure? The distributor may not have engaged the oil pump shaft properly. Have you had a valve cover off? You mentioned that you have a new distributor; it may not be machined correctly and the top end may not be getting oil.

If the above checks out, I'd still take a good look at the wires. If they aren't delivering the spark at the right time it can do some weird things to the engine.

Hope this helps a little. It's a lot easier when the engine is right in front of me....
 
Might be carbon...

Maybe your motor was run so long without the advance working,carbon built up on the pistons,and is now pre-igniting the mixture--I know you tried putting ATF in to break it up,but sometimes it bakes on so hard nothing gets it off but driving for long distances at highway speed..one sure sign of carbon build up is if it grunts and groans when starting it when its hot,and if it pings after it warms up,despite the timing being set to specs..

But if your sure its lifters,I hope it isnt an oil pressure or cam lobe problem!.. :doah: :crazy:
 
are you positive dizzy was engaged with oil pump when initially started? if no oil pressure you would wipe the cam pretty fast and would result in rough running and noisy top end. Hope it is simpler and cheaper than that. :(
 
Just an update, I removed the cintrifical advance weights and left the vac advance unhooked. Low n behold no clacking. I think I have come to the conclussion that my cintrifical advance springs are shot. Basically allowing the rotor button to advance long b-4 the engine is ready for it to. I really thought it had to be the distributor when I went from having a no noise engine with the old distributor to a clacking engine with the new 1. I basically set the timing as far advanced as i could while still being able to start it easily and have it run smooth. My new advance weights and springs will be here Tuesday so i'll be giving an update then. I really appreciate the help all of you have given. By the way my oil pressure is around 50lbs cold and 35 operating temp. The distributor was all the way down at initial startup. No grunting or groaning at startup b-4 the new dist. or after. I removed the valve cover and the rockers have no play to notice. A little side to side but thats it. I do need new wires, I know that for sure.
 
Mechanical advance weights like to stick. Make sure they are moving freely and the mechanism "snaps back" when you turn it by hand. Also, since it seems to be timing related, you should verify that the timing mark on the damper cover is correct. Sometimes they can spin and then all of your timing measurements are wrong.
 
The wieghts are free and snap back. How do I check the damper? I beleive I saw somewhere that the timing mark is supposed to be a certain degree away from the key. Also the distributor I am using now is for a 305 I was told that this should be fine and it does work. The weights however have different numbers stamped into them. I was wondering if the different numbers might mean different weights. Really doesnt matter I guess. I have allready tried the weights and springs from my old distributor. With the same results.
 
To bad you ordered them already. My MSD came with extra bags of new springs. I think they meant to pack it with just one bag of various but sent 3 by accident.
 
You must log in or register to reply here.

Latest Posts

Top Bottom