Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - 1977 Chevrolet K10 - Starting Problems, Weak Idle and Power Loss
View Single Post
  #93 (permalink)  
Old 04-12-2011, 12:14 PM
lt1silverhawk's Avatar
lt1silverhawk lt1silverhawk is offline
"But how do it know?"
 
Last wiki edit: How to rebuild a Rochester Quadrajet 4MV carbureto... Last photo:
Join Date: Mar 2010
Location: Lakewood, CA
Posts: 2,287
Wiki Edits: 132

Thanks: 101
Thanked 24 Times in 17 Posts
hey dsraven,
Quote:
Originally Posted by dsraven
you need to get that lost bolt out of there. take a light and shine it down an ajacent hole while looking down the hole you think it went into. it should be hung up against a lifter or something. you will need a magnet. try not to send it further down.
I did quickly try to put a magnet in there, but it wasn't pickup anything and I became afraid that it have fallen into the engine (now I know it hasn't). I have a serious space/access issue in that area. I have the gigantic brake booster in my way, along with the carburetor on the other side. I must admit it didn't seem the bolt fell into that opening, but not having found it, it seems like the only place it would have gone. plus, the magnet I am using might be too large for the opening (about 1/2" diameter). I will do a double check tonight after work. I am very much tempted to invest in a borescope.




Quote:
Originally Posted by dsraven
have you done ay of these checks yet:
-cooling system pressure test, at the pressure that your rad cap is set for. don'toverpressure the system or you could blow a hole in the rad, heater core or a gasket somewhere. also, check the under side of the oil filler cap for a white milky substance. that would indicate a leak somewhere from the coolant into the engine oil, condensation from that collects on the under side of things like the oil filler cap and valve covers, but may not show in the oil on th dipstick yet.
-check the spark plugs for a rusty looking one, like if that cylinder has a cracked head or leaky head gasket, it would leave that spark plug looking rusty. - The spark plugs were replaced. To be honest, the old ones seemed fine, just had a bit of oil on them.
-check for bubbles in the rad when the engine is running, possible head gasket leak.
- a timing chain slack test, turn the engine over by hand till you come to the timing marks. take the ditributor cap off and make a detailed note on where the rotor is pointing. use some tape on the edge of the distributor housing. also note where the timing marks are pointing to on the harmonic balancer. now turn the engine backwards slowly until the rotor just starts to turn and "catches up" to the crank (from slack in the timing chain). the number of degrees the harmonic balancer moved before the rotor caught up is a good indicator of how loose the chain is. a new engine would basically be zero. some of those old sbc had plastic covered timing geras and the plastic would wear or break off. instant loose chain. they can skip over a tooth pretty easily, causing the cam to be out of time with the crank.
-vacuum check at idle. does the needle skip around a lot or hold pretty steady?
-valve adjustment. include looking for broken valve springs and also check to see if all the valves are opening the same amount. some of the older sbc had soft cams and the lobes would wear off.
-cylinder leak down test. air up the cylinders at tdc ready to fire, see if air leaks past the valves down into exhaust or up into intake. checks for leaking or burnt valves.
-compression test, wet and dry. dry first for obvious reasons.
-carb adjustment, including check to see if the throttle shafts are worn out. also a choke set up. - Carburetor was rebuilt.
-heat riser valve check. - Doesn't appear to have one.
-egr valve check, if equipped. - The intake manifold doesn't have the provisions for one, but it seems it should have one.
-pcv valve check - Working fine.
-vacuum hose check. inccluding the one that goes to the auto trans modulator (if equipped).
-distributor mechanical and vacuum advance check. include check of wear on the mechanical advance weights and springs and freedom of movement. also base and total advance. vacuum advance hose routing from proper connection at carb and (if equipped) does the vacuum temp switch operate properly to allow vacuum to the distributor when the engine warms up.
-condition of the spark plug wires and distributor cap, rotor, coil, plugs. rest of tune up parts like fuel filters, air filter, pcv valve.
All of these were recently replaced.
-adjust timing correctly at operating temp. - I recently messed with it a little and it appears to be fine. However, a test with the timing light is coming soon.
hopefully that helped. sometimes a problem like yours is a combination of a bunch of things being out of whack, or it's something that was overlooked. go through the list and see if all is good.
I underlined the things I have done or checked. It did turn out to be a combination of issues. The truck originally began backfiring after the tune was done last year. Then, someone poured water and debris into the gas tank, which eventually led to the fuel filters being cleaned and/or replaced and the carburetor rebuilt. . Then, the plugs were re-gapped properly and some of the spark plug wires had to be replaced because they were burned. The problem was finally narrowed down to timing. I missed with a bit on Sunday and got it to where the truck idles and revs with no backfires. The only problem left was the oil leaking from the recently replaced valve covers gaskets. Passenger-side was a breeze. Driver-side has given me nothing but trouble. I have now lost two bolts for the same hole by the distributor and firewall.




Quote:
Originally Posted by dsraven
on the valve cover leak, what works for me is to flip the valve cover upside down with the gasket surface on the edge of your workbench or something flat. the rest of the cover has to be supported by a buddy (or your belly or knee) because it will be hanging out in mid air. take a ball pien hammer upside down so the ball is in the bolt hole of the valve cover, give the hammer a tap with a dead blow hammer and watch the bend come out of the cover. when it is all flat, make sure the surface is clean of old gasket material and then glue a new gasket to the cover and wait till the glue is cured, then install it with those little butterfly washers, or get some longer ones at a speed shop. I have seen some that are couple of inches long, they work well. don't overtorque the bolts or you will split the cork gasket. i like to use the neoprene gaskets for that reason. felpro sells a good set but i don't remember the number.
I think I definitely went to town went bolting down the covers. I read somewhere it should be no more than 15 lb/ft. Not sure how accurate that is. I used the rubber gaskets because my experience with cork has been bad in the past. Of course, it could just been have me all along.




Quote:
Originally Posted by dsraven
good luck and keep us posted,
dsraven
Thanks for all the help and tips dsraven! I will post back with results soon (hopefully good ones).




P.S. Good to know I am not the only one who's done something like this:
Edelbrock: Made in U.S.A. - Dyno Room Stories: Manifold Bolt Roulette



----
EDIT: Found this neat trick over at Thirdgen.org :

Quote:
Another trick is to take the magnet off the holder they sell at the auto parts place, thread or clamp it in place onto a piece of flexible rubber hose, and snake it down the runner, it will follow its contours and u can pull it up... pls post a follow up, K?

I am sure this will work, but I want to hear how it goes, thanks.

By jethro, Post #3

Last edited by lt1silverhawk; 04-12-2011 at 12:26 PM.
Reply With Quote