Cliff, Jim Weise assembled the motor for me. The cam is 4 deg advanced. It has ran well for the last 4 yrs/3-4000 miles. Just ran rich. Larry, At 2100 rpm the vacuum is in the low 20's and stays steady...does this point the problem at the distributor? The valve train and pushrods are stock and non-adjustable. FYI the 413 cam is out of the test motor that Jim used (Larry's motor) when comparing the TA roller cam 4-7 swap. Just had a little Dyno time so he gave me a good deal and installed it with my "budget build" If so, could you point me in the right direction of a good distributor please. I am willing to spend the $ if needed. Thanks again guys! Thanks, Matt
I would not condemn the distributor unless the shaft bushings are gone and the shaft is wobbling around. The GM big cap HEI has the coil in cap and they can run hot sometimes dropping spark at high RPM. Not saying this is your problem. I like the MSD ready to run distributor for the 455. Fully adjustable mechanical advance. You can run it alone, or hook it to a box. Have you verified the firing order? I have inadvertently screwed up the firing order in my time:grin:
Larry, 18436572. I thought the same thing about the coil getting hot, so I bought a new Accel coil with the red-white wires and swapped it out and added a new MSD cap and rotor along with new plugs. I verified the firing order before and after. I ordered new wires too. They just showed up yesterday so I will try those when I get a second. The distributor doesn't "wobble" but it has some play up and down. Should that concern me? I found that the timing light bounces around sometimes also. Thanks, Matt
Some up and down play is normal. Check the timing chain. Take the cap off, and turn the crank with a breaker bar one way and then the other. See if there is too much slop in the chain. Shouldn't be, but you won't know until you check. http://www.misterfixit.com/chanslop.htm
Thanks Larry!!! I will experiment when I get back home. Traveling for work really gets in the way when you have things like this you would rather be doing at night. Have a happy 4th of July weekend!! Sent from my iPad using Tapatalk
When u rebuilt ur carb , with the throttle blades closed, was there still some transition slot exposed on both sides ? Also your PP spring, have any coils been cut. ? I have gave myself the stumble by cutting a coil from spring .
I tried the misterfixit trick. The play in the chain is just under 1/4" when measured on the circumference of the harmonic balancer. The spring is new with no modification. I pulled it and it looks good. I am not exactly sure what you mean by "transition slot". I attached a picture of the base plate. I also replace the plug wires and removed the phenolic spacer. No change. When I put my timing light on the light moves when the "miss" occurs. Does this point at the distributor or is the timing changing because of the miss due to a carb issue? Thanks, Matt
Attach the timing light to each wire and look at the light. See if you can identify which cylinder is missing. Once you have done that, investigate that cylinder further. Do a compression check on that cylinder. Watch the rocker arms to make sure they are all moving the same.
What brand and part number spark plugs are you using? Have you pulled them all out to have a look at them?
The timing light was pretty steady on all 8 cylinders. My buddy has my compression tester. I am really hoping it is nothing internal..... I checked the pcv valve. Looked good I taped a vacuum gauge to my windshield and did some testing with all vacuum lines plugged (except the ported vacuum advance was hooked up to distributor) Idle at 900 13-14 in neut Idle at 750-800 in gear 11-12 WOT 1" Cruising at 2500 rpm 18-20" Let off and coast 25-26" I am running new NGK UR5 plugs Thanks, Matt
This is really difficult to diagnose over the net. I'm not really clear on what you mean by rough running. Could it be more of a vibration, possibly a balance problem, or it it definitely missing? What is your fuel system like? Have you checked fuel pressure? I started monitoring fuel pressure when the 470 went in.
Is that a plug you took out of the current misfiring engine? Take them all out and post a picture of them
I found the problem source. Carburetor. I had a buddy bring over an 825 Race Demon. Bolted it on, tuned it, and it ran great! The Buick represented well on the cruise this weekend. Now I just need to figure out the Q-jet issue......Thanks again guys! Here is a pic of our destination. "Adeline's house of Cool" in Central WI Thanks, Matt
