radiateu2

Hey guys,

When you guys do a compression test do you first remove all of the spark plugs and then test compression or do you remove one at a time testing each cylinder and then replacing the spark plug before moving on to the next. One would think you would get a more acurate reading removing all the plugs allowing the engine to spin more freely.

ede

remove all the plugs and block open the throttle blades

radiateu2

#1 153
#2 155
#3 153
#4 160
#5 153
#6 155
#7 157
#8 155

Are these numbers good for a 305 bored 030 over and 081 heads

ede

numbers don't really mean much, it's the differance between them that does, it looks very good

radiateu2

Thanks ede for the feed back guess that answers the question on wether or not I have blown head gasket or not

Vader

Those numbers certainly don't look like they indicate a blown head gasket - or valves, or head cracks, etc. Looks like you just saved yourself a bunch of time.

sqzbox

Why are you wondering if you have a blown head gasket?

radiateu2

I have a miss that has been eluding me, I was wondering if I had a leaking head gaskey so I did a compression test. So now I can concentrate on the ignition system or fuel system. I did find I am running a little on the rich side but plugs 3 and 5 I noticed are a little more fouled than the rest. I am thinking I have aome bad cables there or a problem with my distributor. I did notice some sloppy side to side play in the shaft of the distributor. I am wondering if this is causing my mis. Initially I thought I was running on the lean side. I have my doubts. I started looking inot this cause I have a continuous nagging vibration around 2500 rpm. I thought maybe I had a lean miss. I think the source of the mis is in the ignition system.

Vader

Injectors cleaned/flowed recently?

sqzbox

also, fire it up in the dark and see if 3 & 5 cables are cross firing. Being their on the same side. You might use a stick to move them around unless, you need your molecules re-aligned! Vader can tell you that! He's been zaped one time too many! A slight miss will also cause a rich read by the O2 that will try to lean it out and still not set a code.

radiateu2

well Vader its not FI it has 600 Holley on it with the smallest primary jets Holley makes. numbers 3 and 5 were pretty rich compared to the others. Wires are new accels with less than a thousand miles on them. No O2 sensor either. Do you know of problems with 3 and 5 like 5 and 7. I know 5 and 7 are close in fireing order and sometimes will arc each other. I have moved the wires around while running and aaaahhh none of my molecules were re-aligned as Vader put it. Any other suggestions?

Vader

Not to be an alarmist, but have you checked your cam lobes lately? Obviously, bent or leaking valves are not a problem, as revealed by your compression test results. But inadequate valve opening can cause rough operation, among many other things.

Another possibility would be to install some stock resistance wires in place of the Accels. You can do a temporary installation without even removing the Accels from the looms, just move them out of the way. Inspect the distributor cap and rotor closely for signs of flashover, carbon streaks, moisture, cracks, etc.

What ignition system are you using, anyway?

radiateu2

Vader I am using the non computerized HEI stock ignition. I recently checked the lobe lift and they are the same as the spec card for the cam. I often wondered if the cables I have are the right ones for my car. They were the custom ones that you cut and crimp the new ends on 3 and 5 have me worried though. Do you think the distribuor could be the culprit with its excess lateral motion in the shaft? No moisture in the cap not sure what you mean by carbon streaks or flash over though. No carbon tracking that I can tell and the cap is grey so I think I probably would have seen it. The reluctor is new the module test good the capacitor had been replaced also????????? I am at a loss here. The plugs are Autolite platinum tips. I will test the resistance in the 3 and 5 cables and compare them to the resistance of similar length cables... Thanks for the imput here

radiateu2

Hello Vader.....Anyone

sqzbox

Vader's probably visiting another galaxy this weekend! Wazup?

radiateu2

sqzbx,

Just trying to figure out this miss at 2500 rpm. suspect are the number 3 and 5 plugs they were fouled and the others didnt look bad at all. I did notice some metal shavings on the pickup (reluctor) in the distributor. I wonder if I am having an arcing problem from the metal shavings. What do you think?

sqzbox

I would change all your plugs first. As far as the dist. I would try and figure out where the metal shavings are coming from. That's wierd, I would think they might be from the rotor hitting the posts inside the cap. Could mean dist. is wearing out. I don't think shavings would cause an arc across the cylinders unless they were all over the inside of the cap. Check for carbon tracks inside of the cap. Anyway, if you have access to a compressor or a can of air like you use for cleaning your computer or electronics, blow all the shavings out and see how it runs with the new plugs.
Keep posting results! and good luck!

Ricktpi

If you have excess side to side motion on the dist shaft, the rotor tip is probably grinding into the contacts on the cap. A new or rebuilt distributor is in order.

Marc 85Z28

iTrader: (3)

Accel wires right? 8mm Super Stock? They are junk, junk, junk! Trash them immediately. I had the same problem as you awhile back. I finally settled on replacing my 3 month old Accel wires with ACDelco (which were cheaper BTW) and BINGO! No more misfire. Nothing beats OEM. Except maybe MSD

Nearly everyone I know who has tried these wires have had all sorts of problems with them. As soon as I told them I had Accel wires on my car everyone looked at me like I was retarded. Use Taylor, MSD, or GM. Nothing else... ever.