Engine/valve issue?

[griswald]

Hello,

I have a 1971 IIA. Owned for 6 months. Knew last 3 owners and history of vehicle for past 15 years.

Head was replaced about 4 years ago (less than 5,000 miles I am fairly certain) with RN 8:1 head. I have not yet adjusted valves, but will tonight.

The truck has a vacuum gauge that reads 21 in/hg to 22 in/hg at idle and of course drops under load. I am running stock exhaust and a weber 34 ich?(New about 4 years ago)

Seems to have good power most of the time compared to the other 88's I have owned or driven.



Here are my questions:
1. There seems to be an intermittant popping at exhaust, comes and goes. Has been doing this (per previous owners log entry) since head was replaced. I do not know if adjusting valves will help.

2. SOmetimes after running up a hill, in third or fourth, when I come to a stop and am in neutral, the engine seems to miss a bit, and the vacuum gauge drops, and fluctuates and then returns to normal. If I do not let it
return on it's own, and try to drive, I get a distinct miss, and then after more power is added, it smooths out. This does not happen all the time, and it is again something that comes and goes. (Any ideas)

3. When using a compression tester, should I be cranking the hot motor over to get a reading with either the choke open, or the accelorator on the floor? (or not)

Idle is always around 700rpm.

Finally it seems sometimes that when running at higher RPMS the motor sounds like a "locomotive" healthy but just rather odd sounding?

Pulling plug wires seems to effect idle so I am fairly sure all cyls are firing...

I know that the valve adjustment and the compression test tonight will give me more data. But I was thinking I might ask for any thing to look for too.

I should mention that there seems to be good power on this motor.

Best,
Griswald

[daveb]

compression test should be done with the engine at normal running temperature with the throttle and choke wide open.

I would adjust the valves post haste. if one is adjusted too tight it can easily burn.




Hello,

I have a 1971 IIA. Owned for 6 months. Knew last 3 owners and history of vehicle for past 15 years.

Head was replaced about 4 years ago (less than 5,000 miles I am fairly certain) with RN 8:1 head. I have not yet adjusted valves, but will tonight.

The truck has a vacuum gauge that reads 21 in/hg to 22 in/hg at idle and of course drops under load. I am running stock exhaust and a weber 34 ich?(New about 4 years ago)

Seems to have good power most of the time compared to the other 88's I have owned or driven.



Here are my questions:
1. There seems to be an intermittant popping at exhaust, comes and goes. Has been doing this (per previous owners log entry) since head was replaced. I do not know if adjusting valves will help.

2. SOmetimes after running up a hill, in third or fourth, when I come to a stop and am in neutral, the engine seems to miss a bit, and the vacuum gauge drops, and fluctuates and then returns to normal. If I do not let it
return on it's own, and try to drive, I get a distinct miss, and then after more power is added, it smooths out. This does not happen all the time, and it is again something that comes and goes. (Any ideas)

3. When using a compression tester, should I be cranking the hot motor over to get a reading with either the choke open, or the accelorator on the floor? (or not)

Idle is always around 700rpm.

Finally it seems sometimes that when running at higher RPMS the motor sounds like a "locomotive" healthy but just rather odd sounding?

Pulling plug wires seems to effect idle so I am fairly sure all cyls are firing...

I know that the valve adjustment and the compression test tonight will give me more data. But I was thinking I might ask for any thing to look for too.

I should mention that there seems to be good power on this motor.

Best,
Griswald

[griswald]

Thanks!

I will report back tomorrow. If anyone has other insights, they would be mucho appreciated!

Griswald

[bobzinak]

try removing your vaccuum line and plugging it up.. some carbs have no vaccuum at idle, it may be that you intermitent miss is from the advance on the distibutor not something to worry about. my slll with the stock set up did it all the time. bobzinak

[griswald]

Ok,
So there is a winch on the front of the rover which renders the starter handle useless...

SO, I was able to check the valves by, er, turning the starter dog with a screwdriver, and it was hard to insure that each valve was open all the way, but I think it was close, and all valves were fine.

Compression test was 128, 127, 129, 130.
Which do not really seem to point to a burned or bent valve.

Spark plugs were dry but had black soot on them...

Regapped points, checked the vac hoses, and noticed that a couple of the intake/exhaust manifold bolts needed a bit of a turn (not loose, but not real tight).

Finally the downpipe is rattling a bit off of the exhaust manifold, but the bolts are crazy rusted. Any tips on how to tighten? (Put some PB blaster on them, so we will see what happens over the next few days)

Can anyone tell me what the symptoms of coil failure might be?

Took the Rover for a ride, seemed happy, so who knows, I will fiddle with more soon.

Best,
Griswald

[bmohan55]

As far as the interminttant popping of the exhust mine did that also, went away when I changed the plug wires.

[scott]

black sootie spark plugs, i'd suspect running to rich. is the soot on the tail pipe oily or dry. oily also points to too rich a mix

[leafsprung]

If your valves are adjusted properly and your timing is correct. Your problem could be simple. You are likely getting an incomplete combustion as noted by the sooty plugs. As the unburnt fuel enters the exhaust system it encounters oxygen from the leaky downpipe the hot exhaust provides ignition and you have your popping or backfire. Its probably a combination of carburation and exaust leak. Does it happen more frequently when you are letting up off the gas? Its not likely to be your coil.

[griswald]

The popping is intermittant at idle but also occurs when letting off the gas or going downhill, on a very steep hill going down, I get louder pops but not quite back fires.

The spark plugs are dry and black the tail pipe has a black coating of soot (dry)

The down pipe was loose enough to rattle, but the exhaust did not seem overly loud, but I could definately move the pipe away a bit from the header.

I have soaked the 3 bolts in PB Blaster, and will try to tighten those today or tomorrow.

One other thing is that the vehicle has seemingly lacked some 4th gear power (maybe my imagination) and sometimes it seems to vibrate a bit under load between 2000 and 2500 rpms in 3rd or 4th?

I will keep working on this.

Thanks for all the HELP!
Griswald

[daveb]

Ok,
So there is a winch on the front of the rover which renders the starter handle useless...

SO, I was able to check the valves by, er, turning the starter dog with a screwdriver, and it was hard to insure that each valve was open all the way, but I think it was close, and all valves were fine.



gris:

when setting the valves, you can turn the engine over using the fan if the spark plugs are all out. if the fan wants to spin without turning the engine over then just push on the fan belt a bit between the pulleys to make it tighter. or use a big wrench on the crank dog/nut

[NC Rover]

I had the same symptoms and after doing all of the above...turned out to be a faulty plug wire. May be worth looking at?

[KevinNY]

I agree with Ike, get that loose manifold tightened up and the popping going down hills will stop right away.

[griswald]

Thanks for the help, I am going to try and tighten up the manifold downpipe connection. Will also replace plug wires!

Dave, I did have all the plugs out and tried turning over with fan belt method, but could not get that done...I also tried the wrench, one other question what size is the starter dog?

Best,
Griswald

[griswald]

Ok,
Pickle jar timed, tightened down pipe bolts.

Here is what I am finding.

Engine miss/Vibration type symptom under load, in 3rd or 4th usually going up a hill, in the torque band of 2200 rpm to 3000rpm.

Once over 3000 rpm seems fine. Revving motor with no load does not seem to have ANY vibration, or miss...

Saturday, I will be adjusting points, and valves again and adjust the timing with the previous owner using a timing light... will report back with findings.

Any ideas on what this issue might be? Running Weber 34ich, and std lucas distributor...

Thanks,
Griswald