66 Sat
Well-Known Member
Hi all, I have a confusing problem with my 318 Poly. It was fully rebuilt a year ago and has done about 2,000 miles since, long trips, short trips, driven at least once a week. Car runs faultlessly, or did until I noticed something last week. I'd gone behind the car while it was idling and noticed the passenger side tailpipe sounded very different to the driver's side. Not a nice burble but a farty misfire sound. When the engine is revved the sound is more noticeable - that side is quieter and the miss seems more obvious.
A local expert in all things V8 had a quick listen and thought it was a very slight miss, probably an exhaust valve not seating fully.
I've pulled the plugs - they all look good. Swapped them bank to bank - no change.
Checked each HT lead, swapping in a new one I bought, one at a time. No change.
Checked the distributor cap - all looks good inside.
Compression check - on the side with the odd noise 170, 160, 170, 160. On the good side 170, 170, 160, 170. All cold readings.
The tailpipe end on the good side is warmer to touch than the dodgy side.
It has electronic ignition, new 600 Holley, and runs perfectly from the driver's seat. Performance seems unchanged from a year ago. If I hadn't have walked behind the car I would've had no clue there was a potential issue.
Any ideas? I was thinking maybe a dodgy muffler, or a partially stuck manifold heat control valve - that's all I can come up with.
Interestingly, when I told my son about the issue he said "yeah it's done that for ages - about 2 years". I reminded him the car's only been on the road for a year, and he reckons it's always sounded like that (but hadn't thought to mention it!).
Anyway it's booked in for the guy to go through it properly next week, but I'd be interested if anyone has experienced something similar and what it was.
Cheers
A local expert in all things V8 had a quick listen and thought it was a very slight miss, probably an exhaust valve not seating fully.
I've pulled the plugs - they all look good. Swapped them bank to bank - no change.
Checked each HT lead, swapping in a new one I bought, one at a time. No change.
Checked the distributor cap - all looks good inside.
Compression check - on the side with the odd noise 170, 160, 170, 160. On the good side 170, 170, 160, 170. All cold readings.
The tailpipe end on the good side is warmer to touch than the dodgy side.
It has electronic ignition, new 600 Holley, and runs perfectly from the driver's seat. Performance seems unchanged from a year ago. If I hadn't have walked behind the car I would've had no clue there was a potential issue.
Any ideas? I was thinking maybe a dodgy muffler, or a partially stuck manifold heat control valve - that's all I can come up with.
Interestingly, when I told my son about the issue he said "yeah it's done that for ages - about 2 years". I reminded him the car's only been on the road for a year, and he reckons it's always sounded like that (but hadn't thought to mention it!).
Anyway it's booked in for the guy to go through it properly next week, but I'd be interested if anyone has experienced something similar and what it was.
Cheers