harvs ek 327 wagon

[Harv]

Chasing a new issue on the wagon. Small block Chev, Holley carb, TH350. Has run for quite some time now, so probably not a "installed new parts and they are wrong" issue. Car is regularly abused at Eastern Creek, so breaking something is on the cards. Starts fine, though of late seems to take a little longer to warm up (maybe I'm imagining that bit). Idles fine.

Put it into gear (like when you are stopped at the traffic lights) and it struggles to idle... runs, but will stall after 30 seconds or so if left alone. Put it from Drive to Park/Neutral and the idle comes up and it is happy again. I'm getting tired of throwing back to Neutral in Sydney's stop/start traffic.

Car has become slightly hesitant off idle. At cruise (say 60km/h) it surges. No pinging. Accelerates from cruise with no issue all the way up to WOT. Sounds healthy all the way.

A drive or two before this started I gave the gearbox a workout. Inadvertently left it in 2nd, and did 10 minutes on the freeway. Gearbox got hot (I suspect) and warmed up the engine oil via the radiator. Coolant temperature increased, but did not boil. Oil pressure started getting low (~20psi), but not low enough to put on the idiot light. Got off the freeway, put it into drive, and drove for 20 minutes. Car cooled, oil pressure came back up to 50psi or so. No ill effect noticeable. Have changed the trans fluid since then, fluid looks fine (clear, not burnt at all), as did the pan (very slight amount of grey shadow in the pan, a very small number of ally particles, and just enough steel particles to cover the magnetic sump plug).

Don't think this is a trans issue. Have changed nothing else, but may have busted something in the months of driving this thing gets. Gut feel it is one of three things:

a) the timing is a little tardy. Put the timing light on it, and it is pulling 20.5 degrees at idle. That should be fine. Timing light was playing up so didn't get a chance to check it across the rev range. From memory this thing runs either 32 or 36 degrees all-in.
b) the main metering circuit is slightly lean. Idle circuit must be OK as it idles OK. Accel pump might be crook (hence the slight hesitation) but that does not explain the surging at cruise. Maybe partially blocked main metering jets. It has a fuel filter, which I pulled. No evidence of heavy gunk that might have got through the filter. It's not a filter/fuel supply issue as it behaves fine under heavy throttle (... and still surges with a new filter).
c) it has a vacuum leak. Sprayed Start Ya Bastard around the carb, inlet manifold and at the transmission vacuum connection and did not get a response. Hard to tell though as this thing does not "jump" much in idle even when you spray down the carb throat. Most of the trans line is steel pipe, there is no brake vacuum connection. No rubber caps have blown off the carb.

My plan of attack:
a) Swap timing lights and make sure it advances up the rev range. If it does, then timing is not the problem.
b) Fit a wideband oxygen meter to the exhaust and see what the values look like at cruise. Should be around 13-14.7 AFR at cruise, the lower the less likely to be lean. Results higher than 14.7 or so probably mean it is lean from either lack of fuel or a vacuum leak.
c) Repeat the vacuum test with something that has no oxygenates in it (more fuel heavy like WD40) so I can hear the rev change better.
d) If there are no vacuum leaks, pull the front float bowl, pull the main metering jets, blow them and the passages out with air.

Opinions welcome.

Cheers,
Harv

[ardiesse]

Harv,

Unhappy idle in Drive, hesitation off-idle, and surging at cruise all point to leaner-than-good mixture. But I'd look first at the idle and off-idle discharge systems. At a steady 60 km/h, you're only just onto the main discharge system.

If it's not something like gunk in the idle system or main discharge system, then I'd be inclined to start looking at vacuum leaks. Block the PCV system, if you have one, disconnect brake booster, disconnect vacuum advance . . . in fact, anything that plugs into the inlet manifold. If nothing obvious shows up, then it might be an idea to check for poorly seating valves.

Rob

[Errol62]

Any idea what revs it is doing at idle in gear Harv, out of curiosity?


FB ute fixer upper, EK van on rotisserie

[Harv]

Not sure. Its got a relatively slow idle for the amount of grunt it makes - cam selection is petty good.

Cheers,
Harv

[ardiesse]

Harv,

Not entirely on-topic, but maybe of some relevance -

My FC had a moderate case of raspy-breath which I cured (yesterday) by replacing the manifold gasket and exhaust pipe packing. The manifold gasket had its innards eaten away at the exhaust ports, but looked like it still sealed OK at the inlet ports. For quite a while it had had a fluctuating idle, a "tip-in sag", and surged on light throttle openings; all of which I could cure by going to a 53 main jet from a 51.

These problems have largely gone now. Wasn't expecting that. I don't know whether the cause was bad sealing at the inlet ports, or whether small exhaust leaks upset the mixture at and just off idle.

Rob

[Harv]

Its possible that an exhaust leak is the issue.

The wagon doesn't have raspy breath, but has had it twice before. The Dart cylinder heads have thumping great big ports, and not much gasket face to seal on (the gaskets that came with it are only about 3mm wide in places). The exhaust manifold bolts tend to back off, which doesn't help either. I replaced the reduced-head bolts with allan head set screws, which lets me get a more confident turn on them with an allan key. They are on a 3-month "check if they are still tight" program, and so far don't seem to have backed off at all. I was going to safety-wire the set screws, but ran out of time (Grade 8 stainless is painful to drill).

Cheers,
Harv

[EK283]

Hi Harv,

As a fellow chev owner I can say that it appears vacuum related, I've had the same type of issue.

Changed jets, metering blocks etc etc. The damm thing would just bog and backfire then go then surge.

You need to elimanate all sources of Vacuum leak, could be the manifold seal, dizzy canister, brake booster, hoses, or even the shift canister on the gearbox.

Good luck !

Greg

[FireKraka]

Hey Harv funny you mention exhaust bolts backing off I was going over Franks engine after I got back from the nationals and found one of the exhaust manifold bolts missing altogether, since I have found another couple have also backed off, I’ve tightened them I think twice now, hard to know how tight without over stressing them and not sure if there is an actual torque setting for them, think I’ll have to check the manual.

[Harv]

14-18 ftlb according the manual.

Alternatively, wind them up until they snap then back them off half a turn.

Cheers,
Harv

[Blacky]

Alternatively, wind them up until they snap then back them off half a turn.

Cheers,
Harv

Its a Holden not a Harley

[Harv]

Think the miss/idle may have been the PCV. Blocked it, and car seemed OK. Reconnected it, and problem was gone. Hmmmmm… maybe it hadn’t seated, and disturbing it helped. Drove for a while, and problem would occasionally come back. Got lean enough to backfire twice one morning, and no problem since.

Snapped the speedo inner a while back and replaced it. Drove ok, though last time I was home gave me a mild panic attack. Made a pass down the quarter, and came onto the return road only to hear tick-tick-tick. Ooopsie, must have hurt the motor. Slowed down, and so did the ticking. Thank goodness… just the speedo cable. Ran out of time to sort it out before the run up to Tamworth for Easter.

Clearly my Abuse and Neglect maintenance plan was a poor one, as the speedo crapped out at Murrurundi on the way home. 300km to go, and double demerits. Less Fast and the Furious, and more Driving Miss Daisy was required for the rest of the way home. Took a look this morning and it has done the inner again. Suspect I had the cable kinked under the dash by pulling it into the cabin, then neglecting to push the slack back outside again. The ticking was likely the cable whipping as it spun.

Cheers,
Harv

[Errol62]

I did the same. Was a NOS cable. Somehow ended up with a full kink under the dash when installing it. I abandoned the factory clip that holds the cable and wiring to the pedal box so it doesn’t foul on the wiper arm, in favour of a cable tie, and I am very wary when I reconnect it now.


FB ute fixer upper, EK van on rotisserie

[Harv]

WSID July 2023.jpg (123.25 KiB) Viewed 883 times

Its not a wagon... it's a smoke machine

https://www.youtube.com/shorts/G53e-8l8Zes

Cheers,
Harv

[In the Shed]

No shortage of grunt there Harv

[Errol62]

Awesome Harv!


FB ute fixer upper, EK van on rotisserie