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By chance do you have an anti-fuel drainback valve of some sort installed anywhere between the fuel pump and carburetor? If so you need to remove it and throw it just as far as you can.
There was one on my car (1970 model) and it starved the carburetor of fuel, and caused surging.
Set the dwell and run it with the vacuum advance connected to direct intake vacuum (listen for pinging/detonation) if it occurs plug the line to the distributor and re-test drive. Just don't let pinging continue it can eat piston tops.
Completed this process no pinging but still surging etc.
I disconnected distributor vacuum and blocked hose and dist. Connection.
Had running @850 rpm.
light is dead on the red mark which is way off the white mark I would think is TDC as it has two saw marks each side of it.
I am thinking yellow mark is 5 deg before TDC according to the book.
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Just tested again and now the timing mark is showing about 7-8 degrees before TDC and nowhere near that red mark now.
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Any advice on this red mark please?
Last edited by 5998DownUnder; Jul 16, 2023 at 12:45 AM.
John - Sorry, can't help with those marks. I would "think" the white mark (as you noted sits inside the two saw marks) is TDC & I suspect you've checked the manual to validate what the saw marks represent. Someone most likely painted on the yellow & red marks but what they represent I have no clue. I feel for you trying to narrow down this surging issue - like pulling teeth to find the right one, eh? You wouldn't think these 1st gen engines would be so difficult. So many items come into play on this - dwell, timing, carb (float bowls) and I'll mention the distributor itself and the vacuum advance canister.
I read this earlier this morning, including the history of your 394 & Charlie's 394 rebuild. Setting the timing appears modestly straight-forward; however, this member lists some interesting considerations which may provide some insight. Good Luck!
I read this earlier this morning, including the history of your 394 & Charlie's 394 rebuild. Setting the timing appears modestly straight-forward; however, this member lists some interesting considerations which may provide some insight. Good Luck!
Norm,
That is a great thread to find and supply I have had a read and it explains a lot.
Thank you for the help much appreciated.
I'm not certain exactly which points of consideration might provide the greatest in context for you. I thought it was a well-written explanation. I noted, in particular, the type/model of the vacuum advance canister which was called out.
Just a shot in the dark, but could your points be set to close? Your surge could be the difference from a cold distributor lobes at start up and the expansion after warm up. You might have had a change in the gap( slipped) since the first install and be overlooking something simple.... Tedd
Tedd,
yes they were out now Re set with Dwell meter then did the timing again.
Norm,
Will do the air fuel mixture next and
scouting through this site on another troubleshooting thread you mention to someone with a similar problem to me to change the accelerator pump. I have a spare so I’ll try that also.
OLDSter Ralph I will do floats then.
I notice Joe.P mentioned poss a weak fuel pump in the same thread so will look at this the pump off the other engine worked fine if it gets to that. I have a plastic fuel filter just before the pump and notice it doesn’t fill up over half way.
Thanks.
As has been said before, you need a wideband O2 diagnostic setup to really measure what is going on with A/F ratio. There are many on the market. It's a great gauge to have full time to make sure nothing has gone sideways if it starts running "funny".
As has been said before, you need a wideband O2 diagnostic setup to really measure what is going on with A/F ratio. There are many on the market. It's a great gauge to have full time to make sure nothing has gone sideways if it starts running "funny".
Checked them out and look like a purchase soon.
Thanks.
Kept this accelerator pump as my spare looked a bit different. Floats were a tad out so adjusted same to repair manual specs.
So somewhere between fiddling with the accelerator pump and floats she has come along very well on the test run.
Only a slight hesitation once in a while but huge improvement. A little fine tuning on the floats next day or so.
As a result of great advice from you all I now have dwell set as is the timing, repaired a few dodgey bits of wiring and connections, new coil and good fuel.
