Author Topic: 1969 Fleetwood running very poor  (Read 267 times)

Offline WTL

  • Posts: 93
  • Name: W. Love
1969 Fleetwood running very poor
« on: November 02, 2017, 01:41:52 PM »
Hello all, I want to get yalls take on what is going on with my engine right now. Yall helped tons at the first of the year with my timing set redo, and it did really well for about 5,000 miles, but it began idling very rough sometime last week.  Power seems markedly down.  Wants to overheat.  Vacuum gauge reads around 17 with a decent quiver to the needle.  Lugs some on hills.

I drained the oil today, and it looks terrific.  Pure, deep blackish brown, just what I was wanting to see, no particles.  I dont think there is oil in the coolant either.  I have no compression gauge at the moment, but all the plugs look fairly ok.  I went vacuum leak hunting and found nothing, tightened up a few hoses to no avail.  I tried setting the idle screws better, but it didnt seem to impact idle or the gauge.  Timing is set at about 5, base.  New plug wires. 

I was thinking maybe I had a stuck valve for the past week, so I added some Marvel Mystery oil to both the oil and gas, per instructions.

I pulled the valve covers today, maybe expecting to see something bad...but no, the valvetrain doesnt look like something is off. 

Then I pulled the carb...and this might be it. 

This was the best gasket that came with the rebuild kit I bought for this carb, which I think is original.  I remember thinking the gasket looked a little thin in places, surely this is a big part of my running problem?  Isnt that the idle air bypass, and if it had a blown gasket between the main throttle bore and the passage would it make the mixture off? 

Is there a more correct gasket?  Should I make one myself, in the alternative, which follows the base as a template?  Is this why I'm getting some oily goo that is in various places around the airhorn? 





« Last Edit: November 02, 2017, 01:43:29 PM by WTL »

Offline TJ Hopland

  • Posts: 6794
Re: 1969 Fleetwood running very poor
« Reply #1 on: November 02, 2017, 01:55:22 PM »
That passage is the exhaust crossover so what you have going on that burnt out spot is basically an EGR which you can't do at idle.  Others will have to chime in but I seem to recall hearing there was a certain brand of gasket to look for on those cars that was more resistant to the heat.    You also want to make sure you don't have any sort of exhaust restriction like and EFE sticking.  Any restriction will force more exhaust flow across that spot. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline James Landi

  • Posts: 663
  • 2007 XLR
    • CLC Member
      CLC Member #21920
  • Name: James Landi
Re: 1969 Fleetwood running very poor
« Reply #2 on: November 02, 2017, 03:14:51 PM »
CHiming in on TJ-- a malfunctioning EGR valve can create a problem similar to what you're experiencing.--- stumbling at idle--- lack of vitality.. as you know, the ERG runs on vacuum, and it can get stuck. James

Offline Jeff Rose CLC #28373

  • Posts: 1405
  • Name: Jeff Rose
Re: 1969 Fleetwood running very poor
« Reply #3 on: November 02, 2017, 04:34:56 PM »
Recheck the timing. My car in hi school had a weak distributor hold down and it would rotate and mess up the timing.
Does it have points? Have they slipped?
My 70 doesn't have an egr so I wouldn't think yours would.
Have you checked fuel filters? What is your voltage at the coil?
Check your brake booster for leaks. About a month ago mine started running like crap, no power and the temp light came on. Next day I started it and it wouldn't keep running. The little plastic checkvalve on the brake booster broke off sitting in the driveway. It must have been starting to crack while I was driving it the day before.
Jeff
« Last Edit: November 02, 2017, 04:38:16 PM by Jeff Rose CLC #28373 »
Jeff
CLC #28373
1970 Coupe DeVille
1955 Series 62

Offline TJ Hopland

  • Posts: 6794
Re: 1969 Fleetwood running very poor
« Reply #4 on: November 02, 2017, 04:46:25 PM »
EGR didn't come in till 73 so he should not have one.  What I was saying is his intake is the style with an open exhaust passage in it and looking at the photo looks like the gasket burnt through one of the throttle bores so he was leaking exhaust into the intake stream so that explains at least part of the issues.

I was thinking there was a fairly thick metal clad gasket that was supposed to be used with that style intake. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline WTL

  • Posts: 93
  • Name: W. Love
Re: 1969 Fleetwood running very poor
« Reply #5 on: November 02, 2017, 05:46:11 PM »
There is a stainless steel shim that I had installed on top of the kit gasket, I'm wondering if it wouldn't have been better putting it under the gasket to surely block exhaust from coming in contact with the gasket material. 

After TJ noted what the purpose of the passage was for, I was able to find a pretty extensive discussion of it on a corvette board, apparently they deleted the passage around 70 or so because it was hard to seal, some people even plug the passage if they live in a southern climate.  One guy over there recommended gasket, then shim, then another gasket...

I don't know if there could be a heat riser valve, I crawled under a little bit ago and looked and didn't see one.  I guess I am feeling a little better, as the burn through is probably at least a good bit of answer - I'm sure, there are other issues, but I think we are getting closer.  I had been noticing that the car drove a little worse after 20 minutes or so, and there was some ping, wonder if that was from it getting really hot exhaust that was leaning it out.  Maybe since its on the left bank it would unbalance it, then again maybe not. 

I bought a new brake booster check valve last year, it seems a little loose in there but I cant tell that it is leaking vacuum.  One thing that does need doing is the throttle shaft has some play.  Its got a pretty new distributor, HEI - powered by a clean 12v from a relay.

Offline TJ Hopland

  • Posts: 6794
Re: 1969 Fleetwood running very poor
« Reply #6 on: November 02, 2017, 06:57:48 PM »
If its got a heat riser it should be at the end of the right exhaust manifold.   

The intake isn't split left and right,  its an upper and lower and each handles 2 cylinders on each side.  You can tell by looking it it which are the high ones and low ones. 

I wonder about installing metal carb spacer?  That should block those holes.  Only issue will be getting the choke to work correctly since its in the intake. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline V63

  • Posts: 324
  • Name: W Link
Re: 1969 Fleetwood running very poor
« Reply #7 on: November 02, 2017, 09:12:00 PM »
I would start with the ignition points, remove them and check for pitting. Perttonix (Hall effect electronic ignition) might be a good option.

Offline WTL

  • Posts: 93
  • Name: W. Love
Re: 1969 Fleetwood running very poor
« Reply #8 on: November 06, 2017, 07:53:03 AM »
Well the blown carb base gasket was definitely what was causing the idle problem.   I replaced it yesterday, went gasket, spacer, gasket then carb...we will see if that holds. But it's running pretty good.   

I'm also fiddling with improving the timing, does anybody know what the timing curve for a stock 472 high compression motor looks like?  I swapped an hei in when I got the car, but I think I swapped it from a chevy 454, so I'm wondering if it has too much mechanical and vacuum advance coming in.

Offline TJ Hopland

  • Posts: 6794
Re: 1969 Fleetwood running very poor
« Reply #9 on: November 06, 2017, 08:19:52 AM »
A Chev distributor won't fit in a Cadillac so it has to have been out of a 472-500-425-368.   The shaft is actually the same length but the rest of the body is different.   

Shop manual should have the original specs.  If you have a hand vacuum pump, tach, timing light its fairly easy to check.     All those engines should have similar characteristics which tends to be not a lot of mechanical and all in at a fairly low RPM compared to say a Chev.  One issues is most replacement vacuum cans put way too much vac in.   That usually results in detonation / pinging so most people just back up the base timing which tends to flatten the performance.    The fix is to get a 'performance' vac advance that has or that you can get the little limiting cam for.   Set it for what the manual says and you will likely be able to bring the base back to spec or maybe even a little advanced.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline WTL

  • Posts: 93
  • Name: W. Love
Re: 1969 Fleetwood running very poor
« Reply #10 on: November 06, 2017, 10:15:10 AM »
Thanks TJ. I'm thinking I at some point switched chevy weights, springs, shaft and pickup into the Cadillac base sometime last year when my timing chain was stretching out.  I don't think I thought too hard about the timing curve then, was just trying to get a consistant spark. 

It might all be wrong, and maybe I should just get a stock 77 HEI on ebay, although a low compression 500 might be different too. I have a timing light.  Right now, base timing is 8.5, with 16 mechanical advance, coming all in probably before 2500.  It had more mechanical advance before, but I flipped the centerplate over to limit it.  What would be a good number to limit that vacuum advance for, and on these engines, mine seems to be putting out strong vacuum - so should I do something to the rate of vacuum advance? 

I have a shop manual, but I have no idea where it went. 


Offline TJ Hopland

  • Posts: 6794
Re: 1969 Fleetwood running very poor
« Reply #11 on: November 06, 2017, 12:28:33 PM »
The rate doesn't tend to be as critical as the the amount on the vacuum.     All in by 2500 sounds reasonable for the mech.     Low compression engines seem to do good with more in the mech and less in the vacuum.   Not sure about high comp.   16 seems possible but if you have 20 in the vac you will have problems.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason