Hi guys,



I'm working on a 1960 F100. The original I6 motor had a hole thru the block, but it came with a 272 from a T-bird that the owner claimed had been rebuilt but never installed. I installed the motor with a 3 speed & Holley 2 barrel (Model 2300 series).



However, the thing won't idle unless the choke is 80-90% out. Vacuum gauge indicates low pressure (normal vacuum when choke is on). I left vacuum advance disconnected (and covered up hole on carb) for testing. Power brake hose is also taped off. I did not see any other vacuum ports to plug. Possible that I missed one??



Compression is pretty low - about 100PSI across the board.



I put in brand new distributor, points, condenser, plug wires & plugs. Points gapped to .015". I put the timing at approx. 6 degrees advanced with timing light. Spark looks good.



I rebuilt the carb with a kit from Oreilly's. Idle nozzles are clear, and pump works good. I have tried the nozzles at varying positions from 1 turn to 3 turns. Float & fuel pump keeps fuel right at the sight hole level.



The coolant (water for now) looked a bit milky after the engine warmed up. Engine did not run for at least 5 years, so could have been from sitting. I did back flush the engine prior to installing a new repro radiator & hoses.





What else should I check??



Thanks!!!

You don't mention if you tried to adjust the idle screws? Do they work? And a couple of side notes. No T-bird came with a 272 engine. And I've spawned arguments here before with this; Claims of a rebuilt engine unless verifiable in some way like with documentation, are usually just a salemans hot air. Not able to verify it.. it's not rebuilt! Hopefully someone else here can hit on your idle problem solution..good luck.

Paul

Have you checked thoroughly for vacuum leaks?  Has the carb been disassembled and all gaskets checked for usability?  The older Holley carbs sitting up for awhile are notorious for drying out and needing new gaskets.  Have you double checked that the damper has not slipped thus throwing off the timing marks?  The low vacuum reading could simply be an indication of not enough initial ignition timing.  Be sure to let us know when you find the problem.

Lorena, Texas (South of Waco)

Regarding your compression test: it's a good thing that your numbers are fairly even across the board, but a bad thing that they're low. When you ran the check, was the engine hot? Did you remove all the plugs, and block open the throttle? If not, this will impact your PSI readings.

I think a point gap of 15 thousandths is a little narrow, but it probably doesn't have anything to do with your issues. I think your vacuum readings are telling you to check for vacuum leaks.

Paul - idle screws don't seem to affect it. They were definitely cleaned out. At this point, I'm quite certain that it's a vacuum / compression issue.



Ted - Carb was completely rebuilt with all new gaskets less than a week ago. I did retard & advance the timing to see if it helped. Engine sounded worse both ways, so I'm fairly certain the timing mark is correct.



Joey - Engine was hot. I also checked with throttle & choke held open. No change. I only took out 4 plugs at a time (left/right). I would have expected higher than 100psi, even with just one plug out though.



I did squirt a bit of oil in the cylinder to make sure the rings were sealed, and it didn't affect the PSI readings. At this point, given low compression and vacuum, I'm guessing it's intake / heads / valves / gaskets. Is there anything I should be looking for if I take the heads off? Also, since it's fairly clear that the engine was not rebuilt, should I take the oil pan off and check anything on the bottom half?

Just a few ideas to check, warm engine than hold hand over carb neck to choke it  as you bring revs up high, making engine suck real hard through carb and sometimes can clear things, try it a few times. And disconnect or block PCV if fitted and check for idle difference. good luck. regards bill.

  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

An engine should run smoothly at 100 psi.  I don't think compression is the problem.  Is the idle speed set too low, so that it is the fast idle feature that keeps it running with the choke on?

John - "The Hoosier Hurricane"

You might want to revisit the carb.  Double check the gasket seal between the main body and the throttle base assembly.  Any warpage in that area will disrupt the idle mixture fuel signal. 

Lorena, Texas (South of Waco)

If the engine hasn't run for 5 years, it's not unlikely there could be a vacuum leak. Poor idle quality isn't necessarily caused by a vacuum leak; but a tangible vacuum leak will definitely affect idle quality. You can spray carb cleaner or wD-40 around the base of the carb, around the manifold, vacuum hose connections, etc. to try and spot it. If spraying into a crevice somewhere changes the way your engine idles, then you've found something. Do one area at a time and then wipe it clean before moving on because those fluids are combustible. But in any case, I would replace the carb/manifold gasket just on the basis of them having been sitting dormant for years.

Have you checked valve lash?  Way too tight lash could cause all of your symptoms.  Do that before you consider pulling the heads.