Whatever you plan to do with your carb using that book, you'll probably need one of these:

NEW NOS HOLLEY CARBURETOR CARB GASKET REPAIR RENEW KIT 37-1084

It contains all the gaskets you will be destroying when you get into the carb, and it should have a new power valve in case you need to replace your old one. If it's been a while since the carb has been serviced, this is a good thing to do.

 

Thanks xlt4wd90, the carb. was just rebuilt in July 2017, but it would not hurt to have extra gaskets handy if needed. And I hope the power valve is the problem that's causing the hesitation with backfire. I read that if I turn my idle mixture screws all the way in while the truck is idling. If the engine dies the power valve is not blown.

 

Carb looks similar/same as the Holley in my 65 w/ the 302, which is a Holley 4160 (1850)? If so, and probly already aware, vacuum advance runs off metered vacuum not primary; I use the port located just above the idle adjusting needle on passenger side. Although does not hurt to block vacuum advance line when setting timing I do not. Again, probly aware, any time one adjust timing then need to adjust the idle mixture, visa versa?

If purchased new Holley 4160 believe off the shelf standard jet size runs around 67-68. May consider try going to smaller jets, perhaps around size 62-64? If you decide to go this route; remove plugs and note condition and color, clean before reinstalling, then drive to determine if any improvement? Pull a few plugs and inspect condition to determine if burning cleaner. Not an authority but food for thought.

 

Thanks for your post daveengelson, My carburetor is a 4160 List #9834. As to the vacuum advance, my neighbor who rebuilt the carb. and gave it to me as a gift to run on my truck is certain the truck runs better with the vacuum hose attached to the intake port and insist it should remain there. I appreciate you letting me know about your success with smaller jets(62-64) I do think we are running rich since the #1 plug is very black when we pulled it. What about the accelerator pump discharge nozzle? Any recommendations on what size to run? Thanks again, Jason.

 

Quite possible I misunderstood the question and as I mentioned I am not an authority; having said that, do recall in swapping 2bbl to Holley 4bbl I connected the 'vacuum advance' to a primary source and found tuning became problematic. I decided to block the primary vacuum port and moved the connection/hose to a metered port, in my case solved the problem. My 4160 operates off a secondary vacuum. Looking forward to more knowledgeable member's input.

 

"Backfire" through the carburetor is a timing issue of some kind, by definition, fuel mixture is firing out of sequence back in to the intake. Check carefully for crossed or misrouting of plug wires causing a plug to fire (induction) out of order or, even wires misconnected out of the correct firing order. You mentioned one plug running black, maybe a dead hole? Have you performed a cylinder compression test? Remember that's the first diagnostic for any tuneup.

 

The plugs and wires have been checked and rechecked many times the firing order is correct, the spark plug wires are also new. We did a compression check a few months ago and here is the results, not the best but satisfactory I believe.

 

I tried to upload picture of compression check numbers but failed. Here are the numbers. 1=120, 2=135, 3=130, 4=135, 5=135, 6=140, 7=140, 8=140.

 

Also the #1 plug is the only plug we removed since all the changes, and this was to set the timing.

 

I'm not sure about primary and metered ports. Is the primary port higher on the carb. on the passenger side? And the metered port at the front of carb. on the base? or vise versa?

 

OK. Re-read through the posts just to refresh.

First thing - you could disconnect and plug the vacuum advance ports for now, for test & tuning purposes. It is an important part of the total package but can be ignored for now, it is not necessary nor even desirable to have connected when setting timing. "Something" ain't right, since we can't see it or be there to check, we can only go by what you describe.

Holley carburetors have had power valve protection since 1992, I don't think that's the issue here anyway. Your initial symptoms or faults seemed to be on track - "a tooth off" - TDC on compression stroke just to be absolutely clear and for those following along - there are two TDC's - compression and exhaust - it is a common error to stab the distributor 180° out. The distributor itself doesn't care, so long as the firing order is correct any one of the terminals inside the cap can be "#1", the factory just picks one and goes with it. Consequently a lot of times it's easier just to rotate the plug wires into the new firing order as required, versus pulling the distributor again.

But it's better to have everything lined up according to Hoyle as it makes troubleshooting easier. Seems to me if it were out of phase this way - the timing light won't be accurate? I get a headache thinking about it. Hm. So make sure it's all zeroed out correctly, it's easier that way.

Compression isn't out of line - except #1 is the low man @ 120 psi., and that's the one running black - oil deposits or black fluffy carbon? Carburetor should work fine when dialed in. One plug reading black points to a specific fault, not a general one. I'd try a different plug, maybe swap wires around and see if problem follows. Could be a bum plug, it's kind of rare, but it happens. Champion? Check wires for proper resistance. Maybe a leakdown test on that cylinder etc.

 

Another diagnostic is engine vacuum at factory idle RPM, a healthy stock engine should pull 18" to 20" steady needle at Sea level. If the timing is way off i.e. late ignition timing it won't do this. It doesn't replace a timing light but problems with ignition timing are easily checked with a mechanic's vacuum gauge.

Also check that distributor mechanical advance timing is smooth both advancing and retarding coming from idle to around 4000 and back down, it should stay tight and focused observing the marks on the damper and not scatter, stick or hang up, or return to a different base setting. Want to see about 34° to 38° total mechanical timing on the damper. With vacuum advance connected it will be around 50° BTDC when engine is spooled up, because there's no load on it in neutral.

Lots of Fords have problems with harmonic balancer slippage, the steel weight is bonded to the basket with elastomeric - rubber - so the weight can lead and lag and absorb crankshaft vibrations. When they get older the rubber dry rots and the weight will slip off its clock - and so do the timing marks. If this is the case then the balancer needs to be replaced (or rebuilt). A vacuum gauge will tell the tale.

Adjust distributor for maximum engine vacuum at factory idle and back off about 1/2" on the dial from there - maybe 1".. should be about optimum for pump gas, and usually corresponds to about 12° or 14° BTDC, bounce that off what the damper sez with a light on it.

Test drive and check for engine knock or ping. Full throttle acceleration etc. If it knocks, back off slightly on the distributor etc. When satisfied, re-connect vacuum advance and then dial the canister advance in with an allen wrench. Head back out and check for part throttle knock or ping. A very light rattle every now and then is acceptable. Keep in mind vaccuum advance is part throttle, low load conditions only, distributor is RPM only, they are completely distinct systems and are adjusted independently of each other for best performance and economy. In other words if it pings or knocks with the the vacuum advance re-connected, don't mess with the distributor timing, adjust the vacuum can.

 

Tedster9 thanks again for your time and effort in helping me out along with everybody else that contributed, I am so thankful. First thing I should point out is this carburetor that my neighbor gave me is from 1987 so it is old but rebuilt. I also wanted to say that at this point I do believe the timing is set correctly and not 180 out. As to the valves, yes #1 is low at 120 and #2 has a rattle tap, we have shimmed it twice, this is a issue we have been working with. The #1 plug is black but I believe if I pulled the other 7 they would be black also because the truck is running rich and even throwing black smoke out the exhaust. I will be replying to your next post momentarily.

 

Tedster9 I really liked this post because it's the direction I have been going towards problem solving this carb. My OTC vacuum gauge should be here tomorrow, I'm so excited to put it to work doing diagnostics. My neighbor says the harmonic balancer is in good shape so for now I will value his opinion on this. You have given several different test to run with the vacuum gauge and I will talk these over with my neighbor, thank you... So much of what you typed out here I have been reading repeatedly on the internet and in the new book I bought on carburetor tuning. Again thank you so much, you guys on this forum are the absolute best!

 

Hm. Well a defective power valve would cause a severe over-rich condition. If all the plugs are fouled, not just a single plug, it kind of points to that - or maybe other flooding issues anyway. In extreme case the excess unburned fuel will tend to cause oil dilution or even wash out piston rings.