Roll it over to base circle on the cam. Loosen the bolt till rocker flops around. Tighten by hand till it quits flopping. Every turn after that is around 60thousandths pre-load if I remember correctly. Check with someone else in case my memory is b.s.ing me. If you have too much pre-load it will sometimes cause what you are talking about. If you have the early posi-stop type studs you can make it adjustable with washers under the nuts. Crane and Comp both sell these washers and self locking nuts in a kit. Or you can make your own. It really sounds like you have way too much gas and a late spark coming in somewhere. If you don't have wire separators, it can induce a spark from one wire to the next if they lay too close to each other, or if they follow each other for a short distance. Especially if you've nicked a wire somewhere while working on it. ( Never done that one before,,,,,,,)

 

You would have to put checking springs on & get a adjustable push rod, or make one, to check length. It's important the machine shop controls the valve stem heights especialy with non adjustables, otherwise they can be all over the place. Making it difficult to get a pushrod length that will work in all cylinders. You don't want any more than .04 of preload, and you don't want the rocker tip to sweep the valve tip unevenly. You can shim the rockers some, but at some point the geometry will go to crap leading to all sorts of other problems.

 

Just picked up the carb parts and another set of plug wires. I'll run the compression test again this afternoon and try again. Should I try switching to a 3.5 power valve instead of the 6.5?

Could I have a vacuum leak on the underside of the manifold that would do this?

Wouldn't washers under the nuts make the clearance less on the valves? There is already a washer under the studs to make up for the head being milled. Book says tighten nuts to 28 ft-lbs, which is where they are at now.

I will update again soon, off to spin the wrenches again....

 

The 6.5 should be OK. You cant washer and intake to make up for cutting a head. You need to shave the manifold surfaces also. I have the numbers somewhere and will get them to you.

 

First place I looked I found the numbers. If you cut the heads .050", you must cut .037" off the port to head mounting surfaces and .052" off the bottom of the manifold at the manifold to block mounting surfaces.

 

I'm not sure if the heads were prepped correctly or not then. The PO had a machine shop near everet do the work, they came to me assembled and reportedly ready to install... I know the manifold was not milled any, but reportedly they only took 6 thousands off the heads. (.006 right?) With this little being taken down would it cause issues?

I got the cyl. compression numbers:

#1-185
#2-155
#3-185
#4-165
#5-185
#6-175
#7-165
#8-170

All plugs looked to be firing, with dark brown electrodes and insulators. #4 had a light oil film on the threads, all other plugs were dry. #2 seems a little low, but I'm definitely not an expert.

Right now all I want is to get it to run decently, I'll build up a 514 (or more) with the trick parts to drop into it at the beginning of next year when I get my big fat reenlistment bonus from the navy. I just need it to move around under it's own power for now...

Carb parts are supposed to be here this afternoon, I'll try again to fire it tonight after the power valve replacement and backfire protection kit is installed.

Was there a firing order change on the 429/460's at any year? My books only go back to 1973 and there is no 429 info if they were different.

 

#2 at 155 is the lowest and is outside the 15 percent figure (just barely, 157.25 is 15 percent). Not great but I doubt it is the problem. I still think it is a carb problem and maybe a vacuum leak.

 

Just replaced the power valve, carb already had the power valve saver kit installed. Fired it up tonight and still backfiring out the now mufflerless exhaust. Couldn't tinker with it tonight, too late and the neighbors would get pretty hatey. I'll try tomorrow to get it tuned in better, play with the timing some and go from there I guess. I may pull the intake again and see if it was leaking on the underside tomorrow, other than that I guess I start shopping for a full engine rebuild kit and send the heads out to get done over again (right maybe this time...) The only downside is I really don't have the money to do major work to this thing right now. Oh well, maybe it'll just have to sit.

Thanks again to everyone who has offered their advice, I now know more about holley carbs than I ever really thought I would need to. I really appreciate the advice, if this thing ever runs right I will be the first to let you know what it was.

 

When you get back to the engine. First disconnect and plug all the vacuum hoses coming off the intake and carb. See if it runs better. I had a bad PVC valve this last year (second one in 40 years), made the engine not idle right(to fast and rough) and run like crap. Then try spraying WD-40 aound the carb base while running and see if that improves things, I installed a carb last year after a rebuild with a new gasket and it ran worse than before. The gasket in the kit was the wrong one and leaked.

 

O.K, I'll give it a try.

 

my next thought would be to start pulling plug wires one at a time to figure out which cylinder (or cylinders) are actually doing the backfiring....then you know which valves to check......BTW, you didnt mention if you set the floats or not............

 

Tried to run with all vacuum ports plugged except for the gage and with pcv disconnected, held about and extra inch of vacuum (maybe due to no power brake booster hooked up while feet are on the brake?), but still backfired.

Floats were bench set, checked after running when I shut the engine back down and checked they were almost dead on with just slight dribbling out of the bowl screws. I haven't been able to check with the engine running since I am working alone and I can't get the truck to stay running without holding rpm close to 2k on the tach. Is it better to be a touch high or a touch low?

I just picked up intake manifold gaskets, a tube of the permatex version of gasgacinch, and rtv blue for the end caps. So down I go to pull the intake off and try that. One of these times I will find it...

Another thing I noticed is it seems to be worse with the truck cold, backfiring is less after reaching operating temp (but still pretty bad, just less regular).

I won't be able to fire it tonight since it is kind of loud for my apartment complex, but I will post results tomorrow afternoon. Thanks again for the suggestions.

 

Of course it is worse when cold, the choke is on causing an even richer mixture. You know I'm only about 40 miles away and being retired I do have some time available. With the right invite I just might see my way clear to come beat on your engine with my big hammer.

 

I would be thrilled to have you bring your hammer and give it a whack. The intake is back on, everything should be set to fire tomorrow. I guess this is the last go without getting professional help, or at least much more experienced help.

My carb is a manual choke, even when the choke is off it is worse.

I will post tomorrow afternoon, if it is still a no-go, I'll shoot you a pm Bear 45/70. Boy am I glad I joined this site!

 

not to get off topic, but what rate are you hotrod??


AT2(AW) here, i used to be in Whidbey before cali.


just curious