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1986 Ford Bronco, 351w with edelbrock aluminum top end and holly 600.
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Discussion Starter #361
I’ve also noticed that after blipping the throttle it take an unusually long time for the idle to come back down. Clue.


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The Tennessee Warden
96 XL, 5.8L, E4OD, BW1356, 4.56 gears
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2,953 Posts
That could be your issue. Did you soak the lifters in oil overnight before installing them? I know you don’t want to remove the intake again, so here’s what I would do:

If you have an old valve cover laying around (or even better, two) take a cut off wheel and cut a rectangular hole out of it so you would be able to reach all the rockers with it installed. Remove all the vacuum lines and cap them at the carb, except the vacuum advance on the dizzy. Back the rocker bolts off until they are loose, but not so loose that the rocker will come off the valve when it starts running. Crank the engine and let it build oil pressure. Then, while it’s running, start torquing down the rockers. You will “feel” when it’s right because you can feel the tapping in the wrench and as you tighten it, it will go away. Get them close by feel, and then shut her down. Set the lash.

This job is messy, oil may squirt out of the rockers and may get on your headers and burn off.

If you don’t have any spare valve covers, then go in and loosen all the rockers and put your covers back on and let it run for a few minutes. It will sound terrible with all the tapping due to the loose rockers, but just let it run for a minute and build oil pressure. Then, after a few minutes, remove the covers again and set the lash. Then reinstall the covers for hopefully the last time!

This is the way I did it on an old 302, wrong or right, it worked.
 

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The Tennessee Warden
96 XL, 5.8L, E4OD, BW1356, 4.56 gears
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2,953 Posts
@MS88Bronc what was your timing at with that cam?


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I don’t remember what the timing was set at - I was experimenting a lot back then with different timing settings. It was more of a trial and error thing for me. I’d set the mixture screws, idle screw, and timing and try it. Adjust it again, and try that. I did that until I found the sweet spot, and I can’t remember what that was. I’d probably start around 10° and advancing it until you start hearing spark knock under load while driving, then back it off 2°.
 

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1986 Ford Bronco, 351w with edelbrock aluminum top end and holly 600.
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2,138 Posts
Discussion Starter #365
I’m going to back all the rockers of 1.25 turns and run it and then check lash again.


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Ultra Premium Member
1996 EB w/5.8 TOO much lift, 44" Mudders & 5:43-5:38's
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4,461 Posts
I never install my lifter dry, I use an oil can and pump my lifters up from the hole in the side until it comes out the top hole.
If you didn't pump up your lifters, I might pull the distributor and the valves covers and spin the oil pump until all the rockers get oil.
As far as timing goes, I would skip base timing and make sure you have 32°-34° at full advance with vacuum on the distributor unplugged.
Just my $0.02
 

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1986 Ford Bronco, 351w with edelbrock aluminum top end and holly 600.
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2,138 Posts
Discussion Starter #367
Thanks @cobra

Redoing the valves helped a bit.

Fiddling with the timing helped a bit.

Adjusting idle screws helped a bit.

Turns out I have a pretty good intake leak against the head on the driver side. Not into pulling the intake right now so I just hit that seam with a bead of the right stuff. That helped as well an will do for now.

I’m at about 15-16 on the vac gauge and at 700-800 rpm in park it’s running good.

I have a fair amount of rumble going on - shakes the hood and tires! But I think that it is the cam at this point because it is consistent and throttle response and power are great right off idle.

I’ll probably need to do jets or I may just pull the trigger on a sniper.


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Addicted to Junk
85 Bronco, 309ci I6 w/4bbl, np435, 4" lift, 37" Irok NDs, 4.56 w/ Detroit Locker and tru trac
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11,551 Posts
15-16 is still a tad low for that size of cam. Not terrible though

What power valve are you running? What jets? This is a 4bbl Holley right?
 

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The Tennessee Warden
96 XL, 5.8L, E4OD, BW1356, 4.56 gears
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2,953 Posts
Glad you got er running. I’d still play with the mixture/idle/timing a touch and see if you can find a sweet spot. I liked to run it a little richer than stock but not so rich it would throw black smoke at WOT. I would adjust the idle so that it would be at about 600-650 at idle in drive. It would shake the car and it was badass. To each their own, but that’s what I did.
 

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Addicted to Junk
85 Bronco, 309ci I6 w/4bbl, np435, 4" lift, 37" Irok NDs, 4.56 w/ Detroit Locker and tru trac
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11,551 Posts
Yes, 600 Holley 4B.

Primary Main jets 66
PV 6.5



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That all seems fine to me. I'm running a 6.5 PV at 17" of vacuum. And I think 52 or 54 main jets on my 450.
 

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1986 Ford Bronco, 351w with edelbrock aluminum top end and holly 600.
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2,138 Posts
Discussion Starter #373 (Edited)
So over the past few days I’ve been checking the bolt torque in the intake bolts. Each day after running it I was able to get another 1/4-1/2 turn or so on the intake bolts to 18lbs - specifically the middle ones on the driver side. I think I’ve pretty much eliminated the intake leak and I’ve noticed a much smoother idle. It still has a little rumble but much much better.


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1986 Ford Bronco, 351w with edelbrock aluminum top end and holly 600.
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2,138 Posts
Discussion Starter #374
Changed to oil today at 100 miles. Torqued the intake bolts and got a smidge more out of them. Set my idle to 700, timing to 10, and I’m pulling 16 steady inches. I’m good with that. Cheers!


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1986 Ford Bronco, 351w with edelbrock aluminum top end and holly 600.
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2,138 Posts
Discussion Starter #375
So I read a little more and since I trapped at home during coronageddan I did a little more tuning. Put the vac gauge back on, pulled the advance valve and plugged, warmed it up, and advance timing to about 19 on the vac gauge and could get no more. Retarded back to about 17.5 vac and it looks like I’m about 14-15 on the timing. Adjusted my idle jet screws a bit and set idle at 700. Drove it and no ping. I’ll stay there awhile and listen for any ping. I’ll also check my advance timing like Cobra mentioned in the near future.


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