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By Indianbullet - 2 Months Ago
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Looking for some feed back here as I know there are lots of good minds on this site.
I have rebuilt a 292 with a 312 crank, mains ground down, stock 312 rods. Engine has G heads Mummert intake, valve train, and Ramhorn exhaust, also running a new pertonix flamethrower distributor and an Edelbrock 500 cfm carb.
Issue is I'm at 30* initial timing and pulling only about 13" of vacuum. I'm at 600' elevation. I can't get more advance unless I restab the distributor due to vacuum advance hitting the manifold, and I think it would run better if I did, but dam...
I'm having no starter drag where its at, it runs good, starts good, temp is good, but I'm coupled up to a T-5 transmission and don't have much pull at all in 5th gear, rpm is under 2k at 70 mph with a 3:73 rear gear. Overdrive gear is 0.63 so I don't feel it should be too tall. Only have about 20 miles on her now, btw its in a 56 F-100
Cam is a Howards 292002-10 advertised lift of 0.463 and 255* duration gross lift at cam of 0.315 and 219.8* duration @ 0.50. 110 lobe separation, 106* intake center line. Valve lash is now at 0.020, card request .022.
I'm almost thinking dampener dude may have put my dampener together a bit off. But during assembly TDC was correct with my timing mark. Thinking of stabbing the dist back in with timing mark at 10* and rotating a tooth back to get some manifold clearance for the vacuum advance canister, and see what it does with even a bit more initial timing. No sign of pinging where its at now but it just seems extreme to me. I know these engines love some advance. But what the heck?
Timing set is also true roller from John installed straight up, per instructions.
Yes vacuum advance was plugged off when timing and it's to ported vacuum on carb.
Anyway thanks in advance for any thoughts and feed back.
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By Daniel Jessup - 2 Months Ago
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The first part of your post says you are at 30 degrees initial timing - at what RPM?
It sounds like you definitely need to pull the distributor out, get your damper pulley mark to TDC on the compression stroke for #1, and reinstall the distributor. Ensure that the rotor is set to fire to on #1 cylinder.
Plug the ported advance line to the carb, fire up the engine, and break out the timing light to get your reading. You will not be warm enough to give a full tune, but you will have some indication of where you are at.
Y Blocks do respond well to quite a bit of valve lift and ignition advance. Even 12-14 degree initial is not out of the question for an engine in good condition with some performance upgrades like yours.
For any performance cam the vac reading will vary depending on overlap and valve lash. I would recommend that you put the lash at .022 - anything tighter than what the cam manufacturer recommends will give vacuum readings that will incrementally lower the tighter you go.
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By charliemccraney - 2 Months Ago
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To get an idea if your damper is correct, The red line shows the approximate location of 0 degrees.
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By 55blacktie - 2 Months Ago
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Indianbullett, I bought the same Howard's cam, but it's still in the box. I would very much appreciate hearing from you once you have everything sorted out; please let me know if you're happy with the cam.
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By Ted - 2 Months Ago
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Are you using a conventional or ‘Dial Back’ timing light? There are lots of issues around the accuracy of the timing lights with the adjustable timing feature or a dial. I have the best results using the inexpensive timing lights that simply use a pair of ‘D’ cell batteries for the power source. The older Penske or Sears timing lights also seem to retain their accuracy better than some of the modern high tech timing lights.
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By Indianbullet - 2 Months Ago
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Thanks for the response guys,
30* initial timing is at about 650-700 rpm. Distributor installed with timing mark at TDC, rotor ready to fire #1. Engine lit right off, did cam break in ect.
Ted the light I'm using is my 40 year old craftsman dial back light. God knows it's been abused.
I will reference the keyway on the dampener.
Blacktie, the cam seems to work well with my setup Idles with just a mild bit of a chop, pulls good through the gears, like I said I only have about 20 miles on it. I am kind of concerned about being able to pull off of the 2000rpm mark in 5th gear, not happy with that at the moment. Foot to the floor and no pull, advancing timing did help, hence the reason I want to poor a bit more too it, as I'm not getting any indication of ping at this point. I may try the lightest set of springs in the distributor to see if that helps, it has the medium in it now as I recall.
It may be a few days before I can back on it. but I will keep you all posted.
And thanks again for all your feedback.
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By Ted - 2 Months Ago
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I would check your timing light against a known good one.
Was the camshaft degreed in or simply installed at 12 pins between the marks?
How much total ignition timing? And at what rpm is the distributor timing ‘all in’?
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By 55blacktie - 2 Months Ago
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Indian, you probably are aware that Howard's advertises an rpm range of 2000-5000 for that cam. It could be that you simply need to downshift to 4th to bring the rpm up. I've not owned any vehicle with automatic overdrive that didn't immediately shift down whenever applying just slight pressure on the pedal. Years ago, my dad's 63 pickup (won't mention make) with 3-on-the-tree manual and overdrive would do the same. In your case, it requires a little more effort. With just 20 miles on the clock, maybe you just need to give it a bit more time. I would expect at least 14 inches of vacuum, but your elevation might be enough to bring it down an inch. Nevertheless, keep us posted.
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By Indianbullet - 2 Months Ago
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Ted the roller timing set from John has provisions for dot to dot straight up alignment as in most engines, as well as the ability to confirm and count 12 pins. It was not degreed. I can't tell where the timing is all in at as my tac is in the cab, and I'm by myself.
I'll try to hit up a friend and see if he has a dial back timing light I can confirm against. I've got some work to do for sure.
Thanks again.
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By 55blacktie - 2 Months Ago
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I stand corrected on Howard's advertised rpm range; it's 1800-5000, not 2000-5000.
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By Indianbullet - 2 Months Ago
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Welp, looks like I found another problem. Pulled the Distributor so I could reposition it to have more clearance for the VA. as well as put lighter springs in it. And found this. Looks like the bottom bushing is eating the housing of the distributor? Needless to say I'm not pleased at what could be circulating through my brand new engine. Lots of end play, and some lateral movement. Needless to say it won't be going back in. I'll be calling Summit and Pertonix tomorrow.
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By 55blacktie - 2 Months Ago
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The original Ford distributors don't have a bottom bushing, although having one should be an improvement over the original design. Other than that, all I can say is That Sucks!
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By Brent - 2 Months Ago
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My FBO Ignition setup calls for:
14° initial timing at idle with no vacuum
Full (not timed) manifold vacuum adds 16° at 16” = 30° at idle
at 3400 rpm 22° = 36° all in
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By Ted - 2 Months Ago
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It’s good that you caught that distributor issue now instead of just a few miles down the road. Extended running like that does force some additional wear at both the distributor gear and the gear on the camshaft.
It’s always prudent to measure both the distributor block cavity depth in the block and the gear placement on the distributor to ensure that the distributor gear placement is not more than the block measurement. I have come across my share of Ford V8 distributor block cavity holes that were less than specification and that does force the distributor gear to be relocated in order to compensate. The 351W engines seem to be the worst of the lot but have come across the problem in the 460 Fords and the Ford Y-Blocks to a lesser degree. What few Pertronix distributors I have dealt with for the Ford Y have always had the gear located at the Ford specification but….. if that hole in the block is on the shallow side, then the distributor gear will have an interference fit or said another way, will be in a bind when the distributor is tightened down. As a FYI, the MSD distributors for the Ford Y have always had the gear placed on the shaft at an amount less than the Ford specification and I suspect this is to compensate for those blocks that may have a distributor cavity hole that is less than factory specification.
Just food for thought and something else to check.
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By Indianbullet - 2 Months Ago
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Yeah, Ted I measured it against the original 56 distributor, and just did again and they are both 5" from the base. Gear width is the same, diameter is the same.
Here is a photo of the gear mesh.
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By Indianbullet - Last Month
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Sorry to take so long to get back to this thread, but life happens. I got a new distributor and installed it with 2 gaskets under the flange where it snugs to the block, giving me about 050 additional clearance from where is bottoms into the boss in the bottom of the block.
Repositioned the distributor so the advance won't come up close to the intake as well. I got a cheap HF dial back timing light to compare to my old Craftsman and it checks out the same. Odd thing is it's running good now with about 15* initial, and I may roll a few more * into it. But weather sucks so I can't get it out and drive much I need to adjust the valves again as well.
I dumped the oil, I only have 35 miles on it, but wanted to get any aluminum out that the distributor had shed into it. I cut the filter open and lt caught a good portion of it. I did have a LOT of glitter in this oil dump, but I attribute it to everything being new and finding its home. I still don't like to see that much. I filled it up with more driven break in oil. So time will tell.
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