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Indianbullet
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Hitting on all eight cylinders
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Last Active: 2 Weeks 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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Daniel Jessup
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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.
Daniel JessupLancaster, California aka "The Hot Rod Reverend" check out the 1955 Ford Fairlane build at www.hotrodreverend.com
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charliemccraney
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To get an idea if your damper is correct, The red line shows the approximate location of 0 degrees.
Lawrenceville, GA
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55blacktie
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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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Ted
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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.
Lorena, Texas (South of Waco)
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Indianbullet
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Hitting on all eight cylinders
Group: Forum Members
Last Active: 2 Weeks 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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Ted
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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’?
Lorena, Texas (South of Waco)
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55blacktie
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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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Indianbullet
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Hitting on all eight cylinders
Group: Forum Members
Last Active: 2 Weeks 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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55blacktie
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I stand corrected on Howard's advertised rpm range; it's 1800-5000, not 2000-5000.
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