PRV is 1969 design. I think that qualifies. Igniting mixture before optimum point in compression stroke (for complete flame propogation throughout cylinder) actually works against HP. Ever notice Volvo's E series (European spec) PRV's are timed 10 degrees BTDC, while dometic F series are timed at 13? That's what companies did to meet US emissions. Reduces HP but gives longer (more complete) burn. "Aggressively" timed cars at weekend tracks are very different creatures than our street rods: *IDLE* at 3000 RPM. Red line close to 9000. Of course they're timed very advanced -- can't repeal laws of physics. Their flame spreads at same rate as ours, but engine us rotating at speeds we can only imagine. Humbly suggest you over advance PRV in your DeLo and observe results. Bill Robertson #5939 >--- In DMCForum@xxxxxxxxxxxxxxx, Jim Strickland <ihaveanaccount@xxxx> wrote: > Didn't we have this exact same argument a couple months ago? > > You may be right about timing for engine made before 1980. I would not > and do not know. > > About "performance engines", you are ABSOLUTELY WRONG. Advancing timing > increases HP. This is how Honda achieves high NA horsepower. Aggressive > advanced timing and high RPMs. > > **Please check your facts twice before replying. Please do not say, "I > know and I'll show you" unless the engine has been designed in the past > 20 years. > > Where's Martin when you need him? > > Jim > > > > On Fri, 19 Dec 2003 05:42:52 -0000 "content22207" > <brobertson@xxxx> writes: > > Most performance engines are timed closer to TDC, not advanced. > > Moving > > spark earlier in stroke lowers power. That's one reason HP killed in > > domestic blocks throughout 1970's: 1969 Ford 460 timed 10 degrees > > BTDC. By 1977 moved to 17 degrees. 1978 (last year 460 in > > automobiles) > > timed 20 degrees BTDC. > > > > If you're "knocking" are two different potential problems: > > pre-ignition and pre-detonation. > > > > Pre-ignition: > > Spark ignites fuel mixture too soon > > Sounds like constant drumming of diesel engine > > Worst at higher RPM's, accelerating, under load, etc > > May be unaffected by octane > > > > Pre-detonation: > > Fuel mixture spontaneously combusts before spark > > Is random, like popcorn > > Worst when cruising > > Usually improves with octane > > > > Pre-ignition can be a timing issue. Lots of higher mileage engines > > have never been re-timed. > > > > Pre-detonation usually indicates something wrong inside combustion > > chamber. Can be as simple as carbon buildup (glows red hot, and also > > reduces chamber volume -- increases compression). I suppose a weak > > coil could cause as well (little or no spark). > > > > If you're knocking on 93 octane, suspect ignition time. Even the > > 11:1 > > engine in one of my Lincolns can be timed to run on 93 alone (no > > octane boost). Interestingly do so by ADVANCING time just a little > > from factory spec. > > > > Is your car difficult to start cold? One thing I've noticed about > > over > > advanced cars is engine has to spin much longer than normal before > > it > > will catch. > > > > Bill Robertson > > #5939 > > > > >--- In DMCForum@xxxxxxxxxxxxxxx, Andrew <aos+yahoo@xxxx> wrote: > > > > Better gas. We have no knock sensor to control this. The new > > ignition > > > > system may also help. What are you going to do for a coil. His > > package > > > > didn't include one. Is it extra and how much. > > > > > > I've got no reason to believe I have bad gas. I'm using 93 > > octane, and > > > only buy major brand names, and not always at the same station. > > I've got > > > a couple of jugs of Sunoco 104 in the garage (for fun weekends > > with the > > > other car). Maybe I should toss a few gallons in the DMC and see > > if it > > > manages to knock with that. That is, if it can even ignite it at > > all. :) > > > > > > I'm not expecting much, if anything, from the ignition upgrade > > stuff. I > > > know a lot of people claim it's snake oil, but since I enjoy > > tinkering > > > with things, and it's fairly easy for me to get over to DMCH to > > pick up > > > the parts, I figured I'd give it an unbiased opinion. Hopefully > > I'll > > > finish the install tomorrow. I ran out of light today. > > > > > > Right now I'm still on the stock coil, which I assume is 20 years > > old. I > > > don't believe it was replaced when the performance engine was put > > in. I > > > plan to leave it as it is for the time being, at least until I've > > had the > > > opportunity to determine what, if any, is gained by adding the > > performance > > > ignition package. After that point, I may well upgrade it. > > > > > > Since I have the performance engine, this may well just be a case > > of > > > slightly too aggressive timing, so backing it off a little may > > also > > be of > > > some help. > > > > > > -andrew > > > > > > To unsubscribe from this group, send an email to: > > DMCForum-unsubscribe@xxxxxxxxxxxxxxx > > > > > > > > Yahoo! Groups Links > > > > To visit your group on the web, go to: > > http://groups.yahoo.com/group/DMCForum/ > > > > To unsubscribe from this group, send an email to: > > DMCForum-unsubscribe@xxxxxxxxxxxxxxx > > > > Your use of Yahoo! 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