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distributor welded no centrifical advance?
I just got my new 351c back from the speed shop and my mechanic welded my plates on my distributor for no advance curve. This concerns me a little. The car starts just fine due to a high torque starter. The advance is set to 32 deg all the time! Is this something anyone has heard of?
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Hey Trularin...
Dave, I talked to Dean on the phone about this and I had no clue wheather or not it is a good thing or a bad thing. Any ideas? Clois |
I don't think that is good. All that advance at low RPM could cause a lot of detonation. Detonation isn't a good thing. What were his reasons for this?
Call someone like George Anderson, Kieth Craft, or Bill Parham and ask about it. I think you'll find the consensus is that you don't want to do it that way especially for a street motor. |
I've heard of it being done with high-compression engines with VERY long-overlap cams. Unless your engine is very radical, like as in it won't even idle at less than about 1,200 RPM and has no power at all below about 3k RPM, I'd get some advance back into it.
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There was another thread just recently, "Vacuum or mechanical advance distributors" where one of the guys (scottj) runs just such a set-up on the street with no problems. Try reading that one.
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I've heard of this before in drag racing applications(Always WOT). In some cases because of the long amount of advance, a retard box is added for starting purposes. (MSD makes one I think). Regardless, I wouldn't recommend this for the street. A lot of advance for low RPM driving. Talk to your builder to find out his rationale.
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Another example of old school, race car thinking on street engines. It doesn't work. A race engine is usually kept above 3,000 rpm, so a fixed advance might work. A street motor spends most of the time under 3,000 rpm where the advance works. Put the mechanical, and vacuum advance back in. Just be sure both are adjustable so engine can be dialed in.
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Re: distributor welded no centrifical advance?
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I've heard of it, I run it that way, and it works...for me. I have ZERO issues with the advance locked. From a drivability standpoint my engine is as "user friendly" as street engines making significantly less power. Whether or not someone else would realise the same benefits that I do would depend on their particular engine combination. Scott |
Full advance
dlampe,
I had my distributor stick on full advance after a big rev and it detonated like you wouldn't beleive until I got it above 2K revs. I wouldn't recomend running the engine like that espscially if it's a streeter. Cheers, Bryan |
If you are running a high enough quality of gasoline so there is no engine knocking using a locked advance has some advantages. Low end power is increased, drivability is improved and you eliminate an area of potential problems (distributor advance). If you have a high compression motor(10-1 or higher) you may be forced to run a mixture of racing gas or you may have detonation issues. Remember, you cannot always hear when your motor is detonating so it would be a real good idea for you to use a 95+ octane mixture with your locked advance if you have this kind of compression. Also, if you have any type of cooling system inadequacies a locked advance may exacerbate the problem. You should have a starter retard or you may brake your starter drive if the motor kicks back as is the tendency with motors with locked advance without the retard feature. -Bob
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You have obviously placed considerable trust and money with the builder of your engine combination. It would be wise to approach HIM directly for an explaination. Every combination is different, although some very valid points have been brought up here. Severe damage can occur, primarily to the ring lands and pistons.
Rick |
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I am going to assume your engine builder specializes in DRAG RACING engines. A race combination, properely set up, will spend most, if not all ,of its time in the power band. When this is the case who cares about 1000 to 3000rpm "streetablilty". Most drag cars that are set-up this way have a timing retard for starting or a push button starter that will allow the engine to be spun before turning on the ignition.
Barry Grant states that with todays 93 unleaded octane fuel, a long duration camshaft, and low manifold vacume , about 20 to 22 degrees initial is required to lengthen the burn time in the cylinder to achieve a complete burn. On a street engine 32 degrees initial seems excessive at best. Brent |
dlampe;
Back in my dirt track days we did this on our car (chevy,sorry) because we had to run a stock distributor..... We were running about 10 to 1 compression and had no problems,but,again,this was a dirt track,strictly race car set-up......Not sure how it would work for street driving,but I think for track only use with race gas you would be o-k.... Later on,we went to 12.5 to 1 compression and had a hard time starting the motor when hot.... what we did was attach an old manuel choke cable to the distributor and left the lock down bolt semi-loose,would pull out the choke cable to retard the advance to start the car,once started,push the knob in to the dashboard and full advance and go........ Not sure I would use this for a street car,instead I would suggest an MSD mechanical distributor...... David |
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