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By PF Arcand - 8 Years Ago
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Yes, re check your timing.. Also what Distributor are you using? If by chance it's a 1957-58 distributor, John Mummert says they have too much centrifical advance built in, as the intention those years was to use only about 3* initial. He recommends using the later didtributors with a cammed engine, because of the need to run more initial..
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By aussiebill - 8 Years Ago
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usual to hear valves banging closed with pipe headers.
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By miker - 8 Years Ago
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Back in the late 60's I had a 0.40 over 312 with 11:25 : 1 Jahns pistons and an RPM300 Isky cam. It required the "white pump" scrubron fuel, guaranteed to be 102 octane, but generally ran around 105. It was before unleaded fuel and comparable to Sunoco 260 or something. Mainly race fuel for the high compression muscle cars. That was a 900-1000 rpm idle, and it would diesel and knock like hell on any lower grade premium. Much like you describe. I could clutch it dead since it was a stick.
I've had limited success with octane booster on an OT supercharged motor. But it only knocked under heavy continuous load in warm weather, after you built some real heat in the aluminum head. Taking 2 degrees of initial timing out of it had the same result. It's a comparable experience, but not a comparable motor.
Check out Charlie's comments on the mechanical advance, that might help.
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By DryLakesRacer - 8 Years Ago
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I'll never claim to be an expert, but contrary to popular belief most high performance parts are not ready to go out of the box. Domed Pistons are the worst. Guys and shops just don't seem to want to touch them. All sharp corners, edges, etc must be smoothed out. The edge around your cylinder head chamber also especially after a slight milling. I'll always knock it down with a die grinder and follow up with emory. The top of the bore too.
You don't say if your using an automatic trans and if you are shut off the engine in gear. DON'T let it diesel at all. Back in the day if I had an engine that did it I immediately turned it back on. You can always kill it with the clutch with a standard trans but that's no good either. Right now it sound like you have some hot spots making like "glow-plugs".
I would also look to the center carb as lean at idle. Jetting usually won't have much to do with that. 11-1 is tough on the street without aluminum heads or a computor controlled ignition system. As a thought some racing gas around doesn't hurt. I can buy Sonoco from our local circle track supplier in 5gallon cans and 1/2 gallon of leaded 112 octane can work wonders. Sure makes my old Harley come alive. . . . Good luck.
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By Dobie - 8 Years Ago
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It appears to only apply to computer controlled cars per the instructions.
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By 57RancheroJim - 8 Years Ago
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I think you are really pressing your luck. I would never consider running that kind of compression on todays crap fuels. I doubt any of the snake oil is actually doing much good. Remember that not all detonation can be heard, especially if you have headers. If you can hear it you have the worst condition, but it can also be happening that you can't hear.. So whether it is PING PING PING or ping ping ping eventually it will be KABOOM
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By 30 coupe - 8 Years Ago
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there is one other thing that could cause " dieseling" upon shutting the eng. off, and that is that the idle may be to high. what I mean by that is that the carb throttle plates may not be completely closed. this can cause the problem. Just another idea that I am sure you have not over looked, but I thought I would throw it out there.
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By 30 coupe - 8 Years Ago
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Nathan, yes that is what I am talking about. this is a common problem with some of the older cars when the throttle shafts get worn, they bind and do not let the throttle plates close completely. this leads to the detonation/dieseling when the eng is shut off. I am not saying that your carbs are worn out, only that the throttle plates may not be closed when you shut the engine off. if your problem occurs not only when the eng. is shut off, but also has pinging under load , then you probably have the problem that the others are trying to help you address.
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By NathanxStewart - 8 Years Ago
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Question about what detonation sounds like. At idle I hear a lot of pinging noise but when I put my ear up close to the noise it's he headers making that noise. I read that detonation will sound like a pinging noise or bacon frying in a pan. It sort of sounds like that. Is this detonation or is it just the manifolds/headers making the noise? It's been doing this since I've started the freshly built engine up and I have over 3,000 miles on it now. I'm thinking it's just the headers making the noise. Thanks!
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By NathanxStewart - 8 Years Ago
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Okay, would it affect performance any? Would it be a noticeable difference?
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By NathanxStewart - 8 Years Ago
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And would it be a constant rattle noise? Or just here and there?
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By NathanxStewart - 8 Years Ago
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Okay I think it's just my headers making the noise. Cause if I put my ear up close to the header I can hear the pinging noise and it does it on both sides. This also while it's idling. I'm also not having any performance issues at all. So the engine would shut off if it were to detonate?
The only reason I was curious about it detonating is cause yesterday when I shut it off the engine dieseled. And I read that detonating would make a pinging noise. I have to run an octane booster in this engine otherwise it'll diesel. The engine dieseled yesterday after I shut it off and I had just filled it up and put the booster in. That's why I was confused about why it dieseled, I'm guessing it just had a little bit of a bad mix maybe? Cause I've driven twice since then and it hadn't done it. This might be a dumb question but if an engine diesels that doesn't mean it's detonating right?
Thanks for all the advice!
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By NathanxStewart - 8 Years Ago
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Well let me get your opinion about this, when I first got the engine running it started dieseling. So I started using a Lucas Oil Octane Booster, the diesling stopped, I've put over 3,000 miles on the car. The only time it's ever dieseled on me is when the fuel mixture is off or sometimes if I'm really low on gas but hardly ever. The carburetors (3X2 Fenton Intake, 2110's Holleys) are professionally built, specifically to my set up. Timing is correct, havent checked it in awhile but probably will again. If it was detonating since day one it probably would've already done the damage and hurt the car by now right? Do you think continueing to use the octane booster is the solution? It's been running fine and doesn't deisel when I run the booster
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By NathanxStewart - 8 Years Ago
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Bottle says "don't be fooled by misleading advertising. It takes 10 octane points to equal 1 octane number." It also says it treats up to 25 gallons. It doesn't say how many points it increases the octane. But I see where you are coming from. I've been buying cases of the booster, the big bottles from napa. My Napa guy gives me a great deal on it, $78 for 12 bottles. They sell the bottles $11.99 retail and its $143 for the case retail. I'm able to divide the bottles up each fill up so they last longer. Yeah it's kind of annoying I have to do that but it's not too bad. I always keep the bottles in my trunk and have plenty with me before I go on a trip. Do you think the booster is bad for the engine? This Lucas oil booster seems to work great, I've tried other boosters and it didn't do anything. Engine still continued to deisel. Never does it with the Lucas booster.
I have not checked to see if the carbs are jetted correctly, I can look into that though. They seem to be pretty good, engine is very responsive when I stab the throttle. Plugs are reading good as well, all of them are brown. But they could possibly still need some fine tuning. Cause we were told with my set up, all the engine parts I had and compression ratio that I should be able to get away with running high octane pump gas. But it doesn't want to run on just normal high octane pump gas.
I can't remember exactly all the timing specs, I was planning on going over to my grandfathers tomorrow and use his timing light to check all of that. I do remember that total advance is 36 degrees and it's at 16 degrees at idle. We talked to one of the techs at Clay Smith Cams where I got my cam from and he said that's where it should be. He knew exactly what cam I had in the engine and everything.
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By NathanxStewart - 8 Years Ago
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Okay, and yeah it was just filmed on my phone haha.
That's kind of what I was thinking. What could cause carbon build up? Bad gas? Should I maybe run a fuel cleaner?
https://lucasoil.com/products/fuel-treatments/lucas-oil-deep-clean-fuel-system-cleaner
Says it removes carbon deposits
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By NathanxStewart - 8 Years Ago
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Ahh okay I see. This car is plenty powerful for me hahah, so I think I'm going to leave it alone.
The octane booster seems to solve the issue. Thanks for your time and all of the advice Charlie!
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By NathanxStewart - 8 Years Ago
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If you can't hear it then how do you know it's detonating? Just by the engine losing power? I have my headers plugged and the exhaust running out back
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By NathanxStewart - 8 Years Ago
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Oh awesome! Didn't know there was such thing. So if the green LEDS light up that's at mild detonation does that mean it's fine? Or do you not want the lights to light up at all?
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By NathanxStewart - 8 Years Ago
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Just read that as well Dobie
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By NathanxStewart - 8 Years Ago
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Just uploaded a video of the engine running on YouTube. There's kind a of tick/ping noise but I'm pretty sure that's just the stainless steel headers making that noise since the headers are capped off. It's been making that noise since day one. Had these headers on a 272 and it made the same noise.
Let me know what you guys think!
http://youtu.be/8Dxi_mMhxNU
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By NathanxStewart - 8 Years Ago
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There's some carbon build up on the pistons, could that cause dieseling?
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By NathanxStewart - 8 Years Ago
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I do have domed pistons, they are forged. I got everything from john mummert, he put the whole kit together and said all of those parts would be great and etc. I'm using a WC T-5. It deiseling is never a common problem. In the past when it had desieled, it's because my fuel mixture was off, added some of the Lucas Oil Octane booster, never did it again. Plugs aren't showing any signs of it being lean at all. I've been wanting to run some racing gas through it, but unfortunately it is a little difficult to get it around here. Have to travel atleast 20-25 miles to get some.
Thank you for the advice!
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By NathanxStewart - 8 Years Ago
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Hm that's a thought about the carb plates not closing all the way. When it's idling it's at 1,000 rpms. Which is where it likes to be considering the cam I have. But maybe sometimes the carb plates don't close all the way and is allowing fuel to get in the cylinder walls and then ignites it since it's hot? Is that what you're thinking?
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By NathanxStewart - 8 Years Ago
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I'm running a '62 distributor
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By NathanxStewart - 8 Years Ago
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Charlie, I forgot to mention that it is 36 degrees total advance at 4,000 rpms. Also forgot to mention I am not running vacuum advance, couldn't get it to run right with that hooked up. And these timing controls... are you talking about the timing gears that have 9 slots in them? Cause that's what I have.
But do you think if I keep running the octane booster then it's fine? Ever since I started using the octane booster it quit dieseling. And you mentioned that if it were detonating it would lose power. Well this thing is a handful and hasn't skipped a beat yet. Id rather not tear down the engine and mill the dome pistons down.
Basically the reason it has deiseld in the past was because the timing was off and cause it didn't have high enough octane in it. Well we got the timing squared away and I started running the booster and it's be fine. What do you think Charlie?
Thanks again!
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By NathanxStewart - 8 Years Ago
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Miker, yeah mine pretty much just doesn't want to run on 93 octane. But with the Lucas Oil Octane Booster it quit doing it and had been fine for 3,000 miles. If the engine were to fail or detonate, probably would've done it by now right?
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By NathanxStewart - 8 Years Ago
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Thank you Aussiebill, that's kind of what I figured!
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By charliemccraney - 8 Years Ago
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It is typically just here and there, rather than a constant noise. However, if the engine is under load for a long period of time, like when climbing a big hill, it could seem constant.
Detonation will affect performance. At the very best, power is reduced because ignition takes place sooner than it should. However, in gasoline engines, it typically leads to engine failure if it is not addressed.
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By charliemccraney - 8 Years Ago
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The engine does not shut off when detonation occurs. It will detonate until it destroys itself, at which point it does shut off, for good.
Dieseling is detonation. You need to fix that. It could be as simple as a tuning issue. It can also be a mechanical issue like too much compression, which is a more involved and expensive fix. In your oil pressure drop thread, you stated that you have 11:1 compression. This is usually far too much for pump gas and can very likely be the reason.
The only way you will achieve 11:1 with a 314ci Y Block and iron heads is with domed pistons, which is sort of good news, as you will only have to mill the domes to reduce compression and then have everything balanced again. It should only be machining required, rather than new parts.
If you have not spent much time tuning, then you also need to do that. Spark plugs which are too hot can also cause detonation. Sharp edges can cause it; if cylinders or combustion chambers are not chamfered or beveled after milling, it can be a source of hot spots.
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By charliemccraney - 8 Years Ago
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Re octane booster, there are a couple things I would call problems about using it. First, read the bottle. The front always has something flashy like "Increases octane 10 points!" Read the back, and what you will see is that each of their "points" is a fraction of a point you see at the pump. For this hypothetical, lets say 10 of the octane booster points is equal to 1 point of the number you see at the pump. So assuming that 93 octane is premium in your area, the octane booster makes it 94, rather than the 103 you thought it was if you did not read the bottle.
Now the problems. If that 1 point in octane is the difference between detonating and not, then you are on the ragged edge of what street gas can support. If you ever need gas at a station that has 92 octane, then you will be in trouble. A second problem is a reliance on octane booster. What if for some reason none is available, or all that is available is not as good? How about the increased cost of enjoying the vehicle?
RE the carburetors, have you checked that they are jetted correctly? A pro builder who knows what he is doing and has all pertinent information about the engine absolutely should be able to get them in the ball park. But only once they are on the engine can it be determined if they are right or still need fine tuning.
RE timing, what is the initial timing, how much mechanical advance does it have and at which rpm does it get full mechanical advance?
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By charliemccraney - 8 Years Ago
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If the distributor is only providing 20 degrees of mechanical advance then it is not configured to any factory spec so it is probably not providing too much advance. It might be possible that it is advancing too quickly, though.
If the carb plates are hanging open, you would know because the idle rpm would be higher in that situation. If it is always 1000RPM, then that is not happening. On many entry level carbs, 1000rpm may be too high for the typical method of adjusting idle speed and requires a different method. what happens is that it will idle of of the main circuit rather than the idle circuit. I don't know about Holley 2110,s so I do not know if that actually could be a problem with those.
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By charliemccraney - 8 Years Ago
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Miker made me think of a possible band-aid fix. There are timing controls that allow you to adjust timing on the fly. That might help you adjust to different fuels. However, it will be at the expense of performance and given the cost of timing controls, it could be more expensive than simply addressing the issue and fixing it correctly.
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By charliemccraney - 8 Years Ago
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I mean something like this, https://www.summitracing.com/parts/msd-8680
Your timing is coming in slowly, which is leaving some performance on the table but it may be helping you prevent worse detonation.
If you are comfortable with a reliance on octane booster and it does solve the issue, then keep using it.
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By charliemccraney - 8 Years Ago
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If it is really mild, you may not hear it, and won't notice anything immediately.
There are gauges to monitor that, https://www.summitracing.com/parts/cei-102001/overview/.
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By charliemccraney - 8 Years Ago
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The instructions say for all others an ESC module is required, whatever that is. So it seems that there might be a way to make it work if you get a knock sensor, ESC module and gauge. If it's something you want to consider, contact the company about it. Another, much more diy way to do it is to get an '80s or 90s gm computer and knock sensor, and whatever else might be required, along with a laptop and TunerPro RT, and you can watch the knock count in real time - you're on your own, as far as a Y-block site goes, figuring that one out.
I don't necessarily hear anything bad in the video. Sound quality is not great. Nothing is jumping out as bad. What I hear sounds typical of a solid lifter engine and that is what a Y Block is.
Carbon build up increases compression, which will cause it to knock if it is bad enough. On a new motor, that does not seem right.
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By Ted - 8 Years Ago
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Most detonation is heard when the engine is in a load whether it be part throttle or full throttle. Detonation typically sounds like loose nuts being rattled around within the engine.
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