Total timing with 10.5:1 Compression

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Re: Total timing with 10.5:1 Compression

Post  jgkurz on June 9th 2015, 11:17 pm

The loaner carb is actually a Holley 670 Street Avenger with 65's in the primaries and 68 in the secondaries. I still think it's a good test to swap out the Edelbrock. Any suggestions on primary and secondary jets as a starting point for my 429?

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Re: Total timing with 10.5:1 Compression

Post  kim on June 10th 2015, 12:11 am

That's the beauty of the carb........... until you get into most of our race set-ups where we are running free air flow, and the carb is getting WAY less than 13 hg of vacuum, a 450 to 650 to 850 running above 13hg of booster signal is going to pull the same fuel on a 302 to 460 cu in engine. The higher the signal, the lower the jet you need to apply fuel.... the lower the signal, ie BIGGER carb, the greater the surface area you need. Sooo odds are the 670 cfm carb, if it was doing good on whatever its coming off of, will do well for you.

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Re: Total timing with 10.5:1 Compression

Post  supervel45 on June 10th 2015, 12:13 am

The 65/68 jets are stock, so I would try them first. If it seems lean I would put the 68's in the primary's, and try 70's in the secondary's.

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Re: Total timing with 10.5:1 Compression

Post  78ranger on June 10th 2015, 11:37 am

Couldn't say if it is the carb or not, but can give you some advice on it. I've used the eddys on smaller displacement engines with decent results. Not so much the big blocks. We messed with a 1411 on a 460 that did kind of the same thing. It's calibrated very lean of the shelf. Jetting will help. What we found was at wot the fuel bowls were draining and it would go super lean after a few seconds wide open, start pinging. A change to the high flow needle and seats cured that. But the carb never made good power. I would try the different carb and if it's better, consider how much time and money you want to put in that thing to make it run "okay". Or bag it and put in a more suitable carb. Good luck.

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Re: Total timing with 10.5:1 Compression

Post  jgkurz on June 10th 2015, 12:24 pm

78ranger wrote:Couldn't say if it is the carb or not, but can give you some advice on it. I've used the eddys on smaller displacement engines with decent results. Not so much the big blocks. We messed with a 1411 on a 460 that did kind of the same thing. It's calibrated very lean of the shelf. Jetting will help. What we found was at wot the fuel bowls were draining and it would go super lean after a few seconds wide open, start pinging. A change to the high flow needle and seats cured that. But the carb never made good power. I would try the different carb and if it's better, consider how much time and money you want to put in that thing to make it run "okay". Or bag it and put in a more suitable carb. Good luck.

Your situation sounds very familiar. I will be trying a borrowed Holley Street Avenger 670 in the next day or so. I'm going to jet up from the default 65/68 to 68/71 or 70/73. The 70/73 would probably be a little rich but I would be more confident in eliminating any lean condition during testing. If the carb is the issue I'll tune whatever carb I end up keeping to the proper AFR.

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Re: Total timing with 10.5:1 Compression

Post  DanE on June 10th 2015, 1:59 pm

Many business work at improving carburetors, but unfortunately, at Edelbrock, it is the bean counters that have been working the carburetors over. Sad

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Re: Total timing with 10.5:1 Compression

Post  supervel45 on June 10th 2015, 2:55 pm

jgkurz wrote:
DanE wrote:As has been said before, your carb is probably the problem.

Respectfully, I really want to believe this but I have changed jets, metering rods, fuel pressure and didn't see any real benefit. Trust me, I would MUCH rather deal with a carb issue than a new engine build. Given that 100 octane fuel was the only change that made a significant difference, I am thinking my last option is to verify the timing mark. If it's correct then I need to make some major changes on the engine to resolve. Please elaborate on what more I should do on the carb. The engine is a slightly warmed over 429. I can't imagine the 750 Edelbrock is not enough and that I am running lean. My plugs are a nice brown color but the car spends most of its life under 3500RPM where it runs well. Maybe I'll borrow a Holley from a friend and see if it does the same thing.
When you try the Holley don't forget you really don't know if the timing mark is accurate. I don't see why you don't keep pulling timing, and see what happen's? Also if the fuel pressure guage is not visable from the drivers seat you can't see what it is doing at full throttle. You could have a clogged fuel tank sock, and it would not show without load.

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Re: Total timing with 10.5:1 Compression

Post  jgkurz on June 10th 2015, 3:01 pm

supervel45 wrote:
jgkurz wrote:
DanE wrote:As has been said before, your carb is probably the problem.

Respectfully, I really want to believe this but I have changed jets, metering rods, fuel pressure and didn't see any real benefit. Trust me, I would MUCH rather deal with a carb issue than a new engine build. Given that 100 octane fuel was the only change that made a significant difference, I am thinking my last option is to verify the timing mark. If it's correct then I need to make some major changes on the engine to resolve. Please elaborate on what more I should do on the carb. The engine is a slightly warmed over 429. I can't imagine the 750 Edelbrock is not enough and that I am running lean. My plugs are a nice brown color but the car spends most of its life under 3500RPM where it runs well. Maybe I'll borrow a Holley from a friend and see if it does the same thing.
                                                                                                                                                                      When you try the Holley don't forget you really don't know if the timing mark is accurate. I don't see why you don't keep pulling timing, and see what happen's? Also if the fuel pressure guage is not visable from the drivers seat you can't see what it is doing at full throttle. You could have a clogged fuel tank sock, and it would not show without load.

Call me stubborn but running the engine below 28bdtc is ridiculous and makes the engine a total dog. I don't even want to try. I don't have an easy way to watch fuel pressure at WOT. My fuel system is completely new including filter,fuel sender,and fuel lines. I don't have empirical evidence but I'll take the risk that fuel pressure is not the issue. The timing mark will be checked as soon as Amazon deliveres my TDC indicator tool. Wink

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Re: Total timing with 10.5:1 Compression

Post  supervel45 on June 10th 2015, 3:48 pm

My point was if the timing mark was off how to you know you were at 28* degrees and not 36*. I did not know the sending unit and the tank had been gone through, is why I brought the fuel pressure gauge up. I hope the Holley fixes the problem, as you don't have many options left. The 165lbs cranking compression still gives me hope that you can get it worked out, and it's not all a compression problem, as a 1970 429 made 190lbs or higher stock. Also that you say you can get to 4,500 rpm's before the preignition starts also leads me to believe it's not all a compression issue. The way you described the cam from idle quality and vacuum, I doubt it will pull much over 5,000rpm's anyway, so you are not that for off from solving the problem in a way. If you can get rid of the preignition, and then hook up you vacuum advance, it will help the "doggy" feel except for all out full throttle runs.

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Re: Total timing with 10.5:1 Compression

Post  the Coug on June 10th 2015, 5:21 pm

You pretty much don't like to Listen do you? in 1970 the 429 scj was 11.3 to 1 compression that just a lot to much for todays gas..... and as for what I said about the Edeljunk carb it is what it is, I have tried many many on 460s 454s and every one was so pig rich or so lean and no matter what we did, they just never tuned out good we always had to be tweeking on them, finally got tired of messing with that junk and put a holley on it, then it tuned out fine...
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Re: Total timing with 10.5:1 Compression

Post  jgkurz on June 10th 2015, 5:58 pm

the Coug wrote:You pretty much don't like to Listen do you? in 1970 the 429 scj was 11.3 to 1 compression that just a lot to much for todays gas..... and as for what I said about the Edeljunk carb it is what it is, I have tried many many on 460s 454s and every one was so pig rich or so lean and no matter what we did, they just never tuned out good we always had to be tweeking on them, finally got tired of messing with that junk and put a holley on it, then it tuned out fine...

Wow, that's kinda of a jab when I just gave you props above. I will happily eat crow if the Holley works. I am doing exactly what you said. It just takes time and money which are not in infinite supply so sometimes trying other "cheaper" or "no-cost" things are done first. I didn't have access to a $400.00 carb for testing until yesterday. Sheesh. Don't get me wrong. I am grateful for your time and responses but many other people have chimed in with their opinions as well. I'm new to the board so I have nothing else to go on. If your advice is highly regarded here then great but I would not have know that initially. I will post results good or bad as soon as I have time to test. Again, I am grateful for your input so I don't want to start something when so many people have chimed in and offered to help. I hope that makes sense.

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Re: Total timing with 10.5:1 Compression

Post  supervel45 on June 10th 2015, 7:25 pm

http://www.summitracing.com/parts/sum-g1412 "Cheap Trick" to keep the carb and fuel cool, they make 1/2" ones to, if you don't have much hood clearance.

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Re: Total timing with 10.5:1 Compression

Post  the Coug on June 10th 2015, 8:30 pm

sorry but I am not much of a bush beater, I apologise for being so blunt but it is to much compression for this crap they call gas now days....I have run carters, holleys and Edeljunks and of all the holleys are hands down way better....

have a nice day
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Re: Total timing with 10.5:1 Compression

Post  jgkurz on June 11th 2015, 12:15 pm

supervel45 wrote:http://www.summitracing.com/parts/sum-g1412      "Cheap Trick" to keep the carb and fuel cool, they make 1/2" ones to, if you don't have much hood clearance.

Thanks for the suggestion but I have one already. I used it on both the Edelbrock and now the Holley. I was able to get the Holley up and running last night. I installed 68/71's with a 6.5 power valve and a .035 squirter. I do like the Holley better and had high hopes but it ran nearly identical as the Edelbrock. The engine runs well in all situations except pinging at WOT. Next step is to verify the timing mark. As "Coug" stated I probably have higher than 10.5:1 so I suspect the engine simply has too much "dynamic" compression for 92 octane. Stay tuned for timing mark info....

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Re: Total timing with 10.5:1 Compression

Post  jgkurz on June 11th 2015, 11:32 pm

Tonight my plan was to verify TDC. I bought a tool from Innovate that moves up and down a scale as the piston moves up and down the cylinder. I have good news and bad news.

The GOOD NEWS: A friend and I very precisely checked the TDC tool and determined my timing mark is perfect. 1deg from 0 in either direction and the piston would go down. I'm confident my timing curve is accurate.

The BAD NEWS: I reported a few posts back that I thought my spark plugs looked good. This was based on the old plugs I removed. I have no idea how many miles were on them plus they were 46's so too hot. The new plugs probably have about 150 miles on them.  I assumed they would look a nice brown color like the old plugs did. Here are plugs from #1 and #7 cylinder since they were the easiest to get to. Obviously lean and not what I expected to see. The plugs might be an ok color for good mileage but not for power. I am surprised my mildly built 429 needs so much more fuel. I'm going to jet the snot out of carb and see if that helps..




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Re: Total timing with 10.5:1 Compression

Post  jgkurz on June 12th 2015, 3:33 pm

BTW, these plugs are Autolite APP 45's. Any concern with this brand or p/n?

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Re: Total timing with 10.5:1 Compression

Post  TommyK on June 12th 2015, 6:16 pm

jgkurz wrote:BTW, these plugs are Autolite APP 45's. Any concern with this brand or p/n?

Not a fan of platinum plugs in a performance application.

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Re: Total timing with 10.5:1 Compression

Post  jgkurz on June 15th 2015, 9:37 am

I richened the Edelbrock carb up significantly. Actually to the max richness calibration of 29. I had to give the Holley back. The engine ran better but interestingly was not too rich. Brand opinions aside, I am a little surprised that the Edelbrock 750 is still not enough for this mild 429. Through this process I think I've learned not to buy another Edelbrock carburetor. I will say they are easy to work on but they obviously run very lean. The engine still pings. Might still be lean but I think compression is also contributing. I need to buy a Holley. A big thanks to everyone who responded to this post. I learned a lot through the process and am grateful. Since I bought the car with this engine I don't know much about the internals. I may pull it this winter and do something different. Not sure what that will be at this point. A stroker 460 with a BIG Holley might be cool.  Cheers

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Re: Total timing with 10.5:1 Compression

Post  Mustang-junky on June 15th 2015, 8:12 pm

A wide band O2 sensor wouldn't be a bad idea. Instead of 'thinking' it's lean or rich, you could 'know'. Especially true if it is a street car where checking out plugs after a full throttle blast is not very convenient. There are several on the market and the prices on them isn't that bad now.

Jess
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Re: Total timing with 10.5:1 Compression

Post  maverick on June 15th 2015, 8:29 pm

Also, be advised that a carb's cfm airflow rating is not an indicator of its rich/lean tendencies. It's simply an estimate of its AIRFLOW capability. How much fuel it mixes with that air is up to you. You could conceivably put a 1250 cfm carb on your 429 and still be lean with a bad carb tune.
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Re: Total timing with 10.5:1 Compression

Post  jgkurz on June 16th 2015, 1:20 am

I thought I was done messing with the Edelbrock but it was nagging me that this stupid thing needed so much more fuel then what they recommended on the calibration chart. My 429 is fairly mild. How could my 429 requirements be off the chart? I called Edelbrock tech support and got a technician that actually was forthcoming with me. He basically said it was not a performance carburetor. He recommended I use their largest jet (.119) in the secondaries and the second largest jets (.116) jets in the primaries with richer (070 x 042) metering rods that I already owned. This combo is not in any manual and well off the calibration chart. It's was easy enough to try so I bought the .119 jets and made the recommended changes.

Now to eat crow... I programmed my MSD for 15 initial and 34 deg at WOT all in by 3500rpm. This is far more than the 28 total I was running. I used up the 100 octane mix and only have fresh 92 in the tank. I went out and hammered the engine hard after it was fully warmed up. The engine has never ran better. The ping wasn't 100% gone but it was WORLDS better and barely noticeable. All you Eddy haters were spot on correct. The carb was the issue. I was skeptical but I stuck with it because so many people were passionate that it was the carb. The Holley did the same thing because it was also jetted too lean. I'm sure jets would have fixed the issue.

I can't see myself ever buying another Edelbrock carb, especially if I want to make HP. The Quick Fuel Slayer 750 with adjustable air bleeds looks like a sweet carb if I keep the 429.

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Re: Total timing with 10.5:1 Compression

Post  kim on June 16th 2015, 8:01 am

A 750 cfm carb is SMALL for the engine. Quit playing with the little boy toys, get a real carb. A 750 is a nice carb for a hot 302. 850 cfm plus is where you need to look.

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Re: Total timing with 10.5:1 Compression

Post  BigRigTech on June 16th 2015, 9:27 am

I gained one tenth going from a 750 to a 850 on my 468 a couple years ago...Just a plain old DP with the choke horn milled off, nothing special. Nice gain for the tiny bit of money between the two.
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Re: Total timing with 10.5:1 Compression

Post  supervel45 on June 16th 2015, 1:09 pm

So how many RPM did you take it up to with the new jets and metering rods before it pinged?

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Re: Total timing with 10.5:1 Compression

Post  jgkurz on June 16th 2015, 1:50 pm

supervel45 wrote:So how many RPM did you take it up to with the new jets and metering rods before it pinged?

It would start pinging around 3500-4000 without fail once the engine was warmed up and I mashed the throttle. Pinging didn't happen right away, only when RPM starting climbing. I took it to 5000 last night. The engine probably peaks power somewhere around 5500, maybe less.

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