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Total timing with 10.5:1 Compression

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TommyK
78ranger
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Post  supervel45 May 17th 2015, 1:52 pm

What temp. thermostat? I would try a 160* stat if you are running a hotter one.

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Post  jgkurz May 17th 2015, 2:34 pm

supervel45 wrote:What temp. thermostat? I would try a 160* stat if you are running a hotter one.

The current thermostat is a Stant 180deg. I'll pick up a 160 and give it a try.

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Post  jgkurz May 17th 2015, 5:04 pm

Compression test showed 165psi across the cylinders I sampled. I can't get to all cylinders without lifting the engine up.

The current spark plugs put in by the previous owner are Autolite 46's. The correct plug looks to be 45's, so one step colder. I'm guessing this may be part of my problem?


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Post  rmcomprandy May 17th 2015, 5:27 pm

jgkurz wrote:Thanks for the guidance everyone. I'll try to get the compression and spark plugs checked today. As for the timing mark, that's going to be tough with engine assembled. The most precise way I know is with a dial indicator with the heads off. I'm not sure how accurate I can get through a spark plug hole.

A piston stop through the spark plug hole and a degree wheel always works at locating true TDC for me ... with the engine already assembled.

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Post  supervel45 May 17th 2015, 10:15 pm

http://www.edelbrock.com/automotive/misc/tech-center/dl/carb-owners-manual.pdf Not saying this the cause of your problem, but something to keep in mind on the Edelbrock 750's. There are two of them, model #1407 and #1411. The #1411 with electric choke is set up leaner on the primaries. With 165lbs cranking compression I think you can get the preignition under control with a few minor changes.

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Post  BOSS 429 May 17th 2015, 10:20 pm

jgkurz wrote:I have a 70 429ci with original iron heads and original compression which I believe is 10.5:1. It also has a slightly larger cam, 750cfm carb, Edelbrock intake, and a programmable MSD. I run fresh 92 octane unleaded but can't keep the engine from pinging when accelerating. I can easily customize the timing curve but can't seem to find one that works well. I've tried as low as 32deg all in at 4000rpm and the engine still noticeably pings. I will probably try 28deg next but that is awfully low for any real power. The engine runs well until I get hard into the throttle then ping ping ping.

I'm guessing 10.5:1 compression with iron heads is the issue. Any suggestions?  

Thank you!


compression is over 11 to one on all 70 429s, I bet  WRONG FUEL is your problem, it takes a lot of work to get these to run good on 92 oct.and the larger cam may be making a little more comp also
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Post  jgkurz May 18th 2015, 1:18 am

My particular engine came out of a 70 Galaxie which was rated at 360hp. Every book I have says it is 10.5:1 with the 429CJ's being 11.3:1. Maybe the books are wrong but that's where I got the 10.5:1. If the engine has been bored, which is likely, then compression is even higher.

I was able to get the plugs changed from 46's to the colder 45's. It made a noticeable difference but I still can't go WOT without pinging. I kept the total timing at 32 for the time being. Next up is to verify my timing mark, change to a 160 thermostat, and add fuel to the secondaries. I agree that I need higher octane fuel but maybe I can reduce the pinging enough to make the engine usable until I replace it in a year or two.

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Post  supervel45 May 18th 2015, 9:25 am

http://www.mustangsunlimited.com/itemdy00.asp?T1=DL284+01 Some of the early 429 4V's called for 4* BTDC intial timing, and assuming 22* mechanical advance, this would only be 26* total. From 1968 and into 1969 the intial timing on the factory most decals was 10*BTDC. A few sources list 105/1 compression for 429 2V's and 11/1 for 4V's, but most show 10.5 compression for both. In mid 1970 Ford did raise the deck height of the block, and may have used head gaskets from .022" to .050" at different times, so maybe this has to do with the differences? You said when you checked compression that you could not get to all of the cylinders. Did you pull all of the sparkplugs out and was the engine hot? If not you may have gotten a low reading. If the 165 psi is accurate I think you maybe lower than 10.5/1, the larger cam is bleeding off compression, or a combination of both. Some rebuilder pistons have a lower compression height, and may have been used. AutoLite 124 plugs maybe another option, for a colder plug to try also. It sounds like you are making progress, so keep after it and keep us posted.

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Post  jgkurz May 18th 2015, 11:31 am

supervel45 wrote:http://www.edelbrock.com/automotive/misc/tech-center/dl/carb-owners-manual.pdf    Not saying this the cause of your problem, but something to keep in mind on the Edelbrock 750's. There are two of them, model #1407 and #1411. The #1411 with electric choke is set up leaner on the primaries. With 165lbs cranking compression I think you can get the preignition under control with a few minor changes.

I have p/n 1411. I am confident it has the original calibrations. I'm a Holley guy so I'll need to research how to adjust fuel for WOT. The car runs quite well with good off idle response and power. Pinging is the only issue so I thought I'd do the Edelbrock equivalent of putting in larger main jets on the secondaries whatever that might be. Regarding the compression test, the 165psi reading was just after the car was at operating temp, 180deg or so. The spark plugs were certainly hot....  Very Happy  Regarding timing, 26deg total seems awfully low. Today, with the larger cam, I'm at 15deg initial and 32 total. In the end I may have to drop total to 28 but I don't want to go lower unless absolutely necessary. I appreciate the encouraging words. I will keep the group updated on my progress.

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Post  jgkurz May 18th 2015, 3:09 pm

Just spoke to Edelbrock regarding my 750cfm pn 1411 carb. The guy in tech support was very helpful and suggested I first change the metering rods from .075 x .047 to a small diameter .070 x .042. I thought we should change secondary jets given the car runs so well other than WOT but he was confident this was the first step. This was because the factory calibration was for economy not performance. Stay tuned... HA!

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Post  supervel45 May 18th 2015, 4:11 pm

Did you look at page 15 of the Edelbrock PDF I posted above. That page is for your #1411 Carb and has alot of info. The metering rods the tech guy recomended are richer and #23 on the chart. I would try to get the next larger set of secondary jets also with the metering rods if you are ordering and can get them all together.

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Post  jgkurz May 18th 2015, 4:24 pm

I agree, the manual is very helpful. I may change secondary jets but my personal preference is to make a single change (richer metering rods) and test the results before jets.

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Post  supervel45 May 18th 2015, 4:29 pm

I agree 100% with one change at a time and test. I thought you may be ordering the parts and could save time and shipping if the cost of the jets are minor. I have heard that Edelbrock sends out free metering rods sometimes, hopefully that is your case.

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Post  rmcomprandy May 18th 2015, 5:06 pm

jgkurz wrote:Just spoke to Edelbrock regarding my 750cfm pn 1411 carb. The guy in tech support was very helpful and suggested I first change the metering rods from .075 x .047 to a small diameter .070 x .042. I thought we should change secondary jets given the car runs so well other than WOT but he was confident this was the first step. This was because the factory calibration was for economy not performance. Stay tuned... HA!

The biggest issue with that carburetor is that the IDLE system is set-up for latter model LOW compression engines.

The Idle tubes need to be increased in diameter about .003" more for a higher compression application in order to drive half way decent.
The metering rod change will help but, wont get you where you need to be.  While you have the top off to remove the primary venturi clusters in order to get access to the idle tubes, simply increase the primary jet size to .113", (from .110"),  and leave the metering rods alone.

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Post  jgkurz May 22nd 2015, 1:36 am

I made some progress tonight. I changed the thermostat to a 160deg, added Water Wetter, and changed the metering rods. Now the engine doesn't ping when on a flat road. When I hammer it going up hill it still rattles noticeably. I think the next step is to reduce total to 28.

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Post  supervel45 May 22nd 2015, 6:14 am

http://www.msdignition.com/Products/RPM/Timing_Controls/Timing_Controls/8680_-_Adjustable_Timing_Control.aspx You could just turn a knob. I am glad you made progress. Trying to go up hill full throttle may be asking alot. I would reduce the timing to 30* and see how it does.

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Post  jgkurz May 31st 2015, 8:44 pm

supervel45 wrote:http://www.msdignition.com/Products/RPM/Timing_Controls/TiHehehming_Controls/8680_-_Adjustable_Timing_Control.aspx    You could just turn a knob. I am glad you made progress. Trying to go up hill full throttle may be asking alot. I would reduce the timing to 30* and see how it does.

I finally got time to work on this again today. My MSD is programmable so I can easily set the timing curve with my laptop. I took total timing down to 28 deg and it still pings. It is slightly better than 32deg but not much. The fuel is fresh 92 octane bought yesterday. The only other option I have without putting in a new camshaft is to re-jet. The curious thing is it only pings at WOT. The car runs strong in all other situations including cruise on the freeway where I give it 40deg at light throttle.

I'm starting to think that when the secondaries open that there just isn't enough fuel. rmcomprandy said I need to increase the idle tubes and primary jets. I'm open to anything but the idle circuit and low-mid range seem to work great. Why wouldn't I want to simply increase secondary jets?

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Post  gmsmkr May 31st 2015, 8:56 pm

I know you say it pings are you sure it's a ping or sputter?

You say it drives fine and it "ping's" at WOT does it "ping" while going up hill under a load at light throttle?
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Post  jgkurz May 31st 2015, 9:32 pm

gmsmkr wrote:I know you say it pings are you sure it's a ping or sputter?

You say it drives fine and it "ping's" at WOT does it "ping" while going up hill under a load at light throttle?

It never pings/rattles under light load. I'm certain its not sputtering or hesitation. In all fairness, I never try to drive through the pinging so if there is a lean sputtering it would be hard to know.

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Post  supervel45 May 31st 2015, 10:43 pm

supervel45 wrote:Did you look at page 15 of the Edelbrock PDF I posted above. That page is for your #1411 Carb and has alot of info. The metering rods the tech guy recomended are  richer and #23 on the chart. I would try to get the next larger set of secondary jets also with the metering rods if you are ordering and can get them all together.
Thats why I said to get the jets also, just in case.

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Post  supervel45 May 31st 2015, 10:50 pm

A fuel pressure guage you could watch as you are driving would be nice also, to make sure the fuel pressure is not dropping off, when the secondaries open up.

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Post  rmcomprandy June 1st 2015, 10:24 am

jgkurz wrote:

I'm guessing 10.5:1 compression with iron heads is the issue. Any suggestions?  

Thank you!

Put 100+ octane gasoline in it and find out if the detonation goes away ...

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Post  the Coug June 1st 2015, 1:25 pm

BOSS 429 wrote:
jgkurz wrote:I have a 70 429ci with original iron heads and original compression which I believe is 10.5:1. It also has a slightly larger cam, 750cfm carb, Edelbrock intake, and a programmable MSD. I run fresh 92 octane unleaded but can't keep the engine from pinging when accelerating. I can easily customize the timing curve but can't seem to find one that works well. I've tried as low as 32deg all in at 4000rpm and the engine still noticeably pings. I will probably try 28deg next but that is awfully low for any real power. The engine runs well until I get hard into the throttle then ping ping ping.

I'm guessing 10.5:1 compression with iron heads is the issue. Any suggestions?  

Thank you!


compression is over 11 to one on all 70 429s, I bet  WRONG FUEL is your problem, it takes a lot of work to get these to run good on 92 oct.and the larger cam may be making a little more comp also


Bingo we have a winner I am like Rich in 70s we had way better gas which in turns more compression, in the 70s we could drive up to any pump and get premium fuel, not like this crap they are trying to stick up our butts now.... and I would take that Edelecrap carb and throw it in the junk pile where it belongs, when Carter had that company it was good carbs but not any more....
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Post  jgkurz June 1st 2015, 1:49 pm

I have no doubt higher octane fuel would help but I also think my Edelbrock 1411 is causing a lean condition. I'll put a different engine in before I pay for 100 octane on the street. If I jet up and it still pings I'll try the race gas. If I get really motivated I'll weld in an O2 bung in the collector and datalog the AFR's with an Innovate LM-2.

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Post  BigRigTech June 2nd 2015, 1:58 pm

As Randy stated I would try some 100 octane fuel too. My buddy runs a 10.5:1 347 on the street and the dyno operator recommended he add about 20% AV gas to bump the octane and control detonation. He mixes it 20-30% with no issues so far and it works good. Wink
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