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Timing frustrations


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Jpaz, 

Funny thing is that I decided to call comp's tech division where they ask for all of your engine specs and then select a bumpstick for you.

Guess what they selected for me ? yup you got it.

I did not take the bait and gave comp MY specs and had one built for me.

This cam is not that far from the 270 but with split lift and duration and a lot less overlap and I make 17hg.@ warm idle.

Boilermaster

The PV situation is very odd. I would try to get to an actual carb tech at summit to ask why. The cam is not well suited to a 4V Cleveland but, the overlap is only 50 degrees. It has a 110 lobe separation, a little on the tight side, which can make the idle choppy and lower manifold vacuum. However, I would expect vacuum in the 14 in/hg range. If the cam was not degreed in it could be installed retarded which would give the symptoms you describe. Unfortunately there is no easy way to check this. Chuck

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Well, you need a choke or cold starts will be an issue. The carb was milled? Not sure what that means. The one thing that I can definitely tell you is that carb needs a hole drilled in each of the b

Msd boxes were the cats meow, but recently they are all made in china.

IF it ain't one thing, it's another. It never seems to stop. That sucks man! One step forward a three back. Something isn't right for sure. I really hope you don't end up pulling the motor for a rebui

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C9zx,

The nice thing about comp cams is that they list lobe lift @ tdc , so no degree wheel needed if you actually know where true tdc  is.

Just look up your lobe profile in their master catalog and they give you the spec.

from there you can do the math to figure out exactly where you are.

I must admit that finding my lobes in the pdf catalog was a pain, but no degree wheel needed, just a dial indicator.

So one can actually CHECK cam timing without removing the timing cover, unfortunately changing cam timing is a little more involved.

Boilermaster

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The info about lift at TDC from comp is a good thing to know, thanks. I thought that early in the thread the damper ring position was in question so true TDC was unknown. I may just be having a false recollection. Chuck

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Well, either way, the cam I have is the cam I'm going to have to live with for a while.

 

I'll bump the timing up 2 degrees until I start to ping and then back it off 2 as suggested and see where I land. I'll also call Summit and ask about their secondary PV choice. There has to be a reason behind it. I've been doing some more reading in other places around the web as well, and it seems like of the folks who choose to keep a secondary PV like to match the primary. Not sure what the logic behind that is. Doesn't seem to be a particular rule of thumb on the subject.

 

More importantly I have a lot of PVs from Quick Fuel coming that I can use and play around with and see what seems to work best from a drive-ability standpoint. They even have whole numbers. so I've got some 4s, 4.5s, 5s, and 5.5s coming. We'll see what actually performs best for me, and then further dial it in when I do the wideband.

 

No matter what Summit says about the secondary PV, I'm keeping the carb. Again, I love the choke, and how easy it is to change PV's and other items. The car also idles way smoother than it ever did with the Holley, and it's a lot more responsive to throttle input as well. Probably due to the annular boosters. I'll get it fully dialed in as can be eventually.

Chris - BIG RED MACH 1

Born in '73 - Drive a '73

Former U.S. Army 63B10-H8

1st Infantry Division - The Big Red One

 

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The info about lift at TDC from comp is a good thing to know, thanks. I thought that early in the thread the damper ring position was in question so true TDC was unknown. I may just be having a false recollection. Chuck

 

C9zx,

True TDC is indeed in question here.

My thinking is if I can get Big Red Mach 1 to advance his ignition until it spark knocks and then back off 2 degrees, it could raise his vacuum readings at idle and if his vacuum does indeed increase, that would be a half assed way of confirming that his cam timing is not retarded ?

does that make sense to you chuck ? if Big red hit 15hg. valve timing should not be retarded.

 

Boilermaster

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  • 2 months later...

Soooooo.... Where were we again???? :whistling:

Been a while on this one. My fault. Been working a lot and it's been over 105 degrees in the garage even with fans running so I've not done much. 

However, today I finally got around to verifying TDC. Ordered a Piston Stop...What, two months ago?? Been sitting on my desk. 

Now my guess was that the marks on the balancer were going to be off. I felt like due to the fuel smell in the exhaust, and also the fact that I was running warm(other thread), I was running more retarded that I thought I was by at least a few degrees. Could explain both. Incomplete burn causing the smell and also running hot. Also figured that I was under timed and was over compensating using the idle screw on the carb, exposing too much of the transfer slot (this may still be the case). I've been doing a lot of reading this last couple of months, even though not working on the car a lot. :classic_cool:

So... Imagine my surprise when I was dead-nuts ZERO. :classic_ohmy:

I know that's good, but I was seriously almost hoping to be 4 degrees off, add 4 to my previous 16, set her at 20, and boom done. Problem solved. 

(I rotated it a little after the marking just for the photo. Did the test twice. I'm confident these marks are true. 

20200718_095156.thumb.jpg.8498a6f7da87bd7b49934e1e821256db.jpg

Chris - BIG RED MACH 1

Born in '73 - Drive a '73

Former U.S. Army 63B10-H8

1st Infantry Division - The Big Red One

 

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  • 1 month later...

Played around a bit more with this just a little while ago. Still getting that raw fuel smell pretty strongly, still have a vacuum of around 10-11. 

Since I started this thread, I've done the following;

Replaced rocker arms(1980's) and pedestals(Too Short). Set pre-load. 

New intake manifold (Blue Thunder now) Also have 1/2" spacer under the carb

3 different carbs since starting. Original Holley SA 770 with choke milled off. (Not having the choke was a PITA) Summit 750 (Returned-Leaked) Summit 600 (On car now). Regarding dropping to the 600, really just experimenting. A lot of calculators say a 750 is way over carb'd for our motors. 

New cap, rotor, wires and plugs

Verified dead-nuts 0 TDC with piston stop. 

Timing set as low as 10 and as high as 18. I went up past 24, didn't hear it ping, but wasn't comfortable running it up higher than that. Makes no sense to go that high. 

Also tried the method of setting the idle screw at 1800rpms then turning the dizzy to where vacuum was highest, and locking the dizzy back down and returning to normal idle. Where did I end up? 16. Where I've been through most of this. 

In most all circumstances with all 3 carbs, adjusting the idle screws has barely moved vacuum up if at all. 

Just thinking out loud, Possibly low ignition system output? Could the raw fuel smell be because I'm actually not burning hot enough?  I have no problem replacing the coil and this Mallory Unilite dizzy. I haven't fully trusted it since day 1 anyway. 

I've been wanting to go with this for a while. https://progressionignition.com/shop/ols/products/ford-351c-v8-small-cap-distributor

Temp at each cylinder on the headers is around 350-380F. Sounds low, but they are ceramic. Any idea what I should be seeing? 

I know this thread had a lot of action on it at one time, but I let it go cold because I haven't been working on the car much. We've had about 25+ EXTRA days of +110*F out here this summer. Most brutal summer on record for Arizona, so it's been too hot to spend a ton of time in the garage. 

Anyone willing to jump back in would be most appreciated. 

 

 

 

Chris - BIG RED MACH 1

Born in '73 - Drive a '73

Former U.S. Army 63B10-H8

1st Infantry Division - The Big Red One

 

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General consensus is go with DuraSpark, Performance Distributors made to order by the looks of it. Cheaper too!

https://performancedistributors.com/product-category/distributors/ford-distributors/ford-duraspark-distributors/

Edited by Stanglover
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Geoff.

 I learn something new every day!

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Thanks Geoff! I really like that they take all of your specs into consideration and calibrate based on them. That's very reassuring. 

Edited by Big Red Mach 1

Chris - BIG RED MACH 1

Born in '73 - Drive a '73

Former U.S. Army 63B10-H8

1st Infantry Division - The Big Red One

 

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27 minutes ago, Big Red Mach 1 said:

Thanks Geoff! I really like that they take all of your specs into consideration and calibrate based on them. That's very reassuring. 

IF I were in your shoes, that's what I'd do. If I had not been able to re-curve the Motorcraft I had and get it where it worked for my engine, I would have gone straight to the DuraSpark, no question about it. AND as a bonus, it looks stock. I think there will be a module to be mounted on the apron, but that's ok. imo.

Only downs side, it take 3-4 weeks to get it.

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Geoff.

 I learn something new every day!

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I don't mind the wait for something that will be dialed-in based on my specs. 

Looks like they want;

Duration and lift, no problem, I'll send them my cam card.

Carb size. I guess I'll give them the 600CFM that's on there now. Not sure I won't go back up in CFM's at some point though. 

Weight 3,500lbs. is probably about right. 

Octane. 91 is all I can get around here. I can't get 93. But I do add Lucas Octane booster when I fill up. 

The compression ratio is probably the difficult one. I'm .30 over with the 1970 DOAE-N heads that are 62.8cc with flat top pistons. No clue about head gasket thickness. Or how far down the top ring is on the piston. Any Compression Ratio guru's out there want to take a guess at a round about number? 

 

Chris - BIG RED MACH 1

Born in '73 - Drive a '73

Former U.S. Army 63B10-H8

1st Infantry Division - The Big Red One

 

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4V Clevelands like 20%, or more, cfm than most carburetor size calculators.

CR, 10 to 10.5

Edited by Don C
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“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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So one thing I probably never mentioned is that the car has been very hard to cold start also(cold or hot weather). This did drastically improve going from a carb without a choke, to a carb with a choke. But it still doesn't start as quickly as it should, and honestly these last few attempts have been harder than normal as well. 

The plug and coil wires that were on the car originally had very high resistance. I wouldn't be surprised at all if my coil was failing. I'm going to order a new Duraspark dizzy for sure tomorrow, but I'll probably throw on a new coil in the meantime and see how she acts. 

Chris - BIG RED MACH 1

Born in '73 - Drive a '73

Former U.S. Army 63B10-H8

1st Infantry Division - The Big Red One

 

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You also have to get the ECU, one with a blue grommet has the additional white wire for retard on start.

 

durasparkfinal.jpg

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“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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Currently, my brown ground wire goes from my coil to one of the studs on my valve cover. I have to imagine that's not how it's originally run, correct? Also, you are not supposed to have these coils installed horizontal, but that's how I always see them done on these Clevelands. Anyone make or have a vertical mount that works well? 

Chris - BIG RED MACH 1

Born in '73 - Drive a '73

Former U.S. Army 63B10-H8

1st Infantry Division - The Big Red One

 

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16 hours ago, Big Red Mach 1 said:

I don't mind the wait for something that will be dialed-in based on my specs. 

Looks like they want;

Duration and lift, no problem, I'll send them my cam card.

Carb size. I guess I'll give them the 600CFM that's on there now. Not sure I won't go back up in CFM's at some point though. 

Weight 3,500lbs. is probably about right. 

Octane. 91 is all I can get around here. I can't get 93. But I do add Lucas Octane booster when I fill up. 

The compression ratio is probably the difficult one. I'm .30 over with the 1970 DOAE-N heads that are 62.8cc with flat top pistons. No clue about head gasket thickness. Or how far down the top ring is on the piston. Any Compression Ratio guru's out there want to take a guess at a round about number? 

 

Chris, I'm not sure if these numbers will be anyway near what your engine will produce, but it may give you an idea. I'm attaching a copy of the compression ratio charts I got from UEM Pistons for Keith Black KB177 flat top pistons, which are .020" tall than factory stock, producing  a  piston/deck of.008" from stock.028". The result was calculated at 10.56 CR. Assuming the block has been decked at some point, you're  more likely to be zero deck, as mine was. I had to have my motor re-rebuilt due to an incorrect oil pump being installed, and decided to drop the CR to around 9.5 use KB 148 dish top pistons. This has worked out very well for the gas we have 91 oct. and the driving I do.

As for carbs, mine is a Holley S/A 86670 with mods (holes drilled in primary's and larger #35 squirter), but I sometime feel I could go to around 735cfm, a little over the 20% Don C refers to.

Geoff.

Good luck with your DuraSpark set up

comp ratio.pdf

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Geoff.

 I learn something new every day!

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Thank you Geoff. Great info. Because we don't have 93 here, I would/will definitely drop compression ratio when/if it becomes time to fully rebuild. 

Chris - BIG RED MACH 1

Born in '73 - Drive a '73

Former U.S. Army 63B10-H8

1st Infantry Division - The Big Red One

 

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11 hours ago, Don C said:

You also have to get the ECU, one with a blue grommet has the additional white wire for retard on start.

 

 

Thanks Don! For this,  and the CR estimate. 

Chris - BIG RED MACH 1

Born in '73 - Drive a '73

Former U.S. Army 63B10-H8

1st Infantry Division - The Big Red One

 

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9 minutes ago, Big Red Mach 1 said:

Thank you Geoff. Great info. Because we don't have 93 here, I would/will definitely drop compression ratio when/if it becomes time to fully rebuild. 

If you're still getting pinging with 91 oct. timing curve is critical. It is not necessarily down to octane. I used to waste money on octane booster, until I figured out exactly what my motor needed, now it runs sweet and strong. I currently run with 14 deg. initial and 20 deg. crank plus about 4 deg. vacuum advance on top. I'm sure this is why Performance Dist. need as much info as possible so it's right the first time. Your current dist. may be way off base, so until you get that issue sorted, pining may just be the way it is. Maybe go with 11:1 comp ratio in your specs, but tell them that's a guess. I'm thinking it would be better to be too high on comp ratio than too low.

Just my thoughts on this, not necessarily that of others.

Geoff.

 I learn something new every day!

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On 9/7/2020 at 12:32 PM, Stanglover said:

Only downs side, it take 3-4 weeks to get it.

I ordered it Tuesday knowing full well it will take that long, but I'm already like a kid who just can't wait for Christmas day. Is it here yet, Is it here yet???? :banana:

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Chris - BIG RED MACH 1

Born in '73 - Drive a '73

Former U.S. Army 63B10-H8

1st Infantry Division - The Big Red One

 

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Well, that didn't go well.....

Chris,

Unfortunately the E.D. Module and Coil kit is no longer available and our website has not been updated. We can cancel this part off your order and continue with the Duraspark Distributor or we can cancel the entire order. Please advise on how you would like to proceed? Our apologies for the inconvenience. Thank you.

 

Brian

Performance Distributors (DUI)

2699 Barris Drive

Memphis, TN 38132

901-396-5782

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Chris - BIG RED MACH 1

Born in '73 - Drive a '73

Former U.S. Army 63B10-H8

1st Infantry Division - The Big Red One

 

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“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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They actually suggested that I go with the MSD 6AL box and a blaster coil. They say that's the more popular option for folks right now. So I kept the dizzy and wires on order. I'm sure the MSD box would be superior to this, correct? 

Edited by Big Red Mach 1

Chris - BIG RED MACH 1

Born in '73 - Drive a '73

Former U.S. Army 63B10-H8

1st Infantry Division - The Big Red One

 

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Interesting thing about the MSD box, they are based on DuraSpark, but you are correct, MSD made improvements and they provide better spark, especially at higher revolutions.

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“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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https://www.summitracing.com/parts/msd-8869

https://www.summitracing.com/parts/tay-401001

https://www.summitracing.com/parts/tay-718222

Here is an option that i run on a few cars. Taylor has a better box and is US made, their coils work well too.

Edited by Canted 393
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