How to determine compression ratio? Engine still pinging...
Le Mans Master
Joined: Apr 2006
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It would be interesting to know how much cranking compression you have. Its a little hard for me to believe if the builder ment the engine to be a street engine he would use a flat top piston with 64cc heads, do you at least have the part numbers/brands for the pistons/heads.
Last edited by Little Mouse; Mar 25, 2008 at 04:49 PM.
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From: Overland Park Kansas
Ok well I tried changing back to an open carb spacer and that didn't help at all. I changed over to direct vacuum which also didn't help, but it did let me do one other thing. With direct vac I can set the timing to like 4* initial and it still be around 14 at idle so my headers don't burn up. This does make it run worse but gets rid of almost all of the pinging.
I really don't know where to go from here, so I think my next step is going to be making an a/f meter. I went and got a $20 o2 sensor from auto zone and I'm going to wire up a circuit tonight that will print out the reading, then I just have to get the sensor welded in by the local muffler shop.
I really don't know where to go from here, so I think my next step is going to be making an a/f meter. I went and got a $20 o2 sensor from auto zone and I'm going to wire up a circuit tonight that will print out the reading, then I just have to get the sensor welded in by the local muffler shop.
Drifting
Joined: Oct 2004
Posts: 1,259
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From: Ontario
Ok well I tried changing back to an open carb spacer and that didn't help at all. I changed over to direct vacuum which also didn't help, but it did let me do one other thing. With direct vac I can set the timing to like 4* initial and it still be around 14 at idle so my headers don't burn up. This does make it run worse but gets rid of almost all of the pinging.
I really don't know where to go from here, so I think my next step is going to be making an a/f meter. I went and got a $20 o2 sensor from auto zone and I'm going to wire up a circuit tonight that will print out the reading, then I just have to get the sensor welded in by the local muffler shop.
I really don't know where to go from here, so I think my next step is going to be making an a/f meter. I went and got a $20 o2 sensor from auto zone and I'm going to wire up a circuit tonight that will print out the reading, then I just have to get the sensor welded in by the local muffler shop.
Race Director
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Not sure if I missed it....what dist is in it?
You definitely need to get timing squared away before touching carb. Most carb issues are really timing issues. No need to touch it until timing is correct.
Plus there has to be a way to do something with that trans. That has to be a PITA if it locks up that early.
JIM
You definitely need to get timing squared away before touching carb. Most carb issues are really timing issues. No need to touch it until timing is correct.
Plus there has to be a way to do something with that trans. That has to be a PITA if it locks up that early.
JIM
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From: Overland Park Kansas
OK well I went out and tested the vacuum. It's pinging when there is 0 manifold vacuum so I know the vac advance isn't the problem. It's a HEI dist with a hyfire ignition system.
I know I can change the lockup point for the trans, I think it is like 45mph right now. I'd like to get it changed to make 65. The only problem is I just had the transmission completely rebuilt for $1500 and don't really have a few $ more right now to get them to change whatever spring it is that controls the lockup point.
I know I can change the lockup point for the trans, I think it is like 45mph right now. I'd like to get it changed to make 65. The only problem is I just had the transmission completely rebuilt for $1500 and don't really have a few $ more right now to get them to change whatever spring it is that controls the lockup point.
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From: Overland Park Kansas
Don't waist your time and money on the $20 narrow band sensor. It will not help you much if any. If you want to know the AF, get a wideband. But they are not cheap. Reading all the above gives me the gut feel that you still are dealing with a timing issue. Something is wrong... balancer ring slipped?
Burning Brakes
Joined: Mar 1999
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From: CA
I know I can change the lockup point for the trans, I think it is like 45mph right now. I'd like to get it changed to make 65. The only problem is I just had the transmission completely rebuilt for $1500 and don't really have a few $ more right now to get them to change whatever spring it is that controls the lockup point.
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Joined: Oct 2007
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From: Overland Park Kansas
When I purchased the car the transmission was already messed up, 4th barely worked, and the TC wouldn't stay locked unless you barely pressed the gas. Now the TC stays locked until you get like 85% gas, it's crazy.
Race Director
Joined: Oct 2000
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From: central FL, near the beach.
does sound like a slipped balancer.....this happens now & then as it is 2 metal pieces connected ONLY by a rubber seal. they slip, throwing the mark off.
at 10 mpg an A/F gauge is unlikely to help on pinging. Sure it is nice to have. In 1970 i got a compression tester. in 1998 an AF gauge. In 2006 an infared temp gun. Now, when i work on a car, i use all my tools, but i did a good job back in the 70's without many of them.
if it got 19-28 mpg and pinged one could reason it was too lean. are the plugs black w/10mpg? then an a/f test is probably not needed to stop pinging, it is already too rich. And only 1 guy in 10 can figure out a narrowband; 9 in 10 can use a wideband easily.
a compression test is more helpful at this point. After it runs great, then a wideband would help get the mpg up. Even looking at the plugs could be better than u may think.
have u complained to the trans shop?
once my dads ford had a slip in od 4th, so i told him to use D3; worked fine for years. u should shift into OD only above 65.
at 10 mpg an A/F gauge is unlikely to help on pinging. Sure it is nice to have. In 1970 i got a compression tester. in 1998 an AF gauge. In 2006 an infared temp gun. Now, when i work on a car, i use all my tools, but i did a good job back in the 70's without many of them.
if it got 19-28 mpg and pinged one could reason it was too lean. are the plugs black w/10mpg? then an a/f test is probably not needed to stop pinging, it is already too rich. And only 1 guy in 10 can figure out a narrowband; 9 in 10 can use a wideband easily.
a compression test is more helpful at this point. After it runs great, then a wideband would help get the mpg up. Even looking at the plugs could be better than u may think.
have u complained to the trans shop?
once my dads ford had a slip in od 4th, so i told him to use D3; worked fine for years. u should shift into OD only above 65.
Last edited by Matt Gruber; Mar 26, 2008 at 08:54 AM.
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From: Overland Park Kansas
Well, how would I go about finding out if my balancer has slipped?
Oh, and I called the transmission shop and they were no help at all. I told them my situation and they didn't even know what a hydraulic lockup kit on a 700R4 was. ugh.
Oh, and I called the transmission shop and they were no help at all. I told them my situation and they didn't even know what a hydraulic lockup kit on a 700R4 was. ugh.
Last edited by neuroclast; Mar 26, 2008 at 10:28 AM.
Le Mans Master
Joined: Sep 2001
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From: Unreconstructed, South Carolina
Using a piston stop ... verify #1 piston is at true top dead center ... then observe timing mark at damper/balancer ... it must also indicate TDC.
If balancer/damper mark is not at TDC (when #1 piston verified true TDC) then it has likely slipped & should be replaced.
Curious if a SC shop built the motor & if so, who?
tip: maybe you need to be steered toward better local help ... perhaps you phone Rob at James Island Cycle (843.762.4923) ... when he's not too busy ... ask if he'd refer you to good help. Rob's VERY knowledgable & fair but don't waste his time.
If balancer/damper mark is not at TDC (when #1 piston verified true TDC) then it has likely slipped & should be replaced.
Curious if a SC shop built the motor & if so, who?
tip: maybe you need to be steered toward better local help ... perhaps you phone Rob at James Island Cycle (843.762.4923) ... when he's not too busy ... ask if he'd refer you to good help. Rob's VERY knowledgable & fair but don't waste his time.
