Motor issues.

-
Ricks70Duster340 said:
The rods bouncing means the lopey idle vacuum is overcoming the spring. Get the Edelbrock tuning kit for your carbs & change the rod springs to a lighter set. Start with one level weaker at a time until the bouncing is resolved. This will keep them from bouncing and will lean out your idle mixture so you can properly tune those guys. I had the same problem with my 408.
Click to expand...
I did this. Used a blue 3in. spring for now.
 
Bewy said:
That cam is the old Mopar Perf 296 cam. Lash is 0.028" in, 032" ex hot. With iron heads, you can set the lash cold & it will very close to specs. Vacuum will THEN increase.

Note that the cam has a lot of duration; it will need at least 30* for best idle quality & may require more.
Set lash properly & THEN check exh temps.
Click to expand...
30* of initial timing? Seems like a lot. What about total timing?
 
moparmarks said:
Soooooooo, your disagreeing with what we have on the motor?????
#3 plug looks the same as the others.
Click to expand...
If the #3 plug looks the same as the rest of them I would not worry about it.
Post some close up pic's of the plugs so we can all see.
 
moparmarks said:
Where I live at 4600' 160-180# is real good.
Click to expand...
160 is good, and 180 is real good but;
If you are saying that yours fall between those number,
then the range is NOT good.
Yes I know it falls into the factory acceptable range, but that don't mean much(squat) in the real world.
If it was mine, I'd be running a LeakDown Test, and I'd probably end up pulling the heads, cuz I have never had an engine with a variance that big, and that there wasn't something wrong with it.
 
Not I'm saying that this
AJ/FormS said:
160 is good, and 180 is real good but;
If you are saying that yours fall between those number,
then the range is NOT good.
Yes I know it falls into the factory acceptable range, but that don't mean much(squat) in the real world.
If it was mine, I'd be running a LeakDown Test, and I'd probably end up pulling the heads, cuz I have never had an engine with a variance that big, and that there wasn't something wrong with it.
Click to expand...
No I'm not saying that tis motor falls between those numbers. I was just generally speaking that those are the numbers that motors can have at this altitude.
 
MM,
Until you set the lash to the correct amount, stated earlier by me, you should not attempt any tuning of the carb or ign.

You think 30* is a lot of initial? My 1966 GTO, as well as millions of other GM cars, drove off showroom floors with well over 20* of initial timing. 26* for my car to be exact, with a veeery mild cam.
Sadly, you are not understanding this relationship & I have explained it so many times on this & other forums that I do not feel like doing it again. Initial & total timing are different. You set initial first, & then total by modifying the curve in the dist. Some people use locked dists, so if the initial is 34*, it has 34* from 0 - forever.

Here is a quote from D. Vizard in his Holley book. Think about why idle timing is mentioned in a carb book......
Page 30: ' The optimum idle advance is typically about 35-40* for a short cammed street engine & [ though not commonly realized ] as much as 50* for a street/strip engine.'

Failure to note this excellent advice will result in less than best idle quality & off idle response.
 
Okay first of all I'm not telling you what to do I'm just going to share my experience with what I did and you can take it for what it's worth.,
I've always set my lash cold so don't burn myself and get hot oil all over everything. When I have iron heads I set the lash about .003 loose and when I put aluminum heads on .006 tight.. it's just a nature of the beach how things work when warmed up... My cams are usually about .020-.022 lash and is the above differences when cold.,. That should be sick before you even start the motor...
With my high performance engines and even performance engines they like a lot of initial timing and that's in the 18 to 22°. But that said generally don't want to go over 34. So your timing mechanical curve should be around 14 to 16° of total mechanical.... Personally I don't use vacuum advance and that's just me not telling people what to do., Also I generally put the second to the lightest friends in so the ramps up pretty fast..
As far as the carburetors I did a lot of studying on this and one thing that popped up was if you look at Edelbrock carburetors that are sold as dual quads the carburetors are set up slightly different instead of exactly the same as you would think...
He might find one that has a smaller Jack or a larger Jack or smaller or larger metering rod or different springs as compared to the other one....
Of course this is all for Street performance and throttle response as opposed to just matting it to the floor at the drag strip and wanting both carburetors running exactly the same...
Again of course this is just what I do with my stuff and I'm not going to argue with people whether it's wrong or whether it right or any of that stuff it's just the way I do things not telling you what to do...
 
Also solid lifters should sound a little sewing machine like not super quiet .
 
Bewy said:
MM,
Until you set the lash to the correct amount, stated earlier by me, you should not attempt any tuning of the carb or ign.

You think 30* is a lot of initial? My 1966 GTO, as well as millions of other GM cars, drove off showroom floors with well over 20* of initial timing. 26* for my car to be exact, with a veeery mild cam.
Sadly, you are not understanding this relationship & I have explained it so many times on this & other forums that I do not feel like doing it again. Initial & total timing are different. You set initial first, & then total by modifying the curve in the dist. Some people use locked dists, so if the initial is 34*, it has 34* from 0 - forever.

Here is a quote from D. Vizard in his Holley book. Think about why idle timing is mentioned in a carb book......
Page 30: ' The optimum idle advance is typically about 35-40* for a short cammed street engine & [ though not commonly realized ] as much as 50* for a street/strip engine.'

Failure to note this excellent advice will result in less than best idle quality & off idle response.
Click to expand...
Thanks for your input. I do understand the difference between initial and total timing and what a locked distributor is so no need to be sad. I was asking you what you think the total timing should be. I'm going to have a dist. built for this car once I figure out what it needs. The motor actually idles pretty good now. I'm wanting to get the lash right before setting up the carb as I stated earlier.
 
MM.
Unless you put the engine on a dyno & try different amounts of total timing, there is no way of knowing what that engine wants for max hp.
If this is not practical, you need to find similar engine builds & see what timing is being used, & use that as a guide.
 
248 @ 50. 296/ 557. I would set them 22 cold. I really like that cam, pulls hard and idles nicely. At least 24 inital 36-38 total.
 
You must log in or register to reply here.
-

Back
Top