Dialing in a cam on a 250

[jahearne]

Since there isn't an aftermarket timing set out yet, I'm stuck. I checked the part number on the crankshaft timing gear, S415 - 1969 to 1977 250 ci motor. I've read on this forum that the later timing sets retard the timing for emissions. I would have never known that info if it weren't for this forum; this place is priceless! Well, I didn't think to check the part number on the cam gear. I wonder if it's possible to use the wrong gear. Would a 200 camshaft gear fit?

I just installed CSC-264/274 (110*) Hydraulic Dual Pattern Camshaft and dialed it in to learn that it's 4* retarded. I've double checked this and studied Clay Smith video in detail. Intake came out at 114* and the exhaust at 106*. 114-106=8/2=4* the larger number on the intake side means that it's retarded.

Now here's my problem:
I can't get the motor to idle well unless I'm running s#!+load of static advance somewhere in the neighborhood of 24 degrees. Anything less than that the vacuum drops real low and idles very rough or not at all. I've checked the TDC mark with the head off using a dial indicator and it's dead on.
When I run the motor around 2500 rpm after about 2 minutes the headers start to glow RED HOT, the water temp spikes and the radiator spews!
I am using a DUI distributor with the vacuum disconnected. With the dizzy connected to manifold vacuum, I can turn it clockwise, retard it a bit, and still idles well, but I get the same results = RED HOT.

I replaced the head with Offy triple intake with my stock head from '66 200 engine running single autolite 1100. Checked for intake leaks, got none. I cc'd the head, piston/deck and took head gasket into consideration and running 8.9 to 1 compression. Using adjustable rockers, the motor is new, the radiator is also new and borrowed from my BB Cyclone. The only other thing I can think of is that the carb is too small and running lean.

Unless I can get a timing set that I can adjust, I thought about mixing and matching parts. Any suggestions would be greatly appreciated. help

Thanks,

 

[addo]

Hey John, a step backwards may yield some results.

This is an "interim" proposal until the real parts are sorted. Dial the old cam with the new gears, and have it reground relative to the results found.

Regards, Adam.

 

[Bort62]

Sounds to me like the timing chain may be a tooth or two off. The glowing red hot sounds like its running REALLY retarded.

I had this problem once on a SBC, and it turned out that we had installed the timing chain off a tooth and it was causing the cam timing to be wrong as well as the ignition timing to be retarded enough to glow the exhaust manifold red hot.

 

[falcon60]

John-

My 200 in the Falcon (just built last fall) has the same cam. Fortunately for me I have the adjustable roller chain/gear set that you can't use. If you've degreed the cam and found it 4 retarded,then of course it's not a tooth off.
I have my cam installed 4 advanced and still have to run 12 degrees initial timing and 10 degrees vacuum advance at idle (total of 22 at idle) or the engine will not stay running. That's fairly common with a 110 lobe sep cam with a lot of overlap compared to stock so I think that's ok.
Your red-hot manifold is of concern though. Most times in no-load situations if the exhaust is way too hot it is rich rather than lean.That allows extra fuel to continue burning in the manifold and exhaust ports and really heats things up. Before messing with fuel I'd try setting the timing so that you have 36 degrees at 3500 rpm (should be fully advanced by then). Set that with the vac unhooked. Then limit the vacuum advance to 10 degrees or so by adjusting the vac can or limiting the travel inside the distributor,and hook the vac to full manifold vac. That will give you 20-25 deg advance at idle,and 36 under wide open throttle,and nearly 46 at light throttle cruise.
You can test the effects this will have on manifold temp (before modifying anything)by simply adjusting the dist to 46 deg while holding the speed at 2500 rpm. I think the exhaust will be cooler.
Anyway,that's what I've done and it works great on mine. Give it a try if you like.
Oh.....isn't there an offset crank key available to adjust cam timing? I thought there was,but I may be wrong.Might give Mike a call about that. I really doubt that 4 deg retard is the whole problem though.

Terry

 

[fast64ranchero]

Do all of your header tubes get red or just part of them? to me it sounds like a combo of both timing and fuel, if your Dist. timing is retarded and fuel is rich it can cause this, also if your running lean on the idle circuit it could cause this also, if your running the Offy intake and three carbs it had to believe it lean but it could be, I don't think it's your cam timing but if you want to change that you can buy a FE (390) offset crank key, or a, I hate to say it small block chevy LONG key (there is two sizes) and mod it buy grinding the bottom (round part) of the key to help get you there, might even play with the other cam gear, if you got the chain and gears in a set then you have the retarded cam gear, hope this helped. Walt

 

[jahearne]

Only part of the headers get red hot, the first 6 or so inches out of the head starting with port 1 and 6 get hot first then the others turn red immedately afterwards. I've set the idle mixture by leaning it out until it starts to idle poorly and then richen it until I get the highest vacuum reading.

I'll try your settings Terry. Thanks for the suggestions.

I found these part numbers off an older post: "Use a chain and gears from a 1969-71 250. The NAPA numbers are S414 for the cam gear, B415 for the crank gear, and 9-363 for the chain."

I'll make sure I have those parts handy and some offset keys before I take the motor apart again. I can always return them, if I don't install them.

Thanks for all the replies and suggestions,