'65 200 not running right

lilgoomba

New member
Long story short, I have a freshly rebuilt 200 bottom, CI aluminum head and intake, 390 cfm Holley, and DUI ignition. I have yet to get this combo to idle at all, although it will run, poorly, at a higher rpms. As you let the rpms drop, it will sputter and die.

Things I've checked:
Ignition - I was getting a very poor spark from the DUI, so I sent it in and they said it had some kind of defect. They did fix it for free, but I'm still not totally confident that this dizzy is reliable.
Compression - I'm getting almost exactly 150 on all cylinders. Hopefully this means that the valvetrain is working right, but I could be wrong. This brings me to...
Valves - I set these according to the procedure in the shop manual. They seems to be opening and closing properly, and I don't hear any clatter.
Carb - This has been difficult to tune since I can't get the engine to idle. The float level seems good on both bowls, and the idle mixture screws are set out about 2+1/2 turns. It's fed by an electric pump.
Vacuum - Now this is where I think it has a big problem. I'm getting very poor vacuum when I hooked up a gauge to the carb base. I've sprayed carb cleaner around to test for leaks, but can't find any.

Other notes:
I don't know if it's because it's a new build, but this thing runs HOT! Within a matter of a coulple minutes, the electric fan kicks on and cools it off. It almost defies physics as how hot it gets and how fast. This makes me think that there's some kind of massive vacuum leak. THe water pumps seems to be working ok because the heater hoses and radiator hoses also get hot.
Sometimes it makes a squealing noise when it gets really hot like that, so I kill it immediatly. I'm going to try taking the belt off and run it cold for a short time to see if it's the belt or an accessory.

My technical level is shade tree, so hopefully someone out there can help me out with this. It's really starting to hold up the whole restoration.

 
Ok, I'll give it a try. Unfortunately it'll have to wait until tomorrow since it's late and dual 40 flowmasters tend to irritate the neighbors. If I recall, I roughly set it at 8BTDC when I dropped the distributor, but that was just from lining up the timing marks at 8 and pointing the dizzy to #1 spark plug. Is there a better way to do that? I'm not even sure if the timing marks go up to 20.
 
use a dial back light if you can if not estimate it , its just a test , ALSO , if you have a vacuum gauge hook it up to a manifold source and get a reading
 
You didn't mention your cam specs - some of the CI cams, for instance, result in a very rough idle and/or very low vacuum. I had the Clay Smith 264/264/110 in a 200 with a large log head, 2-V adapter, Autolite 2100, and headers, and the engine idled quite roughly with low vacuum. Sometimes the engine died at traffic lights (Houston has a lot of traffic lights and you spend a lot of time waiting if you drive very far in Houston). My understanding (from Mike) is that the aluminum head makes the cam profile "feel" larger because the ports (especially the intake ports) are so large and efficient on the aluminum head.

Also, did you or anyone else degree the cam? It's possible that the cam was installed incorrectly, or even manufactured incorrectly or wasn't the cam that was ordered (unlikely, but still possible). Degreeing the cam would confirm that it was the cam that was ordered, manufactured correctly, and installed correctly.

That said, if the cam profile is one that should product a reasonable idle and vacuum, installed correctly, I would look to either a vacuum leak or a carb issue. I had a mysterious issue with my rebuilt Autolite 2100 that caused fuel droplets to intermittently drip from one of the venturi boosters. When this happened, the idle would become very rough. Look into the carb bores with a bright light while running (you might need a second person on the gas pedal or throttle lever to do this) and check the carb float level. My .02 is that it's not a fuel delivery or spark delivery issue if you can run at higher RPMs (it could still be distributor related in that it could be a timing issues as FSD says).

Bob the Builder
 
Heat might be timing issue as per previous post.
At what rpm will it run without dying?
My 264/274/112 gets kind of thumpy below 1000rpm but it will idle at ~750rpm.
Probably need to do a wide-band tune to get that carb dialed in.
 
The cam is the Clay Smith 264/264-110, probably the same as the one you're describing. The specs didn't seem that aggressive, but given what you mentioned about the aluminum head ports, maybe that is causing of these issues. I had the cam dialed at a reputable shop that has always done good work for me on previous builds.

I don't have a tach hooked up, but I would estimate that it will run around 1200 rpms before dying. It sounds like the engine speed is going up and down at about two second intervals. On the down cycles, it will quit sometimes if I don't rev it a bit. Very frustrating!

I'm going to tackle this again tonight and mess with the timing a bit like FalconSedanDelivery suggested. Since I got the DUI back from being repaired, I haven't messed with it too much.
 
I got my car yesterday after installing aluminum head, 264/264/110 cam, duraspark II and bunch of other small things.
My guy is an hour away and the car was driving fine but after 30 minutes it started to give me some troubles. I had a hard time moving from the stop light. The car was stalling and sometimes it was able to go and sometimes it died. My mechanic told me that because that aggressive cam the car has not enough vacuum. He recommended to install a vacuum reservoir
http://www.summitracing.com/parts/mrg-3701

he didn't do it because i picked the car on Sunday and they were out of stock day or two before.
But in meantime my starter died. I almost didnt make home. I put the car in garage and that was the last time i was able to start it. and now because i have all those parts on and headers i cannot remove the starter. So the car is going back to the shop on the flatbed :(
I want to scream
 
I hear ya, I'm nearly at the end of my rope with this engine setup.

The vacuum reservoir seems like a good idea if the power brakes are killing the engine at stops. I added one of those to a street/strip '70 Mustang and it really did make a difference when running a brake booster with a massive cam.

However, I just don't consider the 264/264/110 cam that big. The aforementioned '70 Mustang had a 347 stroker with a HUGE cam (FR B303) and single plane intake, and it still idled better than the 200 with the aluminum head.
 
Good news, everyone!

So tackled this problem again tonight and made a lot of progress. As FalconSedanDelivery suggested, I move the timing up to roughly 20BTDC. It was already starting to run a lot better, then I tinkered with the carb a little bit, adjusting the idle mixture and idle speed. The combination of those fixes seems to have it idling ok now. Not perfect, but decent.

I would say by ear that it's stable around 700-800 rpms. It even allowed me to put it in gear for the first time (c4 automatic), so the rpms went down a little lower and it was still ok. I can finally see the light at the end of the tunnel!

Oh, and the squealing noise was just the belt. The sound was echoing off the firewall, so it sounded like it was coming from somewhere else. A little tightening solved that problem.

Thanks for your help guys, I really appreciate it. I'm hoping to get it into a shop soon where they can install a wide-band O2 and do some more accurate tuning, but for now, I'm a happy camper!

And BTW, this thing sounds mean with 3 > 2 headers and a pair of 40 flows! You'd never know it was a six.
 
Ok , BUT NOW you need the Dist re-curved , setting it a 20 initial is fine , some even like up to 26 , BUT without limiting the total , YOU will kill the engine , I also think its LEAN , as using more initial increases the Vac signal , the suggestion for lots of initial was not , a OK that's it , it was a lets see what that does , if you were in PA , I could have your combo fixed up and smiling in just a couple of hours
 
i think your dual flowmaster exhaust is way to big for this engine.
with a 2x 2.25" setup or bigger, you loose a lot of power in exchange for a lot of noise bacause you don't have enough backpressure.
with a 2x2.0" setup it should be better, but with your 200cid engine, it's probably still to big.
i used to have a 2x2.25" setup and it sucked. now i have 2x1.75" setup from mike and i think it's perfect for my build. -> viewtopic.php?f=48&t=63391
 
When you use the Term ( Back Pressure ) you are telling those that know , that You Don't Know what your talking about as it applies to an exhaust system on a car :banghead:
 
@FalconSedanDelivery maybe reading my full post would help. :banghead: :banghead: :banghead:
yes i am indeed referring to the exhaust system and not talking about his idle problems.

@super4ord as long as your engine is stock and not using headers, an over sized exhaust won't be that much of a problem.
but for the math: 1x 3" (~750CFM Flow) is still smaller then 2x 2.25 (~2x400CFM Flow).
both are way to big for a non turbo charged small six. you would loose a lot of torque at low rpms.
 
I read your WHOLE Post , Back pressure is a Misnomer , you can have loss of Velocity which effects SCAVENGING , But Back Pressure being LOW is ALWAYS a good thing ,still waiting on time slips for your combo :beer:
 
FalconSedanDelivery":20uvwkep said:
I read your WHOLE Post , Back pressure is a Misnomer , you can have loss of Velocity which effects SCAVENGING , But Back Pressure being LOW is ALWAYS a good thing ,still waiting on time slips for your combo :beer:

i checked and your right, back pressure is not the right translation for this problem.

but still, if he is using headers and i'm pretty sure he does, he will run into problems if the secondary pipes are too big, because the scavenging effect will not work at low rpm, because the expansion of the gas will have a negative effect on the flow velocity.

by the way, we don't have drag racing tracks in Switzerland, but i might to do a dyno run next year.
 
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