This is where it gets kind of interesting. #1 and #5 are nearly perfectly clean. The rest are covered with carbon as one might expect from my initial rich condition. What do you think?

Recheck the valve adjustments. Sounds to me like a couple are too tight.

What does it have for vacuum vs the rating of the power valves?

Mike

double checked firing order 137...
tightened intake manifold bolts
checked float level
messed with idle mixture-now 1.5 turns open
messed with timing-now about 10 btdc
quick look under the valve covers

It seems like things smoothed out a little when I tighten the manifold. How can I tell if I have a vacuum leak. I've been told to spray wd-40 along the seam and see if things smooth out. I think I'm going to slap my old carb back on and see what happens.

Later, Boss66

To check for an intake leak, use spray carb cleaner. You'll hear a difference if there's a leaking gasket. Good Luck!

Where is the best place to measure vacuum? A port in the manifold I assume.

You want to check Manifold vacuum. You'll find it below the throttle plates. Ported vacuum is above the throttle plate and works in reverse of manifold vacuum. Adjust your idle screws for max vacuum and idle speed, the reset your idle rpm and do it again. With your cam you should get 16-18+ inches of vacuum at 800 rpm. It'll probably happen about 3/4 to 1 1/4 turns out on your idle screws. Good luck and keep us posted.

SteveW

I was just thinking why I might have a vacuum leak at the manifold. I used an engine lift plate that bolts directly to the top of the manifold. This was the first time I'll done this and I was a little worried about lifting the engine from an aluminum manifold. The lift plate says it is safe for up to 1000 pounds, even with an aluminum manifold.

Of course I haven't confirmed this theory, but has anyone had any problems with using lift plates that bolt directly to the manifold. Boken manifold or vacuum leaks?

Still running rough, with carbon covered plugs. I thought maybe my 17 year old ford ignition might be the problem so I slapped on an MSD ignition and blaster coil. So much for my cheap engine change. Maybe a little better. The only thing left is the carb or or the distrib. I'm thinking the carb just isn't doing it's job correctly.

More to come.

What rpm should I be able to get it to idle at? gt40p, b303, X'ccelerator intake, 625 carb. When it's warm, it idles decent at 10-1200 right now.

Also, now that I've switched to MSD, where do I attach "tach" output from the MSD to get it to the dash guage. I can't seem to find any wire that works.

Your motor should idle as low as 700-800 rpm.

Can you stall the motor by blocking off the choke plate with your hand?

If you have a intake leak, it would be more likely the result of a mismatch from machining or poor gasket seal than damage from lift plates.

------------------
SteveLaRiviere/Webmaster -- MCA # 47773

The idle speed screw will not decrease rpm below 1000. It loses contact with the little lever at that point. I have got it to idle at 1000 now, but like I said the idle speed screw becomes ineffective at that point.

Well I think the car will get me to work in the morning. I will drive is very easy until I get it dialed in a little better.

Any ideas as to why my idle speed screw won't decrease rpm below 1000?

Franklin - why do you think blocking the heat passages made your car idle so rough.

Thanks all for the help this weekend. All things considered this was a pretty smooth engine swap.

Later, Boss66

I'm afraid you still have a vacuum leak. If you think this through, you have the throttle plate closed all the way with your idle screw backed out. So where is the engine getting the air to run 1,000 rpm? Either that or the carb's throttle plates aren't closing fully. Good luck, and congratulations so far.

Boss66, if you don't want to spray carb cleaner on your new paint you can try a propane torch, unlit of course. The propane will mix with the air and effect the idle if there's a leak, I've never tried it, but it should work! The main thing is to make it run right, and the secondary thing is to look good while doing it, right? I've had engines that wouldn't run under 1200 rpms and thought it was "the big cam" but looking back it was the vacuum leaks! A roller cam should idle very well especially compared to the same hyd. cam. Keep us posted!

I like the idea of the propane torch to discover vacuum leaks, but don't smoke while conducting this experiment and watch out for backfires.

Should I be reading more than 16.5 on my vacuum guage?

What do you guys think of the Mike Urich tip in the "Holley" book that suggest to drill a 1/8 inch hole in each primary throttle plate on the same side as the idle circuit in order to lean the idle mixture and make the idle mixture screws more effective?

A steady 16.5 inches should be ok. As far as drilling the throttle plates, that trick should be reserved for "really nasty cams". You know the cams that idle at 1500+ rpm. The holes allow the engine to reach the high idle speed without opening the throttle plates too much and idling off of the main jets. I'm out of ideas I'll pass the torch (propane) now! LOL

OK I won't pass the torch yet. After reading your last post I agree with you about the carb. That's just not right especially for a hi dollar demon. I've never worked with them before, only Holleys. What was it they told you about a allen screw when you called them? Maybe another call is in order. Are you sure the carb gasket isn't interfering with the throttle plates? (Just an idea) Could the accelerator pump linkage be holding things up? Look for anything that might keep the plate from closing. Good luck, and let us know. I'm sure Mike is curious too

Also, have you checked the plugs again? Are #1 & #5 still lean?

Try the carb cleaner, it will penetrate better and will find the leak. Also check the pcv valve by pinching the hose closed with vice grips. Good luck, I'm passing the torch 'til the weekend 'cause I'll be on a business trip. Good luck, you'll find it

Great job!! So I guess the propane does work, like I said I never tried it myself. It stalled because it was too rich with the added propane to the air from the leak. Anyway, where was the leak? At the front of the intake? If so maybe the front galley gasket is too thick. If you used the rubber gaskets that came with the intake gaskets, you might want to try hi temp silicone or the new gasket maker in the aresol can. It's expensive but great for intakes!! I'm out in the a.m. and I want to check this post Friday eve. and see that it's running like a top! OK? CU and good luck

I changed the intake gasket and tried again. No change. The vacuum reading is still about 16. The carb still won't idle below 1000, unless I force the throttle plates to the extreme closed postion. I still have the idle mixture screws about 1/2 turn open. I have the primary and secondary idle speed screws completely backed out. I spent all night searching for a vacuum leak and I'm 99.9% there isn't one. I just can't figure out what's going on. It won't slow down and It doesn't idle as well as it should. I'll keep searching for answers and let you all know.

Later, Boss66

What do you recommend I set the timing at? It likes a lot of advance. Right now I've got it set at about 15 btdc (900rpm) with the vacuum advance disconnected.

With the butterflies completely closed, can the carb get enough air through the idle circuit to keep it running at 1000 rpm? Visually, the butterflies are closed.

I'm stumped.

Boss66

I may just run it as is. All the fine tuning has resulted in a fairly decent idle at 900 with initial timing set at 15 btdc. If I advance timing a little, it will idle a little faster (1000-1100), and there is nothing I can do to slow it except physically put force on the linkage to force the butterflies closed just that little bit extra. The car performs great on the road. Lots of power, even though I haven't really pushed it much. The idle mixture screws are only open about 1/2 turn. 1/4 more turn in will kill it.

I may try bending the linkage just slightly to see if I can get the primary butterfly to close a little more before it hits the accelerator pump linkage.

I put a very strong return spring on during my experimentation.

Is is normal to need to have the idle mixture screws set at 1/2 turn open? Demon says typically those screws should be 1.5 turns open. I have never, in my limited experience, had such a fine line between too rich (to the extent that idle suffers) and too lean (car dies). Any ideas?

Are you guys sick of tuning my carb yet? I promise to quit asking these boring questions very, very soon.

I'm back, and I see everyone has been taking real good care of you! I don't have much to offer at this point, except that I would try a different carb. Even a 2bl with an adapter at this point! Give something else a try, "even if it doesn't look as nice". Let us know what's happening!

Hope you figure it out soon Boss66.

You guys are great..

Don

It was a happy ending, & no one shot JR

Thanks to everyone who once again helped me solve a problem. I learn a lot about my car by going through this sort of discussion.