Totally out of Ideas - Engine Runs Poorly

[abnovak]

Ok, first I really tried to look back at all of the posts that I could find to try to fix this but I am total out of ideas. Second, I am something of a newbie although I have some experience and good advisors. Here is the situation

'66 200 cyl: Bought a "rebuilt" engine (cheap) from a guy who decided to go V8 rather than rebuild the tired 200 that came with the car. Everything in it was completely new (pistons, cams, rods, rings, bearings etc) and unused. I do not know if they used a stock cam. Stripped car down completely and its sitting on block so unable to drive. Want to get drive train working properly before I start paint.

Problem: Starts easily but runs very rough. With my hand at the exhaust, sputters distincting. No smoke. Doesn't hestitate or stall after acceleration. Set timing at 10 degree with dist adv plugged. Vacuum hovers around 10-12 but is erratic. When accel, vacuum increases but stays erratic.

New Parts: new rotor, cap, duralast wires, autolite plugs, pertronix ingition, pertronix coil, completely rebuilt and bench tested autolit 1100 carb from Pony Carbs, all new hoses and lines (every one), teflon tape at all vacuum joints (careful not to block openings), alternator, PCV, and just about everything else in the engine compartment.

Tried:
- starter fluid at all vacuum points (no change) although I might have missed one or two on the integral head around the expansion plugs (going to recheck once I reassemble the head)
- converted back to points from electronic (no change)
- checked dist gear does not appear to be worn nor does the shaft have play
- adj mixture on carb both in and out 2 turns until it starts to stall. returned to position when shipped by Pony Carb
- no vacuum at the dist vacuum port on the carb (normal per Pony)
- vaccuum at the auto choke (normal per Pony)
- compression test: no variances at all between cyls both wet and dry although compression is low at 90 lbs each.
- spring height (compressed and uncompressed) within tolerances
- new tappets and push rods (gaps are not adjustable on the 200s)
- pulled head. lots of carbon esp for such little use. pretty evenly spread throughout each cyl but only within the head up by the valves. Cyl's and pistons themselve are still pretty clean.
- was missing one oil seal which I probably screwed up when assemblying the head/valves. going to replace all oil seals.
- valves do seem to have too much play side to side within the head (may be the problem with compression)

My Theories:
- Vacuum leak within the integral head that I have not been able to find yet.
- Valve guides in the head are worn (although a mechanic friend feels that they arent that bad)
- Wrong cam for this engine.

Before I pull the cam to determine any problems or ship the head to a shop for work, does anyone (!) have any (!) other suggestions. Please, I'm beggin.

 

[D.Hearne]

If it's got non adjustable rockers, and the head was milled too much , you may need shorter pushrods now. If so the now too long pushrods may have too much preload on the lifters, keeping the valves open slightly. That would also explain the poor compression readings. Scenario #2; The cam's not timed right. #3; What 12 degree setting do you have the ignition set at? 12 degrees before or after top dead center ?

 

[mustangdave]

Double check the firing order. IIRC the erratic readings for vacuum indicates a valvetrain problem. You might want to play with the rocker adjustment with it running. There is always the possibility that there is an aftermarket cam involved too. I tend to lean toward rockers misadjusted though.

 

[abnovak]

- I dont know the history of the head but it did not appear to be milled when I got it. I can't say for sure. I guess after I get it running smoothly, I can try the shorter rods to improve compression but would that make it run roughly?

- Timing is BTDC

- I don't have a lot of experience building engines so I am not sure how to degree a Cam properly. Before install, I did check to make sure that the dots on the timing gear were aligned with the cam gear.

 

[abnovak]

MustangDave - what is IIRC in your post? The rockers are not adjustable ont he 200. My only option is to go with over or undersized push rods.

Also, I have quadruple checked the firing order but will again.

 

[rbohm]

since this came out of a 66, i will assume that you have to old load-o-matic distributor. if that is the case then that maybe a big part of your problem. the load-o-matic is an all vacuum dist, and isnt the best way to go. find a dual advance dist from a 68 or later 200 and swap it in. if you get a point type dist you can keep the pertronix unit. as far as timing the six, the dampner rings were not the most reliable at staying in place on those engines, meaning that the ring may have shifted position in rotation from where it should be and you are getting false readings from your timing light. best way to time a six is to advance the timing until you get pinging under acceleration, then back it off until it stops.

i doubt the cam timing is off, one tooth = 16 degrees of timing, and most engines wont run when the cam is that far off.

 

[5.0ina66]

I agree...ditch the Load-o-Matic dizzy. I'd go to AutoZone and get a Duraspark dizzy and blue-tag box for a 1980 Fairmont with a 200 I6. Should be under $80. Alternatively, if you wanted a direct swap, Autozone has a 68 200 I6 dizzy for $40. Read www.fordsix.com for more info about either the load-o-matic or the Duraspark swap.
HTH
--Kyle