Timing or distributor issues?

[Lvspider2k]

Hey all. I have a '79 spider 2L (Original CA emissions car) that I recently did an 1800 intake and EMPI 32/36 carb conversion. I also changes the timing belt, tensioner, water pump and hoses while I was in the engine bay. It runs smoothly but develops a backfire though the intake during acceleration and I haven't had time to diagnose and solve. Here is the thing, with the timing at 10 degrees BTC (the factory setting), it idles nicely but backfires under load and generally lacks power. I advanced the timing to about 25 degrees BTC and it idles rough but makes great power under acceleration. I changes the coil and ignition module out several months ago to a Vicks dry coil setup with new wires and plugs. I'm thinking the vacuum advance ( or the mechanical advance) may not be working properly but I wanted a second opinion before I tear ino the dizzy. To my knowledge, the distributor has never been rebuilt but the previous owner had receipts from less than 1000 miles ago indicating a new cap, rotor and vacuum advance module. I seem to have decent vacuum from the intake but I can not see the vacuum advance module move when I rev the engine in the garage. Should I focus my efforts on the vacuum advance module and rebuild the rest of the dizzy while I have it out?

I am interested in hearing your thoughts.

Thanks in advance!

[bobplyler]

Why don't you put a timing light on it and see what it does when you rev it.

[SLOSpider]

I would start with double checking your timing marks. You may have the intake cam off its mark. It would run fine without the vacuum advance working. Check your TDC crank mark and confirm it with a screw driver down number 1 spark plug the check your cam timing marks on the cam housings.

[So Cal Mark]

certainly I'd recheck timing marks but we've found many times we need to use a larger low speed jet when using that carb on a 2L. Usually one size larger is adequate. Do you have any means to check your fuel mixture?

[Lvspider2k]

I appreciate the quick responses. I have double checked all of the static timing marks and they are all aligned. The timing does slightly advance (~10 degrees) when I rev the engine with a timing light connected which is why I suspected the issue may be lack of vacuum advance.

Mark, I was curious about the primary jet size as I have heard that others have had similar issues. At this point, I do not have the means to check the a/f ratio as I am still running the stock 4-1 exhaust manifold. What ratio do you usually target for a stock 2L with a 1800 intake and EMPI carb? I do have an old-school analog CO meter to hook into the exhaust buts its quite "wonky" and I'm not sure I trust its measurements. How much is the larger primary jet?

Thanks again...now if only I could add 2 or 3 extra days to the week to work on my baby before it warms up...but such is the of a classic project car.

Kevin

[So Cal Mark]

does it "pop" when goosing the throttle or on steady acceleration?

[Lvspider2k]

Under load, it with hesitate and backfire under acceleration. Is that what you mean?

[greenspider81]

Hey to all. I have an 81 spider 2.0 that was running really well but i noticed i started to have some leaky oil seals. That said, I have recently pulled the engine and transmission. I replaced all of the oil seals and oil pan and tanny pan gaskets and seal and the timing belt. Also, I replaced the distributor cap and rotor and plugs. I dropped the engine and tranny back in. After hooking up the fuel lines and most of the electronics I set the cam sprockets and aux cam according to the book, and most of the posts I have read. The crank is set to 0 TDC and the distributor to #4 cylinder. After two turns of the crank all feels good. The problem is that when I start the engine i am getting a lot of clicking. I have reset the cams like 25 times and tried adjusting the aux. sprocket but I continue to have a lot of clicking noises that sound like they are in valve areas. The Aux. sprocket is at the 33 degree mark or 1 o'clock. The crank is set to the furthest most finger which I interpret to be 0 TDC and the #4 cylinder is at TDC. When I turn the Aux. sprocket by hand , I do feel a slight bind at about the 1 o'clock position.
Does anybody know if this is normal or could I have a bind in the oil pump? Any responses would be appreciated.

[So Cal Mark]

did you remove the cam housings to replace the gaskets?

[greenspider81]

did you remove the cam housings to replace the gaskets?

No...I did no engine work. I just replaced all of the engine oil seals and the oil pan gasket. I did remove the cam sprockets, aux. sprocket, and crank pulley. I also replaced the rear oil seals. Oil pressure is good when i start the engine but the clattering continues.

[So Cal Mark]

are the cam sprockets plastic? Do you have the thick washer along with the sprocket bolts?

[greenspider81]

are the cam sprockets plastic? Do you have the thick washer along with the sprocket bolts?

Thanks for the response. The top sprockets are steel and the aux. sprocket is plastic. The sprocket bolts do have a washer in front of the sprocket. What do you mean when you ask about the thick washer?? Each sprocket has a washer of the same size. I checked the Distributor today and made sure the rotor is lined up with the #4 plug wire. I cleaned off the nub behind the intake and exhaust cam sprockets and lined up the holes in the cam sprockets. The exhaust and aux. sprocket have one hole in them and the intake has two. ( I am assuming these are right??) I can't find any info in the book on this matter. But i have read threads claiming that the exhaust and aux. sprockets are the same. It almost sounds as though the oil pump is banging on the #2 nut but i've moved it three teeth to the right with no change. I have lined up the sprocket at the 1 o'ck position and also got out a protractor and set it to 33 degrees. I pulled the #4 plug and it looks like its burning really rich.

[greenspider81]

I haven't had any response in a while. Anybody able to help me with this problem. Could i possibly have some valve problems??
This is really strange,,I just changed the oil seals!! Dropped the engine and tranny in,,hooked up the fuel lines and electrical lines,,,started her up and click click click....

[greenspider81]

I haven't had any response in a while. Anybody able to help me with this problem. Could i possibly have some valve problems??
This is really strange,,I just changed the oil seals!! Dropped the engine and tranny in,,hooked up the fuel lines and electrical lines,,,started her up and click click click....

Well,,I never got any responses so i continued trouble shooting. I changed the plastic Aux. sprocket from plastic to steel and rest all timing marks. I checked the oil and connected all water hoses and rechecked all the electrical connections. I started her up and the clicking continued. AFter about 2 minutes there was a different kind of click and then all of a sudden the clicking was gone. It was an eary sound that sorta scared me but befor i could react by turning the engine off she cleared and ran really nice. I re-filled the radiator and engine with antifreeze and cleared the air in the lines. Now she runs like she did befor i changed the oil seals. Mind you,,I believe the problem was an oil problem..not enough pickup from the oil pump. I'm not a mechanic so I really can't tell ya but she if running good. I did learn about setting the sprockets and the Aux. sprocket and timing. I read and read and read all the threads from most of the pages on this site and they we all quite helpful. For the help that i did get I that you!! I am now changing the rear brake compensator and the oil seals on the rear axle.

[SLOSpider]

Good to hear she is back to running.