Couple weeks ago, I had a guy stop at my house, he saw me outside working on my other 84 vette. He said hey I got one the same year and color. He told me that he was going though. divorce and his ex was trying to latch on to the car and his 2014 vette. He said he was going back to Canada where he was from and it would be to much of a pain in the butt to take the 84 with him. I got the thing for 1000 bucks. I checked the oil while looking at it and the oil was gray, so I knew the heads were cracked. Ot has an Edelbrock performer intake, older style.
I replaced the heads valves and seat with brand new Flo Tech 200cc 2.02/1.94. I checked the lifters and they looked like brand new. He told me 3 years go he put NEW cam and lifters in it. According to the guy it is a Comp Cams 12-609-5 cam round 550 lift. Awful big cam for an auto trans with no stall.
It is all back together but my issue is it backfires through the carb. It will start nd run on the initial two or three pumps of the gas pedal but when that fuel burns and you give it more gas it backfires and dies. I have tried adjusting the carb but it won't idle.
I took the Edlebrock carb off, to see what kind of shape it was in, the gascket is not in the best shape but not the worst I have seen either. I put a known good Holley 4150 on it just to see, same issue. I have check the dist cap and coil, the coil checks out on the multi meter for voltage.

Only thing I can think now is the check the timing chain and the cam. I turned the engine back and forth with a breaker bar and the dist have no hesitation when it rotates, does not mean the timing chain is lined up right though. But the guy O bought it from showed me videos of the thing running last year. It sounded good ut I didn't do the work on the engine so I do not know what this guy did.

I have not check the dist pick up coil yet. I did replace the dist module. This thing is driving me nuts. Nay ideas

 

Are you sure the distributor isn’t off a tooth? Plug wire firing order is correct? Cam timed wrong?

 

The dist is in correctly, I have noat checked the timing chain yet ,,I haven't felt like dropping the oil pan and all that. Firing order is correct.

 

still hving this issue, cheked the timing chain by turning the engine with a breaker bar the dist moves instantly so the chain must be tight, only thing I can think of is the timing dots may not be lined up right. I set the timing at 10 dgerees and put the dist in so that it lines up with no 1 plug wire,, same result backfires out the carb and dies.

 

As much as I hate to I guess I will have to pull the time cover off and check the timing chain while I have th thind tore down I am going to go ahead and take.a look at the cam.
One thing does come to mind,,maybe the push rods aare not the right length. Solid lifter cam. I have never messed with one I normally use hydraulic. It could be that I just am not getting the lifters adjusted correctly. I have seen several wys to do this on you tube The ICE ethod and a couple of others,,,no matter which way I go about it it still backfires thorough the carb.

 

Do a compression and leak down check on it. You might have tuliped valves. That would cause that as well.


Also 10 degrees at idle? Kinnda doubt that's enough for that cam. Get it running and adjust the idle timing by vac gauge and by ear. Advance it and the idle rpm should rise. Keep going untill it gets worse, back it off and try it.. then you will have to mess with the full timing and what not.

All this after you get the valves adjusted right and pushrod check like you said. I wouldnt put too much thought into the timing chain. At least not yet.

 

valves are new heads are new...springs are the one from the original heads. double springs.

 

another thought is,,,I adjusted the rockers by the cam card, and was not thinking that this is for hot engine, I need to readjust the valve .006 tighter for a cold engine.

 

I finally got tired of jacking with it and went with my first diagnosis over a onth ago...i took the cam out and one of the lobes was gone and so was the lifter .......The previous owner took it apart and found out and didn'r want to mess with it..all the bolts were finger tight and the timing chain was just slapped in not even bothering to put in correctly. not even close. I replaced the cam and lifters got finish putting back together and break in the cam in the next couple days.