I need some advice on getting my car to run right. About 4 years ago, I put a Recon reman 350 in my camaro, and all the stuff you see in my sig. I've got it to idle and run alright, but it's lacking power a little. Right now it runs a 15.33 @ 90.81mph.

I don't expect a 13 second car with my current setup, but I'd love to see the mid-high 14's.

The engine internals are completely stock. Stock cam also. I do not know the compression ratio either.

It was bogging badly when I dropped the throttle, and then it would pick up great. But it's always breaking up around 4,000-4,500 rpm.

With my current timing advance: 18 deg. BTDC and the carb setup as it is (I did change the jets and metering rods), it still bogs (not as bad), but the high rpm break-up is still there.

Anyone know what I can do to get the most out of my setup?

Thanks!

 

18* is too much initial for a stock motor, and you're going to be overadvancing with your mechanical advance up top, which is why you're losing it around 4000-4500, so either less mechanical advance (at max advance it should be 36*) or you need to retard your initial timing.

I'd try it at 12* initial advance and pull a time, i think that'll knock about a half second off your ET if the rest of the motor is fine.

pretty much you're fighting physics throughout the band.... pushing your pistons backwards most of the way through the powerband, and up top you're so far advanced that you pretty much can't rev any higher...

You may think that down low you have more torque, and you sort of do, butonly at minimal throttle, wide open your mechanical advance overshoots your piston speed and fires so soon that your pistons wanna shoot backwards.... and yea bad things happen.

 

I must admit that I am quite uneducated on the difference between initial advance and mechanical advance.

I timed my engine with a timing light, turned the distributor, and had the vacuum advance disconnected, high idle. Originally I was running something crazy, like 32* or something (way, way off of the timing tab) and thats when I pulled the 15.33. A bunch of older guys who said they knew small blocks dropped it to about 12* and my next run was a 15.8

So I put it to around 18*. Haven't been to the track since, however.

 

ooo.... not good man..... ummm how long do you think it was at that 32* ?

well, initial timing is determined by where the timing is at without vacuum advance and little to no mechanical advance (in other words vacuum lines pulled and idle below like 1000 rpms should be fine) However, total advance (when it stops advancing mechanically) should be around 36*.

Now, that 18* initial might be fine... if and only if, it's already started to advance and it's not initial (which is dependent on your timing curve and your rpms where you're testing) or if you have a big cam. You said you tested at high idle...? depending on how high, it might have already started to advance at that point and thus, it may be fine, but we have to make sure.

well, basically the old guys were right, that baby shouldn't have that much advance, 32* initial is parts going in directions they shouldnt and pinging, and it flat out not starting half the time, if even at all. 18* initial in a bone stock motor is a similar story just not as severe. 12* would be a good place for it to be, however you lost time at 12*....this is curious.

I've got a few thoughts about that, either you're checking your advance once it has already started to advance (check at low rpms, like i said before under 1000 should be fine) OR you may have a defective timing light....lol however that'd be too easy and extremely unlikely. You probably had it tuned to run good at 30 some degrees advanced, so at 12* initial advance, reset your idle, your accelerater pump, your idle mixture screws, your floats, everything, I can't imagine any of it would have been right, because you'd likely have to run rich to keep from pinging, and since it was probably rich, your spark plugs are probably fouled. if it turns out that you didnt retune anything between switching from super insane advance to normal advance make sure you do, it's important.

and i also have another thought... it's an odd one but it could happen i guess.... so anyway here it is.

if you had one of the weird harmonic dampers (the big round thing that you shoot the timing light at) that was setup for the timing tab to be attached to the timing chain cover, and your timing tab is a seperate little bolt on plate... those dampers had the mark in a location that would make it look an extra maybe 12-16* more advanced than it actually was, so it's a thought if you robbed the damper off of a different motor and didnt double check the timing marks, but it is unlikely that you have one.

 

come to think of it, when those old guys were setting the timing, they had it running at like 2000 rpm or so. I thought it was high, but didn't question them about it. So if it read 12* at that rpm, the mechanical advance would already have kicked in.. giving it a really low initial advance.

 

yea, that is definitely not good, it could be anywhere initially and you have no idea where, unless you happen to know what the advance curve is... but then you'd be like a freak er something....

 

Thats the least of my problems now. I started the car last week and let it run. Came back 20 mins later to find it running at about 250-260*. So i shut it down and let some coolant into the overflow. Started it back up, the temp went down, and then the upper hose was collapsed.

So yesterday I replaced the thermostat and started it up, and it worked fine, but the car's backfiring alot. Once it was warmed up, it seemed to idle ok, but then as soon as I put it in drive, it started backfiring again. Through the intake and exhaust. And it would only get worse when I gave it gas. Then it would stall once I let off.

I'm thinking maybe it burned a valve. I'll put a vacuum gauge on it one of these days and try to figure it out. If a valve is burned, hello new heads!

 

that definitely sucks, sorry man.

Hopefully it aint a burnt valve....maybe it's just lean, hopefully it's just a bit lean, that works.

But hey, best of luck to you, and if you need anything come back and we'll help you get it back up and running

 

You've given me more actual "help" with this subject in the past 2 days than anyone ever has before. Thanks!