73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 74chev4x4 on September 24, 2010, 01:58:26 pm
-
74 Chevy 350 with 305 heads, I have it timed at 12 degrees and it sounds good but seems to be running rich. It does not respond when I floor it it just slowly comes up to speed and when I get off the gas it will backfire once or twice. It runs Ok but not much power. Any advice on where to time it motor is stick with a mild cam and 305 stock heads.
-
Maybe back it off a bit and see if it changes. Try 8 BTDC. What condition is it in otherwise, as far as tune up parts? Sounds more like carberetion than timing.
-
perhaps accelerator pump? perhaps vacuum leak?
-
Did it just start or did you do something. Usually if its to advanced you will get a spark knock so it does kind of sound like a Carb problem have to know more
-
Just did the intake manifold gaskets to fix an oil leak, put it back together ran great went for a drive and it started stuttering and backfiring. Plugs, wires, cap, rotor, coil are all new. Motor is pretty solid, but the heads r not in the best shape. I can see a lot of blow by coming out of the breather and its in there tight. I will clean the Carb and check for vac leaks and adjust the timing.
-
spray some wd40 around intake gasket and hoses and carb base when idling and see if rpms go up. I bet the gasket on the intake slipped or something.
-
Do Sgt said. Did you have to readjust the settings on the Carb?
-
350 with 305 heads
Problem found....
-
yea not real happy with the 305 heads either but that's what it had on the motor, sprayed around intake no change at all. Did nothing to the Carb but take it off and put it back on.
-
Stupid question but you sure the firing order is right? And all have good connections
-
I will go double check the firing order, but would it run this well if they were off? Thanks guys. Also I keep thinking about swapping the heads on this motor, but have never done heads on a small block. Is it as easy as take the intake off unbolt the heads do head gaskets put new heads on and bolt up the rockers? Can I use the same pushrods lifters and rockers if I just go to a set of stock 350 heads. I would really like to do this to ditch the 305 heads, but not sure how hard it would be. Thanks.
-
found the problem, the number one spark plug wire is arching across the header tube. I tried electric tape around the boot, stopped it for a few mins, now its arching again. Whats the best fix for this new wire? These are the 90 degree boots for headers also.
-
You probably can't save that one wire, but on the next one use these asbestos sleeves. You can get them at o'reillys, etc. Mine are touching the header and they haven't even shown discoloration after a few thousand miles.
-
new wires arcing? solution? Take 'em back where ya got 'em from and demand replacement or money back. Most have warranty.
-
Bought those spark plug boots like grim said, but was only able to by 1 2pk because they are $20 bucks a pack, so hopefully this takes care of it for now until I can swap those heads out for some decent 350 heads, I need to look into how difficult this will be. Thanks.
-
Autozone sells individual spark plug wires they are behind the counter take in your old on they will match it up best they can they are about 4 or 5 bucks can't remember but I'm sure its under 5
-
i keep old wires in my garage--never know when you might need one. I don't have headers, that tends to complicate the deal though with 'regular' wires.
-
350 with 305 heads
Problem found....
Out of curiosity, please explain the 305 heads on a 350 phenomenon. I have heard of alot of people swapping 305 heads onto a 350 to run in demolition derby cars, but have never really understood the reasoning behind it. What is it supposed to accomplish that people would want to swap, and what would those heads do that would cause symptoms like what the OP had? Thanks
-
They bump up the compression I guess, not much performance though my truck has very little torque.
-
They 305 have smaller chambers so the compression is more, but they rpm limited to about 5000 rpms.
-
They will not increase the compression the compression ratio will be higher. The problem is they don't promote good breathability.
-
So what would it take to put on some 350 heads, pushrods, lifters?
-
prob some 350 heads ;D
-
Funny! No I mean can I use the same pushrods from the 305's and the rockers and everything, except head bolts and gaskets must be new I know. What is a good head to put on a stock 350 for around $250-400.
-
all the associated parts are the same.
-
Any suggestions on a good 350 head captkaos that is around 300-450?
-
unless you find some good rebuildables $400 for a pair of good heads is a lil cheap. You won't find all that much. I would look for some vortecs and just grab a vortec intake.
-
http://newlondon.craigslist.org/pts/1964695512.html
-
oh really, I see all the machine shops around here selling rebuilt ones for 300-450 so I thought those would be ok? I can look for some vortec heads.
-
This is the stuff I see from machine shops near me
http://portland.craigslist.org/mlt/pts/1974286168.html (http://portland.craigslist.org/mlt/pts/1974286168.html)
Not sure if any of these would be good or is it just a waste?
-
If you after "good" flowing heads I would get Vortecs.
I probably wouldn't spend much money on anything from 73-88ish for an SBC.
The last SBC I built I just exchanged heads for $150.