Newbie with cam and timing question

[Beej]

I'm new to the site, I introduced myself in the Welcome Area, My name is Ken. I have to admit it has been a long time since I have torn into a Chevy 350, so... the story goes like this...

I bought this 1975 C10 for my son and I to work on, it's coming along nicely. It has a 1977 350 engine that has been rebuilt by a reputable shop. It has an Edlebrock Performer 4bbl and intake with Flowtech headers and 40 series Flowmasters. We decided to put a reground 270 cam in it. Specs. are; Dur Deg @ .50 Int. 224 Exh. 224, Valve Lift Int. 467 Exh. 467 Grind is #270 (hence the name) and the cam number is #274.

I assumed that it would be installed just like a stock cam and lined up the crank and timing gear marks as stock, crank at 12 o'clock and cam gear at 6 o'clock, right? Well, after getting it all back together and the distributor in the right place, I adjusted the valves, also as stock.

Here's the problem... When we started it... it started right away but idled at about 1600 rpm and we couldn't bring it down at all and it got real hot real fast... headers got red... Tried to set the timing but when I turned it back it would just die... Any Ideas? Would valves being too tight cause this? I haven't adjusted valves in many years and may have got it wrong. I tried rotating the distributor 180 degrees but it just backfired so I must at least have that right.

[enaberif]

Originally Posted by Beej

I'm new to the site, I introduced myself in the Welcome Area, My name is Ken. I have to admit it has been a long time since I have torn into a Chevy 350, so... the story goes like this...

I bought this 1975 C10 for my son and I to work on, it's coming along nicely. It has a 1977 350 engine that has been rebuilt by a reputable shop. It has an Edlebrock Performer 4bbl and intake with Flowtech headers and 40 series Flowmasters. We decided to put a reground 270 cam in it. Specs. are; Dur Deg @ .50 Int. 224 Exh. 224, Valve Lift Int. 467 Exh. 467 Grind is #270 (hence the name) and the cam number is #274.

I assumed that it would be installed just like a stock cam and lined up the crank and timing gear marks as stock, crank at 12 o'clock and cam gear at 6 o'clock, right? Well, after getting it all back together and the distributor in the right place, I adjusted the valves, also as stock.

Here's the problem... When we started it... it started right away but idled at about 1600 rpm and we couldn't bring it down at all and it got real hot real fast... headers got red... Tried to set the timing but when I turned it back it would just die... Any Ideas? Would valves being too tight cause this? I haven't adjusted valves in many years and may have got it wrong. I tried rotating the distributor 180 degrees but it just backfired so I must at least have that right.

When you installed the cam did you rotate the engine so the dots were at 12 cam and 6 crank? If not you put the disitrbutor in at TDC #6.

You need to put the engine back to TDC #1 on compression stroke them drop the dizzy in at around 8-10*

[Beej]

No, I put the cam at 6 o"clock and the crank at 12 o'clock... I lined up the timing marks as if stock. I'll try that tomorrow...

[Beej]

BTW... Thank you!!!!

[rich weyand]

GM service manual shows crank mark at 12 and cam mark at 6, lined up next to each other. The crank can never be at 6 with the cam at 12: a half turn on one is a full turn on the other.

Valves should be set with the engine off. Set exhaust 1-3-4-8 and intake 1-2-5-7 with the engine in #1 firing position. Set exhaust 2-5-6-7 and intake 3-4-6-8 with engine in #6 firing position. Tighten down until the pushrod does not spin easily between your thumb and forefinger, then one full additional turn. Some will say 1/2 or 3/4 additional turn. GM service manual says one additional turn.

[Beej]

Thank you Rich... That is exactly what I did... So I must have messed something else up... Could I have gotten them too tight? The valves I mean...

[rich weyand]

Originally Posted by Beej

Thank you Rich... That is exactly what I did... So I must have messed something else up... Could I have gotten them too tight? The valves I mean...

Sure, then the valves won't close all the way. Weird things will happen.

So put the disti on #1, back the listed valves off till you can just spin the pushrods in your fingers, then tighten them one full turn, then do the same to the other list with the disti at #6.

Of course, it could also be something else entirely, but let's take things one at a time.

[JJLT1]

welcome Beej / Ken

getting hot and headers glowing is retarded timing, advance it more,
get it running,, and set it about 30* for the cam breakin..

the carb is probly on the choke fast idle, which is not a bad thing for cam breakin,,
2000-2500 rpm for 20-30 minutes.. don't let it idle..

if it runs? its not 180 out..
the crank gear dot is allways at 12oc, allways, that's TDC for #1 and #6..
cam dot at 12oc is for #1 compression stroke..
cam dot at 6oc is for #6..

[Beej]

Thanks for the input guys... It's all starting to come back to me now, I even dreamed about 350 Chevy engines last night... Oh brother! Anyway, It looks like I have things right but I'll redo the valves to be on the safe side. JJ, I never thought about the fast idle on the carb, thanks for that too. I'll work on it after work today and let you know how it goes.

[geezer#99]

Don't spin pushrods, wiggle them.
Here's a link.
http://www.crankshaftcoalition.com/w...raulic_lifters

[Beej]

geezer#99... Thanks, that's a great article!!

[Beej]

I would like to say thank you to all who pitched in and gave me advice!!!!! I was able to get it going tonight and it really runs great!! Turns out the valve/lifters were too tight and I was a tooth off on the distributor.... Again, thanks for all the help, I hope I can be as helpful to someone else and pass it on!

[rich weyand]

There ya go. Excellent.

Now, connect the vacuum advance on the driver's side (manifold vacuum) port of the Edelbrock, not the passenger's side (timed vacuum, 1968 pollution mandate nonsense).

Then dial in the mixture: the Edelbrocks are notorious for being set up rich from the factory. Here's a tune that should work for you. (I am assuming the smaller Edelbrock here, like the 1406.) I got it with an AF/R meter, and it seems to work on most 350s with stock to mild cams and low compression heads. Primaries: jets .092 (#1425), rods .062 x .052 (#1441); secondaries: stock; step-up springs: 8# (comes with #1464). You will also need to replace the airhorn gasket (qty 5 is #1499) when you change the primary jets. Adjust the float bowls while you are in there, as they will be wrong.

Then dial in the idle mixture. Start at 2 turns out. Keep dialing them out 1/4 turn at a time until the rpm peaks, then starts to drop. As soon as the rpm starts to drop, turn them back to the peak rpm, then one more quarter-turn in.

Finally, dial in the timing. Start at 12* BTDC, and check that you don't get pinging when pulling hard up the steepest hill near you. Dial it up another two degrees and try again, when you get pinging, back it off 2 degrees. Or you can just set it to 16* BTDC, which with the 20* mechanical advance in the stock HEI is sort of a sweet spot for the SBCs, and test for pinging there. You shouldn't get pinging with your setup until about 20* BTDC, so 16* BTDC is pretty safe.

And thanks for checking back in so someone searching with the same symptoms has some things to try.