Just finished installing Chevy 454

[josh0325]

Hey guys, I need a little help as I'm confused about timing my new engine.  I know that Initial timing should be something simple but it's got me frustrated.  Before initial fire up I set the TDC mark on the balancer on the timing pointer 10 degrees btdc, then I dropped the dizzy in on #1.is this okay, or should I have set the TDC mark on O and used the distributor to set initial timing.  Would this result in late valve timing???  Please help, I do not want to mess this engine up.

[bd]

Distributor position has zero effect on valve timing.  Valve timing is controlled by the rotational position of the camshaft in relation to the crankshaft.  That relationship is fixed by the timing chain.  As long as the timing chain was installed correctly and the cam was properly timed during assembly of the short block, valve timing is fine.  If you stabbed the distributor one tooth advanced, the vacuum advance may not be in the optimum position once the timing is properly set using a timing light - meaning the vacuum advance may interfere with other components in proximity.

[Rattler12]

Make sure #1 piston is at tdc on it's compression stroke. Mark your distributor on the base dead center below #1 on the cap. Set your balancer mark at 10 degree btdc as indicated on your timing cover. Measure 2 1/4 inches to the right of your initial mark on the dist and mark. Looking down into the engine take a long screwdriver and turn the oil pump tang to line up with # 5 intake valve. Turn the rotor to line up over your second mark. Slide the distributor down into the block and it should fully seat with the rotor contact directly over your initial mark at # 1 on the dist. Take off the rotor. Turn the dist to match the triangle on the shaft to the closet triangle on the base and tighten up the dist to the block. This should allow the engine to readily start. When it warms up and you can get a steady idle, plug the vacuum port from the carb  to the dist, attach your timing light to #1  and set it at your desired timing. I set my 454 @ 10 degree btdc. Some folks like to set it higher but in my experience while it makes it run better it makes starting it harder after its at running temp. My 454 runs like a scalded dog and starts with a click of the starter hot or cold.

[josh0325]

Thanks for the heads up, I was pretty sure I had it where it needed to be, it starts right up, and it idles like a popcorn maker.  But, when I hook up my vacuum gauge for carb adjustment it flutters in the red, and it reads incorrect valve timing, intake manifold leak.  Intake and carb do not respond to carb cleaner sprayed around base of carb or around the intake.Pretty sure cam was installed correctly, and straight up as well.  Has me puzzled

[VileZambonie]

Well if it sounds like a popcorn maker then you wouldn't expect to see solid vacuum gauge readings. Is it a stock cam? What is the base timing set at?

[josh0325]

cam is not stock.  Advertised duration .296/.296 . Duration at .050 is .238/.238, lift is .542/.542.  was just worried because vacuum gauge connected to full manifold vacuum at intake says late valve timing, leaking intake etc.  Checked the intake and its fine, don't understand about late valve timing.

[josh0325]

Base timing is set at 12 degrees initial, and 36 degrees all in by 3000

[bd]

cam is not stock.  Advertised duration .296/.296 . Duration at .050 is .238/.238, lift is .542/.542.

^^^^ This is the low vacuum reading....

[VileZambonie]

Yeah if your valves are properly adjusted and with that cam you shouldn't be looking at a vacuum gauge at idle.

[josh0325]

Lol...that's what I kinda thought, just ticks me off a little bit, because the cam manufacturer tech told me it would operate mybrakes just fine.  Also said I wouldn't need a stall converter since it's decent cubic inch engine.  I appreciate all of the help from everyone.  This is the biggest cam I've ever used, and this is third time I've had to pull the engine and had it built.  Wife is ready to put a slug in the truck.  Is there a gtbing I could do to help vacuum quality??? I suck at tuning...

[VileZambonie]

So is your problem lack of vacuum for your brake booster? I run much more aggressive cams than that without issue.

[josh0325]

Yes, it feels like it had manual brakes.  I tried eliminating outside sources of vacuum issues.  Plugged off all vacuum ports at intake for brake booster, and modulator for trans.  Still same reading.  Tried to post a video of engine running, but says document too large when I try to post.  Gauge is reading fluttering needle between 5 and 10 in hg.  Gauge indicates late valve timing, leak at intake or leak at heat riser.  I don't have a heat riser, and I don't know how to eliminate intake as the issue.  When I spray starter fluid around intake the tan just blows it away, and I cannot efficiently reach the rear due to firewall and dizzy.  I'm really scratching my head on this one.

[josh0325]

Sorry read gauge wrong, reads between 10 and 12 in hg

[Rattler12]

I've got just about the exact same cam in my 454 and 12 is about all you're gonna get at idle. Doesn't seem to adversely  affect my brakes though

[bd]

Will the brake booster hold vacuum?  Check the brake booster vacuum check valve.  If the check valve is leaking, the booster may not store sufficient vacuum to function properly.