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Old 04-09-2010, 07:10 PM
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First BBC, urgent help with timing!

Hey guys, bear with me, I picked up my first car with a built BBC(454) in it, and I want to get it running properly. It was an ex-race car I think someone took off the original carb/dist and bolted on a crappy carb and distributor and didn't know what they were doing, so I'd like to sort everything out properly but I'm learning as I'm going.


Here's what the car's doing: When I picked up the car, it was barely turning over when you'd bump the starter, and would only fire if the engine temp was under 120(meaning you couldn't drive it somewhere, turn it off, buy a coke, and get back in it and fire it up). I put new plugs in it and drove it home that way. It ran fine from 2-3k RPM and poorly everywhere else in the rpm band. The new plugs(gapped at .035) did make it run a lot smoother as several of the others were wet/fouled when I pulled them. Apparently, this is because the timing is too far advanced, so I loosened the distributor and turned it counterclockwise a little. Then when I fire it up it wouldn't hold idle then stalled and blew a flame out of the carburetor. I decide to reset the timing myself.

Currently, the plugs and wires and cap are off the car. Half the plugs were fouled black from my 2 hour trip home. #5 even had gunk covering the electrode. I assume this to be from the valve seals(more on this later). I plugged #1 cylinder and turned the motor until it pressurized. But now I'm confused, do I turn the crank until the timing mark is at 12' noon, or until it's at 0* timing on the marker? Which one is TDC, and what's a surefire way to make sure it's not 180* off without pulling the timing cover?

My next question is a stupid one; How do I turn the rotor to point to #1 cylinder? Do I have to remove the distributor, or just turn the rotor by hand? It's currently pointing at about 4 O'clock when it should be at 5:30?

Also, I was told the valve seals need replaced(burns a little oil). Only the drivers side smokes. Do the heads need to come off for this?

Another observation about the car, if I hold my hand over the exhaust pipe, the exhaust pulses are reasonably stronger on the drivers side of the car compared to the passenger side. I'm not sure what this means?


I really need help with this because it's my only source of transportation right now!

Thanks in advance!

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  #2 (permalink)  
Old 04-10-2010, 03:55 PM
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Hi,
Welcome to HotRodders.com Glad to have you with us.

Chevy's Dist. rotate clockwise, so buy turning the dist CC. you were advancing the timing further.

I have a buddy that can't get this right either, so now he takes the valve cover off & watches for both valves to be closed, then lines up the pointer at 0*

It's not necessary to change the dist location, you can just change the location of the wires, after you have #1 at TDC wherever the rotor is pointing, make that tower the #1 plug wires new home.

Plug gaps, fool around a little with the gaps, you may find a closer setting may work better for you

You can change seals while the heads are still on
Rich

http://boxwrench.net/specs/chevy_bb.htm
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Old 04-10-2010, 06:40 PM
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Richard, thank you very much for a warm welcome and a helpful answer, I was beginning to lose faith, but I guess these are simple questions for you guys!

So am I safe pointing it at 0* on the timing pointer? This carcraft article suggests installing at 12* BTDC: http://www.carcraft.com/howto/ccrp_0...tor/index.html

Any reason why they do this?

What if the rotor isn't pointing directly at a point?

-D

Quote:
Originally Posted by richard stewart 3rd
Hi,
Welcome to HotRodders.com Glad to have you with us.

Chevy's Dist. rotate clockwise, so buy turning the dist CC. you were advancing the timing further.

I have a buddy that can't get this right either, so now he takes the valve cover off & watches for both valves to be closed, then lines up the pointer at 0*

It's not necessary to change the dist location, you can just change the location of the wires, after you have #1 at TDC wherever the rotor is pointing, make that tower the #1 plug wires new home.

Plug gaps, fool around a little with the gaps, you may find a closer setting may work better for you

You can change seals while the heads are still on
Rich

http://boxwrench.net/specs/chevy_bb.htm
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Old 04-10-2010, 07:42 PM
richard stewart 3rd's Avatar
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D,
12* advance is better, more power, but remember, the further you advance the more prone it is to detonation,(real bad thing) & the higher the octane rating required to overcome it.

The rotor doesn't need to be pointing directly at the tower, that's what the turning of the dist fixes. (adjusting the timing)
Use a light.
Rich
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Old 04-10-2010, 08:39 PM
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Does this motor have a race cam in it?
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Old 04-11-2010, 01:35 AM
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Quote:
Originally Posted by F-BIRD'88
Does this motor have a race cam in it?
Hey, I'm glad you mentioned this... Can you tell me how mild or wild this cam is? I attached the cam specs sheet below. I don't understand how it says .320 lift, shouldn't it be more like .530, esp with 1.7:1 rockers? Or am I reading it wrong?

I know it's a 4-bolt main block, forged crank, forged pistons, 10:1 compression, aluminum heads(I was told edelbrock? I'm not sure where to look for the edelbrock stamp at to verify), Performer RPM intake manifold, Chevy 427 "dump truck" exhaust manifolds, and someone bolted on an Edelbrock 1407 carb. I don't think I can fit long tubes, and I feel like the carb is way too small for a 454. If I get it running right, will "shorty" headers and a 850cfm carb wake the car up? I have no idea what kind of power it should be making.

I will do the timing tomorrow and let you know how it goes. Thanks for the advice, I'm learning a lot of this hands-on stuff as I go. Anyone have a good link to a DIY valve seal install?

-Dustin
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Old 04-11-2010, 06:48 AM
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the .320 lift is lobe lift, multiply it by rocker ratio to get valve lift (.544)
BTW that looks like a relatively conservative cam for a big chevy.
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Old 04-11-2010, 01:36 PM
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Well I found out the cause of the weak compression on the passenger side, and so the plot thickens...


So on a whim, after I set the crank and rotor today, I decided to pop the valve covers before I buttoned things up. The drivers side looks fine, but it looks like 3 pushrods on the passenger side pushed through their rockers. I attached a pic below... Can anyone ID these rockers by looking at them? I guess I'm going to need to replace the pushrods too. If I unscrew the rocker arm, will the valve fall into the cylinder? What's the procedure for this?

Thanks everyone for your help so far!

-D
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Old 04-12-2010, 05:57 PM
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Hi,
Look like GM rockers, A guy at work had this happen all the time 67 chevelle 396, just unbolt the rocker & replace it, roll the push rod on a piece of glass to be sure it's straight, & make
sure it's not clogged also.
Rich
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Old 04-12-2010, 06:52 PM
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Quote:
Originally Posted by Forza1
Hey, I'm glad you mentioned this... Can you tell me how mild or wild this cam is? I attached the cam specs sheet below. I don't understand how it says .320 lift, shouldn't it be more like .530, esp with 1.7:1 rockers? Or am I reading it wrong?

I know it's a 4-bolt main block, forged crank, forged pistons, 10:1 compression, aluminum heads(I was told edelbrock? I'm not sure where to look for the edelbrock stamp at to verify), Performer RPM intake manifold, Chevy 427 "dump truck" exhaust manifolds, and someone bolted on an Edelbrock 1407 carb. I don't think I can fit long tubes, and I feel like the carb is way too small for a 454. If I get it running right, will "shorty" headers and a 850cfm carb wake the car up? I have no idea what kind of power it should be making.

I will do the timing tomorrow and let you know how it goes. Thanks for the advice, I'm learning a lot of this hands-on stuff as I go. Anyone have a good link to a DIY valve seal install?

-Dustin
With that compression, you should be running the highest octane pump gas you have in your area.
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Old 04-13-2010, 02:55 AM
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Quote:
Originally Posted by S10 Racer
With that compression, you should be running the highest octane pump gas you have in your area.
Thanks for the heads up, I plan on running 93. However I didn't think it was too bad considering the aluminum heads. I used to have a LS1 with alum. heads/cam and the compression was 11.2:1 and it ran great on 93 octane. But that's a completely different engine.

I know the car needs valve seals, and I'm wondering if I should just get a cam kit for $350 and change my cam, rockers, lifters, timing chain, push rods, seals, etc... I don't really have the tools for precise measurements and clearances.

-D
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Old 04-13-2010, 05:55 AM
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Quote:
Originally Posted by richard stewart 3rd
Hi,
just unbolt the rocker & replace it
Not so fast. I put a very mild cam in a 396. Even so, the rocker slots bottomed out on the studs, causing similar damage to what you see here. Closely examine the valve end of the slots and the studs to see if yours are bottoming out. Then buy a set of rollers.
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Old 04-13-2010, 01:03 PM
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By "rocker slot", so you mean rocker arm? Or is this a specific part of the rocker arm? I've never heard the expression before.
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Old 04-13-2010, 01:17 PM
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the slot that the stud comes through
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Old 04-13-2010, 01:19 PM
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Quote:
Originally Posted by Forza1
By "rocker slot", so you mean rocker arm? Or is this a specific part of the rocker arm? I've never heard the expression before.
With any aftermarket higher lift cam than stock, you need to check and see that the slot in the rocker arm is not hitting the rocker stud when the valves are open.
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