Thread: Need Help SB350

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Hi all, I'm new to this forum and need help. I have a 1923 T Bucket which was built by Street Rodder Magazine in 1985 as a Cover Car and a Sweepstates giveaway car. Engine put in this t-bucket at time of build just shows 1978 SB 350 from a Camaro. Originally was built with a 4 barrel carb on it and then changed later to 3 dueces which I took off and put back as a 4barrell.

I have just put on a Edlebrock performer manifold and performer 600cfm carb. Engine is running rich and plugs are fouled with black carbon. If I try and give it much throttle I just get alot of black smoke out of the headers and it backfires.

Here are my questions:
I am using Delco Plug R45TS which shows as correct plug for a 1978 Camaro. I'm not certain what the plug gap should be. In 1978 most applications used HEI ignition and this motor just has distributor and points. So I'm thinking that the normal .045 is to big a gap and maybe .035 should be used not sure.

I'm not sure what timing should be. I've got it set at 12 degrees BTDC now.

I'm not sure what the dwell should be but from what I've been able to ascertain maybe around 29-31 degrees.

Also this engine was built using a Holley Fuel pump and I don't know how much pressure it puts out but my Edlebrock insts. state that I should not have more than 6.5 lbs for their carb to function correctly. I will get a regulator and put in the line and hopefully that will take care of the rich condition. I will check distributor points.

I guess I'm asking what things to check and what would cause this engine to run so rich and lose power and backfire when I'm trying to accelerate with it. I'm ok going slow around town without using much throttle.

Thanks for your Response Kenny W.

I will check again the dwell and set time around 8 degrees. I adjusted the air mixture on the carb on that seems fine they adjusted ok. Idles good.

I will recheck the firing order on spark plug wires. I don't know how to adjust valves. They are hydraulic arn't they? and should not need adjusting.

This was running fine after I made the change just running rich when I would get on the accelerator. It was just last week when I got on the freeway then gave it the gas and got black smoke and popping or backfiring in the headers.
It ran fine but just was rich and every time I check the plugs they were covered with black soot. Should the plug gap be at .035 for points instead of the .045 I've got them at?

Also Edlebrock stated that they have two ports for vacuum timed vacuum and manifold vacuum port on the carb. I hook my vacuum line to the manifold vacuum. I think that the other timed port was for emissions.

Thanks for your comments.

"Should the plug gap be at .035 for points instead of the .045 I've got them at?"
Yes.
Use this tutorial from Edelbrock to dial in the carb......
http://www.edelbrock.com/automotive_...ers_manual.pdf

Was that the yellow T bucket with graphics on it? I sort of remember one like that as a giveaway car.

Welcome to the forum. BTW, how did the car run with the trips on it? What was your reason for swapping them out?


Don

Edelbrock carburetors like around 5-5 1/2 lbs. of fuel pressure. Holleys will tolerate a little more than Edelbrocks will.

Thank you all for your replies. This forum really helps with getting info from other knowedgeable folks. I will put in a new pair of plugs gapped at .035.

This car was red and built by California "T" Components in 1985 for Street Rodder Magazine. It was the cover car on the October 1985 issue. Street Rodder featured this car again with me in it in their April 2006 edition. I took off the 3 dueces because I would usually only run around town using the center carb and then the end carbs would stick shut and the linkage would freeze up on me. Cannot use the car much in the winter in Idaho.

The car was not backfiring until I took it on the freeway which must have fouled the plugs to the extent that they now would not work, and that .045 gap sure must not have helped. I will let you all know how it turns out. Sure alot of fun to drive this T-bucket around town though. I hope the fuel regulator will solve most of the fuel richness problem.

is your choke working correctly???
Almost sounds like it's not opening properly

Yes, I check it after I warm up the car first to see that it is off the high step of the cam then take off the air cleaner to look and make sure that it is fully open before I start off. I will check it again while driving to make sure that it is off and open. I can look thru the windshield at it.

A note of caution....Holley has two identical looking regulators; one
adjusts from 1-4 psig and the other 4.5-9 psig. Their part numbers are
one digit apart....If you're trying to go 6 psig, one wont adjust!! (ask the guy who has tried)

mike in tucson

HI all, I think I'm finding the problem why my engine is running rich and was backfiring and the plugs are all carbon fouled.

1. Rechecked the plugs - I had them gapped ok at .035
2. Checked Dwell it was 32 degrees. Too much dwell I understand will not give the points enough time closed to build up a spark. I reset it at 28 degrees, then set timing at 8 degrees BTDC.
I went for a drive around town and no smoke now much and no popping. But what I did find out is that when I set initial timing at 8 deg. and then put the distributor vacuum line back on I should have got the timing to retard and I can't see that the vacuum advance is working. From further study, and since most my driving is around town at low idle speeds, it appears I need this vacuum to retard the timing to keep the plugs clean, is this right? I will look into getting a new HEI distributor.

I still need to get a fuel regulator though to make sure that I'm not getting more than 6.5 lbs of pressure also to my Edlebrock Carb. So all I have is probably centrifugal advance and this is probably why when I get on the gas pedal there is a point that nothing happens fast and then it sort of takes off.

Vacuum advances the timing. Yours should be ported (venturi). An advance unit that works well should wake this thing up.Dwell is the time that the points stay closed, not open. And your 28-32 degree range is good. When you switch to HEI, your vacuum will go to a manifold scource.

Thank you. That is right, now I understand. Vacuum advances spark at idle and cruise conditions for more effiecient burning. My Edlebrock carb had two ports one for timed vacuum and one for manifold vacuum. I put the hose on the manifold vacuum port to the carb, should I have put it on the timed port? Remember this is just an engine in a T-bucket and not setup in a car with emissions equipment on it.

thanks for your help.

On your distributor with points, the idle timing will be where you set it initially. As the rpm's advance, so does the vacuum to the distributor. With an HEI, you will have the timing advanced with a source at idle. Thus, the reason for ported for points, manifold for HEI. As you sit right now, put it to the "timed" port. when you change it over to HEI, change the vacuum source.

What I read in the Street Rodder magazine article was that the engine was a 1978 chevy 350 from a Camaro.

I know there was put in a New Mallory distributor when this T "Bucket" was built. One of the owners it appears took out the distributor and looks like there is this old looking one in it. When I put in a HEI distributor how does it hook up electrically. I only have one wire going from the coil to this distributor.