350 sb issues
 

My project truck is working me over...again

Now I'm having engine performance issue which arrears to be a combination of timing and intake.

I have a stock intake with a Edelbrock 1902 carb.

When I pulled the plugs I got a mix of rich and lean results. This doesn't surprise me since my intake is stock.

So what are my options?
Replace the intake or can I correct the issue another way?

Replacing the intake leads to another question.
What is a good affordable intake for general driving?

The second issue I'm having is the distributor is worn out. Any suggestions for a replacement?

Re: 350 sb issues
 

Well, you will get a lot of advice on this....but I always first ask, whats your budget to fix this?.....$500? $800? $75?....don't say 'as little as possible'..there is a realistic, reasonable number in there somewhere.
That will help steer the choices to fix this.
The other major driver in this is what is your level of technical skill on changing out the distributor and working on the carb?
I would say find a good used HEI Distributor OR buy a new one (budget dependent).
I would then suggest making sure your carb is clean, complete and well tuned....is it now? or? (carb kit?)
Have you tuned up the motor?.....current timing? used a vacuum guage?
Lots of blanks to fill in here...but 'fill 'em in' and you will get better and more complete responses.
All Good
Coley:chevy:

Re: 350 sb issues
 

Coley,

I like the was you state there is a reasonable budget.

Since this project truck is for a basic driver with some small performance improvements I would be willing spend $400-$500 for the distributor and intake, but would really like it to be $300-$400 (I know this low would really limit me). I'm after cost Vs. quality, there is always a trade off.

As for my skills...well I'm developing them. I have a well rounded background, but I lack in the detailed knowledge of automotive. I'm a electrical engineer, while growing up I worked in the shop of the family trucking doing simple wrenching, I'm an avid woodworker specializing in large furniture, and have done radio controlled aircraft (planes and helicopters)....... So in a nut shell I'm not afraid to learn and never shy away from a challenge.

With that, my plan is to pull the engine this fall and do a basic rebuild (rings, gaskets, seals..etc), if the engine is past a basic rebuild my contingency plan is to get a crate 383 (this will hurt the overall budget). During that time I was going to rebuild the carburetor..... unless it needs it sooner.

To be honest in the past I have been bitten buying used parts. So if the part is complex and prone to waring out I try to buy new. So with the distributor I would like to buy it new and the intake I'm willing to buy used.

Just last month I did a tune up. Plugs, wires, cap and rotor. A friend of mine help me set the timing. At that time he mentioned that my distributor wasn't healthy.

Re: 350 sb issues
 

get an HEI distruter from a doner and put new parts in it and put on an edelbrock performer intake. good everyday results

Re: 350 sb issues
 

I'd say your issue is a whole lot more timing, carb and spark than intake. Your intake is little more than tubes, shafts, piping (take your pick on words) angled and shaped in such a way to provide the cylinders with air and fuel at whatever given spec the manufacturer was after. That's not to say I wouldn't replace the intake, I just wouldn't expect my plugs to burn evenly with an intake swap.

As far as recommendations- an HEI distributor can be had for around 120-130. Check summit, some are better than others but even the cheaper ones will far surpass a worn out original.

Intake- you'll be after a dual plane. Lots of companies make them. Most magazine dyno shootouts ( i take them with a grain of salt) has edelbrock dual planes making more consistent average hp and tq. Edelbrock has a couple that would suit a stock engine well.

Re: 350 sb issues
 

Save your time on buying used parts. Get a new hei with wires.
http://www.ebay.com/itm/SBC-BBC-CHEV...05d85d&vxp=mtr

Sure, they may be made off shore but what isn't anymore!
Get your timing optimized and leave the carb alone for now.
You might be surprised what a simple timing upgrade can do.

Re: 350 sb issues
 

I'm looking at new distributors and see reference to shaft size and cam type. Before placing an order can someone explain to me hos to tell the difference if I pull my distributor?

Re: 350 sb issues
 

Not sure what you mean by shaft size!
Cam type refers to whether you have a roller cam or a standard flat tappet cam. A roller cam takes a different drive gear on the bottom of your dizzy. You won't have a problem using that one I linked to.

Re: 350 sb issues
 

Maybe you should start with a compression test first. See just what condition your engine really is in before throwing parts at it. A new ignition system won't fix a weak or worn out motor.
Also the stock intake is not the reason for uneven cylinder firing. Yes an aluminum intake may flow a bit more than a stock one but not enough that you will feel it in the seat of your pants, all other things being stock.

Re: 350 sb issues
 

Just a thought here before spending a dime Now I am a big fan of the aftermarket intakes and what they offer but consider this if the problem your having was due to a stock intake, wouldn't there be some history of that type of intake producing uneven spark plug results? meaning if the General had a small block part that was causing plugs to be rich on some and leanout others wouldn't they have fixed that problem in design do overs or a improved intake? That is my main reason to discount the intake as the culprit. As far as the dist goes the skip white should be fine and while on e-bay you can pick up a Cyclone dual plane they looks to be copies of the Edelbrock at about half the price since your not a used part fan. I would look for the performer copy that has dual bolt holes for both patterns of carb and a idle to 5000-5500 rpm range. Jim

Re: 350 sb issues
 

I couldn't agree with these comments more.

Re: 350 sb issues
 

As previously stated, your intake manifold is not the problem. I've seen dyno tests on dual planes and the factory chevy iron intake is not very far behind the aftermarket aluminum ones.

IF the distributor is worn out, replace it first before you replace any other parts. Like Boog said though, a compression test would be a good idea; you may have some valve issues.

You also might have some valve seal issues making some of the plugs appear to be burning differently than the others. How about some stats on the engine: Miles, age, what repairs have been done, compression ratio, what kind of cam, exhaust, anything and everything. Any smoking upon start-up or when driving, is it an automatic trans or a manual, etc. A leaking modulator valve from the trans can put out some sneaky symptoms in it's early stages of failure by sucking in small amounts of ATF, and progress into a smoke machine.

If you do go aluminum intake, I recommend you go Edelbrock and get the Edelbrock choke linkage rod so that your divorced choke will continue to work. Keep in mind that you are disturbing the adjustments on the choke stove so you will have to play with that awhile until you get it right. You may have to play with the carb base gasket thickness but for starters make sure you use what Edelbrock recommends to go with their linkage to get the choke at least close.

Re: 350 sb issues
 

Edelbrock carbs are notorious for having vapor lock from heat and also if you have too much fuel pressure they will run like crud.

So you might need a spacer to avoid heat, and you should definitely run a regulator if your fuel pump pushes more than 5.5 psi.

Gary

Re: 350 sb issues
 

Sorry for the slow reply, but I got busy with my daughter's graduation. We are nearly empty nesters!

I had some time this weekend to collect a bunch more information about the engine.

First of all, I know nothing of the internals, meaning I assume the cam could be stock as well as the engine may never have been rebuilt.

Based on the casting number and engine code numbers the engine is a 350 from a 1975 Vette.
cast number: 3970010
code number: V0417CHB
Block VIN: 15s424153

I got a loaner compression tester (Brand model: OEM/27138) from Autozone and did cold/warm compression test.

• Cold / Warm
• Cyl 1: 90/108
• Cyl 2: 90/110
• Cyl 3: 87/103
• Cyl 4: 88/106
• Cyl 5: 87/103
• Cyl 6: 95/115
• Cyl 7: 88/105
• Cyl 8: 87/104

The carb is a Edelbrock 1902, which is a relabeled Q-Jet. So I don't think the 5.5 psi limitation applies to this carb.....does it?

Re: 350 sb issues
 

I think before i replaced an intake i'd do the distributor first, you say its bad so make sure its fixed or replaced before moving on to other things. then a new set of plugs and run it for a bit and check the plugs again.

You say you have a mix of rich/lean results on the plugs, without pictures of each plug and what cyl its from its hard to determine what your issues could be, is it oil fouled, or too rich, it could just be that now need some valve guide seals, or maybe a good carb rebuild and adjust.

For general driving your stock intake should be just fine.

Re: 350 sb issues
 

Thanks for all the advice.

After the compression test I decided to move forward with a new distributor (the one suggested by geezer#99).

As for the plugs when I took them out to do the COLD compression test they all looked wet and dark, then when I took them out again to do the WARM compression test they were dry and clean looking. Hmm, Am I fighting two problems at a time.....well with a new distributor (and coil) I will only have one option left the carb. BTW the internal of old distributor is corroded/rusty and the weight are loose on the pins (lost of slop).

At this time I'm going to leave the intake as is and maybe in the future change it out.....maybe.