Thread: Engine running trouble with Chevy 350

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I'll see if I can't pick up some power valves tomorrow and 2 blowout kits. I work right next to a speed shop so I'll head over there tomorrow.

Thanks for the advice from everyone. I'll let you guys know how I make out.

Autolite 86's at .025 or so.

drop your plug gaps down to .020, see what that does.

I agree with NTFDAY time to look at the carb, while you have it apart pull the secondary bowl off and check to see if it has a powervalve in the metering block as wel.

drop your plug gaps down to .020, see what that does.

I agree with NTFDAY time to look at the carb, while you have it apart pull the secondary bowl off and check to see if it has a powervalve in the metering block as wel.

Stupid question: have you replaced the plug wires? Sometimes it's the little things... Foul wires cause your timing to go haywire no matter what dizzy you use, and sitting for a year doesn't make your wires better. Check them.
Any cracked vac hoses? These can also cause your engine to run like the Dutch National football team...
Second:
Take off the carb and clean it (dissassemble and soak it in carb cleaner). recheck whether it runs better or not. Alternatively borrow a similar carb off a running vehicle (from a friend or steal it from somebody you don't like )
If that doesn't help it's not the carb, so buy a crate of beer and visit your friend again. Borrow his dizzy (if it's a HEI or a good running points type thing).
Mostly there's no need to dish out a chunk of greenies until you've found the problem.
I mostly look for the problem with borrowed parts (of which I know they work well) first before I start dismantling things for fun when I don't even know they're the cause of the problem...
If the car was in a really damp environment it's just possible that you have rust inside your engine, which will give you crappy running any time. Small burrs on the cylinder walls from long use won't catch oil and thus rust if exposed to dampness for a long time. This would mean a complete teardown... But that I guess is the worst case scenario...
I would check carb and ignition with borrowed stuff and come back here if it's none of this.
If you're not into racing this vehicle, don't go bigger than 650 cfm with the carb, i would even go for a 600 and a good manifold.
Hope I could help,
Max

Thanks for the reply. I appreciate all your advice. The rust in the engine is an interesting though that I was afraid to even think about.

So here is where things stand. The engine really started to misfire the other day. This engine used to have a problem fouling the #8 spark plug when it was in my old car. So I pulled the #8 spark plug last night and sure enough it was soaked with gas. I replaced that plug as well as #6, although #6 was fine. I need a special wrench for #4 and #2 so I wasn't able to check them. I am sure that the carb is the culprit. I am definitely going to buy a new carb and distributor. Not just because of this issue but because I know the carb is crap and I'm not really liking the mag anymore.

Can I get a low profile HEI that will fit in a 2nd generation Nova? I know that some people get lucky with a regular HEI, as far as firewall clearance goes, but it doesn't look like I will be able to. I really dont feel like spending alot of money on an MSD and ignition box.

Let me also ask you this, I plan on installing the Edlebrock Top End kit in the near future. I dont want to have to buy a carb twice. Will I be able to run the Edelbrock 750cfm carb on what I currently have now so that it will work with the top end kit when I decide to do that?

1969 Chevy 355 (4 bolt main w/steel crank)
Vertex Magneto distributor (internal coil)
Holley 650cfm DP carb
Edlelbrock Performer intake
Fuelie 2.02 cyl heads
Comp Cams 280H cam
TRW 10.1 flat top pistons
Hooker fenderwell headers
Aluminized 3" exhaust with H pipe
Flowmaster mufflers
Muncie M20 4 speed trans

Thanks again for all your help

IMHO opinion what you have is pretty good for the street except for two things. Pull the 650 DP and put a good rebuild kit in with power valve blow out protection and start with 66 jets in the primary and 76 jets in the secondary and also buy a primary shooter kit and the kit with different accelerator pump cams. Then buy a good book that explains how to tune a Holley. I'd scrap the Edelbrock performer (I believe Edelbrock manifolds are over rated) and buy an Offenhauser 360* square bore manifold. Square bore Holleys run better on a square bore manifold than they do on a spread bore manifold. If you are dead set on running aluminium heads that is fine, but iron heads like you have will work well on the street if they have hardened valve seats, a good three angle valve job, and springs to match the cam.

I agree. I never wanted that Performer manifold on there to begin with. It was the only manifold that would fit. I had my heads decked (I hope it was the heads and not the block) and after that it wouldn't accept even a brand new Edelbrock Performer RPM that I purchased. The bolt holes wouldn't line up. I can't remember why the heads/block were decked. Kinda strange that the performer even fits My intake ports may even be off some....that not good!!!

I dont think that I am going to rebuild the Holley. Its just not worth the effort to me. This particular carb is crap. I dont even think that the metering plates are the original . I would just rather put a brand new carb on it. It doesn't have to be an Edelbrock but I heard some good things about them so I figured that I would go with it since I didn't have much luck with the Holley. Nothing against Holley at all. As a mtter of fact I might even consider getting a direct replacement for what I have now.

So you think that 650 is a good cfm even if I plan on changing the heads?

I will highly consider your advice. Thanks for all your help.

[QUOTE=southerner]drop your plug gaps down to .020, see what that does.

Why .020? I would think that the mag puts out a pretty healthy spark and I believe I'd increase the gap to at least .035.

Do you want to sell that mag then ?

You can run smaller gaps with the magneto ignition because the AC voltage generates a hotter spark. So you can close up the gap and save your plug wires.

Originally Posted by DennyW

Not argueing with you, but I thought the purpose of a mag is the increased voltage to burn the fuel at the regular gap. Decreasing the gap gives you a fatter spark, but also is closes the ignition gap. My Judson puts out 70,000 volts, compared to a stock, or hi power coil of 40,000 volts. Never had a mis fire, even at 6200. And I'm still running dual points.

sorry I just have to ask the question what type of ignition is a judson ?

Another thing to think about: I know I'm always the one for worst case scenarios
Are you sure the #8 plug is being fouled by gas? It might be that your heads have a crack. Then the plugs would foul very fast and they would smell of gas, because the cylinder won't fire with water in it, so you have unburnt gas and water on the plug. Looks really yucky and stinks to high heaven AND means you'll have to tear the engine down. To test this quickly take out #8 plug and spin the engine. Hold a piece of card near the plug hole and see if anything comes out. Water will most probably spatter out if there's any in your angine, gas won't spatter, because it's distributed finer. Even small amounts of water standing in on cylinder for only about a week will ruin any engine. I had that happen to me on a 3 year old rebuild I bought (not my rebuild )
Do a compression check! If your cylinders vary by more than a couple of points, then you'll have to at least pull the heads and give it new gaskets. Otherwise you'll seriously damage something.
Holleys are very good carbs, but not so easy to tune and deal with in general as for example Edelbrocks.
As I said earlier, first check everything and try to find the error BEFORE you spend any large money on parts you wouldn't have needed in the end...
As always, that's just my opinion...
Hope this helps,
Max

PS: Give us your compression results on all cylinders if your not sure if they're good or not. A compression test will give you a rubish reading in all sorts of cases: Rust anywhere on the cylinder wall, cracks anywhere, blown or weak head gaskets, valves not seating, rings worn... Almost all internal engine faults will show up on a comp test, the test will only be perfect if all internals are in perfect order.

I appreciate your thoughts MadMax. I don't belive that there is water in the engine. The oil would be "milkshake" like....yes? The fouling of #8 does not happen all the time. This is the first time that this occurred with the engine being in this car for over 3 years now.

I want to buy a new carb and distributor anyway, definitely carb first, so I am not too concerned about the $$$ although I appreciate the advice.

Thanks

It's never a bad thing to buy new things, I do that myself all the time
Just sometimes you don't have to go that way. Water in the engine won't neccesarily cause your oil to go milkshake. Not at once, only over a longer period. I only noticed after a thousand miles or so of using my "new" engine. And as I said, it's only a thought, and it's never a bad idea to do a comp test, just to be on the safe side. But of course it's your free choice
Best of luck,
Max

HMMMMMMMMM interesring, so by looking at it , it repces the original coil and it goes to a normal distributor. looks fairly robust with that big heat sink to dissipate the heat.