My 350 engine in my 57 Chevy

BFS57 · September 30, 2018, 09:02:18 PM

Hello!
Well, all I can say is that the engine was really running nicely. Then after starting it cold in the morning, it Backfired out the (I think Carb) and that was that! (it was a loud pop!)
Today I hooked up the Vacuum Gage to see it fluxulate as I could hear the motor do a miss! (not like a dead miss) As it misses the needle dips slightly. It got worse as it warmed up! I just spent a crap load of $$$$$ on this thing, New Chrome valve covers, added a serpentine kit, New Wilwood Brakes, Disc on all 4 corners, Cleaned and painted the motor, and Brand new exhaust system including headers!!!! WHY ME!
First fix will be simple, change the cap and rotor. My distributor is from Spark Man. (HEI) It has preformed really great! Next will be looking for burnt valves??!! I also added new AC Spark plugs! I really wanted Motocraft Plugs but the parts store didn't have any.
Anyone got any words of wisdom? Im pretty much brain dead when it comes to technical engine issues. I can bolt things off and on but these kind of issues?
Thanks to any one giving me a shout back!

Bruce

phat46 · September 30, 2018, 10:15:11 PM

Quote from: "BFS57"Hello!
Well, all I can say is that the engine was really running nicely. Then after starting it cold in the morning, it Backfired out the (I think Carb) and that was that! (it was a loud pop!)
Today I hooked up the Vacuum Gage to see it fluxulate as I could hear the motor do a miss! (not like a dead miss) As it misses the needle dips slightly. It got worse as it warmed up! I just spent a crap load of $$$$$ on this thing, New Chrome valve covers, added a serpentine kit, New Wilwood Brakes, Disc on all 4 corners, Cleaned and painted the motor, and Brand new exhaust system including headers!!!! WHY ME!
First fix will be simple, change the cap and rotor. My distributor is from Spark Man. (HEI) It has preformed really great! Next will be looking for burnt valves??!! I also added new AC Spark plugs! I really wanted Motocraft Plugs but the parts store didn't have any.
Anyone got any words of wisdom? Im pretty much brain dead when it comes to technical engine issues. I can bolt things off and on but these kind of issues?
Thanks to any one giving me a shout back!

Bruce

What carb is on it?

58 Yeoman · September 30, 2018, 11:24:42 PM

What Motorcraft plugs would you need?

BFS57 · September 30, 2018, 11:41:22 PM

HELLO;
phat 46; The carb I'm running is a street Deamon with the phenolic fuel bowl
58 Yoeman; I forgot the number I'll have to look at some of my notes, But a friend of mine seems to like these new multi point Plugs (C o3?)
I do know that the carb is a Holly Creature and the reason I put it on is because this is the only way I had to deal with boiling gas in my Edelbrock! I switched to the Deamon and I like the performance but my next quest (after this mess) is to do a FiTech system!
My new headers, the pass side fits just absolutely fine but the drivers side the first plug is too close and the last plug wouldn't go in till I had some "distancing" done.I also changed plug wires which also may be a problem. Think I'll go back to a new set of MSD or Taylor! Anymore, it's a crap shoot for any kind of quality products out there.
Keep the thoughts coming!!!

Bruce

chimp koose · October 01, 2018, 01:05:41 AM

I think the pop was a lean backfire as you said the motor was cold . You may have a broken power valve in the carb . this will cause a surging idle as the engine gets really rich and will eventually soot up the spark plugs .The fluctuating vacuum is the motor going rich making the idle fluctuate as it takes on extra fuel. the power valve will be in the metering block on the primary side between the fuel bowl and the carb body. when you replace it (probably a $10 part) you might want to clean your plugs . Demon carbs are pretty rich right out of the box . I have one on a stock 351w motor and the idle mixture screws are almost shut for highest vacuum at idle . I am going to put in larger idle air bleeds some day to get a better idle adjustment on mine , motor is on the garage floor right now waiting to be installed in my 65 mercury truck

BFS57 · October 01, 2018, 09:00:16 AM

Hello;
Sounds like kind of what I was kind of thinking!
OK! The plugs I want are the Autolite # 26 Those did fine in my car.
I will educate myself where the power valve on the carb is and get a part but me and carbs don't get along too good Ive had some successes and some failures.
As i looked at some info (looked at the instruction manual on line) on line It looks like the Deamon 625 I have seems to not have a power valve as with "traditional Holly" Carbs, or at least any parts identified inside there is no mention or showing of a power valve!
Thanks and keep any more ideas coming.

Bruce

UGLY OLDS · October 01, 2018, 10:29:05 AM

Look to verify that no vacuum hoses popped off when the engine back-fired.....
Also try spraying some starting fluid (BE CAREFUL !!), around the BASE of the carb & see if the engine speed increases.....
The fluctuating vacuum gauge reading is usually an indication of a vacuum leak somewhere .....

Bob...

58 Yeoman · October 01, 2018, 06:16:17 PM

Sorry Bruce. I've got 7 boxes of NOS Autolite spark plugs, but not that number.

BFS57 · October 05, 2018, 09:33:12 PM

Hello;
Update; I got a new cap and rotor on the car and then I noticed that the plug wires had some problems! OK! Im Guilty of purchasing what seemed to be a pair of nice headers. in reality, only the passengers side was nice. The drivers side was absolutely Hideous! Had the #1 and & 7 plugs so that you cant put #7 on without taking off the header! Tried to get some distance but didn't work so now, Im faced with taking the darn thing off and finding someone to modify the * thing! Which aint easy in California!!
Im thinking of cutting the #1 and & 7 outlet pipes (I don't have any kind of equipment do do any of that) on the header and somehow separating the distances to get more space!! I only need 3/4" or so!
Once again, Im not a welder or fabricator so Im lookin for someone to take care of this problem.
Anyone know someone, that knows someone, that knows something about this kind of thing?
Im in the San Fran area (East Bay to be exact)
Thanks for your support without it I wouldn't know as much as I do now!

Bruce

Rrumbler · October 09, 2018, 04:16:39 PM

Ah, the "small block Chevy header nightmare" raises it's ugly head once again. If you are not able or comfortable with trying to modify them, seek out a good muffler/exhaust shop and pay the price. I never found but one manufacturer that ever fit without some tube flattening on the spark plug side of most of the tubes. The only ones I ever had that fit well were Thorley Tri-Ys on my small blocks. I bought a set of Crower headers once, and the fit was so bad that I called them - they were in the City of Industry - and trailered the truck up to the shop at their plant. The guy in their development shop took them off and beat on them for a while, put them back on, and they had enough clearance to get to the plugs. They gave me my money back, and thanked me for bringing the problem to their attention; I don't know if they changed their patterns or not, though - they are long gone, now. As an aside, those headers were still on the truck and in reasonably good shape for their age when I sold it; they were twenty years old.

BFS57 · October 09, 2018, 09:05:51 PM

Hello;
Its only on the Drivers side that the header does not fit! SO . . . Im going to take the darn thing off, take it someplace here and cut the tube on the #1 and#7 and try to insert a "sleeve" and hopefully bend those 2 tubes to give me about 3/4" more space away from the plugs. I hope my idea works or it's OLD MANIFOLDS ARE BACK!!!!!

Bruce

BFS57 · October 25, 2018, 11:31:52 AM

Quote from: "BFS57"Hello;
Its only on the Drivers side that the header does not fit! SO . . . Im going to take the darn thing off, take it someplace here and cut the tube on the #1 and#7 and try to insert a "sleeve" and hopefully bend those 2 tubes to give me about 3/4" more space away from the plugs. I hope my idea works or it's OLD MANIFOLDS ARE BACK!!!!!

Bruce

Hello;
Update! So, I got sick and tired of the headers not working for me so I re-installed the old manifolds, after cleaning and coating them (they look pretty darn good!)
OK! Start up! Problem exists!!!! Found that my Passengers side exhaust is backfiring quite a bit! Drivers side, not so! Now I don't know just what to do to find the cause of this problem! I looked for a Vacuum leak but did not find one so far! but Im not finished there. I did find my carb was a little loose so I tightened it down, next I will examine the booster and related hook up!
Some suggestions from you guys would certainly steer me in the right direction!
As far as engines go I don't have an over abundance of knowledge so to keep me from "royally" screwing up, I need to get someone that knows what Im facing here!
As usual, thanks for any and all suggestions coming from all of you!

Bruce

chimp koose · October 25, 2018, 05:32:57 PM

firing order issue ?

enjenjo · October 25, 2018, 10:15:10 PM

Bad cam?

BFS57 · October 26, 2018, 12:16:19 AM

Quote from: enjenjoBad cam?[/quote

Hello;
Well I checked all my hoses and replaced one that looked suspicious. Then I checked the carb and it was a tad loose tightened that down!. Fired it off and it seemed to run pretty good, only time will tell!
Next back to the exhaust shop for new connections to my new system.
Fingers Crossed! * I need some good luck!

Bruce