rsm688

Okay guys well I have a 351C in an old Ford Truck I have. I got the truck from a guy that had the motor fully rebuilt and then it sat for a while and only had about 200 miles on the motor since rebuilt supposedly (looked that way to me so I believe him). Had some issues with it popping out the carb and not running well and found out the cam had wiped a lobe. Figured he didn't break it in right or let it sit for a long time and then fired it up without priming the oil system or something along those lines. Found a rocker that had a spot worn into it from a valve and decided to replace them too (looks like they reused the original rockers). Put a new Comp cams cam, lifter, and rockers on, new intake seals, new MSD full ignition system (6A box, distributor, and Blaster coil). Comp Cams break in oil, put 10 gallons of fresh 93 gas in the tank and a little seafoam, new fuel filter, replaced the metal hard line from the fuel pump with a brake line from the local auto parts store as the original one was kinked. Filled the carb with fuel through the vents in the top. Distributor dropped in at 10*.



Tried to fire it up and it would start up for a few seconds and run but it sounded weak and like it wasn't really firing up completely and wouldn't go above 1000 rpm and there was one pop out the exhaust. Killed it and tried changing the timing some and still wouldn't fire up right. Pulled the valve covers and turned it over and all the rockers looked to be moving well. We hooked the timing light up to each wire and all were getting spark. Pulled the fuel line off the connector before the carb (Holley) and there was no fuel. There was fuel in the bowl but was about dry when we were digging in to what could be the problem. So I know I have a fuel issue, although I feel like there might be more than just that because it didn't fire up and roar even when we first started it (and fuel had been poured into the carb).



For the fuel issue, my fuel pump was off the side of the motor for a good 5 weeks. Is that long enough to dry out the diaphragm and warrant it being replaced. I am in Mississippi so it's been super hot but it's always pretty humid out. I'm going to try and put some vaccuum on the line and see if I can pull fuel through it. If the fuel pump was pulled and the line between it and the carb replaced and a new filter installed. How long does it take to prime it? Any way to prime it without just sitting there cranking the motor, with a brand new cam I don't want to just sit there and turn the motor over for a long period of time to prime the system? The fuel system was working just fine before everything was pulled 5 weeks ago for the cam swap. Is it possible to install the fuel pump wrong? I felt tension on it when installing it and tightening it down like it was against the fuel cam.



Now on to it not firing up and roaring like it should even when I had poured fuel in the bowl. Any ideas where to start on this? I plan on pulling all the plugs and checking them to see what they look like, I guess I should probably check compression on all the cylinders as well while I am at it. The plugs were installed when I was diagnosing what my problem was before I found out the cam had wiped a lobe. The truck would fire up and run pretty strong before cam swap, it would just pop like a fool when you gassed it and would bog. Could there be some problem with my MSD ignition? It's all brand new. I know it's at least getting spark to all cylinders since checked with the timing light and the fact that it did run weakly for a few seconds. Could the coil not be making enough power? I know it's unlikely but I'm just kinda stumped here. What about timing or the distributor not being right? When installing the timing chain set the metal woodruff keys on each gear were directly facing each other when it was put on so should have been at TDC right? Nothing was touched on the crank during installation of the balancer and all so it still should have been right. Then we dropped the distributor in with the rotor pointing at Number one on the Cap and adjusted it to 10*. Tried it with the timing at like 12 and 16 or so as well and still nothing. We checked firing order several times. Did not see any mention of the new Comp cam having a different firing order anywhere.



Also, the intake seals I used and the manifold I have definitely didn't match. I have the small ports on my heads, and thus used the small\ Felpro intake seals (have both actually). They fit nicely around the ports on the head. The ports on the manifold are much bigger. I have no clue what it is off of but was on the truck when I got it. Looks like it was a factory 4V intake manifold. It has the funky little line/ridge in the top around the holes where the carb sits (saw it might be some strange variant from 73). It had a metal valley pan gasket on it when I got it and was RTV'd around the edges. There are two holes in the heads not covered up by the intake manifold. When I got the truck these were covered in RTV. I stuck a probe down there and they don't appear to go anywhere. I left them open for now but was going to silicon them just to keep crud from building up in there. The thought has crossed my mind that maybe there is some kind of leak going on here which might be keeping my motor from firing up strong/right combined with the lack of fuel making it to the carb.



I am by NO MEANS a mechanic or mechanical expert, I'm a very mechanically inclined motorcycle builder who is very competent in auto stuff like wiring, suspension, brakes, customization, etc. However old engines/timing/auto carbs are by far my weak point.. I know a fair amount but My buddy who is a mechanic and has his own shop was helping me through all this and did the timing setting, timing chain installation, and distributor install but I am one who never trusts anyone, ever. So if something I described doesn't sound right please let me know.

Here's a few pics even though they might not help. Notes for the pics: Gaskets are the large ones I did not use, the ones I used look identical but with smaller ports. I also noticed a little silver spot on top of one of the pushrods, although it could have been from when there was a stuck lifter from the wiped cam lobe. They all looked clean and straight and had very low miles on them so were reused:





Any helps would be greatly appreciated. I've hit every minor bump in the road possible with getting this truck to run right and after getting it all finally together again and running into all this I'm about to the point where I just want to pour gas all over the entire truck and watch her burn lol.





















Thanks,

Spencer

rsm688

We found TDC at compression by turning over the motor with the rocker cover off and finding with the front valve (closest to front of the block) (can't remember if it is intake or exhaust, mechanic buddy knew though) on cylinder 1 opened and turned it til the timing mark on the balancer was lined up and pulled the distributor cover and the rotor was pointing directly at cylinder 1

Figured out the fuel issue, hooked a mityvac up to the fuel line off the carb and it had pressure but nothing came out at all like it was clogged. I pulled the lines off the pump and found the pump clogged full of old rubber where the rubber line attaches to the pump coming from the metal line off the frame. Looks like the hose broke down and clogged it up. Replaced the fuel pump, and rubber fuel lines. Stuck the mity vac back on near the carb after and fuel sucked right on through so one issue solved.

Pulled the plugs and they were black. Plugs were new right before we figured cam had wiped a lobe and replaced it. They weren't super bad but they definitely were black. Got a new set to throw in before we try to fire her up again.

Have a new Fel-Pro valley pan gasket for the 4V manifold coming that will be here Tuesday that should seal up the intake manifold if it's leaking. We put a blow gun onto one of the vaccuum ports on the manifold and blew air in and sprayed some fluid around the port areas looking for bubbles but didn't see any. I'm still not confident its not leaking though.

Once the new manifold gaskets get here and we get them on we will try to fire her up again. What should the initial timing be sat at for a 351C before trying to fire it up. We started at 10* tried around 14* and 20* and also tried around 5* with no luck in any range. Very well may have been due to these other issues going on. Should I try it at 10* again or a little higher?



Thanks,

Spencer

Chris_1

iTrader: (1)

Do the compression stroke on #1 again. You can even put your compression tester in that plug hole just to be sure sure. Now roll it up with a socket till you get to 10 degrees BTDC - those old motors usually ran at 10 to 12 degrees before.
Now with the crank at 10 deg, the distributor rotor should be pointing at #1 on the cap at the same time that the cog on the dist. shaft is exactly in line with the pickup sensor inside the distributor (we used to say just as the points start to open - same effect)
That should get spark timing close enough to run.
For the rest of this, I'm just reaching, but you're probably ready for anything that might help, so...
The cam and crank gears - usually there's a dot stamped in each gear that get lined up, what you said about lining up the keyways didn't sound right, but maybe it is on that old monster - would be worth doing your research on that just to be sure one way or the other.
Cam order - if you have the rocker covers off, you can slowly rotate the engine with a socket and follow the pattern of the intake valves opening just to make sure the firing order is right for the cam - the firing order should match the cam order exactly.
Not revving up might have been a fuel issue most likely.
As for spark, I'll usually get another spark plug, ground it with a booster cable, then stick a spark plug wire on it. Best done in the dark or semi dark if you can manage it. I look for a healthy blue spark. A weak yellow spark usually means a weak coil and doesn't ignite the gas well or at all. It has a harder time even being a spark when it's trying to jump through compressed air inside the engine.
And those mismatched intake ports aren't going to work well, the air fuel mix isn't going to be entering the cylinders smoothly at all, maybe try to hunt up an intake that matches your heads a little better if you possibly can.
That's all I got off the top of my head, maybe something in there will click. Good Luck !

Chris_1

iTrader: (1)

Found this cam gear pic


If that's the way yours went on, it should be good.