SBC 350 hard start (1 Viewer)

[projectfj]

The PCV valve is brand new, and rattles nicely when shook. I replaced it when I first saw it was seeping oil to see if that would fix it. While running, the hose from the carb has a nice vacuum on the PCV. I heard you mention blow by, but said it was usually in older motors. My motor was a crate from the Chevrolet dealership and has less than 3k miles on it.

It still smokes white and wants to turn over for a few seconds when hot. When it finally does crank, for about 15 seconds it wants to sort of choke itself out and sometimes shut off if I don't keep gas to it. After that though it runs like a dream. Any suggestions of something I'm missing, overlooking, or haven't checked yet?

 

[pb4ugo]

Did you check the compression yet? Like I mentioned b4? You say it blows white smoke, which is usually antifreeze or water. Have you checked the coolant recently? Is it low? I only mention this because in your plug pic 9:00 looks like it has a greenish tint to it, plus other plugs appeared to be fouled. I know you said it's a new motor, but that only means it's still under warranty.

 

[projectfj]

I haven't yet, but plan on it in the next few days. The coolant does get low from time to time, but I've had the thermostat gasket and just about every coolant hose leak on me at some point (hose clamps were a major contributor) so I just wrote that off as another leak I'd eventually find. While I'm at it I might as well check the fuel pump pressure. I'll let ya'll know what I find out.

 

[projectfj]

Well the college life has been robbing me of free time. Luckily I have a back up vehicle. However, for those bearing with me I have a break next week and I plan on doing some serious work on the 40. I am going to do a compression test first and foremost. From what I've read about the coolant disappearing, they are signs of a blown head gasket? Also I've been noticing oil leaking from the front and rear of my intake manifold. I'm going to get somebody that knows what they're doing to replace that though since I've replaced it twice (apparently doing a bad job both times) and it still leaks. I also read that if I do have a blown gasket, air getting in could be contributing to the air/fuel mix causing a hard start. Expect updates next Tuesday/Wednesday and thanks for all the help so far.

 

[projectfj]

Also, I finally found my stock charcoal canister so in the mix of all that other work to be done I plan on getting it hooked back up. Will a stock Toyota CC work for a sbc conversion or should I get a Chevrolet one? I just don't care for the idea of venting gas fumes in the engine compartment. Thanks again.

 

[albee]

I had similar hot start problem with my SBC, then I added another new ground strap from block to frame. Everthing is good now.
Good luck
Al

 

[pb4ugo]

Blowing the seals on the ends of the intake mainifold are also indications of something wrong similar to a head gasket. It is building up pressure internally and blowing the the seals. Do a compression check 1st & maybe a cydlr leak down test.. You need try to ID the problem b4 you tear it apart. Is still under warranty?

 

[user42]

Also, I finally found my stock charcoal canister so in the mix of all that other work to be done I plan on getting it hooked back up. Will a stock Toyota CC work for a sbc conversion or should I get a Chevrolet one? I just don't care for the idea of venting gas fumes in the engine compartment. Thanks again.

I picked up a charcoal can from an early 70's camero for mine. Found it on e-bay. Any charcoal canister would work though, provided you can connect it properly.

 

[projectfj]

pb4ugo: The warranty ran out before I even got the motor in, as I said before I'm a full time college student and don't have the luxury of much spare time. I watched some videos on compression tests and they did both a wet and dry test, do I need to do both or will just a dry test give me the answers I need? Also, I didn't use the rubber gaskets that came with the intake gasket kit, I just used silicone. Does that make any difference?

user42: I have access to motor alldata so maybe there are some diagrams on there, if not I know a few guys that work in the parts department of Chevrolet and could get some diagrams from there.

 

[user42]

Wet Vs Dry compression test, in a nutshell:

You first run a "dry" compression test. If your numbers are all good, then you don't necessarily need to run a wet test. If your compression numbers are low in certain cylinders, you would then quirt some oil in the cylinder and run the test again. IF the number improves then the cylinder rings are bad, the additional squirt of oil provided some additional sealing between the rings lessening the blow-by.

If the compression does not improve with the quirt of oil, then the valves or head gasket are leaking. If you have very low compression, and equal, on two adjacent cylinders, its possible the head gasket has failed between the two cylinders.

I personally would run a compression test, record the values, run a wet test and record the values. I would then take the heads off so I could see what's going on. Those spark plugs are worrisome, two of them look to be oil fouled.


The bare minimum connections for a charcoal canister would be one end to the fuel tank vent, the other to the air cleaner

 

[pb4ugo]

What user42 mentioned is good. I doubt the wet test will show bad rings if the engine is as new as you say, other than confirming the problem is in the top end. The bead of silicone instead of seals is a racer trick. I prefer to use the supplied seals w/a dab of silicone on the corners. The silicone bead does work, did the silicone squish when you did it? Right now I'd confirm & I.D. The problem. If you have to pull a head you Will be replacing those seals anyway.

 

[Alz Toy]

You running a aftermarket aluminum intake? Some ( Edelbrock's ) recomend the Felpro print-o-seal ones, to get a good seal. Same w/aluminum heads on a cast iron block, not just any head gasket will seal right, due to different expansion rates of the different metals. All this is in reguards of the white smoke at start up/coolant loss. Just some random thoughts, good luck

 

[projectfj]

Well as my luck would have it, it rained last week so I didn't get to do anything except look through the window at the rain fall on my old fj. That's the benefits of not having a shop to work in. Anyway, I have finals the next two weeks, but after that come **** or high water I WILL finally make some progress on getting some much needed (and delayed) work done. Sorry for inconveniencing you all with waiting, but thanks for sticking through the unfortunate circumstances with me. Also for future reference, do any of you use the supplied intake gaskets that go on the front and rear or do you have better luck with just using silicone all the way across?

 

[projectfj]

Finally did a compression test! I had 140-150 across the board for the dry compression test and 160-170 for the wet compression test. So does that narrow down what is wrong with my fj?

 

[RWBeringer4x4]

Finally did a compression test! I had 140-150 across the board for the dry compression test and 160-170 for the wet compression test. So does that narrow down what is wrong with my fj?

Nothing seems outwardly out if place there. Seem like pretty normal, good compression numbers to me...

 

[projectfj]

Could it be that the intake manifold gasket leak is causing the coolant loss and may be contributing to the hard start?

 

[RAYJON]

Glad the compression # were normal, , I always ran good felpro intake gaskets with a uber small bead of silicone arround the coolant passage, and a big bead for the ends, the front and rear intake gaskets never seem to stay in place, silicone does, just run a big bead let it setup before you put the intake on, even gm did this In The later years.

With good compression, if the fuel pressure comes out ok, I still go back to ignition first, good cap, rotor, coil, and run a Separate ground for the distributor if it doesn't already have one, get someone who knows what they are doing to run it on a scope, the ociliscope will show what all 8 cylinders are doing when firing, if that tests good then. Adjust the idle and jetting in the carb to fit your altitude,

you have a sound motor just the little stuff,

Good luck,