Engine starting issues.

[Steelcityslicker]

Hey,

I recently tore down my ThunderTiger Evo .12 cleaned it up and assembled it all back together again.

I sealed the pullstart, the carb, the exhaust port and the coolling head with an RTV sealant. Now the engine won't start. (It fired up very breifly after the first pull once, and has not started since.)

It appears to still have a lot of compression when I turn the flywheel by hand, but I can't get it to fire up. I set the needles back to the factory specs for now with the hopes that it would have remedied my problem, but I guess I was wrong.

I have come up with 2 possible scenarios myself, but am looking for input/ideas on what else it could be.

After the rebuild, I had to loosen (essentially twisted it) the carb and reposition it to clear a support brace. I was lazy and did not reseal it. Could this be causing me issues?

When attempting to prime the engine, I notice that it is rather difficult to get the fuel up the lines to the carb (little or no vaccuum) but even when it does finally reach the carb, the engine still will not start. The glow plug is still glowing nice and bright, so I can't imagine that being the issue......

Any other ideas as to what my issue could be?

I fully intend on resealing the carb, but I really dont think that it is my issue at this point. Could my vaccuum issues be the culprit? How would I goi about diagnosing them? Is there an easy way to check for leaks?

Any help would be appreciated. I have one of my cars waiting on an engine to arrive, and another that wont start. The nice weather is here and it is driving me nuts!!

 

[Rolex]

You have found the problem. Carburetor seal is critical. If it's not properly sealed, it sucks air AROUND the carb instead of THROUGH it.

 

[Steelcityslicker]

So the carb is the cause of the vaccuum issues as well as the non starting?

Damn.......I really had no clue it would impact the vaccuum.....I thought that because the air is still getting drawn in from the carb, whether it is through the seal or not. I just RTV'd the carb though, so in 24 hours I will find out!

Thank you!

 

[olds97_lss]

You RTV'd the head? You should pull the head, clean off the RTV and only use the proper head shims to make the seal. The shims are typically made out of brass which is soft. It will make a good seal if you tighten it properly.

Also, you said you sealed the pull start... did you seal the pull start housing or where the backplate meets the crank case? You shouldn't need to seal the pull start housing to the backplate.

 

[Steelcityslicker]

The head had no shim....the guy I bought the car off of stated that he removed it to bump up the compression........

 

[Rolex]

Seal the carb, make sure you have a good O-ring in there also. Unseal the pullstart, (no reason for that) seal the backplate, and get a copper shim for the head. Then get back to us.

 

[olds97_lss]

The head had no shim....the guy I bought the car off of stated that he removed it to bump up the compression........

The guy you bought it from obviously doesn't know it's pretty much a required part. You can get thinner shims, but you always need at least one.

 

[rccars411]

Seal the carb, make sure you have a good O-ring in there also. Unseal the pullstart, (no reason for that) seal the backplate, and get a copper shim for the head. Then get back to us.

yeah thanks for posting a pic of a paradox :LoL:

 

[Rolex]

That's so he knows what an old shim looks like. Has nothing to do with a pair of ducks.

 

[olds97_lss]

I like ducks...

 

[Steelcityslicker]

The guy you bought it from obviously doesn't know it's pretty much a required part. You can get thinner shims, but you always need at least one.

haha, I am well aware of what a shim looks like )

It ran without a shim (quite well I might add) for some time. I am going to try and fire it up tonight using other suggestions here, and if it fails to start, then I will try and source another shim.

The pullstart it'sself was never sealed, just the plate it mounts onto.

Thamnk you everyone for the suggestions, I will post up how it turns out!