Broken insulator bolt

[pete379]

I've got a question for you fellas, I got a 28.5 cy in my MCD rally car and lately i've been snapping insulator bolts like crazy. The first time I did it I got 1 1/2 tanks through it and noticed the car running lean, so I checked things out and noticed one of the insulator bolts had snapped. I was able to get the remaining portion of the bolt out with no damage to the threads so I put everything back together and put another 1 1/2 tanks through it and the new bolt has now snapped. As you can guess I'm getting alittle confused because I can't figure out why I'm snapping bolts. I don't know if anybody might have any suggestions or has quite possibly had this same problem could enlighten me a little. Thanks

 

[pete379]

That is strange. I've never snapped an insulator bolt. An exhaust bolt yes. But never a bolt on the carb side.

Anything knocking the airfilter?

No, thats where I'm getting confused, theres nothing putting pressure on those bolts, they just up and snap.

 

[Bigger the Better]

Is it a stock insulator or alloy one?

Are you sure your motor is fully tightened to the chassis and nothing is moving or hitting the filter set up to snap them? Is the bolt too long and hitting the head when installed?

Just a few questions.

 

[pete379]

Is it a stock insulator or alloy one?

Are you sure your motor is fully tightened to the chassis and nothing is moving or hitting the filter set up to snap them? Is the bolt too long and hitting the head when installed?

Just a few questions.

Its the stock insulator and yeah I've checked everything you mentioned and all is good. Very confusing!!

 

[Bigger the Better]

:white-flag:

Any photos?

 

[pete379]

no, know photos, i'm going to try and get the remaining part of the bolt out of the cylinder head and if all is good I will reassemble everything and recheck the bolts that hold the carb and velocity stack on...maybe something is going on there and it's such a small problem that it's hard to reconize, just grabbing for straws here.

 

[Timmahh]

sounds like weak bolts (over hardened0 and your stressing them when tightening too much. but im surprised you haven't pulled the threads out of the cylinder in the process of tightening. thats what seems would have me going WTF?

 

[pete379]

sounds like weak bolts (over hardened0 and your stressing them when tightening too much. but im surprised you haven't pulled the threads out of the cylinder in the process of tightening. thats what seems would have me going WTF?

Well I kinda thought the same thing about the bolt strength,first bolt was the stock bolt that came with engine, second bolt I bought from Largescale RC and it was a better quality of bolt than the stock bolt not to mention when I install the bolts I don't really crank down on them all that hard. This is probably my 5th car I've owned and I've never had this issue before.

Do you think the bolts that hold the velocity stack and carb on are slighty to long and putting unwanted pressure on the insulator bolts in turn causing one of them to snap? The weird part about that is i'm running the exact same setup as far as carb,velocity and insulator on my FG race truck and I haven't had a bit of trouble only difference is it has a Zen and not a CY.

 

[Timmahh]

not sure. possilbe.

have you tried a Zen or aftermarket billet intake?

i know sometimes the cy carby bolts have to be shortened 1 to 2 mm to work with the billet intakes? maybe th CY is a smidge shorter than the Zen intake.

 

[pete379]

I was thinking about trying a aftermarket intake but don't know yet, once I scrape some money together to get a new head kit i'll start over and see what I come up with.