On my latest test drive it was a hot day and I noticed some vapor lock on hot starts. I did some research and based on what everyone is saying a spacer will fix it. There doesn't seem to be much clearance under the hood, maybe 1/2" tops if that. So what are some good options? I've seen there's different materials, including wood which seems like a fire hazard at first glance. For daily driving what would be the best option? Or is jerryrigging some kind of carburetor heat shield a better option than off the shelf? Thanks.

 

I use this type:

FelPro 1905 or similar

 

I've used a 1" wood spacer for years. It's a great insulator.

 

How tall is your air cleaner? If you're already using an aftermarket open unit with a drop base, maybe you can go with a shorter one to add clearance for a carb spacer

 

I've been using the mounting gaskets that came with Quadrajet Power's rebuild kits. Up until we got some warmer weather it had been enough, the car really struggled with hot starts the other day, do you think doubling up on these might fix the issue?

 

Never would have guessed.

It's a regular stock Thermac type air cleaner. I'd prefer to stick with it as it makes cold starts in cold weather go better. This is meant to be an all year driver.

 

Moroso has a 1/2" wood spacer. Too bad the Mr Gasket 1" plastic 4 hole spacer won't squeeze in worked for me.

 

OP, use this one, it's only a 1/4" gasket, and this is why it's made.

 

First of all, "everyone" is typically a great source of misinformation. Second, your 1978 uses a hot air choke that has hard lines to the choke stove in the intake crossover. If you raise the carb with a spacer, these will no longer reach the carb, forcing you to change to an electric choke. This is called collateral damage.

Is this REALLY vapor lock? Exactly what symptoms are you having?

 

You can carefully stretch the hot air choke lines with a 1" spacer, I have done it. Qjets are pretty resistant vapor lock as far as carbs go. Try adding fuel from a bottle when the symptom occurs, then it proves it is vapor lock.

 

Good point about the choke, I had forgotten. That said it is just a metal tube with a compression fitting on the end, a new one can be made if needed although I'd rather avoid the extra work. So here's what It did: It took a lot of cranking a few pumps of the gas pedal to get it started, and then it struggled to run and stalled. Next attempt I had to rev it to keep it from stalling, after it cleared its throat it idled perfectly fine. It only did this when the engine had been on the road for a while, fully warmed up as I was running multiple errands the other day, and it only happens on hot days. This occurred after I went to the grocery store for about 20 minutes on my last stop before going home. In the evening when I drive it around or earlier this year when the weather was cool it never did this and started right up hot without issues. This sounds like classic vapor lock to me, especially since I run it with regular e10 gas which as we all know is prone to this issue.

If a single 1905 mounting gasket can fix it as opposed to what I've been using, then great. I will be doing some more carburetor cleaning this weekend so I can change it out then, it had issues from the ethenol residue from sitting for a string of unrelated problems, the idle circuits are cleaned so it idles better than any time since I got it, but it still has off idle stumbles and random bogs so there's clearly other circuits that were overlooked. This is the only other problem with it right now.