Hey guys what type of effect would a blown hot box gasket have on the performance of your engine. Some people refer to it as a flange gasket i believe.

But yeah would it effect the performance of your car. My a12 just hasn't been running right laely and seems to be struggling to cruise at any speed. Once it revs up over 3000rpm it's not as bad but feels like it's loosing compression or somthing when cruising. Then today i noticed that my hot box/flange gasket had gone to god and was wondering if the two would be related. I will be replacing the gasket next weekend but just wanted to know if fixing that will fix my performance problem.

What do you guys reckon? Would it interfere with the performance or compression of the engine, or would it simply mean the car would sound a bit louder?

Cheers
Trav

Gday Trav, My 120 did that for a while, really p.m.off!! Look for a vacuum leak I found 1 of my vac hoses died!! Runs fine when you,re into it but when u cruise it just pigroots and stutters as it,s 2 lean.. Hot box gasket will just fume u out and be noisy shouldn,t affect the driveability.. Cheers Steve

Ok it's still giving me troubles,

This is what i have done so far to rectify the issue.

New points
New Plugs
New fuel filter
New oil filter
Timing fixed up
New dizzy cap and rotor
Oil change

Beast of burden was right when he said.....runs fine when your into it but when you cruise it just pigroots and stutters and it's 2 lean......so i checked the vac hoses that i know of and they seem fine except for the vac hose that runs from the side of the dizzy to the carby. Correct me if i'm wrong but when you pull that pipe off at the dizzy end and hold your finger over the end of it, isn't the engine meant to stall? Mine didn't. Is this right or am i just mistaken. When i put my finger over it i can really hardly feel and suction. Also what are some of the other main vac hoses i should check cause as i said, i only know a couple that could effect the car this way.

The things i have already checked and replace mean that the car is idling so freaking smoothly. Just purs at idle. It's just during low revs acceleration and when cruising in 3rd and 4th. Once i get over about 3k revs it's not as bad.

What else do you guys reckon i should check? I'm just trying to knock out the easy/cheap stuff first cause i really don't want to spend money on this engine. It will only be in there hopefully no more than six months, but i still want it to run well. Any ideas?

Thanks heaps
Trav

ummm hot box gasket???? im lost

Yeah, gasket in section where the manifold fits to the exhaust.

Don't worry about that though, found out it doesn't cause the issues that i am having with my a12. I'm trying to find out what is.

Cheers
Trav

Sounds like there could be some crud in the carby.

Give this a try.

Put plug lead No.2 on No.3 plug and plug lead No.3 on plug No.2.

Start the car and give it a couple of light to medium throttle revs, you will get some back firing happening through the carby which is the point of the excercise.

Once that has been done put the plug leads back in their correct locations and see how it drives. If its better you at least know where the issue is and can either pull the carby apart and clean it out now or wait until it plays up again then clean it out.

Ok thanks mate. Will give it a try in da morning.

Cheers
Trav

Hi Trav, Nah thats just ported vacuum at the carb 4 the dizzy, It might stall if you pull the pipe off an leave it open{Vacuum leak then}.. Has it just started to do this or have you played with something?? I,ll have a think about this an get back 2 u.. Cheers Steve

Interested to find this one out...cos I have the EXACT same problem
Coulda sworn it was a carby problem...Ive had the jets,filter replaced and checked twice now...still the same issue.
Is this with a 32/26 on the A12 like mine Trav?
Seems to happen right in the middle just before the second barrel opens (im assuming)..unfortunatley at the absolute WORST range for city driving.

Mine is just a stocker a12.

Tried the swopping of the leads thing that mls suggested but with no success. So the carby must be clean.

Your exactly right though wurzel, i was thinking about it on the way home tonight and it could be a problem with the first barrel not opening right on the carby, cause once the second barrel opens it seems to fix itself a little and run a bit better.

Well thanks to BigD i have his old a14 carby in my possesion and that seems in good working order. As i understand it a14 carby's run just fine on an a12. So i might have a go at changing that over tomorrow if i get time after searching around for a new exhaust flange gasket and buffing my car up. I'll let you know how it goes though.

Cheers
Trav