304 engine won't rev and popps head gaskets

[stokievh]

hi everyone, just wondering if anyone has experienced this.
not running high compression and not too much timing.
recently installed vn heads with aftermarket manifold without egr. didn't check to see if egr ports in heads were welded up as expected this to have already been done.
if they're not, could this be causing the problem. could pressurization of the crank case cause the engine to peak rev's below 5500rpm and pop head gaskets?

 

[v8commy]

dunno but would love to before i put em on my car

 

[stokievh]

yes should of,but didn't, be interesting if anyone has or know of someone that has had the same experience

 

[ari666]

popping head gaskets???? that seems like a pretty serious problem... you sure?

i have been told that the VN heads dont have EGR. i am still confused to what the little U shaped port in the center of the head is for but no one answered me. IF and IF the vn's have an egr its isnt gonna pop a head gasket cos its not related in the slightest.

in an VK 308 (VT engine prefix) if you put a manifold on that doesnt cover the egr ports itll pressurise the valley and do all sorts of crazy things like fill your valley with hot burned gasses, blow you dipstick right out of its hole, blow thick black smoke everywhere and generally behave like an beach.

but popping a headgasket is a significant problem. when you say "keeps popping head gaskets" how many times have you replaced them? what procedure did you use? i.e. torque sequence.

edit* oh and 5500 RPM is pretty good dude, i set my limiter at 6000 cos 308's dont really enjoy revving that hard. i wouldnt be doing that too often if i were you.

 

[stokievh]

has only just happened the once, was pretty sure they can rev to 6500 with no problem but feels like doesn't want to bugge anymore than around 5000?

 

[DANNY8]

Our old 308 would rev to 5k and that's about it with stock heads (carby heads not vn heads)....chucked YT heads on and went to 7k no worries.....we never take it that high tho lol.

 

[ari666]

we never take it that high tho lol.

lol, mine would too. i just dont let it. naughty 308's.:banstick:

 

[383 hatch]

Ari, that U shaped cut out in EFI heads is just a blind hole in the casting, It doesn't go anywhere. EFI 5 litres don't have an EGR of any description.

OP, when you say popping head gaskets out, where exactly does it blow them out? What gaskets are you using? Some more info would be nice....

 

[VrWagz1]

I honestly have no idea, but would an injector not firing or the like cause a head gasket to blow??? prob not but it would explain the revingissue, but jst trying to think bout loud

 

[v8commy]

mine revs to 6k all the time no probs