Big valve head vs small

satancom · Post by **satancom** » Thu Dec 31, 2009 6:51 pm

I cooked my 3.5 Rover V8 a few days ago and am replacing the heads with a bigger valve version off a disco/range rover.

Will I notice any difference in performance? It wasn't exactly sluggish but a hike in power is always nice

I did a compression test after the overheat (sevear) and got around 80psi per cylinder.. one was 120psi though, nice smooth running!

Boosted LS1 · Post by **Boosted LS1** » Thu Dec 31, 2009 10:45 pm

The one at 120 psi is the good one

satancom · Post by **satancom** » Sat Jan 02, 2010 8:09 pm

Got a straight edge on the heads I removed.. and they realy were banana shaped. 60 thou out in the centre!

New ones back on today and she started up and sounded a lot more healthy! Road test as soon as I get the rad sorted!

paul c · Post by **paul c** » Sat Jan 02, 2010 10:08 pm

Have you done anything besides swapping the heads? How severe was the overheating, did it lock up, I guess you have checked the bores, but rings may still have lost there tension also.

satancom · Post by **satancom** » Sat Jan 02, 2010 11:09 pm

Checked the bores and they were fine. It didn't sieze up, the only indication that something was damaged was the heavy miss under load, confirmed with the compression test.

I checked the oil which was not burnt and there was no contamination between water/oil so all was well there! I hope the rings haven't been damaged as they only went in 3000miles ago

I will have to see in a few days when I do another compression check!

satancom · Post by **satancom** » Mon Jan 04, 2010 9:26 pm

All up and running nicely now. New rad, new heads and new head/valley gaskets. All in it cost me £180 I guess.

£180 I wouldn't have had to spend if I hadn't used the stupid electric fan fixings that go through the rad. Next dry weekend project is making some steel mounts for the fan.

Didn't open it up as it was very icey and im on cross ply tyres

Quagmire · Post by **Quagmire** » Tue Jan 05, 2010 1:42 pm

That happened to me too! This was before i fitted the v8.

My new rad had the fan properly mounted on the frame, not on the cable tie type pull through things...

Luckily i noticed, and although the leak was very bad i was able to top up with water and roll down to halfords to get some leak stopper stuff, before driving to work eyes glued to temp gauge.

It wasnt the end of the world though as the was about 2 months before the v8 went in and the a new rad was on the list.

I do know now that a v8 rad massively overcools the 2.25 4 pot

satancom · Post by **satancom** » Wed Jan 06, 2010 10:14 am

Quagmire wrote:
I do know now that a v8 rad massively overcools the 2.25 4 pot

I bet

Im going to make up some mounts for the fan using the old radiator as a template. This should prevent it from hapening again at least