some cars use studs (e.g. crossflow) to hold inlet and exhaust manifolds to the head whereas others use bolts e.g. Rover v8.

Are the two interchangeable, i.e. can I use bolts on the crossflow? What is advantage of one over the other?

(I already have bolts for the inlet - not fitted by me) that seem to give no problem as yet.

think from an engineering point of view and especially on the exhaust manifolds on a cast iron head that studs are best with brass nuts as a result of the temperatures and possible ceasing up and potential for ringing off when trying to remove a bolt with the knock on problems of drilling it out.

With studs i can think of two advantages:
There are two thread areas (stud and nut, stud and head) that can release so if one gets siezed there is still another to release.

Less likely to snap with a stud.

Darren

I replaced the studs on my R1 engine with bolts (following advice from MNR) largely because the original studs were just slightly too short. It turned out that the old exhaust rings were so corroded onto the cylinder head that I thought they were part of it and so added new rings on top. I've had no problems with it and the bolts have been easy enough to remove.

If it's an ALLOY block - then studs are considered safer.

TBH for the amount of miles/maintenance a kitcar has the arguments for/against are probably somewhat diminished. Cars are expected to last 200,000 miles + with longish service intervals.

Kitcars typically do around 3,000 year (if lucky)

I personally use STUDS as I have a Zetec - which is alloy block and I do a few trackdays where the under bonnet temps get quite high.

HTH

Cheers,

Murray

Apart from the engineering advantages of studs its much simpler to hang the manifold on the studs then bung on the nuts than fiddling about with lining up bolt holes. At least with the limited space in my engine bay its much easier.

I always use studs, if nothing else they are so much easier to use, as ^^^ said, you can just hang the manifold on then add the (in my preference) brass nuts. Mush easier than trying to hold a large mainfold in place with one hand whilst trying to line a bolt or two up. Also, brass nuts look better IMO, although some nice cap headed bolts come a close second.

On my RV8 I've used studs with brass nuts to good effect. Been running for 12 months with no probs.
As the other guys have said, with ally heads, studs are the way to go. If a bolt seizes in the head or heaven forbid cross threads, then you have problems.

Cheers

Dave

The advantage of studs is its easier to slide the manifold over them than line up holes for bolts.

However sometimes there isnt room to slide a manifold over studs so bolts are required.

If you remove your manifold a lot you will eventually strip the threads in an alloy head if you use bolts. Unless of course you Helicoil them which you should for any thread into alloy.

My head originally had studs but I now use stainless 12 point ARP bolts for installation reasons.

Another method is to use a longer fully threaded bolt and a nut, run the nut up the bolt till it's just under the head, install bolt through manifold and into the head to the required depth then tighten the nut onto the manifold while holding the bolt head with a second spanner to prevent it turning, when dismantling hold bolt head with one spanner and loosen nut with another then remove bolt .The threads in alloy heads will love you for it.

Wimmera