Thread: Rebuilding a Rover V8

Originally Posted by mike 90 RR

New Head bolts .... Only if BD or others tells you to ...


Mike

Originally Posted by Traco

I assume your engine does not have the later stretch type bolts. If it does they're a no goer for a second use. The non stretch type can be re-used ok, but of course new ones are even better insurance. By far the best option though is to discard the head bolts altogether and fit a set of ARP head studs.

G'day guys;

well I've just come back from BMI , I was advised the head bolts on Rover 3.9 are Strecth type Bolts ,sothey "SHOULD" be replaced with NEW Head Bolts on Fitament of a new head gasket , so I have taken Traco's advice on this and have purchased New set of head Bolts , if anyone would like part numbers please refer to the Pics below.

ERR2943
ERR2944



I will also replace the Alternator head bolt Part # 602200

Khos, tin gasket engines do not have stretch bolts.

They came with composite engines.
There are some/many who believe that the higher torque on stretch bolts is one cause of the blocks cracking behind the sleeves.
I personally will use non stretch bolts on any rebuild I do.
Regards Philip A

Originally Posted by PhilipA

Khos, tin gasket engines do not have stretch bolts.

They came with composite engines.
There are some/many who believe that the higher torque on stretch bolts is one cause of the blocks cracking behind the sleeves.
I personally will use non stretch bolts on any rebuild I do.
Regards Philip A

For conversation purpose only ....

I am constantly bemused by .... Stretch bolts vs non stretch bolts ... Why not just normal High Tensile Bolts

Maybe heads release over time because Stretch bolts finally let go rather than the head gasket is the problem

Also .... these bolts are tightened to a low torque as compared to Cast Iron heads ... So why do we need stretch bolts??

Asking the Q ... As I don't know the science on this subject

Mike

Originally Posted by PhilipA

Khos, tin gasket engines do not have stretch bolts.

They came with composite engines.
There are some/many who believe that the higher torque on stretch bolts is one cause of the blocks cracking behind the sleeves.
I personally will use non stretch bolts on any rebuild I do.
Regards Philip A

Looks like you're right again PhillipA I go the wrong set for nothing then ? the set of New Bolts look like they are Stretch type ones and the old ones from the engine were not-stretch type , so then I should be able to resuse the old ones ?y/n? so back to BMI I go for a refund then.

I called then back and gave them the engine number and I was advised wrongly earlier , that the Engine number ie 38D25986A right upto Suffix 40D uses the non-stretch type Bolts.

As long as the old ones are in perfect condition they can be reused a couple of times. BUT your motor has been done before so it may be best to get new "non stretch "bolts.
I reused mine but it was first rebuild.

BTW Mike 90RR
First google.
all_head_bolts
Regard sPhilip A

I've fitted ARP studs in siti on Rover cars but not Discos. I used SD1 head bolts on the Disco instead.

Phillip A's right, it has been speculated that stretch bolts MAY contribute to or even be the cause of cracked bores (along with a number of other supposed factors). Apparently a well-known Rover engine rebuilder noted that almost all cases of cracked bores occurred next to stretch bolt holes.

Extractors are not really warranted on the Disco and, in fact may be detrimental to torque output.

The standard cast iron headers are pretty good surprisingly. TVR/Litchfield used them when they built their hot special Discos (1995) and these were putting out around 348 ftlb with detuned 5 litre TVR engines. Even the TWR/ Bastos works SD1s used the standard exhaust manifolds, bored out.

Just to Clarify the make/model of the vehicle , as it has been refered to a
couple of times in this Thread as a "Disco" , it's actually a RRC with a 3.9 motor that I'm doing the head gaskets on

PhillipA , How do I tell if the NON-STRETCH Bolts are okay to re-use ?

Khos, AFAIK there is no objective test other than they must be perfectly straight, not rusty, no damaged threads, and I guess you could add undamaged heads.
I have reused them with no problems.
I guess it is up to you whether you feel happy with the current bolts.

BTW remember to get new washers if you get new bolts as non stretch bolts do not have integral washers. That is how you tell them apart.
You could use the short stretch bolts on the outsides of the heads as they will only be cosmetic.
Regards Philip A