15 replies to this topic

[Barman]

Hi guys,

Finally putting my engine back together and hopefully starting this weekend!

Question: When I took it all apart (it is a 1973 1275GT, single HS4 carb) there was an 'insulator' between the carb and the manifold.

I am re-assembling everything with a 'Stage 1 Kit' and alloy manifold.

Simple question, do I re-fit the insulator between the carb and manifold or is it now redundant?

Thanks in advance for your help.

[Tommyboy12]

It would be preferable. The insulator is an attempt to reduce heat transfer from the manifold. It can boil the fuel in the float in some cases which causes some rather poor running conditions.

[Barman]

It would be preferable. The insulator is an attempt to reduce heat transfer from the manifold. It can boil the fuel in the float in some cases which causes some rather poor running conditions.

Excellent - thanks for your prompt reply!

if I'd left it out I would have needed shorter studs anyway!

[jaydee]

You need the insulator, or you can have problems like vapor lock or whatever its called due the the transfer heat from the engine.
If you have clearance problems, fit this type:
http://minispares.co...rs/MFA338.aspx?

[Barman]

You need the insulator, or you can have problems like vapor lock or whatever its called due the the transfer heat from the engine.
If you have clearance problems, fit this type:
http://minispares.co...rs/MFA338.aspx?

Thanks!

[Barman]

Bah!

I hadn't really thought this through....

With the insulator fitted there is no room for my (beautifully restored) air filter...

I really wanted the car to look as 'original' as I could but it simply won't fit with the insulator there...

I guess it is back to the cone filter and sub stack.

Don't you hate it when that happens...?

Does anybody have any ideas for connecting the two breathers to the cone filter please?

By the way, what is that carb connection that I have closed off with the PVC tube...?

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•  SAM_1190.JPG   31.03K   6 downloads
•  SAM_1191.JPG   31.89K   4 downloads

[jaydee]

Thats why i've suggested this particular adapter..

You need the insulator, or you can have problems like vapor lock or whatever its called due the the transfer heat from the engine.
If you have clearance problems, fit this type:
http://minispares.co...rs/MFA338.aspx?

Being a lot shorter, you sholdnt have clearance issues. I've been using this insulator type on both Hs and HIF carbs fitted to earlier subframes where bulkhead clearance is a problem.

[Barman]

Thats why i've suggested this particular adapter..

You need the insulator, or you can have problems like vapor lock or whatever its called due the the transfer heat from the engine.
If you have clearance problems, fit this type:
http://minispares.co...rs/MFA338.aspx?

Being a lot shorter, you sholdnt have clearance issues. I've been using this insulator type on both Hs and HIF carbs fitted to earlier subframes where bulkhead clearance is a problem.

Thanks!

I did look at that but I already have a vacuum take off - I guess I could plug one of them tho...?

I'm racked with indecision now as I've fitted the cone and it looks quite good and has the sub-stack in it and does away with the elbow that Vizard dislikes so much! It is certainly a space saver under the bonnet.

I guess if I bought and fitted the smaller insulator now I'd have the option to fit either filter and see if there is a noticeable performance difference...

Good point - I'll order it today!

[EDIT] But if I remove the original insulator I will need shorter studs won't I...?

Attached Files

•  SAM_1193.JPG   57.11K   5 downloads

Edited by Barman, 28 September 2012 - 11:41 AM.

[madaboutcherry]

hi barman, keep the original filter, with a kn element there is no loss of airflow as you have already drilled some holes in the casing, it's so much quieter.

where did you get the right angle servo union from?

[Barman]

hi barman, keep the original filter, with a kn element there is no loss of airflow as you have already drilled some holes in the casing, it's so much quieter.

where did you get the right angle servo union from?

I did want to keep it as original as I could. The original filter already has a new K & N in it...

I guess I'll have to find some shorter studs.

For the servo union I bought a AHU2396 oil pipe for about a tenner and sawed the end off!

[ukcooper]

Buy one of these then adjust it so that the filter dose not hit the bulk head.

http://www.ebay.co.u...=item27caaf5ad2

[Barman]

Buy one of these then adjust it so that the filter dose not hit the bulk head.

http://www.ebay.co.u...=item27caaf5ad2

Thanks...

I think it needs more than that.

I'm happy with the engine as I have the top steady fitted (new bushes) and two bottom steadies...

Engine would have to move a loooong way forward to squeeze the air filter in...

[Ethel]

You'll be somewhere between the carb jet hitting the cross-member and the filter hitting the scuttle, so an adjustable steady bar will worsen one to improve the other. The abutment spacer (spacer thingy) also comes in aluminium so you sometimes only have the insulating effect of the gaskets; it also provides clearance for carb cable linkage. I'd assemble it all without the abutment spacer so you can see what is likely to work, and do some measuring up.

[jaydee]

Thats why i've suggested this particular adapter..

You need the insulator, or you can have problems like vapor lock or whatever its called due the the transfer heat from the engine.
If you have clearance problems, fit this type:
http://minispares.co...rs/MFA338.aspx?

Being a lot shorter, you sholdnt have clearance issues. I've been using this insulator type on both Hs and HIF carbs fitted to earlier subframes where bulkhead clearance is a problem.

Thanks!

I did look at that but I already have a vacuum take off - I guess I could plug one of them tho...?

I'm racked with indecision now as I've fitted the cone and it looks quite good and has the sub-stack in it and does away with the elbow that Vizard dislikes so much! It is certainly a space saver under the bonnet.

I guess if I bought and fitted the smaller insulator now I'd have the option to fit either filter and see if there is a noticeable performance difference...

Good point - I'll order it today!

[EDIT] But if I remove the original insulator I will need shorter studs won't I...?

The studs will work the same, no problem on the HS4, the vacuum take off is blanked off by a screw.
Standard airbox is better for noise level and usually provides better performance than the cone (a cone filter works at its best with a stub stack fitted).

[Barman]

You'll be somewhere between the carb jet hitting the cross-member and the filter hitting the scuttle, so an adjustable steady bar will worsen one to improve the other. The abutment spacer (spacer thingy) also comes in aluminium so you sometimes only have the insulating effect of the gaskets; it also provides clearance for carb cable linkage. I'd assemble it all without the abutment spacer so you can see what is likely to work, and do some measuring up.

Sage words!

I was just thinking the same thing... The 'insulator' is aluminium so I'm not convinced that it is capable of doing a great deal of insulating - other than moving the carb further away from the exhaust manifold...

I'm just taking it off now to see how it looks...

Thanks for your help.