H72 head on an A15? help?

[rbastedo]

I've got this H72 head and a dual SU intake manifold and I want to replace the econo head and hitachi downdraft on my A15.

There's a pair of SU HS4's going to bolt up.

Where might I be able to get gaskets - today??

Any gotcha's I should be thinking about?

[datzenmike]

Gaskets; buy a sheet from an auto store for a few bucks. Get a hand held hole punch from a dollar store. Trace out the gasket using the carb or intake. Use hole punch for the bolt holes and to start the large holes and finish with sizzors.

[rbastedo]

That will be fine for the carbs, what do I get and where for head gasket, intake and exhaust gaskets?

[rbastedo]

I got the job done yesterday, the new head fit perfectly and the gasket set was just what I needed.

 

I ran into trouble with the pair of SU carbs.

Here's the story:

 

The carbs started out running VERY rich, putting out much smoke from the exhaust.

My friend Bill was helping me get it running.

Bill started tuning them, they didn't want to respond to this very much.

After a few attempts we sat and thought about it, and I remembered the Facet fuel pump I installed for the Hitachi downdraft carb had 4 to 6 pounds pressure, too much cor the SU's.

 

Bill quickly located a low pressure fuel pump and I installed it.

Things got better momentarily, but then started going bad again..

Quickly swapping in another fuel pump the thing started again, but back to smoking.

The rear carb was over boarding, too much fuel going through it.

Bill tried adjusting and got it to about where I could maybe drive it and I took off.

 

Within several hundred yards I had to pull off, it was running so badly that I just couldn't go. I called Bill and he said to try richening both carbs, so I did that and it would take off again so I started out.

I barely made it to the nearest gas station and filled up.

Between there and the freeway it was just running badly, but running.

I got on, driving in the far right lane with my flashers on.

I got off at High Point Way, about a mile, where there was a road I could take all the way home so I wouldn't be on the freeway.

The carbs changed to racing away, running roughly at high rpm.

I managed to shift between 3rd & 4th most of the way and after quite a while made it home.

 

So - now what to do?

I have only ever had the HS series carbs before, this type SU is new to me.

It may be that they are simply not usable as is. I really don't know.

I plan on going out today and trying to adjust them and see if I can get it to running.

 

Any pointers at all, things to look for, what to do next advice GREATLY appreciated.

[rbastedo]

 

[rbastedo]

It turns out I had the fuel inlet hose hooked up to the vent on the rear carb.

Reconfigured and tuned and WOW - this little MG Midget goes like a Rocket now!!!

[LenRobertson]

Great your story ended happily ever after. Everyone must be working on their cars or off playing this weekend. I expected some replies to your question. I was about to wade in with the little I know about SUs. Lucky for you it didn't some to that. I will put in a plug for the SU DVD from Z Therapy. Exhaustive amount of information on SUs. I haven't put any of it into practice yet. I have a set, but haven't tried them. They have worn throttle shaft holes that I'm too cheap to have rebushed, so I'll probably install them the way they are, screw around for days trying to get them to work, then give up and have them fixed right. The story of my life.

 

Len

[rbastedo]

Thanks Len, that really made me smile!

Funny, I was with a group of guys representing well over a century of British car knowledge and nobody saw the obvious mistake.

I think the fact that it said "Nissan" on the rocker cover just confused everyone.

I had to look at the manual, look at the carbs, over and over until I finally said "hey, somethings wrong here..."

 

Personally I like John Twist's youtube videos.

[LenRobertson]

Thanks for the mention of John Twist. I didn't know about him. The drawback to the SUs DVD I mentioned is it something like 3 hours long, so to go back and review details is challenging (well, at least to me). The shorter Youtube clips look much handier.

 

I'm watching HRH's fuel injection conversion thread and giving serious thought to trying that. But FI won't look like SUs, and the money I'd spend on finding a 280Z manifold and having it rewelded would go a long way toward having my SU bodies rebushed. I need to get my 510 back on the road with the Hitachi before planning that far ahead.

 

Len

[rbastedo]

First drive to work this morning with the new setup -

Starts right up and runs perfectly all the way.

Freeway driving is great, straight up to 70 then whenever needed there's lots more gas pedal.

This is the best!!