Are you Bored? Bang for Buck Engine recipe required.

[ed.harris]

Thanks errol62 for your Input.

I am going to look at the carbs this morning, I will check the throttle shafts for wear.
The owner bought the carbys a long time ago and he has no history of the previous tuning of the Engine or that build, if any.
He did use the to run a cam in on a stand recently. He had no problems with flooding etc.

The strombergs I have need everything done as they are just donor carbs.
So I might as well play with SU's especially since there is a performance improvement without fuel economy loss.
The SU set up looks sound, so I might be lucky.

In regards to 98ron, I would definitely prefer to use 91ron.
I was just using that number as a reference. Generally regard the extra price for 98 Ron is not warranted.
On other non related engines I am running, respond to 98 ron by allowing more timing to be applied.
These engines have a static compression ratio of above 10:1.
This build might be changing as I have a lead on grey motor with lumpy top pistons at 10.5 to 1 ratio and a very large Camshaft.
I might use my Camshaft in that Engine which will be more streetable.
This engine may respond better to 98 ron than the J motor I am currently playing with although lower octane would be preferred and at this compression ratio, tuning for different Ron ratings may or may not make a difference.

I will be looking at this Engine soon.

Thanks guys keep the comments coming.

Cheers Ed.

[Errol62]

I did a run Willunga to Echuca a few years ago on 98 and home again on 91. Could not perceive any difference in performance, and economy was identical. 186 X2 with standard static compression. I since raised the compression with a small chamber head and I now have to run 98 or it pings.


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[Harv]

98 will help with pinging. Depending on who you buy it from, it can be more dense, and can be made from blending components that improve acceleration.

The effect of worn throttle bushings can be tuned out, within reason.

The use of round throttle shafts is more an issue. The clamped on arms used in twin/triple setups rotate on the shaft over time. You then need to retune. W-clips are notorious for it.

Have seen the round bar setups tack welded, which can help.

The hex-bar shafts are less prone to this.

Carb Service Co at Strathfield use to make elegant, non-slip clamps for the round bar. Wish they were still operating.

Cheers,
Harv

[funkyscooter]

When I rebuilt my triples which are a cobbled to together 1 fuel bowl forward, 2 back configuration, I ordered rebuild kits online from SUMidel. Couple hours later the phone rings and its a guy from SUMidel wanting to confirm my order. I explained what I had, has asked for the parts numbers on the fuel bowls and the bodies, and what it was going on. Gave him the info and he tells me the fuel bowls were not correct for a red motor. I explained that the set up was off a red. Then I remembered that of the 5 SU's I had, 2 were off a twin setup from another car and I had used one of those fuel bowls and that was the part number I had given him. He gave me a long explanation of why it was wrong and would flood/tune badly (think red motors have a 30 degree angle to the head and the twins had a 20 degree angle).

Anyway - long story short, I would get on the phone to SUMidel, very knowledgeable and helpful.

And as Harv points out, hex bar will help with locking in the carb balance. Weberperformance sell the hex style kits, Redline sell the round ones and parts for the round ones.

[Brett027]

[quote=ed.harris post_id=277973 time=1781183042

Another said the standard fuel pump will be fine as SU's do not like high fuel pressure.


In my experience this is not good advice. Standard holden fuel pumps in reasonable condition give about 7psi which suits the big floats in downdraft Strombergs, but will overwhelm tiny SU floats and cause flooding. You will need a regulator to get to 3psi which is the pressure SUs work best at. If they don't flood with a standard fuel pump it is likely in need of a service or has a very weak spring. I have been using a Malpasi filter regulator for my bomb and it is a great unit.
To get multiple carbs at their best once all the mechanicals are right, you will need an airflow meter and preferably a see through spark plug and or an air/fuel mix measure. Without these gadgets you will just be playing.

[Errol62]

Can’t hurt to run a regulator as Brett says, as long as it is a good one such as the malpassi one he suggests. My experience is different to his though.

I initially ran a cheap Speco regulator, well it was around $130. I guess that is cheap. After a few months it sprang a catastrophic leak due to failed flexible diaphragm. Roadside assist was called and turned out to be a guy I had met who has an injected black six FE ute. Same guy did Drew’s wiring in his wagon.

He bypassed the regulator and said I don’t need one with the SUs, so I thought I would give it a try. Gledge also was running unregulated triple webers on his beast Leon and said I shouldn’t need a regulator. Been running it that way since with no dramas. Not sure if it was before or after the big trip to Bunbury but it’s done plenty of mikes of varied driving in all conditions and not missed a beat.


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[Craig Allardyce]

It may not flood, BUT the fuel height in the bowl will be higher as the float will take more force to close the needle against the higher fuel pressure. The higher fuel level will give that force to some extent, BUT, now you will be running richer, or in worse case spilling over into the throat. With inclined carbs you might not know but you will suffer from fuel dilution of the oil and cylinder wash down, both will increase engine wear. Horizontal carbies will also leak fuel back out the intake so fire risk is real!

[Errol62]

Yes, I did have to shim one of the seats to resolve a weep when I first did the delete. Interestingly the sedan, as built by 60 Special runs the same regulator as my Speco with no failure, so far. May have to reconsider fitting a reg to the ute.


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[spanners]

I got around the overfueling issue on the HAMBster by running a 1/4" line out of the back of the fuel block and into the fuel tank so the fuel circulates. I've also got a fuel pressure guage running off the fuel block and to regulate pressure I put a pop rivet into the line to restrict the fuel going back to the tank. yes, I took the stem out of the rivet first and only used the rivet. It gave a nice 1/8" hole to slow the fuel down. I run a Holden Blue motor pump because we're not allowed to have a glass bowl for tech certification.

[ed.harris]

Thanks guy fot the replies.
Well, I did buy the carbys.

I will post pictures today.

The advice is appreciated.
The setup does have round throttle shafts and there is evidence of slippage with different screws fitted to the W clamps.
The guy who sold them to me explained the basic operation of SU Carbys.
I have had a AFR gauge bung welded to the extractors and will be running an AFR gauge in the cabin.
It seems running a fuel regulator is the go to eliminate possible problems.

I also bought the historic race motor off the same guy.
It was a spare Engine and has little use about 10 hours.
The head is off and wasn't his best head but is still modified.
The porting is not as extensive as the one I had done at Galloway's.
It has had the top of the hear drilled then plugged for steam holes (not in use).
Not sure which head to use, might get additional porting done.
I have 3 head gaskets which I bought through Harv during a previous gasket run.
Thanks Harv

The bottom end has had a lot of work done.
Lumpy top Ross pistons, 10.5 to 1 comp ratio.
Balanced standard crank and rods
Billet centre caps.
Ross balancer, timing pointer.
6 bolt flywheel lightened 5 lbs.
Full flow Oil filter conversion but no hoses or filter from the fittings in the block, he'd had the filter on the fender anyway.
No distributor.

I was I had found this motor before but I couldn't pass this one up.
The engine is now living in the back of the wagon until I get myself another Engine Stand.

I think this engine will need at least 95 Ron to run depending upon how much timing is applied.
Time will tell.

Cheers Ed.

[ed.harris]

Hi guy photos attached,
Please add comments or advice about the carbys if you spot any issues.
They are going on a humpy so no battery or heater box to worry about.

[Errol62]

They look tidy. Fuel bowls facing forward is good for firewall clearance, well in an EK at least. Long runners = good torque. As said the round linkage shafts, but you know that.


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