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Learning webers on a 1700 supersprint


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My 1996 7 supersprint is new to me so it is getting a very thorough once over. New carb kits from Peagsus installed save for the needles since they are aftermarket pieces and not viton tipped. Likely work fine, but so should my current viton.

 

I wrote down my baseline for all jets in both carbs. Both float heights were VERY incorrect and not consistent side to side. Now set to AEAP (as exact as possible!) by eyeball and calipers to 12.5mm and 25mm with gasket.

 

All jets are as suggested for the supersprint save for the large idle jets. I have read that stock should be 45 and most switch to 50's. Mine currently has 65's. Upon startup with fresh gaskets and float levels the car seems to already be running better and settles into a smoother lower idle than was possible before the new bits and float reset. I made sure the independent 'idle' screws were all closed and I will go through a full balance and airscrew reset this weekend. My question is.. are there ANY other Supersprint owners out there with idle jets this big on a stock 135hp? At idle it smells rich and stumbles at the 1/4 throttle mark and sounds like it is trying to clear up. Once past say 3k it is nice and clean sounding.

 

What say you general public? Is this a common change or was a previous owner trying to counteract some other issue with big idles?

 

Worst case i will grab some smaller from pegasus and give it a whirl but wanted to check in with the knowledge base beforehand.

Thanks for any and all...useful...input!

 

Ryan

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I'd put 50's in it and see what happens, it's really difficult to go off what others are doing, there area so many variables that will influence idle and low speed operation.

 

Spark timing, cam timing, exhaust designs.

 

You have done good by taking them apart, cleaning, and making everything match will give you a good baseline to tune from.

If you cant dial it back with the mixture screws, It's likely that the low speed jet is too big.

 

I think the Viton tipped fuel needle will provide better service and low speed operation. (a more consistent float level)

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My 2 cents after playing with a wideband on my crossflow- I started with 45F9 and that was running too lean at part throttle low engine speeds. 50F9 was running a bit rich, sometimes below 12:1. I’m running 50F8 now and I think that is helping to split the difference. 65’s sound like they would be too large.

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My 2 cents after playing with a wideband on my crossflow- I started with 45F9 and that was running too lean at part throttle low engine speeds. 50F9 was running a bit rich, sometimes below 12:1. I’m running 50F8 now and I think that is helping to split the difference. 65’s sound like they would be too large.

 

The 65s sound rich to my yet untrained crossflow ear. The not crisp running seems to be about 5 to 25-ish % throttle. I'll see what Pegasus has for me. (quick looks shows f8 and f9 in stock sizes by 5's...sweet)

Edited by rdhunt1
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Pegasus will sell you several sizes of idle jets and reimburse you for the ones you don't need. I would go down to 50s and see how it runs. My car had too narrow jets and had hesitation for the first 33 years of its life. I had bigger idle jets installed and its like night and day. Pulls nicely through the whole rev range.

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Keep it coming...please! Exactly the experience/advice i'm looking for. I did grab both 50 f8 and 50 f9 on saturday. The switch from 65 f8 to 50 f8 was drastic!! The crap 1/4 throttle response is 100% gone and the intake is beginning to sound nice and crisp! I think it may even be a bit lean now. I get hiccups through the intake when the car is cold. Interestingly, the hiccups seem to be through the two forward venturies on each carb. I will likely try the 50 f9 since Elise111 said they were a touch richer based on afr. Huge improvement already!

 

I did find that i am not getting very good response from the #3 cylinder mixture screw. I took it and the #2 out to compare and didn't see anything of significance. No damage or bends. No length or diameter changes between the two checking with good calipers. Possibly plugged?? Investigation on this will continue. You can definitely alter idle speed with the other three. #3 cylinder, not that much.

 

Next question for those still willing to share... best source for distributor cap/rotor? Lucas dizzy, with Aldon sticker and Pertronix ignitor inside. Do I need to get serial/model ##? I have read the Aldon modded dist may not have the best curve for the Supersprint. Thoughts ?

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Agree with @Bent Wrench - chased a similar issue on my pre-crossflow through HT leads, dizzy and cap, etc. before finding weak valve springs on 3 while doing leakdown testing and checking valve tappet clearances.

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Hmm, interesting. I had just adjusted the valves before I noticed the hiccup but very confident they are set to perfect .022" and .024". Granted, they were set cold. Weak springs is a new one to me (hell, most of my toys don't even have cams and valves!!) but logical enough. I have seen a torque wrench type tool that can check spring pressure while the spring is still installed. I'll see if anybody I know has one. Otherwise... leak down wouldn't hurt. I am actually resisting the temptation to pull the head, just for a look see. I don't know if it is the totally flat head or the one with a little bit of bowl to it. Likely stock. (whichever was stock on a 1996 supersprint)

 

Having just had the carbs off for a through once over it is plausible a chuck of crap got in the idle circuit. Usually quite scrupulous but those are some tiny little passages.

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Anker - sorry, I misread the thread. This is all very helpful for me. My BDA hesitates around 3500 RPM. Didn't know about buying several size jets from Pegasus. Hope I can tune that out in the spring.

 

I did, just giving some advice!

4

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Mine hesitated between 2K and 3K RPM, and then picked up from 3K and up. Best of luck getting it fixed. It made a huge difference to me to finally get it right!

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There is a yahoo group called sidedraft central. The gentleman that runs it (Keith Franck) sells his own weber parts which myself and others have had great luck with. He has a lot of great tutorials and troubleshooting resources up on the group page.

 

Glad going to 50's worked. Tip-in seems to be the most common challenge most face with webers. Generally it is a combination of idle jets and progression holes. You may have luck getting closer to perfect with Keith's tubes.

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  • 3 weeks later...

AF Meter.JPG Get yourself one of these if you are running side-draft carbs. Really good for syncing them.

Graham.

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  • 2 weeks later...

first drive with the 65 pilots changed out for the 50f8. Idle and run quality is drastically improved! Off idle throttle response is significantly better than with the 65's. Did get increased popping on decel. Small hesitation around 3k. Switched to 50f9 but ran out of time for further testing.

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Get yourself one of these if you are running side-draft carbs. Really good for syncing them.

Graham.

 

I used my old uni-syn last night. Found a slight front/back carb variation, and then a very slight #3 cylinder variation that i fixed with the small bleed screw. All of them seem really nice but the uni-syn does bounce a little. Does your airflow meter Bounce or is it damped?

 

Distributor is next. I used one of the programmable timing lights and tried to map my ignition curve from 600 to 4000. Surprisingly easy and, hopefully, accurate. As well as not enough advance (10 to 12 degrees) I think I am getting some scatter at rpms higher than 4k. It is an lucas/aldon dist with pertronix 1 ignitor.

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Compression check:

#1 - 205 psi

#2 - 205 psi

#3 - 180 psi

#4 - 205 psi

 

Wonder what's up with #3. Checked valve clearances and they are ok. Sprayed wd40 in the plug hole and tried again. 195 psi. Hmmm... rings? at 16K? On one Cylinder?

 

Quick email to Pegasus. Their 164-03 Motorcraft gasket has an ID of 83.74mm. They have updated their website to note this for those of us with 1700's!

Also to note: their Fel-Pro Perma-Torque 164-03PT has a bore of 83.34mm.

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