Racing Fuel Systems

Re: More Tunnel Ram Help

2023-09-12T17:02:53+01:00

So, I had thoughts to run the Demon at the drag strip just to see what it will do. Trying to stall the car (foot brake style) then floor it, it was not happy. Large bog. With the 660's not having anything from the factory other than 0.025" squirters, I ordered 4 (2 per carb on center squirters) and drilled 1 set to 0.031". This solved 85% of the bog. I then redrilled to 0.033" but due to weather, I have not been able to retest.

Statistics: Posted by 71GSSDemon — Tue Sep 12, 2023 5:02 pm

Re: More Tunnel Ram Help

2023-07-25T20:34:39+01:00

Yes I have a link to Tom Vought's discussions. I believe he also mentions drilling this plug (I used a hose barb instead) to lean the mixture instead of drilling the throttle blades. This set up is working amazing, for me, how I drive and what I need it to do. I understand adding the power valve, more idle mixture adjustments, etc would help fine tune this, make it more efficient and possibly more power but it truly is working remarkably well as it is set. As for adding PCV hose to this port, I would have to think about sizing. Typically PCV is 3/8 hose while this is a 1/8 hose barb. Not sure I would gain much even reducing it and splitting it across each carb for a total of 1/4. Also, my thought was any oil film in such a small hose, it could become blocked/clogged easily.

Statistics: Posted by 71GSSDemon — Tue Jul 25, 2023 8:34 pm

Re: More Tunnel Ram Help

2023-07-19T10:37:36+01:00

Do you have a link to Tom Vaught's discussion? That is where the PCV valve hooks to.
These carbs don't have a power valve , correct? This is why they will run pig rich at cruise on a street car. When you bleed air in thru this port you are leaning up the fuel mixture as would hooking the pcv valve there, to some extent.
I would replace the metering blocks with something that has a power valve.

Statistics: Posted by rgalajda — Wed Jul 19, 2023 10:37 am

Re: More Tunnel Ram Help

2023-07-18T18:38:36+01:00

Here you can see the passage and the hose barb.

Statistics: Posted by 71GSSDemon — Tue Jul 18, 2023 6:38 pm

Re: More Tunnel Ram Help

2023-07-18T18:28:11+01:00

This hole is below the throttle blades and the passage leads to both secondary bores. This is described by Tom Voight (Holley engineer) as a tuning port instead of drilling holes in the throttle blades.

Statistics: Posted by 71GSSDemon — Tue Jul 18, 2023 6:28 pm

Re: More Tunnel Ram Help

2023-06-21T07:04:49+01:00

Does this hole exit above or below the t/blades?

Statistics: Posted by GTO Geoff — Wed Jun 21, 2023 7:04 am

Re: More Tunnel Ram Help

2023-06-20T21:44:31+01:00

So, it has been a while since being on here. The 660 carbs have a passage that connects the rear barrels to a pipe plug on the side of the baseplate. I removed this plug and installed a hose barb with a 0.125" hole in each carb. This is originally where my vacuum advance connected (in the front carb, rear carb was plugged). This removed 50% of my stumble issues. So if it got better, I decided to try removing the plugged rear carb barb. This took all stumble and surge at 2700-3200rpm completely away! I installed an equal hose barb to each air cleaner so that the air bleed was filtered air. I also leave the vacuum advance off, removing the canister from the distributor all together. There was thought that the very fast ramp and manifold vacuum source it was far too much timing and getting hosed up. Car worked amazing on a 7hr each way road trip and managed 11mpg. The plugs still appeared a tad sooty so I opened the office from 0.125 to 0.136 being the next drill bit size I had. This is the first time the idle picked up; so it is happier. Just will keep monitoring the plugs to make sure not too lean. The picture is an 850 Center Squirter from EBay add that has the same hose barb bleed.

Statistics: Posted by 71GSSDemon — Tue Jun 20, 2023 9:44 pm

Re: More Tunnel Ram Help

2023-05-10T13:07:14+01:00

Thanks Geoff. I have manual brakes and neither the tunnel ram, nor the carbs have any additional fittings. I may just have to remove the top and add one.

Statistics: Posted by 71GSSDemon — Wed May 10, 2023 1:07 pm

Re: More Tunnel Ram Help

2023-05-10T06:18:04+01:00

If you have power brakes you can use a Tee fitting in the vac hose for vac adv. Same for any other vac hose, except for the PCV hose. Some intakes have plugs in the ports. One of these can be used for vac adv, does not have to come from the plenum area.

Statistics: Posted by GTO Geoff — Wed May 10, 2023 6:18 am

Re: More Tunnel Ram Help

2023-05-09T18:14:46+01:00

UPDATE:

So I drove the car a couple weeks ago and it continued to run terrible in the same 2700-3200rpm range. I tried adjusting the idle mixture screws to see if that helped and 1.25 turns out helped vs 1.5. I then tried disconnecting the vacuum advance, not because of timing, but to have the open 1/16 pipe nipple open. 50% of the issues went away. So this past weekend (weather finally got nice) I added a 1/16 pipe nipple to the rear carb as well. The placement of these in the 660 is open to both rear barrels. Adding the additional nipple netted 95% fix of the stumble and now I can also go from cruise to WOT with barely a hiccup. I am on the right track. It was pig rich and needed the extra air. Need to fine tune the hole size and make a port to reconnect the vacuum advance to see what that does.

Statistics: Posted by 71GSSDemon — Tue May 09, 2023 6:14 pm

Re: More Tunnel Ram Help

2023-04-13T21:17:53+01:00

Sorry for the very late reply. Yes this is for street use. Thank you for the help for those that have. The transition from cruise to WOT and idle to WOT is what I need to tune. Cruise to 3/4 throttle works very well. WOT itself works very well. Starting, idling and cruise...all I am happy with.

Statistics: Posted by 71GSSDemon — Thu Apr 13, 2023 9:17 pm

Re: More Tunnel Ram Help

2022-12-20T03:47:56+01:00

I do drive this "toy" as much as life and weather allows. I DO still want to fix the tune issues. Yes I am not hung up on the numbers but also understand the importance. I am considering Innovate dual O2 this summer.

Statistics: Posted by 71GSSDemon — Tue Dec 20, 2022 3:47 am

Re: More Tunnel Ram Help

2022-12-19T21:24:16+01:00

GSS,
I think your latest post shows a very sensible approach to carb tuning a 'toy' car; ie not getting too hung up on numbers. Good luck with it!

Statistics: Posted by GTO Geoff — Mon Dec 19, 2022 9:24 pm

Re: More Tunnel Ram Help

2022-12-19T21:21:45+01:00

Rg,
Not sure when Edel first started selling the AFBs, but I believe it was late 80s/early 90s.

Statistics: Posted by GTO Geoff — Mon Dec 19, 2022 9:21 pm

Re: More Tunnel Ram Help

2022-12-19T13:18:31+01:00

Statistics: Posted by 71GSSDemon — Mon Dec 19, 2022 1:18 pm