Mark Reid RCR-40 Build

Jac-Mac-once you mentioned that staging ratio,I thought about this manifold set-up.To see what I mean,go back to the 1st page of this build log and look at the carb mounting configuration and the various photos.I think the can of worms just got bigger. A.J.
 

Randy V

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Jac - You're right about it not working well for fuel distribution at part throttle...

However - All is not lost. Holley does make a special throttle plate for the 80507 that's 1:1..

Holley Performance Products Throttle Body And Shaft Assembly*112-110

Not likely to be cheap...

I can't tell very well from the pictures of Mark's engine if the carbs he has are already equipped with this throttle plate or not...

Part number 112-110

Note the throttle plates drilled in all 4 throats..

medium112-110.jpg


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Hopefully this image will post - it shows Mark's carbs a little better. They may already be equipped with the 1:1 throttle plates.
GT-40engine016.jpg


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Throttle Body And Shaft Assembly - HOL112-110 by: Holley - Doug $180

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Holley 20-122 - Holley Pro Series Secondary Linkage Kit - JEGS $30
Not sure if it would work on the 80507 but a call to the Holley Tech line might be able to tell you...
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Randy/AJ, I enlarged the pic to 400%, & they definitely look like they are staged.

Its always going to be a *#*### to get to idle due to the very small plenum if any under each carb plus there is no connection between the two plenums to help smooth out the uneven intake pulses each carb will 'see' when any two cyls fire one after the other and there is then a gap---- eg 1--265-- on the front carb & -37---48 on the rear, or 15-26--- on the front carb & --4--378 on the rear, depending on the cam /firing order used.

If you convert it to full IR service with no plenum then each barrel @ only 97.5 cfm wont be enough to feed it & even if you share two barrels diagonally as they do on the FE it will still be short @ 195cfm per barrel.
He is already short on aircleaner space so the only real option is to cut the manifold base down if possible, create a mini plenum by blending the runners in the base and link the two plenums by a reasonably large hose from underneath.

Some of the older Offy/Weiand/Edelbrock low profile twin 4bbl manifolds might be a better option--- or one 4bbl on the Victor like he had. Another thought, brand new, no leaks, corrosion etc to worry about.

Blue Thunder pn- BTIM2898V
 
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Randy V

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Jac - I did not blow up the pictures as you have...
Admittedly the larger the plenum the better the idle and mid-range response will be.. I don't know that Mark's machinist didn't open up the ports to each other thereby creating a small'ish plenum on each end of the manifold.. If he did not open them up and he does have the progressive linkage from primary to secondary - you're right that it will not run right at all with the exception of WOT..
In that these carbs do have 4-corner idle circuits, an IR configuration is possible and it should run really no worse at an idle and probably even better than my Weber 48 IDA setup.

The 390 CFM carbs - I recall (it's been a long time) - were rated at 5" of vacuum.. I don't know what they would flow at 3" like most 4 barrel carbs.. In that these carbs, in a single carb configuration, were sufficient to run a 650-700 HP restrictor plate engine, I'm thinking that perhaps a pair of them in a semi-IR configuration would be able to support this engine in a non-competition (not max HP) mode.. I scrolled back in this thread and unless something's changed - this engine displaces 342 cubic inches.

I'm sure that Mark will have plenty to add to this conversation upon his return from Carlisle..

-edit-
BTW - I like that Blue Thunder intake.. Mark could always achieve the same basic look that he has with this modified Tunnel Ram by using the BT intake with a pair of 2" spacers...
 
Wow, very interesting conversation while I was gone! Lots of good input and I appreciate it. You guys are always great!

Let me clarify a couple of points:

1. The 4150 HP (390 cfm) carbs are set up for progressive linkage and I plan on leaving them that way (see the next point). During troubleshooting we found one of the linkage bars was bent, holding the secondary open. Fixed that.

2. I used the Weiand tunnel ram manifold as I already had it from another project. Recognizing that I want to take full advantage of the progressive carbs, when I removed the top half of the manifold I milled the center dividers down 2" and blended them to the intake ports and towards the carbs. I then added a 1" open plenum spacer to the top both providing an additional plenum area and a mounting flange for the carbs. The real challenge here is to get both carbs balanced, then it should run really well, with four cylinders able to take advantage of four barrels as needed without sacrificing too much bottom end. It is a light car anyway, so I don't see this as a problem.

3. I had not anticipated the drilled throttle plates. I selected a fairly aggressive mechanical roller cam (Lift: .586I/E, duration at .050: 243I/E, adv. duration: 288I/E) with the expectation of decent vacuum given the above set up and an idle around 1000 to 1100. This engine has all the parts to rev to 8000 rpm (it is the one Ron Earp had built, but I changed the monster cam and springs he had installed). The fact that I have taken every bit of primary and secondary idle adjustment out and brought the 4 corner mixture screws down as far as I safely can and it still idles at 1800 to 2000 rpm, gives me great confidence that when I close them up I will have a fair idle with excellent response. That is after I do as Randy pointed out, tune the jetting, air bleeds, and transition circuits. I am pretty good at carb tuning (one of the reasons, I finally gave up on the efi stacks on the coupe) and feel that if I can get the idle down, I will have a real shot at making this set up work well. I like the idea of epoxy, will it hold up to continual exposure to gasoline? Otherwise, Jac Mac's rivet idea is the one I will go with.

4. Finally, Carlisle was a blast! Great day on Saturday and rainy and miserable on Sunday, so we got out of there quickly this morning. It was great to see Fran and Ron McCall (his car is stunning and looks like it is ready for the track at a moments notice) again and I have to say my car looked great sitting with all the other beautiful machines. I got lots of positive comments on it and one reason I went with this set up was the wow factor and I got a lot of wows.

If all else fails, I'm having fun and I can always put one of the other 3 or 4 manifolds I have sitting around with a boring 750 cfm Holley on the car!

Thanks again, folks!
 
During my conversation with Ron McCall, I asked him about throttle cables. I am using a 144" Lokar braided cable and I don't like it. I need a longer cable due to coming in from the side to throttle my carbs. The Lokar is too stiff and it has stretched a coupe of times already and I haven't even driven the car, yet!

Ron gave me a Fiero cable to try and while it is too short, the ends are correct and it doesn't bind at all. The perfect cable, just too short. While looking for a longer cable, I found the Fiero Store (Fierostore.com: The Fiero Store) and they measured cables for me and we found one that will work! It is for a 1984 Fiero 4 cylinder, their part number 63890. For $39.95, it is a real bargain! Hopefully, this helps someone else and I'll let you know how it works.
 
I got my idle down to a sweet 1000 rpm! I plugged the holes with rivets and then bonded them to ensure they won't come out. I sounds wonderful, but I am running a little rich at idle. I didn't have time to do any tuning or set the timing where I want it, but will this week.

Ron and I also started working on mounting the dash. It is now completely in position and we need to figure out how we will mount it.

I hope everyone in the US and UK has a great holiday (also, anywhere else with Monday off)! Please pause tomorrow and remember a veteran.
 
Mark,
Having installed some rivits myself, I was wondering what size and type you used. The reason, I hope they were of aluminum and I am sure they were very small. You might want to look at the butterflys and make sure they didn't flex as they gave grip. Just a thoght.

Bill
 

Rob

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Mark,
Throttle cable sounds interesting. Please post pics when available. I too am using the Lokar, but no issues. Worked great for front attached weber set up.
 
I've not been able to work on my GT for the last month or so given work and travel commitments. All I have left to do is make front and rear wiring harnesses for the lights, align all four wheels and install the interior. A good weeks worth of solid work, but I also have to install railings on my deck. I'm now getting some grief from the building inspector (hey, it has been 18 months and it is 12 feet above ground in one place). Anyway, I did finish the panel alignment and love this shot, so I thought I would share:

GT-40129.jpg
 
Mark, i want to thank you for making the time in to show me your car today, i was very impressed with your build and the mods that you had done A+ thanks again Bob Peckham maybe the next RCR owner
 
Mark,
On the first page of your build thread you talk about taking the engine to have it dyno tested. I was just curious as to why you didn't. Wouldn't that have helped sort your carb problems so when installed in the car it was ready to go?
Just asking ,not being critical.
 
Mark I thought you might like these pictures I took of your GT-40 today. I had to move it outside to get another cobra in the paint booth and when I looked back the light was just perfect.

I'm going to miss this one when it leaves:cry:

Ron
 

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Rob

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Looks fantastic Ron. One question, what's up with the little black marks on the rear quarters behind the tires...... Oh...right...our little secret man. Just get em cleaned up before Mark comes by.;)

Lookin good....................:thumbsup:
 

Randy V

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Is this like Deja Vu all over again?

Gorgeous car... But it seems like some posts may be missing....
 
Hell, I'd like to find a little time to actually work on it. I haven't touched it since I made the final panel alignment over a month ago. I'ts kind of taking up space at Ron's and I know he likes having it there, but it needs to come home so I can finish it. I only need like two weeks of solid work to finish it. My goal is to drive it to Carlisle next year.

Hey Rob, Ron know he can use the tires as long as he replaces them. BTW, gluing globs of rubber back on doesn't count!
 

Sandy

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During my conversation with Ron McCall, I asked him about throttle cables. I am using a 144" Lokar braided cable and I don't like it. I need a longer cable due to coming in from the side to throttle my carbs. The Lokar is too stiff and it has stretched a coupe of times already and I haven't even driven the car, yet!

Ron gave me a Fiero cable to try and while it is too short, the ends are correct and it doesn't bind at all. The perfect cable, just too short. While looking for a longer cable, I found the Fiero Store (Fierostore.com: The Fiero Store) and they measured cables for me and we found one that will work! It is for a 1984 Fiero 4 cylinder, their part number 63890. For $39.95, it is a real bargain! Hopefully, this helps someone else and I'll let you know how it works.

What was the issue in using the Lokar cable? I was going to get one for my car.

Sandy
 

David Morton

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Mark - next time you are over we'll go to see Hugh Absolem at
Spot-on-Control Cables in Arborfield near Reading. You can have the 'Rolls Royce' of control cables then. He supplies lots of race teams in UK and Australia and they come back year after year for more.
Dave.
 
Im not sure that the Lokar throttle cable will have stretched, its more likely that the outer braided sheathing will have compressed or shortened slightly giving the impression that the inner cable has stretched.
 
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