Race Cars and Motorsports

MG V8 racers,

What are your thoughts and opinions on induction to the 3.5 Rover V8 via the Holley 390 P/N O-80507-1 (390CFM) carburetor -WITH - unlimited choice/allowance on the selection of the intake manifold - AND bearing in mind that the restrictor plate is 0.060" flat steel or aluminum with four (4) 1.16" holes positioned within 4" of the throttle butterflies.

Too, note that the SCCA has restricted the MGB GT V8 and the RV8 - in the GT 2 class - to ONLY the 3.5 litre Rover V8.

How do you maximize the horsepower derived from this setup on induction ?

keep them on the track

phillip g

Hi Phillip! Sounds like you've made or are making progress with SCCA in removing that original silly single-restrictor-plate rule.

I don't have personal experience with Holley carbs. Have you been in touch with Jerry RIchards or Les Gonda about this issue? I believe both of them have used Holley carbs on their 3.5L race engines, and I have some snapshots from last year of Jerry's 4-barrel carb/intake (below). He swaps between it and a set of four Weber DCOE's, but I think he told me the Holley works pretty well for him on shorter tracks.


(I'm not sure which model Holley carb Jerry uses. His manifold appears to be an Edelbrock Performer 2198.)


(I'm skeptical about this air cleaner for racing... but I guess it keeps mice out when the car is stored.)



Later that same day, the Weber's went on:

re: 4x 1 1/16" diameter holes

Phillip, am I correct in thinking that the Holley 390 has four 1 7/16" barrels (as measured at the baseplate gasket)? If so, how upset would you be about putting a taller (~4") bulge in the center of your hood, so that you could install a converging spacer between carb and restrictor plate?

Hi Phil, since I spent some time again widening the wheel arches @ Mark Canaday's shop,
and having the opportunity to drive your beast @ "moderate" speed around the S. paddock
@ HPT - it was smooth until the secondaries opened up - WOW! Your car has a kick.

Are you happy with the new trans.? I haven's talked to Clancy for weeks.

Bill

Thanks for letting me drive the Beast @ Heartland Vintage Racing's S. Paddock.
What a kick from an MG in close quarters. How's the new Trans. working out?
Mark Canaday did a wonderful job with the body.
–Bill

Curtis,

Thanx for leading a discussion on the best approach to the restrictor plate problem on the Holley 390 carb. The 4 each 1 1/16" holes in the restrictor plate above the 4 each 1 7/16" Hollley carb barrels would certainly seem to benefit by a gap or distance from the base of the carb's 4 barrels - with the rules restriction of "no more than 4" above the throttle butterflies".

We already have a sizeable bulge on the RV8 hood - which is a fibreglass copy of the original RV8 hood - and by the SCCA GT2 rules we can add a larger/higher bulge to the RV8 (original size) copy. The GT2 rules state that the racer is a "replica" and must have the appearance of the original MG Rover RV8 (plus all the size and dimensions of the original RV8). So a larger hood bulge could be accommodated on the RV8 hood - within certain "replica" GT2 rule allowances. So we will probably, once again, have to go to the fibreglass "forms/mold" maker and create yet another RV8 mold - another expensive venture.

Next is finding or making a precision restrictor plate that will fit into/onto the Holley 390 carb. Does Holley or any other manufacturer make off the shelf restrictor plates ? Finding one "off the shelf" would certainly help with the advancing of the project.

This bump in the "MG V8 GT2 project" road is not really a problem - for the real problem was the original requirement of the building and fitting of a .38 mm SIR (Single Inlet Restriction) tubing, flowing unit from the front of the car to the Carb. The restrictor plate is obviously a much better path to induction on the Rover 3.5 motor.

keep them on the track,

phillip g

Bill,

Nice to hear from you via the Brit V8 Forum.

I am very glad you got to test the RV8 in the S Paddock at HPT. You probably discovered yourself that we had a real problem with the transmission early on in the weekend. By the second day of the HPT event we had replaced the stock shifter with a new short shifter unit that transformed the original gates and greatly shortened the 5 throws or the 4 throws between 1st and 5th gear. This was a tremendous improvement, where on Saturday we had no use of 5th gear and even 3rd & 4th gear changes were most difficult.

The transmission is a completely rebuilt GM T5 unit from a late model Pontiac Firebird, with good gear ratios for road racing. We started the first weekend event (in the SCCA logbook) with the GT2 car using the original toploading GM shifter and after the change over to the new short shift unit in the pits (THANK YOU BILL YOUNG !) we had a totally new racer under us and finally could make the shifts from 1st to 5th. Our next problem was the final drive - a worse problem yet. We had been unable to find the time to change the 4.55 final drive to the 3.90 final drive we had on hand. So we/you drove the "Beast" with the 4.55 final drive. No top end with a 4.55 final drive when sticking to under 6,000 RPM, especially with a new engine. Not good !. You found that out, too, I am sure in the South Paddock of HPT. A new rear axle and a 3:05 final drive will mean some high speeds in 5th gear.

Neverthess, we still made progress in developing the car and have big plans for a totally different rear axle & front suspension/brakes before the first real event next spring, 2011. Nothing fell off, we broke nothing and had a great weekend.

You and Mark Canaday deserve ovations for your body work on the RV8. The symmetry of the 4 corners and the symmetry of opposite corners - front and rear is simply amazing. If one carefully studies the body work, curves and arches that you two artists put into that body work - one can only shake their head and walk around the "replica 'in disbelief. Widened by 8 inches and flared beyond amazement - the GT RV8 still looks just like an original RV8 !

You and Mark are welcomed to drive the RV8 any time you want. Sincerely.

keep them on the track,

phillip g

In reply to [forum.britishv8.org]

So strange. Why would anyone put a restrictor above the throttle plates when it is so much simpler to just put them below the carb base the way NASCAR does it?

JB

Jim wrote: "Why would anyone put a restrictor above the throttle plates when it is so much simpler to just put them below the carb base the way NASCAR does it?"

As I read the rules, the restrictors are to be installed BELOW the carb, and ABOVE the plenum that's cast integrally into the intake manifold. (I'll paste the rule verbiage below for convenient inspection.)


(Notice how the four carb barrels all feed into a common cavity - plenum - in this manifold.
Incidentally, more Rover-compatible manifolds are shown here: [www.britishv8.org] )

My interpretation of the rules is that the restrictor plate should look exactly like a standard carburetor baseplate gasket except (a) metal and (b) with smaller holes. If you go on eBay and shop for Greenlee radio chassis punches, I think you'll find it's not too hard to find one of the appropriate diameter. Once you have the right punch, making the plate should be a piece of cake. The harder part is making the spacer. Above the spacer, you'll want a regular carburetor baseplate gasket (with 1 7/16" holes).


ref:

Quote:

Grand Touring
GT2
1. #2356 (Phillip Leonard) Allow alternate induction on MGB GT V8 & RV8
In 9.1.2, GT2, Engines, BLMI, add to Notes: “Alternate induction: Holley P/N 0-80507-1 (390 CFM) on unrestricted manifold
with a mandatory plate between the carburetor and plenum of 0.060” flat steel or aluminum plate with four (4) 1 1/16” holes.
Spacer is unrestricted. The restrictor plate shall be positioned within 4” of the throttle butterflies. All inducted air shall pass
through the specified restrictor plate.”

Philip, thanks for the compliment. But Mark C. did 99% on your car, I only suggested stuff while restoring my '64 TR4.
Sounds like you'll be designing a Bigger Bulge for the hood. I'm @ Mark's every Thurs. and have been known to drop
pieces off @ Clancy's. Glad to hear about the new trans. It was a tad annoying in the previous iteration.
Gotta love Bill Young's abilities!
–Bill

Phillip, Not seeing a sketch, I'm envisioning a "tapered bore carb spacer".This would taper at top, from throttle bore sizes, down to 1.160" bores/restrictor dia's ? Obviously you would want as tall of spacer, as "legal" hood would allow ? "Smart" tapered carb spacers add hp, on the dyno. Good Luck, roverman.



Edited 1 time(s). Last edit at 10/04/2010 08:25PM by roverman.

Phillip, I don't remember how much clearance you now have between the carb and the hood, but if there's room I believe I'd sandwich the restrictor plate between a couple of aluminum tapered pieces to form a venturi and remove the air cleaner in favor of a carb hat from Spectre and a cool air intake behind the grill. [store.spectreperformance.com]

Bill,

Right on. This SpectrePerformance item is just the thing for cool air from the grill area to the carb - and easy to install - just in front of the restrictor plated carb. Isn't it great that the SCCA rules committee gave us a break on induction. It allows us to move on to other pressing problems.

Thanx for the pointer on the product - should be an easy adaptation.

We need to do this first -induction rules take the lead. The rear axle is our most difficult and BIG NEED before the 2011 Nationals.

keep them on the track.

phillip g

Racers,

We pulled the locked MG differential from the RV 8 this weekend. We discovered that the ratio was 4.875 - used the very first time we really tried out the GT 2 car at Heartland Park last summer. Not good.

Now we have installed a locked 3.9 differential and just know the change-out will be significant. A Ford 8 inch is in the wings.

First real SCCA logbook event will be Heartland Park Topeka, May 30, 2011.

Anyone interested in being on hand is welcomed. Let me know and arrangements will be made for your credentials.

keep them on the track,

phillip g

Fans of MG racing,

Still looks like the first official race for a SCCA GT 2 MG (aka) Rover RV 8 will be at Heartland Park Topeka, April 30/May 1.

I hope some British V8 Forum members can be on hand.

I will find credentials for anyone who wants to join us at the Heartland Park track, pits, and paddock.

keep them on the track,

phillip g

Phil, I'll be there on Sunday for sure. Kent and Kathy Prather are hosting their annual Picnic at the Races that day as well. See you then.

Phillip, When are you racing, out west ? Go Gettum, roverman.



Edited 1 time(s). Last edit at 04/01/2011 04:50PM by roverman.

SCCA racers,

We have now located the mandatory restrictor plate necessary for compliance with SCCA rulings for the GT 2 RV8.

Between the Holley 390 carb and plenum, is the SCCA GCR (mandated for the 3.5 Rover V8) "mandatory" plate of 4, 1 & 1/16 holes, made of steel or aluminum plate.

We are in compliance - and have no idea how the restrictor plate will affect performance. Which means, another trip to the chassis dyno to adjust jetting andf flow. Nah - ran out of time for testing of the restrictor plate. We will run what we have and see how the restrictor plate affects performance. The Rover 3.5 engine is capable of a lot of horsepower and after many tries will produce enough to run competively with the other cars in the GT 2 class. We have the weight advantage - our weight is mandated at 2001 lbs with driver and all fluids aboard.

Our first real SCCA race in the GT 2 class is planned for Saturday, April 30, 2011 at Heartland Park in Topeka, Kansas.

Join us. Any help in the pits will be much appreciated.

keep them on the track,

phillip g