Advice on upgrading 61

[Steve M.]

I have a 69 BB vert, 75 vert, 07 vert and my latest baby is a jewel blue fully restored 61, with a single 4 barrel set up. ( 20 K original miles, number match)

I have a couple of questions for the C1 experts who I respect greatly. Thanks in advance.

I want to get advice on how involved it is converting it to a dual 4 barrel set up and if there are any warnings or advice against it.

I don't want to do anything that can't be reversed and I really don't plan on hammering it. ( I have the 07 for that) However, I'm not sure I can tolerate the the stooges at the local car shows poo - pooing a beautiful car because it doesn't have FI or at least the dual set up.

I do know the tach would have to be matched up etc.

I am open to all opinions on this.

thanks

[Scott S.]

Re: Advice on upgrading 61

However, I'm not sure I can tolerate the the stooges at the local car shows poo - pooing a beautiful car because it doesn't have FI or at least the dual set up.

If you change a beautiful, original classic American sports car in order to satisfy a few people at a car show, isn't that starting down a slippery slope toward a no-win situation?

Just a thought.

[Steve M.]

Re: Advice on upgrading 61

If you change a beautiful, original classic American sports car in order to satisfy a few people at a car show, isn't that starting down a slippery slope toward a no-win situation?

Just a thought.

I agree deep down with your point.

[Scott S.]

Re: Advice on upgrading 61

If you have some pictures of this car, please post a few so we can take a look!

[Steve M.]

Re: Advice on upgrading 61



More photos coming when I get off the road from hockey school this weekend.

[William C.]

Re: Advice on upgrading 61

I can think of several disadvantages to the low horse 2X4 setup and virtually no advantages. Limited performance advantage with the stock cam, loss of vacuum advance in the distributor (although the vac advance distributor can be made to work, it takes some rotational repositioning of the distributor to clear the rear carb) Two carbs to maintain vs one. Really nice looking car, enjoy it!

[Steve M.]

Re: Advice on upgrading 61

This is why I love this board. Prudent advice.

I have been a C3 guy all my life but there was something about his unique blue colour that I couldn't resist.

It just has to cruise to the local beach, Grand Bend, Ontario....

[Duke W.]

Re: Advice on upgrading 61

The single four barrel is a lot more trouble free, and I seriously doubt that the 2x4 setup actually produced 20 more gross horsepower with the base cam.

Keep what you have well maintained and original. lt appears to be a beautiful unmolested example.

If you really want "more power" the Fall issue of The Corvette Restorer will have an indepth article on how to build "cheater motors" than don't look any different than OE and can pass a PV.

Duke

[Richard M.]

Re: Advice on upgrading 61

Steve, IMO, I would just leave the hood closed. The car is gorgeous as it is pictured. I'd just let them drool over the Jewel Blue. If they ask you to open the hood just tell 'em the hood latch is broken and it's going in the shop in the morning!

So.......as a 24 year owner of a 59 with dual-fours..........

Sure they're good looking, they get some "wows" and "ooooo's" when the hood is open, but there were many occasions when I first got the car that I was tempted to remove them. My engine is the Duntov cam, solid lifter, 270HP version. Well, it was. I got sick and tired of valve adjustments, poor idle quality, etc, and in 1995 when I rebuilt the engine I decided to step it back a bit. I went with hydraulic lifters, a slightly aggresive cam, and a few carburetor mods. The result was a much better idle, more driveable in traffic, and overall much more pleasant to work on.

Also, dual fours have a issue with hot starts that you may be unaware of. On very hot days a restart of a single four hot engine can be helped along by keeping the throttle open to allow maximum air intake. In a single four car, it's easy. Just hold the pedal to the floor, crank, and when it kicks over, feather the throttle a bit and you're good to go.

In a WCFB dual four engine you must be careful, very careful on a hot restart. You must NOT push the pedal to the floor.....only half to the floor. The dual four setup uses a progressive linkage. From 0 to 50% throttle, only the primary(rear) carb is active. From 50 to 100% throttle, both the primary and secondary(front) carbs are active. Overall, from 0 to 100%, fuel intake progresses from 2 barrels, to 4, then to 6, then to 8.

WCFB carburetors do not have throttle shaft seals. From rest, when the pedal is pressed to the floor, both the primary and secondary carburetors get a shot of fuel from their accelerator pumps. Using the "single carb" method to restart a hot engine can be dangerous on worn dual WCFB's. The front(secondary) carburetor would get a shot of fuel from the accelerator pump also, and on engine start would never allow the fuel to enter the intake manifold as the engine is now running on only the primary carb. You would have to press the pedal past 50% to open the secondary carb throttles, which of course you wouldn't want to do because the primary carb would be wide open.

The fuel from the initial pump shot would then puddle on the secondary carb throttle plates. If the throttle shafts are slightly worn, the puddled fuel could leak out both sides, ultimately onto a hot manifold. A backfire could happen due to the hot restart, or if going downhill the fuel could leak down to the exhaust manifolds, and the spilled fuel could catch fire.

BTW, I've written this based on factual experience!

Rich

[Edward B.]

Re: Advice on upgrading 61

From a performance standpoint, the dual set-up with hydraulic lifters won't be felt but will bring a load of reliability issues you don't need in a driver. On the other hand, if you are trying to replicate the 245 HP engine the tach will be fine as it is and you will be able to use the finned aluminum valve covers in place of the plain stamped steel ones. If it were my car I wouldn't do it.

[Peter V.]

Re: Advice on upgrading 61

As a wise man once said (along with others on this subject), "If it ain't broke,.........

[Steve M.]

Re: Advice on upgrading 61

It is decided. I'm not going to mess with beauty.

Who and how much $ do I owe for the great advice.....?

[Richard M.]

Re: Advice on upgrading 61

Steve, Good choice.

Rich
p.s. I'll take a beer next time you're in Florida!

[Loren S.]

Re: Advice on upgrading 61

Love the Jewel Blue. You could get a new Edelbrock 2x4 setup for about a grand, probably more reliable, and definitely cheaper than a WCFB setup.