327 or 377 for tube frame 1969 "Vintage Look" road race Vett

[pamotorman]

the question you have to ask yourself do i want to race or do i want to win and the answer depends on the size of your bank account before you start.

[bosco]

Got to say, after seeing this at GT-Racecar and now here, I love the idea of this build.

Thanks it has been fun and frustrating. Next, I would like to do a tube frame Grand Sport with a Weber carb 377. At almost 66, I am gettin' kind of old for this...but, still have the addiction.

[mekilljoydammit]

Got to say, after seeing this at GT-Racecar and now here, I love the idea of this build.

Thanks it has been fun and frustrating. Next, I would like to do a tube frame Grand Sport with a Weber carb 377. At almost 66, I am gettin' kind of old for this...but, still have the addiction.

I'm at the "drawing stuff out" stage of chassis design for an IMSA-styled 1st gen RX-7 for GT-2, so I know what you mean, though I've got a few years to catch up.

[bosco]

Got to say, after seeing this at GT-Racecar and now here, I love the idea of this build.

Thanks it has been fun and frustrating. Next, I would like to do a tube frame Grand Sport with a Weber carb 377. At almost 66, I am gettin' kind of old for this...but, still have the addiction.

I'm at the "drawing stuff out" stage of chassis design for an IMSA-styled 1st gen RX-7 for GT-2, so I know what you mean, though I've got a few years to catch up.

Saw all those Racing Beat and Downing cars back in the day. Had been to every Daytona enduro since 1964 (Continental 2000 KM) until this year when I was feeling too lousy to go. I have little interest in IMSA today with nothing but factory built cars, Balance of Performance, no innovation allowed, and all the FIA type crap. I enjoy HSR, SVRA, Trans Am and club racing. This Corvette will run in SCCA club racing SPO, HSR group 9 and the like.

[mekilljoydammit]

Thanks it has been fun and frustrating. Next, I would like to do a tube frame Grand Sport with a Weber carb 377. At almost 66, I am gettin' kind of old for this...but, still have the addiction.

I'm at the "drawing stuff out" stage of chassis design for an IMSA-styled 1st gen RX-7 for GT-2, so I know what you mean, though I've got a few years to catch up.

Saw all those Racing Beat and Downing cars back in the day. Had been to every Daytona enduro since 1964 (Continental 2000 KM) until this year when I was feeling too lousy to go. I have little interest in IMSA today with nothing but factory built cars, Balance of Performance, no innovation allowed, and all the FIA type crap. I enjoy HSR, SVRA, Trans Am and club racing. This Corvette will run in SCCA club racing SPO, HSR group 9 and the like.

At the risk of dating myself, one of my earliest memories is my dad and step-grandpa taking me to IMSA stuff at Road America in the 80s. Watching from the woods stuff thundering down to turn 5 or up to turn 6, spitting fire under overrun. I'm with you on the state of things nowadays even though we're of a different vintage.

[Krooser]

I sat in Canada Corner in '58 watching my brother flog an Alfa Romeo G production at the June Sprints...then we blasted home in his '55 XK 140 at 140 mph on two lane Hwy 57... A bad influence on a 10 year old.
I'm at the "drawing stuff out" stage of chassis design for an IMSA-styled 1st gen RX-7 for GT-2, so I know what you mean, though I've got a few years to catch up.

Saw all those Racing Beat and Downing cars back in the day. Had been to every Daytona enduro since 1964 (Continental 2000 KM) until this year when I was feeling too lousy to go. I have little interest in IMSA today with nothing but factory built cars, Balance of Performance, no innovation allowed, and all the FIA type crap. I enjoy HSR, SVRA, Trans Am and club racing. This Corvette will run in SCCA club racing SPO, HSR group 9 and the like.

At the risk of dating myself, one of my earliest memories is my dad and step-grandpa taking me to IMSA stuff at Road America in the 80s. Watching from the woods stuff thundering down to turn 5 or up to turn 6, spitting fire under overrun. I'm with you on the state of things nowadays even though we're of a different vintage.

[j-c-c]

One thing I have noticed over the years of building road race stuff - the fast guys running in restricted classes (head or intake restrictions) usually prefer smaller stroke engines - longer power curve up top so they can rev more past peak & keep it on song.
But it does take a good driver to see the best from a shorter stroke engine - it's easier to let it get off the boil & less forgiving to mistakes, but faster when the driver is good.
Longer stroke is more forgiving & a better option for closed public road tarmack rally type racing where the driver is often unfamiliar with the course.

This is my thinking also, putting the power (torque) down is tough, passing at end of straight with peak hp is the game IMO.

To the OP. why the no IRS?

[bosco]

One thing I have noticed over the years of building road race stuff - the fast guys running in restricted classes (head or intake restrictions) usually prefer smaller stroke engines - longer power curve up top so they can rev more past peak & keep it on song.
But it does take a good driver to see the best from a shorter stroke engine - it's easier to let it get off the boil & less forgiving to mistakes, but faster when the driver is good.
Longer stroke is more forgiving & a better option for closed public road tarmack rally type racing where the driver is often unfamiliar with the course.

This is my thinking also, putting the power (torque) down is tough, passing at end of straight with peak hp is the game IMO.

To the OP. why the no IRS?

No IRS because stick axle type work just fine in these applications ie: Trans Am cars, Trans Am II cars, SCCA GTA and GT2 cars, etc.
Also because of the cost factor for a samll gain that would show up mostly on tracks we don't run. We have had good luck with quick changes and nine inch Ford types.

[Larry Salisbury]

Got to say, after seeing this at GT-Racecar and now here, I love the idea of this build.

Thanks it has been fun and frustrating. Next, I would like to do a tube frame Grand Sport with a Weber carb 377. At almost 66, I am gettin' kind of old for this...but, still have the addiction.

A cleverly built hi-revving 340cid SBC (4.00"B x 3.375"S) by ex Traco employee Frank Schmidt for John (Buck) Fulp for the 1966 USRRC nearly took out the numerous/dominant Traco engines that year for the championship. The Schmidt 340 Chevy was equipped with the same 58MM DCOE Webers as the Grand Sport Corvette. Schmidt, who helped build the original Corvette Grand Sport motors with Jim Travers and Frank Coon, found deficiencies in the Traco design process, expanded on them, and successfully applied his improved design to the 340 Fulp engine after leaving Traco. Fulp's Lola T-70 scored a second place in the USRRC championship that year. A modern Gen I/II 340cid SBC build would be quite interesting, and something I would consider building for vintage racing.

Larry

[pdq67]

IMHO, no more than a 4.165" b x 3.00 s = 327" engine will do fine and should rpm to the moon for a long time!

And mine will be a 325" engine..

pdq67

[bosco]

Got to say, after seeing this at GT-Racecar and now here, I love the idea of this build.

Thanks it has been fun and frustrating. Next, I would like to do a tube frame Grand Sport with a Weber carb 377. At almost 66, I am gettin' kind of old for this...but, still have the addiction.

A cleverly built hi-revving 340cid SBC (4.00"B x 3.375"S) by ex Traco employee Frank Schmidt for John (Buck) Fulp for the 1966 USRRC nearly took out the numerous/dominant Traco engines that year for the championship. The Schmidt 340 Chevy was equipped with the same 58MM DCOE Webers as the Grand Sport Corvette. Schmidt, who helped build the original Corvette Grand Sport motors with Jim Travers and Frank Coon, found deficiencies in the Traco design process, expanded on them, and successfully applied his improved design to the 340 Fulp engine after leaving Traco. Fulp's Lola T-70 scored a second place in the USRRC championship that year. A modern Gen I/II 340cid SBC build would be quite interesting, and something I would consider building for vintage racing.

Larry

Thanks for that interesting history

[bosco]

An update on this project: I ended up calling this Corvette a 1968 as it resembles the OC cars and they were 68's. I elected to stay with the lil motor, which is actually a 4.155 bore by 3.0 and therefore I believe just under 326 ci. We ran the car at Sebring in June for its' debut but a carb problem and then rain made the weekend abbreviated for us. We fixed the carb issue by going to a Bo Laws 750 and took it back to Sebring in late August with CFR SCCA. Found and fixed a couple more issues and were set for a good race no. two. Lee Arnold was driving, we got about 3/4 of a lap in the dry and the bottom fell out. The race was red flagged after lap three and then called. Lee had moved several spots and we ended up second overall and first in SPO. First overall was a SCCA T1 Mustang that we likely could easily handle in the dry. The two fast GT-1 cars had trouble in the rain. So, again rain kept us from getting much needed laps.

In September we ran with CFR SCCA at Daytona, theByron Koury mill was running fine, but after the first session we realized the body needed some more bracing and we needed to get the nose down as we were catchin too much air and the car was light in the tri oval. The tranny was beginning to act balkiy as well (old T101). We lowered the car a bit, plugged up those two big holes under the chin with some Home Depot aluminum and went out for race one with Lee again driving. The car was pretty quick and Lee felt much better with the body braced up. The car was at 7300 plus in the tri oval with a 27" tire and 3.40 gear which computes to almost 180 mph. Not too shabby for a first time out on a near 100 degree day. The oil temp was nearing 300 on the guage, which did not sound right as the water was only at 200. We worked on that, but suspected a faulty guage.

Sunday we replaced the clutch as it was beginning to slip and sent Lee out for race two. Lee elected to start in the year due to the clutch and tranny issue. Lee passed 6 or seven cars by turn one and picked several more by the end of lap one. He was running comfortably about fifth overall and second in SPO when the tranny started getting worse and the oil temp started heading for 300 again. He backed off a bit and cruised to the finish losing one spot and still finishing second in SPO to Todd Coury in a Hendrick Nationwide true road race car with 700 plus HP. Todd was cutting 1:55's which is outstanding for the heavy car on a hot day. We hope to get to an HSR race soon, but it looks like I am gonna have to spring for another tranny or find some new parts for this old T101.

[bosco]

We ran this tube frame 1968 Corvette in the January SCCA Hoosier Tour races at Sebring with new driver Bobby Kennedy. Bobby, a talented, sometime Trans Am Series competitor in TA2 was making his first start in the car. We battled handling and tranny issues on the test day and the Sat. race. We replaced the tranny and got some effective set up help from Tommy Riggins and Bupp Motorsports. Our transponder failed during qualifying, so we had to start in the back of a huge field on Sunday. Bobby started 38th and quickly moved through the strong field to a 13th overall finish and 9th in GT-1. The little "327" performed well hitting 8200 rpm down the back straight for nearly 160 mph. The best lap was a 2:15 coming through traffic. Bobby passed ex Rolex GT Porsche's, TA2 cars, Ferrari 458 challenge car, Corvette GT2's, Ford GT etc. on his way. With a vintage type 520 HP or so we were pleased. We learned a lot and seemed to be a crowd favorite.

We ran the car again at Sebring a few weeks later, finishing 3rd on Saturday with a best lap of 2:12.0. Our lap times are now down in the range of the fast old DEKON Monza that sometimes runs in HSR and SVRA. That was always our goal as we intended this to be an HSR car. We had a timing chain break on Sunday, but luckily the damage was slight. The motor is at Byron Koury Racing Engines for refreshing. We plan to return this fall and run in HSR at Sebring and Daytona. We will focus on two other road race Corvette's we are working on a C4 for SCCA improved touring, and a vintage type 1963.