Be careful boxing in those front frame horns.....specifically the passenger side. If you are putting in a big block, and big block radiator, the outlet hose on the bottom fits INSIDE the front frame horn and a gusset will interfere. I looked at this closely at Carlisle on a big block....and will not work. No problem on driver side. I don't think a small block radiator is an issue on either side. I would like Reno Staillion to let us know if his gussets worked out ......IF he has a big block radiator.

 

I do not know yet but will post if it's a problem

 

That is some beautiful welding done....and that vertical piece in the front crossmember is going to be HUGE in keeping sag from every happenning,..and will also make the front virtually solid. I do believe that the large triangular gusset, and the front frame boxing on the passenger side will have to be cut away. You have completely blocked access to thelower radiator hose fitting. Its great idea, but it is hard enough getting the rubber hose attached with the little amount of room there is in a stock unmodified frame. Unless you have an alternative plan.....like maybe pulling the radiator up and out with the hose attached, but again...even doing that is one of the hard jobs. Alot depends on the radiator size and configuration. If you are using electric fans....that also may save you.

I am absolutely NOT claiming to be an engineer, or understand hi level science.....but I believe the problem with the front rail extensions is that the was the sway bar is mounted to the lower surface of the open C section. It allows vertical flex of the C flange. The boxing of those front rails would be to reduce the twisting or the bending of that lower flange upwards / downward. Boxing them helps prevent this and better transfers the sway bar action to the frame. If I am correct on that, the horizontal large gussets do little to improve this. Those gussets would strengthen the front rails in the event of a forward crash? The Chevy Power Book did not include those gussets....they only box the frame. The gussets on the lower control arm mounts are to strengthen that fairly weak connection to the crossmember, therefore make perfect sense.

Lastly,.....and I am not picking at the strengthening, because I have done almost all the same, even though I have no intention of racing. I think this is all worth it when the frame is bare, and all it takes is some welding. Your front crossmember is now effectively a solid piece.....very very strong.......so all the flex loads will now be back in the S-bend area of the frame. My paranoid thoughts about this make me wonder if repeated frame flexing, now concentrated on the S-bends will result in eventual cracking there. Before gussets, the twisting would be spread across the entire area....now concentrated on the S-bends only.

Anyway....just random thoughts, ones that I have been considering as I do most of the same mods. Sometimes, changes have consequences. I have found it to be true in many mods done to these cars. You fix one thing.....break it in another way.

 

I really appreciate the detail you provided. You mentioned an attached spreadsheet ... is that an attachment in the post or someplace else ?

The small weight difference between an all (or mostly) aluminum big block and an all-iron small block like my current engine is a green light for the big block. And no extra 300lbs Between your two examples ... how about the 640 with a more mid-range cam ? Or would that be too much of a miss-match of flow for the current heads ?

I completely agree about the rear suspension. In addition to the setups in the links you sent, have you looked at SRIII ? Check out the solution at the bottom ... C4 suspension grafted to the factory frame.
https://www.sriiimotorsports.com/196382corvette.html

Or how about Street Shop ... they do C4 and C7 suspension also ...
https://www.streetshopinc.com/frontp...-corvette.html

 

The new Ozark track is on my list, whenever I can get things to work out.

Pulled the engine out last fall for a cam swap. I don't know what configuration guys use when comparing different engines, but I just left everything on the engine that I could so I could get a measurement of how much the engine was contributing to front axle weight. (Some of the unseen parts are the starter, flywheel, pressure plate, bellhousing, motor mounts, 6 quarts of oil, and about a gallon of coolant left in the block). The distributor/shield and air filter assembly wouldn't fit with the engine tilter, so add about 8 pounds).





It's a moderate power big block. I've got the car down to 2700# (with full factory interior), so I can get a decent power to weight ratio without having to worry too much about breaking parts from excess engine power.

 

FYI 69427's engine has an aluminum block, he is very weight concious.

On the C4 suspension, it is better than the C3, it has 4 forward links?? IIRC, replacing the trailing arms, so it has some anti-squat, which the C3 does not. I am unsure about the toe-in issues on the C3 being resolved tho, because it still uses the half-shaft as a link. 69427 has the C4 added to his car, and he races it, he would have much better input.

I guess the spreadsheet did not attach the first time, here it is. A lot of credit goes to Yellow Bullet for starting this... I just added to it.

 

Is that 2700 with or without engine ? In either case that seems really low ... any special secrets to getting that much weight out ?

 

leigh1322 69427

Since I need to have both frame reinforcement and suspension changes performed by someone else, figuring out what will get the job done, and who to rely on, is really a challenge. I've found 6 or more shops and I'm sure there are more. My first question for them will be horsepower & torque ratings, and how many customers are racing a setup like I want. I appreciate the information you've offered, and leigh1322 especially for the spreadsheet. If you have any additional info on what works well with high horsepower big blocks on the track I'm all ears !