Need advise restoring 1971 C3 454

Hello, I’m a new member to your site (by the way, good job to whoever put it together).

I’m in the process of restoring a 1971 Vette, T-top with a 454 TH400. There’s many areas I need help in:

1. I plan on building the existing engine as follows: 496 cubic inch stroker crank, using exisiting #820 open chamber heads, high lift cam, 850 Demon carb, possibly headers. Horsepower goals are in the 500 to 600 range. I recently had the rear end freshed up with new bearings/seals. The TH400 will be rebuilt to handle bigger HP. My questions are as follows:

- Will the stock rear end & suspension handle this kind of horse power?

- I’m playing with the idea of re-gearing the rear end from 3:08’s to 4:11’s then replacing the TH-400 with one of the newer GM overdrive transmissions (I believe called 700R). Has any had any experience in using this 700R trans. in a C3 & will it withstand the 500 to 600 horsepower?

- The #820 open chamber heads are the large oval port type. I understand these can be ported and larger valves installed. Has anyone done this? Do the current head configuration flow well enough?

- I understand the aluminum radiators work best. Does anyone have a good source for these?

- Headers make horsepower & I’ll need a set to make this engine breath. Has anyone put headers on a 71 C3 454? It’s already a very tight fit with the stock cast iron manifolds. Headers look like a nightmare to install?

- I found a couple of sources for new 2 ½” exhaust kits on the internet. Can the car handle 3” exhaust from header to mufflers (keep in mind the exhaust runs through a cross member)? Do you have any sources?

2. I need a source for all of the emblems, weather striping, bumpers, interior seat covers, center console, door & kick panels, etc, etc, etc. There’s probably hundreds of companies on the internet selling these items. I would like the best price but don’t want to sacrifice quality. Who has the best quality at a fair price?

3. All of the vacuum junk under the hood will need some attention (wiper doors, H/Light doors, etc). Does anyone know of a good book on diagnosing these devices?

4. Does anyone know of a good instructional book on fiberglass repair.

Hello, I’m a new member to your site (by the way, good job to whoever put it together).

I’m in the process of restoring a 1971 Vette, T-top with a 454 TH400. There’s many areas I need help in:

1. I plan on building the existing engine as follows: 496 cubic inch stroker crank, using exisiting #820 open chamber heads, high lift cam, 850 Demon carb, possibly headers. Horsepower goals are in the 500 to 600 range. I recently had the rear end freshed up with new bearings/seals. The TH400 will be rebuilt to handle bigger HP. My questions are as follows:

- Will the stock rear end & suspension handle this kind of horse power?

- I’m playing with the idea of re-gearing the rear end from 3:08’s to 4:11’s then replacing the TH-400 with one of the newer GM overdrive transmissions (I believe called 700R). Has any had any experience in using this 700R trans. in a C3 & will it withstand the 500 to 600 horsepower?

- The #820 open chamber heads are the large oval port type. I understand these can be ported and larger valves installed. Has anyone done this? Do the current head configuration flow well enough?

- I understand the aluminum radiators work best. Does anyone have a good source for these?

- Headers make horsepower & I’ll need a set to make this engine breath. Has anyone put headers on a 71 C3 454? It’s already a very tight fit with the stock cast iron manifolds. Headers look like a nightmare to install?

- I found a couple of sources for new 2 ½” exhaust kits on the internet. Can the car handle 3” exhaust from header to mufflers (keep in mind the exhaust runs through a cross member)? Do you have any sources?

2. I need a source for all of the emblems, weather striping, bumpers, interior seat covers, center console, door & kick panels, etc, etc, etc. There’s probably hundreds of companies on the internet selling these items. I would like the best price but don’t want to sacrifice quality. Who has the best quality at a fair price?

3. All of the vacuum junk under the hood will need some attention (wiper doors, H/Light doors, etc). Does anyone know of a good book on diagnosing these devices?

4. Does anyone know of a good instructional book on fiberglass repair.

ME: I restored/modified my 1970 454 T Top Coupe , 4 speed . , so, ill try to help you with the just the things i can shed light on :

1. WIth my engine rebuild, im running 560 gross h.p./ 600 tq. according to Desktop Dyno software -- I have the original 4 speed and rear end. Have had no problems with either but it all depends how you apply the power ; im not too hard on the car . Fortunately, your tires will act as a safety valve by spinning which 'should' protect your mechanicals. Going from 308 to 411 will make a huge improvement on low end torque so long as you dont do alot of highway driving. I have a 370 rear which is ideal for low end grunt and for my 90% town/10% highway driving. I have Hooker Super Comp full length Headers on mine -- they make a difference. I dont have a/c and they fit pretty well. Had to 'ding' one of the headers what was right up against the tie rod end though. Big improvement over stock exhaust manifolds. Ive heard that Headers wont fit if you have a/c ...dont know that for a fact. I swapped out my original iron heads for Edelbrocks #6045 Oval Port Alum Heads with the larger valves in them (2.19 and 1.88) -- could tell a tremendous difference in power and flow just by feeling the exhaust air coming out of the exhaust tips. These Edelbrock Heads are very high quality too -- didnt need any porting . I would seriously consider them . A better flowing dual plane Intake would make a nice compliment also-- im using the Edelbrock RPM AIr Gap Intake (had it ported) with an L88 hood / fresh air chamber ; Yes...your can use 3" exhaust and they will fit thru the crossmember ; it will be louder though. Im using 2.5" with series 33 Ravin race mufflers , and i punched out the exhaust tips from 2" to 2.5" . There are some guys on corvetteforum.com in the C3 section, who have put in 3 " all the way.

You should read Hib Halversons multi-part writeup on 'The Big Block from Hell' series ; it will give you lots of great ideas. I think its about 14 parts and Idaho Corvette Club has it in its entirety on their website, or , just do a google under BBFH. Thats what i patterned my modifications from.

With the increase in hp., youll need a cooling system that will be up to the task ; a bigger radiator and water pump . Get a Stewart Water Pump...they really move the water. I have the 6 impeller one . Im running twin electric fans and have no problem cooling the beast. The electric fans also frees up some h.p.

2. I went to Mid America , Dr. Rebuild, and The Last Detail for those items.

3. Mid America has a good book on troubleshooting the Vettes Vaccuum System ; Dr. Rebuild has some great diagrams also.

4. Cant help on the fiberglass repair book ; fortunately, i didnt need to do any on my vette.I bought it in great body condition.

Take your time, dont be anxious on the restoration/mods cause its not an overnight thing. Youll learn alot from doing it, and youll have alot of pride in it when y oure done.

Dave

Dave, thanks for the reply. Very helpful! Sounds like you've accomplished what I'm shooting for. I bet it's a "grin" to drive!

Dave, thanks for the reply. Very helpful! Sounds like you've accomplished what I'm shooting for. I bet it's a "grin" to drive!


ME: Yes it is a grin to drive ; took a good 5 years though to get the vette to the finished level that its at. Its nice not having to work on it for countless hours -- instead, i can take it to car shows , long runs, etc... and really enjoy it. The experience of restoring and rebuilding it was valueable though .

Dave