Thinking about putting a 427 in my 1968 and was wondering about what upgrades I would have to do.

 

Was your Corvette originally a Big Block or not? Are you talking about a Small Block 427 or the original Mark 4 Big Block like the ones that these cars came with? I bought a 1968 Corvette and it had a 350 in it. After looking the Corvette over we all realized it was a L71 Corvette when new. Since my Corvette came with a Big Block it was not very hard to put one back in. My C3 has all the high power parts underneath and I did not have to change anything there. It is the little things like the machined caps on my U-joints versus the straps used on lower HP Corvettes.

Is your Corvette a manual or automatic transmission? This is a mild hurtle but a bell housing that fits is needed as well as a new Clutch and flywheel. I was lucky as mine is a 4 speed.

First you need the complete 427 engine. I bought a factory OE Big Block made in August of 1967 and it was a "CE" engine. From what I have learned the CE engine were replacement engines for Warranty claims. I also bought a pair of heads at the same time at Corvettes@Carlisle. I chose the parts and built my engine for power. It was not cheap building the engine in the first place. Then you need the exhaust manifolds for the 427 unless you want to run headers. The exhaust manifolds are designed like a High Flow exhaust and are cast iron, they cost about $1000 a set for new replacement manifolds.

Your distributor should work on the big block but you will have to buy all the pulleys and other misc. parts to make the Corvette work with the 427. I ordered new Pulleys and mounting brackets from Paragon and then started assembling the engine as if it were in the Corvette. You will need all the little things like water pump and larger radiator for the extra cooling capacity needed for the big block's heat. I switched to a Be Cool Radiator and dual Spal Electric cooling fans using a DeRale PWM Electronic Fan Controller. One painful lesson was I replaced the pulleys with the original copies, in January 1968 there was a recall on the Big block Corvettes and they changed out the water pump pulley to make it spin faster keeping the engine cool. The one I ordered was the first generation so I had to go to a different pulley to make the engine run cooler. Eventually I got sick and tired of the various belts on my C3 so I bought a March Serpentine Pulley Conversion kit. Today I have but one belt and that is enough for me.

When the engine was actually installed I had it done by a group of professional Corvette mechanics. They had my old engine out in no time and the next few days were spent making the engine compartment look nice and new with fresh paint. They also replaced a wiring harness that had some issues. When they finished they had rebuilt the shifter making it tight again with new bushings and such.

In the end, the BIG question is How much do you have to spend on this project? I spent well over $12,000 on the engine and the install work. If you have a original Big Block and you put another Big block back into it their value goes up considerably. If you don't have the skills needed like in my case then you spend, spend and spend. In the end I spent more on the 427 than I did on the entire Corvette when I bought it. It is worth more but who really cares? I did it to" drive it" and that is the only reason to put a 427 into a Corvette.

My C3 has a 3.36 rear in it and the folks at Comp Cams told me that I needed to change it to a higher number rear to get more power. After installing the 427 I went to a drag strip and proceeded to beat two 1970 LT1's in the quarter. The best was when I took down a 1969 L89 Corvette that was stock. I was told not to go below 13 seconds as I didn't have a roll cage or bar. I ended up turning 13.05 @ 122 and several other 13 second runs. The engine spins the tires past the 1/8th mile mark at the track. It can also accelerate from 25 mph to 100 mph just simply giving it gas in fourth gear without any issues. The 427 is an amazing engine that produces locomotive like torque and amazing HP numbers as well.

Speed Costs MONEY, Lots of it!

Corvettes with Big Blocks are guaranteed to make you "smile while driving"! Even at the gas station filling it up...

I just installed a Holley Stealth Sniper EFI system on the C3 and it is working out well so far, much better cold weather starting not that I do much to start with in a 53 year old Corvette.

 

4speed small block car the engine is from a 1967 vette and I know the owner real well and the engine is complete. I was wondering if the front end has to be beefed up.

 

If the front springs are original, you may need new springs to accommodate the added weight. I put #550 springs when I switched to a BB.

https://www.vansteel.com/index.cfm?f...owItem&ID=2423

 

👍 thanks

 

1. new springs,
2. big block radiator support its a 68 only
3. big block radiator...make sure you have all the seals...66 and 67 will fit the 68..I have dewitts 67, check the C2 forum
4. big block radiator shroud....unless you go electric puller fan...I do and my motor stays below 200F on the highway on a hot day
5. increase the size of your air dam or you wont get decent air flow up into the front of the radiator
6. you will need the exhaust manifolds and new down pipes to graft to your exhaust or headers
7. headers will need some massaging on the passenger side at the idler arm
8. make sure you get all the pulleys and brackets...small block ones wont work
9. you can use a 10.5 inch fly wheel, clutch and housing, they came with that setup factory for a short while.
10. If you go with the 10.5 get a good clutch, I use the McLeod super street pro...rated at 500Hp...no issues
11. extra rear tires....they tend to spin in most gears especially of you run a 4.11 rear
12. You need the big block hood minimum, I use the L88 hood and still have clearance issues
13. find a low profile intake and low profile base for your air cleaner
14. I went to solid motor mounts and kept the urethane trans mount...no vibrations. Urethane motor mounts will melt with headers
15. speaking of melting get a heat shield blanket for your starter, just in case
16. radiator hoses, make sure you have the spring for the lower hose
17. make sure the heads or intake has a 1/2 inch NPT threaded hole for your temp gauge
18. You may want to insulate your floor under the carpet...I dint have any issues with cabin heat ever until I put in the big block...just bought ceramic headers to alleviate that issue...might how with something like dynamat this winter and maybe wrap the pipe from the collector to the side pipe
19. I bought a rear end with the big block yokes and the 3 inch half shafts...probably wasnt necessary but I tore up my 3.70 and 3.55 rears with the 327....that was a fun little monster
20. think about a 5 speed for you next upgrade if you do any highway travelling
21. You gotta just stuff it in there....
22. 
    
    
    
    

 

Thanks it looks like I’m going to have to open up the wallet 😎 Your car looks awesome 👍

 

Those six packs are "really beautiful" but when faced with my situation I chose to go with a single carburetor as they make more HP this way. Thank you Rescue Rogers for the beautiful example of the six pack! I am a bit concerned with having glass fuel pressure gauges near the moving belts. If one should break you might have some excitement you don't really want. On my 427 I ran the fuel lines in from the rear of the intake and I also insulated them to prevent the fuel heating up.

On my C3 I also use an L88 Hood. I found one at Carlisle that was from an original 1968 L88 that came with the wedding cake assembly. The L88 hood is the best cold air intake there is for a Corvette when used with the wedding cake. How do you get a L88 Hood to close on that six pack air cleaner? Are you using an L88 hood without the air passage under the hood?

The list that Rescue Rogers made for you is very complete. I learned a lot of that going back to the 427 in my C3. My C3 was built the first week of October in 1967 and there were a lot of 1967 parts used on building it. This was documented by the Guys who installed my engine. Buying all the parts will get very very expensive unless you have some of them already on the Corvette if it had been an original BB Corvette like mine was.

I am still not clear what type of 427 (SB, BB) that you are planning to use in the Corvette. Is it a Mark 4 big block like these cars came with or is it a 427 small block? If it is the BB Mark 4 type then you will have to upgrade the springs to hold that extra weight. Use as much Aluminum as you can to save on the weight, an Aluminum intake, and water pumps are good places to start.

The 550 pound springs were a bit too tight for me and they make my Corvette ride rougher than it needs to be.

 

It is neither a six pack or six barrel those terms were coined by Chrysler. Pontiac used tri power.

 

When I was a kid there were six packs, dual quads, blowers and fuel injection...those were the special names. The names that made you stop and look,.... like Loni Anderson....ohhh LOni. I still remember that poster. I still call mine a six pack once in a while although if I need parts I search chevy tri power of course.


As for my wedding cake cold air intake I had to cut a triangle out of it to fit the triangle air cleaner up into the hood plenum. Its not pretty but it still corrals the cold air into that intake area. I had looked at making a six pack lid work from a shaker style system but it hits the distributor and shield.

 

Hello again Rescue Rogers, et al!

Are you able to seal out the warmer air from getting into the Air Intake? With some creative engineering you can do some pretty amazing things when you put your mind to it.

I was out to buy an "replacement" for my Hood and I just happened to find a Guy selling the factory original L88 Hood. He had a copy of the paperwork proving that they indeed ordered a new L88 from GM in early 1968, pictures of the Corvette as well after delivery. He and his partner removed the hood right away to install a Tall Intake Manifold. A couple years later the car was totaled and the the hood was still on the shelf. He brought it to Corvettes@Carlisle asking $2500-3000 for it on Friday. By Sunday after noon he wanted to go home so he sold me the hood for a deal and a half. About two weeks later a box shows up and it was all the additional L88 parts he had left including the wedding cake assembly in Chrome. The lower drop base-plate and the screen cover were both Chrome Plated and looked sharp.

I do not use the ignition shielding on my 427, it interferes with the L88 parts. Being made for the 1968 model Corvette it also lets me use the original windshield washer cover and clears the distributor without any problems. I had to make my own radiator seals to completely seal any air from getting around the radiator.

The sad thing is that my High compression engine is destroying the Ceramic coatings and the extra heat has been "cooking" my expensive hood. I am getting ready to re-paint the the hood and trying to figure out a way to keep the under hood temperatures down. I see some "reflective" heat insulation in the future of my hood assembly, I will mount it above the headers and other HOT spots.

Are you using headers on your 427 or the stock exhaust manifolds? I have Hedman Headers that have been on the Corvette for over 25 years and still work, they look like "poop" but they still work. I was thinking of taking the original factory Cast iron Exhaust manifolds and having them ceramic coated. That would look nice and rid the engine compartment of the headers tubes. The ceramic coatings might actually help and the exhaust manifolds would look 100% better.

How are you sealing the hood around the base of the carburetors? That must have been a fun project, I would love to see how you did it.

I have been thinking of putting an external Oil Cooler and mounting it behind the gills on the drivers side and having a fan mounted to it. Keeping the oil temperatures down would certainly help. It always blows my mind when You reach out in cooler weather and you can feel the heat coming out of the gills.

 

I'm not sure insulation will do anything but trap heat in the engine. Maybe.a new set of headers ceramic coated would be a better answer.

 

I installed hood vents to let the heat out the top. I used 66 big block vents. with my paint scheme they arent too obtrusive. I was thinking at one point of putting fans in the gills to push the heat out. Before I put the vents in the hood I would pop the hood on longer highway rides to let the heat out. I worked pretty well at keeping the ambient temps down. I dont have a seal for the air cleaner yet, its just a tight fit into the plenum. I was thininkg for gluing a rubber seal around the bottom that the CAI would bump up against.




If I put rubber around the bottom of the filter like the hood seal at the radiator support it should keep out the heat from the cold air intake



these are directly above the headers

 

From what I have been able to piece together, my '68 began life as a SB car and somewhere along the way a 427 CE was dropped in it. There are a few things that have not been mentioned regarding differences between '68s with a BB versus a SB. The info that I am about to throw out I believe to be true, but I am no expert by any means and so if someone out there has better intel, please correct me. From the factory, some of the differences between SB and BB '68s were 7 leaf springs (BB) versus 9 leaf springs (SB) presumably to allow more power transfer. Rear brake lines had armor at the rear calipers on BBs. None on SBs. Not sure of the purpose there. The half shafts have caps (BB) versus U-bolts (SB) where they connect to the rear end. SB cars had no rear sway bar, BBs did. The front sway bar on BBs is a little beefier. Hope this helps. Lee

 

Seal that 6er up for that cold air, cracking the hood helps a bunch as you know
Id keep headers you wont notice underhood any cooler with manifolds...plus you lose some power. Perhaps recoat what you have?