jeffreyrinek

Hello,
After years I am finally getting to my car. It has a factory warranty replaced 327/350hp, M21, 355 rear. I bought the car from a great Corvette person in Canada. My wife and I drove it cross country and it was one of the best times of our lives. I want to fix it up and do it again. I am not the original owner and a previous owner put on dart heads. I don't know what the cam was, but the lobes flattened on our way back. I need to replace the cam. I also need to redo the cooling as the car ran way too hot for its good. I am thinking of side pipes. I also need to fix or replace all the gauges. I am not taking it off the frame. I also want to upgrade the ignition, intake and carburetor. I have looked through threads but I am still learning and thought this could help. Thanks for any input.

toobroketoretire

Id simply use another 327"/350 hp cam and break it in correctly. With a 4 tube radiator and 7 blade clutch fan you shouldn't have any cooling problems at all. Most of the "running hot" problems I have encountered were the result of a wrong temperature sender for the gauge being used. Only buy temperature senders from the Corvette vendors to make sure you're getting the correct one.

jeffreyrinek

Thank you! Any preference on cam manufacturers?

regatta

Replace the instruments. Not a hard job pulling out the center console. Just be careful of the bezel that hold the instruments and screws into the dash. Pot metal and breaks easily. To fix the instruments will cost as much as replacing them. If you are replacing the speedometer and Rpm Gauge it is a little more difficult removing this part of the dash. But no real big deal. You can drop the steering column, remove the covers around the steering column first, remove all dash screws in this area, pull forward, and not much room,
but you can reach behind the gauges and unscrew the cables. The 68 does not have a clip on either gauge, it just unscrews.
To get the temp. down go with an aluminum radiator and electric fans. I went from 220 degrees to 180 with the Dewitt radiator and fans.
Use dynomatt or something similar and insulate under the carpets for a little cooler cockpit area. The 68 gets very hot inside the cabin without this. I live in Texas.
If you beef up your cam, remember that your car is all vacuum, and it does show down the vacuum operated wiper doors and headlights.
Good luck!

regatta

Go with the Comp Cam.

regatta

The side pipes look good, they came out in 69 and were not an option in 68. You will have to change out the valance under the rear bumpers which also contain your back up light assembly. Then what happens to the back up lights. This may be hard to find. The 69 had the back up lights in the tail lights. To do it right you will need a way to cover or glass in the area where you existing tail pipes come out.

Lupigiato

My 68 327 upgrade included forged internals
TRW dome pistons
Performer RPM heads
Comp XR282HR-10 ROLLER Cam
Int @ 050 inch lift: 230
Exh @ 050 inch lift: 236
Lift: .510/.520
LSA: 110
Crane Full Roller Rockers
Manley pushrods.
Performer RPM Air Gap Manifold

Go crazy!

BKbroiler

I hate to open this can of worms but, to the OP, if you put a flat tappet cam back in you need to use the proper oil or you will flatten lobes again. You need lots of zinc.

jeffreyrinek

Thanks for all the advice. I love it gets me pretty car excited. I am going to the roller rocker. It seems the flat tappets seem more sensitive than the roller rocker. I really appreciate the gauge advice, and I am no longer thinking of side pipes. I will get the exhaust redone. I also want to replace the headers. Please keep it coming.
Jeff

ignatz

MSD 6AL ignition and distributor is a nice and relatively easy upgrade.

BLUE1972

I'd put in a 383 or 350 crate motor and keep the "original" in the garage sealed in plastic. The new crate will cost less and run better.
All your parts will fit. and you can make it look like the original.

Go with a roller cam if you can.. the motor will last longer.. and the oil issue goes away. I just did on my 71 and love it ..

augiedoggy

roller rockers are not the same thing as a roller cam...

that being said a roller cam has an advantage over flat tappet...

I used a lunati voodoo 262 cam on my 350 build because the profile was as aggressive as they come without being a roller cam and the performance numbers and curve was much better in the dyno2000 software than any of the comp cams near its mild size (I tried them all)
I too have dart heads (iron eagle 180/64cc) and this cam just seems works well with the flow characteristics of those heads..

I used the engine breaking lube and zinc additive and so far I only have about 1,500miles on the engine but I just checked my rockers (1.6 roller rockers) for play and everything is good...

augiedoggy

I pulled my original motor and swapped out another I built but I had an L48 station wagon motor stock... the 327 is a different animal. many times the original engines get scrapped or sold when new owners take possession of these cars and this will have a big impact on the value of the car...

I'm glad I chose to build my own and learn about engines vs just buying a crate motor and having it swapped... I think the OP's excitement shows that he wants to learn more about the car himself...

I took my car to a carshow Wednesday and It was funny to talk to some of the other c3 owners... many either bought thier cars restored or paid someone else to do everything...I was amazed at how little some of them even knew about their cars compared to many other car owners there... Ironically those people were mostly the ones bragging about how much their crate motors cost or "who did their interior" many of them thought I was pulling their leg when I mentioned I have learned how to do all my own work to my c3 and what it cost me...
I'm not saying a crate motor isnt a good option for everyone, just that its not the best option for everyone either...

BLUE1972

I have built 4 motors in the last 2 years.
I did the comparison of rebuild versus price. A "stock" crate is $3000, my rebuild on the 71 - 350 was $5000. Line bored and honed, valves.. ++++ It's a roller cam, hardened steel crank, forged rods etc. I'm at 400hp and 440 torque. Yes it's numbers matching and will now run forever. Swapped the 4 speed for a 5.

I know what you mean, I just "fixed" a car at the last show, his vacuum line was off the distributor - no clue,,,, he paid $$$$$ for the car. Another that was throwing belts... wrong pulleys.... again $$$$$.
Another with messed up vacuum lines.. like you said the list goes on...

A friend is putting the GM package - LS3+ trany into a 63 split .. I would not but he is.. it's a great project and will be a blast to drive.

If you do the math to properly build a motor, not freshen up a motor, it's more cost and time effective to get a crate + 3 year 36000 mile warrantee. I'm a builder and it was hard for me to say that. Even after putting a crate into a friends car a few weeks ago.. and doing the math.

jeffreyrinek

Can you please advise about roller rockers and roller cams, and I presuming the cam you mentioned is neither. Thanks

wyocat

I have the stock and original L79 (327-350HP) I love that engine. It is awesome in stock form. I would build the 327 with a roller cam.
read this
http://www.superchevy.com/features/s...vy-l79-engine/

Now if you want exotic .. you could make a 302 out of it.

To answer question about Roller Rockers and Roller Cams..

Roller Rockers on top side of head
http://www.summitracing.com/parts/pr...make/chevrolet

Stamped Steel Rocker arm
http://www.summitracing.com/parts/su...make/chevrolet

Roller Cam has roller lifters and inside engine
http://www.summitracing.com/parts/cc...make/chevrolet

Flat tappet Cam have "flat" surface
http://www.summitracing.com/parts/su...make/chevrolet

Newer modern engines use Roller Cams because they are better and add to reliability and accuracy of the valve train. Older engines like ours use Flat tappet caps (increased friction) so we need high Zinc oil to keep them from going flat. Opinions will vary.

BLUE1972

One other thing - Zinc and phosphorus was removed from the oils due to the introduction of catalytic converters. The PVC system sucked oil mist into the combustion chamber and thus it clogged the converter.

You can look up = ZDDP - Debunking The Motor Oil Additive Urban Legend

Also as time progresses the new oils may / will not maintain the proper wear characteristics of the "old" engine flat tappet cams. We now have 0-10 oils, where 20-40 was the norm many years ago.
The higher the valve spring pressure the greater the issue may become.

augiedoggy

Yes the cam I used is neither... its a flat tappet with an aggressive ramp profile much like a roller cam.

My engine was a budget build I had lots of time so I searched Craigslist and ebay for parts... I found a freshly rebuilt longblock for $300... it came out of a 76 heavy duty pickup.. 4 bolt mains and supposedly High nickel from the .010 and 020 markings (debatable I know)

Anyway the shop owner who sold it to me actually pointed across the street to the truck where it came from he told me the owner wanted a 383 crate so...
I tore the engine down and found it had an old comp 268HE cam. the crank was not forged and the bearings and crank had some bad grooves for a broken ring (which the seller told me was fixed and the block was rehoned but they never addressed the worn bearings/crank.) He also gave me a ton of other new hardware like chrome accessory mounts mounts spacers, and flex fans

Soo I replaced the crank with a scat crank which is supposedly like 20% stronger than cast stock cranks, I also replaced all the bearings and checked tolerances. replaced the cam with the voodoo 262 and lunati lifters and springs to match. I used +.100 hardened elgin rocker pushrods and the dart 180 heads I bought with the harland sharp 1.6 roller rockers (for $300).. I used felpro .15 shim gaskets which give me a good quench with my speedpro 4 relief flat tops and a polished rpm clone intake and aluminum High flow water pumps. together with the other stuff like the valve covers, air cleaner mounts hoses and tack drive HEI distributor and now the avenger 670 carb I just added I'm at about 1,600 bucks total for the engine including the hardware to rebuild my steering pump and a chrome housing for it and the same for my alternator. I also added a new heat wrapped mini starter and fuel pump.
the 3 core radiator was about $200 shipped and the sidepipes where $850 with the sweet thunder inserts..
For $2,500 I would say I made out very well.... It would have cost much more for all forged stuff but my car is a cruiser which sees spirited on road use only... Its not a drag car. It will not see over 6,000 rpm so the additional cost to build it for such use Is not practical. So many people overlook this here its ridiculous.
The pics below are older I have since changed out that crap fuel filter and the edelbrock carb...

bluedawg

I'd spend the extra money and go roller, it dont sound like you want to Rev the tar out of it, so hydraulic roller( probably the xe262hr if its an auto or the xe268hr if it's a manual) and replace the valve springs to match the camshaft. Being that you want to drive across the country and all, I'd go rpm air gap for the intake, if you still have the Quadrajet send it to lars for a complete rebuild. As for distributor, if you have an hei, send it with the carb, if you dont have an hei, that's all I'd do I'd up grade to an hei distributor, a stock replacement. Keep all the original parts in case the original bug bites you. Don't forget that if you havnt tore the engine since the lobes went flat you'll want to do that as well. Now then my reasons for recomending the roller is a you want to drive it across country and yes you can break a flat tappet in and it survive for the life of the car, but more and more we see flat lobes, some say it oil, some say it's ramp rates, my xe262h looked as new when I pulled it as when it went in, the cost of a good roleg is worth not having to redo the work involved. Just my 2 cents.

augiedoggy

Correct me if im wrong but more and more we see people who buy these cars not understanding you need zddp or an equivient added as well right?
and most of the new engine breakin gone wrong are likely contributed to nebie mistakes and directions not followed correctly... like using the wrong springs with the wrong cams and not following breakin procedures correctly... I have one of the more agressive cams that would have been more likely to fail and I had no problems by following all the directions to a T... I guess I'm just lucky and all these cams are just hit or miss junk these days?

I'm just saying that extra $500 or so could go a lot further where it counts like towards new heads...
Or in this situation, you could just put an 86 or newer roller engine in the car I guess since they are actually cheaper to find and rebuild than the roller upgrade kits. and you already have to rebuild an engine anyway..