Dalannex

I have the 300 HP 327 out of my 68 torn apart. It is time to go through it. What is the compression ratio of this engine? Looks like it could be kind of high. I want it to run on pump gas so will I need some new pistons. I would like to use the stock camel hump heads, but am willing to consider some new heads. What cam should I run and what parts will I need to get her to run on pump gas? Auto tranny. Rear gears??????? 3.08 I assume. Build sheet says positract axle 3.08R.

xfactor974

hi, i'm on my brothers screen name, i'm a camaro owner and i saw your post. i'm building a 350 so i'll list what options i'm planning, and maybe it'll assist you in your decision
350 block std bore or +.30
10.5:1 pistons
eagle I-beam rods, stock lenght
comp cams xtreme energy 274 hydraulic lifter cam
trick flow 23 degree aluminum heads 2.02/1.60
edelbrock AIR GAP RPM manifold
holley 650 DP
roller rockers 1.5 ratio
new bearings

i'm also planning a 700-r4 a 2400 holeshot converter and a 3.55 gear ratio in the rear with a posi.
my engine should be putting out about 425-440 HP, so in a 327 it should be like 360-375, not sure about the 327 #'s, but somewhere around there. i'm planning the 700-r4 becuase they take off quicker and have a 4th gear. i want the 3.55 gears so i take off quick, and a posi so i leave 2 strips of rubber :D

my advice to you is that whatever you decide make sure you do extensive research on your decision, many people make the mistake of buying stuff too quick and come out with a motor that could be porforming much better for less $$$. good luck.

Smokehouse69

The compression is 10.25-1, sort of high for cast iron heads. Have you thought about stroking it out to 350? I wonder if a 350 crank will work?
9 or 9.5 to one is about the limit with your cast iron double hump heads.

JIM

when i rebuilt my 327/350 horse I used the stock 11:1 forged pistons they are more expensive than cast, an engle cam which not a lot of people use for street but has a nice lope too it, engle offers four different ones i went with the 2nd one not sure of part no.s but i do have the cam card. Definetly go with the 1.6 rockers. I have had no problem running on pump gas.Since my rebuild I put alum heads and intake still no problems with pump gas.

63Banshee

Port the intake runners, heads, and exhaust manifolds.
Three angle valve job with hardened exhaust seats.
CC combustion chambers.
Lightweight 9.5:1 pistons.
Deck the block and heads.
Line hone main bearing journals.
ARP bolts/studs where ever possible.
Split duration performance cam.
Tune carb and distributor.
2.5” exhaust.

Add all the needed parts to support these modifications and you will have a very high performance “sleeper” 327 … assuming the builder knows what he/she is doing.

gkull

I don't have the parts book in front of me. So I don't know if your 327 is the small journal crank or not. But lets just say your crank is good and it's a steel forging. Buy a master racing rebuild kit. With rods and Keith Black hyper pistons. Get good rings and bearings. Your block - just take it to a good machine shop and have a balance and blue print. I would never have a crank ground. Your better off just jumping to the whole 355 kit. I'm a Crane cam person and a 272 for 327 or a 278 Powermax hydro cam work fine. Your heads can be refreshed for a couple of hundred with the new springs that come with the cam. Use Chromemoly retainers and 1.6 roller tip comp cams rockers. Go with screw in studs and guide plates. Both of these cams require .100 over chromemoly push rods.

KB pistons have two valve reliefs and have lots of clearance for 2.02/1.6 valves. 10.5 C/r for iron heads with 64 cc are no problem for 92 octane with either Crane cam. The 278 with headers make 375+ hp with a 355

Dalannex

Would you suggest I try to stay in that 9.5 to 1 C/R? I also have a 4 bolt main 350 that I could put in the car. It needs a rebuild as well. Anybody think that would be a better way to go. I would need to buy a set of heads for that if I went that way. What heads would you all suggest. I don't want anything too crazy. My 81 is stock except for the comp cams 260H and I like that, so what would the 350 with a comp 262 or 268 like to have for heads? I suppose I could go ask the motor, but that would make me look kind of crazy. :crazy:

Rocket Ron

I am a racer but a purist. I would rebuild the stock 327 to factory specks with fordged pistons and a hotter cam, plus a thee angle valve job.If you have an auto trans then go with a converter that is 200 to 500 above stock.You can even change the rear gears if you want beter performance.This way the car will look all stock and keep it's value.
On the other hand you can't beat a 350 4 bolt ,unless of course you go with a big block.

Dalannex

That's kind of what I was thinking. I was thinking some different pistons to lower the compression ratio a little and a little hotter cam, along with a rebuild to stock, 3 angle valve job, and all the other regulars. What cam would you all suggest? You guys did such a good job of suggesting the cam for my 81' I'll ask you all again. Also, the car has a Carter AFB carb on it. Is this stock???? I thought Carter wasn't an option in 68', or is that just a nasty rumor? Should I go with and Edelbrock carb and intake, along with HEI dist. or stick with what I have now? I am pretty sure I want to go HEI, but what about the carb and intake?

majglc

68 has the large journal crank.

Dalannex

Thanks, that was going to be my next question. What are the sizes of the journals on the large and small journal cranks? I would like to know so that I can check my crank and make sure before I do anything.

yooperod

Check this site fro some specs. http://www.mortec.com/journal.htm
rod

68shark

Seeing you have the 300 HP version/auto/3.08, I'd be inclined to rebuild it close to stock. You might want to check the "Superfast80" archive article on the road test of the '68 327/350. It comments that if you want off the line power, the 300hp is a better choice than the 350hp which is lazy until 3000rpm. With this in mind and presuming you don't want to lose the lower rpm pull off the line, I'd use cast or hypert. pistons, designed to keep comp ratio at or below 10 to 1. Stock is 10.25:1. I'd use the Comp Cams or Crane "copy" of the 300hp cam with stock heads. If you wanted to liven it a bit, maybe a comp cams XE 256 or 262 (not more than this though) as you have a stock convertor and low gears. I wouldn't do much more than this unless you wanted to consider gear change and maybe converter change, which opens up a lot more options!

Dalannex

I will be getting a new converter when I overhaul the transmission in a couple weeks here, so what do you think now?

63Banshee

I think you should consider installing 3.70:1 gears and read my previous posting. Just remember to use a SPLIT DURATION cam.

Darrell's 68

The 327 300hp motor for your 68 should have 10:1 compression, which will run fine on 93 octane without pinging. (I have the same engine in my car) You didn't say if originality or power was the most important thing, so I would have a different opinion on both.

If you want power, aftermarket heads, a short duration high lift hydraulic cam, and MSD ignition will give you a lot of reliable power without sacrificing drivability. Good cast pistons will also do the job very well unless you are going to be serverely abusing the engine at a racetrack. It all depends on how much money you want to spend and what kind of driving you want to do.

I don't really race that much, I mostly drive it and cruise. I left my engine looking stock on the outside and made modifications inside. I have good cast pistons, short duration high lift hydraulic cam, screw in studs & guideplates in the original heads. It runs great although I would like more power. I have a M-20 with 3.55 gears for good torque off the line. Not going to beat a C5 but no dog either.

Hope that helps but I'm sure you're going to get 20 different opinions!

nunus79

If you decide to stay with the 327, consider getting a lower rear gear like 3.70 etc. I drove a 30 over 327 before and they love to rev up.

If you decide to stay with the 3.08s, consider stroking it to a 383 and use that torque.

So before you make any engine decisions, decide where you are going to take the whole Vette build to and then stick to it (or else end up putting in extra $$$).

Dalannex

I would like to stay stock if it'll run on pump gas that way. If it's 10:1 it should. That would make my decision easier. The car will be a cruiser only, no racing, no getting too crazy. Should I run a stock cam or go with something different?

68shark

Given your intended use and auto/3.08, I'd stay with the stock cam. You won't want to give up the low end torque and with an auto, and not racing or anything, that's the "band" you are driving in. You'll enjoy the low rpm on the highway also.