Does anyone know what the factory specs are for the cam in a 78 350 vette? Or better yet where this type of information can be found.?

 

78 L48 or L82?

3896929 Hyd. - 194/202 - .390/.410 - 112 - L48
3896962 Hyd. - 224/224 - .450/.460 - 114 - 350 L-46, L-82

 

3896929 cam dur @ .050 195/202, lobe sep,112,open/close@.050(10.5) 25.5 int,37(15) exh,lift .390/.410

 

I do have an L48 - I would like to give it some more power. Trying to figure out what to use with the factory quadrajet, and a set of vortec heads, blackjack headers and dual exhaust less cat and nobalance tube.. Need to decide on an intake, cam & lifters, timing gears, etc.. I am during all the work myself just don't know a lot about what to us to get the desired finished product, with in the budget.. Car will be driven, especially on nice days.

 

For future reference:

http://www.geocities.com/MotorCity/D...00/cmspec.html

Budget is the key word - with that I'd be happy to offer some guidance.

 

Well thats not too bad. You are kind of limited to either a Performer or Weiand 8004 intake. I'd use a set of Cloyes street roller gears and an either an Engle Cams 1015H or 1018H depending what your Vortecs can handle for lift and where you want your power band, driving style etc. The 1018H is a real nice cam with 9.25-9.75:1

Part #: 1015-H
Grind #: EP-15/18HY Int. 437"
Ex. 458" Int. 248"
Ex. 260" Int. 291"
Ex. 310" Int. 207"
Ex. 216" 112°
Part #: 1018-H

Grind #: EP-18/20HY Int. 458"
Ex. 468" Int. 260"
Ex. 268" Int. 305"
Ex. 310" Int. 216"
Ex. 226" 112°

 

Roller gears - is that an all gear set up, no chain?
Are cams all that confusing?

 

It has a chain. Roller timing set was meant above.
At least Trans. should be stated for cam.

 

Roller timing set - is that a set that is all gears or a type of chain set?

Next question has I am trying to piece this together - looking at edelbrock intakes - Is the quadrajet a square bore? What is the difference?

 

78 L48 w/ vortec heads

cam w/ lifters: summit sum-K1103

head gasket: felpro 1094

intake: professional products 52007

any timing set will do OK ... no need to spend lots here ... stock lasted a long time ... vortec has about same spring pressure as L48 ... most any cam that works with L48 piston & vortec chamber will be relatively mild ... K1103 is & works w/ any trans-gears

 

Chain set. Q-J is spreadbore, small primarys & large secondarys.
oO
oO

Squarebore has 4 same size.
OO
OO

 

Thanks changes the intake I picked

 

Okay here's what I got so far - What do you all think?
Comp Cam: 12-210-2
Comp High energy Hydraulic lifters: 249-812-16
Edelbrock performer Intake: 2116
Jegs Queit timing gears: 555-20310
Comp magnum roller lifters w/ p. rods: 249RP1412-16
all these items were found on Jegs
Any other suggestions? Am I missing anything?

 

If this is a budget build, why are you planning to buy a gear drive?

 

They just seem to make since - Still tossing the chain around because of the money.

 

You will spend $100 more than you need to with a gear drive.
A timing chain like this one http://www.summitracing.com/parts/CLO-C3023/
is completely capable of handling your needs, and it wont make an annoying whining sound either.

 

I have to admit to some surprise that any recommendations can be made with no budget. Vortecs are GREAT budget heads...but they are budget heads, with more power to be found with better heads...all determined by the budget. If existing heads, then a spring swap may be the first step.

There's absolutely no reason to run a gear drive on the street - regardless of the advertising hype. I'm also not a fan of roller (even roller-tip) rockers for a mild street engine, but there's no reason NOT to. However, those rockers are not self-aligning, which are required for Vortec heads.

An important consideration is the head gasket - if the engine is stock, the piston is .020 - .025 down in the hole. Combine that with a typical .040 composition head gasket and you've got an ugly quench (distance between the piston crown and head surface) number - and lower compression. Get the heads off and measure the piston deck height, and consider selecting a thinner gasket to get to around .045 quench.

You won't know the pushrod length until you mock up the assembly.

Finally, picking the right cam is all about the operating range of the engine, along with matching the capabilities of the head. What trans/diff ratio do you have?

Bolting together a bunch of parts without careful planning generally results in spending $$$ just to break parts or fail to achieve a real boost in performance.

 

This is exactly why these forums are so good - besides getting to know great people...........

Didn't know about needing self aligning rockers - will look up correct #

Another person I know said about using a thinner headgasket to increase combustion ratio

How can I find trans/diff ratio? It is a '78 L48 automatic

 

Ok - will go with the cloyles chain set -I quess the chain set would have less friction

 

Stock diff ratios for 78 with L48 and TH350 automatic were:

Standard - 3.08
High Altitude - 3.55 (cars delivered to +4,000' altitude)

My 78 has a bone stock L48 w/3.08 diff so I'm following your thread closely. I think Vortecs will be well suited to my driving - no racing, but really twisty mountain roads and some long trips.

Good luck!
Jerry