350 Engine Mods asking for advice!
Thread Starter
Melting Slicks
Joined: Oct 2004
Posts: 2,662
Likes: 8
From: Knoxville Tennessee
350 Engine Mods asking for advice!
Next year I will be updating my stock 350 engine in the 79. I want to have 300 to 325 HP when I'm done. It is an auto and I will also be adding a 2004R Bowtie tranny coupled to 3:55 gears. The car has 89,000 miles on it so I don't think I will be taking it down at present. I don't plan to race it; just a lot of crusing. What would be the best approach to add 100 to 150 HP to this engine? I will appreciate the advice and encouragement I know I will receive!
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
My '72 L48 was rebuilt but basically stock mild cammed....idles really smooth at 600 rpm....stock as a stove throughout by external appearances.....
SO by keeping the muncie, and adding L98 TPI setup, using a MAP type system/computer and aftermarket chip...I doubles the fuel economy and made the car a fun thing to drive/own....
maybe not 320 hp or so, but not so very far off, as with dual exhausts, and so forth...it was improved over 250 anyway....
GENE
SO by keeping the muncie, and adding L98 TPI setup, using a MAP type system/computer and aftermarket chip...I doubles the fuel economy and made the car a fun thing to drive/own....
maybe not 320 hp or so, but not so very far off, as with dual exhausts, and so forth...it was improved over 250 anyway....
GENE
Le Mans Master
Joined: Jan 2000
Posts: 8,721
Likes: 108
From: Canada
this link will give you a lot of possible combinations
http://www.ryanscarpage.50megs.com/combos1.html
http://www.ryanscarpage.50megs.com/combos1.html
Thread Starter
Melting Slicks
Joined: Oct 2004
Posts: 2,662
Likes: 8
From: Knoxville Tennessee
Thanks for the info guys. I am sure that heads, cam intake, carb and headers coupled to the true duals I already have will be the answer. I just have to explore what combination will give the best results. I am lucky in that I have time to compare different combinations to give me the performance and reliability I am looking for to rival the 300+ HP cars currently in production. It isn't like I want to beat them; the Vette was the first muscle car and I want mine to still run with the herd! 
Race Director
Joined: Jan 2003
Posts: 15,176
Likes: 88
From: State of Confusion
Originally Posted by BerniesVette
C3Stroker, I was thinking along those lines. What intake, carb, heads and headers? I was also thinking about a cam to go withese mods; any suggestions?
Better-flowing inlet (carb/intake/heads) and exhaust (heads/headers) won't matter much if the cam doesn't lift the valve off the seat much, and I'm figuring your stock '79 camshaft is something along the lines of:
.390" lift Intake/.401" lift Exhaust, with durations at .050" lift of 195* intake and 202* exhaust, respectively.
I'd think that a hydraulic cam with specs of approximately .420"-.450" lift, and duration at .050" lift in the .216*-.222* range (the old 327/350 HP L-79 "151" cam is very similar) would deliver a nice, torquey grunt, and a bit of a 'choppy' idle, perfect for cruising around town, without placing much stress on the valetrain, work well with your 3.55 gears and stock torque-converter, and deliver good performance, probably running mid/low 14-second 1/4-miles in the 94-97 MPH range.
Just my $.02-worth.....
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Melting Slicks
Joined: Jan 2004
Posts: 2,672
Likes: 1
From: New Cumberland PA
The idea of changing heads is to increase the engine's capacity to take in a fuel mixture and the spit it out. Even with a stock cam it should improve things; however, the cam will dictate as much as the heads. It's sounds like you have reasonable expectations. Installing a cam with more lift and duration along with heads, intake will make a significant difference. Like many other things in life there are bottlenecks. By changing one thing, something else becomes the botleneck. I would go with a cam similiar to the L-82. It's not all that radical and should perform decent in a street driven car. I don't have the specs but lift is in the .450 range and durartion anround 220 degrees.
Le Mans Master
Joined: Mar 2004
Posts: 7,493
Likes: 1,502
From: Little Rock AR
I did that to my '80. Went with small chamber 64cc aftermarket heads and an L-82 350/350 cam. Recurve the distributor and you are good to go. It is a very good basic combo to run in these cars. It is the way they should have been built in the first place. Not real expensive this way. You might want to pick heads in the 200cc intake port range if you think you will ever upgrade the bottom end in the future. If the block needs a bore job do not build the 355, see below.
When you have the bucks and time, a 383 stroker is the next step in my opinion. Wait till you need a bore job first. The cost to bore the block, fit new pistons etc is getting very close to the cost of the 383 and the performance will be MUCH better with the big cube small block. If my 350 in my Vette ever gets worn to the point where it need to be punched out, it will definately get stroked. The late C3 vettes are a perfect match for the torquey 383.
-Mark.
When you have the bucks and time, a 383 stroker is the next step in my opinion. Wait till you need a bore job first. The cost to bore the block, fit new pistons etc is getting very close to the cost of the 383 and the performance will be MUCH better with the big cube small block. If my 350 in my Vette ever gets worn to the point where it need to be punched out, it will definately get stroked. The late C3 vettes are a perfect match for the torquey 383.
-Mark.
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
The GM 151 cam is a very good choice for a hydraulic cam.
Originally Posted by Glensgages
I don't think you'll really see all that-much gain (100 HP-worth) just by swapping-out the carb, intake, heads, and exhaust.
Better-flowing inlet (carb/intake/heads) and exhaust (heads/headers) won't matter much if the cam doesn't lift the valve off the seat much, and I'm figuring your stock '79 camshaft is something along the lines of:
.390" lift Intake/.401" lift Exhaust, with durations at .050" lift of 195* intake and 202* exhaust, respectively.
I'd think that a hydraulic cam with specs of approximately .420"-.450" lift, and duration at .050" lift in the .216*-.222* range (the old 327/350 HP L-79 "151" cam is very similar) would deliver a nice, torquey grunt, and a bit of a 'choppy' idle, perfect for cruising around town, without placing much stress on the valetrain, work well with your 3.55 gears and stock torque-converter, and deliver good performance, probably running mid/low 14-second 1/4-miles in the 94-97 MPH range.
Just my $.02-worth.....
Better-flowing inlet (carb/intake/heads) and exhaust (heads/headers) won't matter much if the cam doesn't lift the valve off the seat much, and I'm figuring your stock '79 camshaft is something along the lines of:
.390" lift Intake/.401" lift Exhaust, with durations at .050" lift of 195* intake and 202* exhaust, respectively.
I'd think that a hydraulic cam with specs of approximately .420"-.450" lift, and duration at .050" lift in the .216*-.222* range (the old 327/350 HP L-79 "151" cam is very similar) would deliver a nice, torquey grunt, and a bit of a 'choppy' idle, perfect for cruising around town, without placing much stress on the valetrain, work well with your 3.55 gears and stock torque-converter, and deliver good performance, probably running mid/low 14-second 1/4-miles in the 94-97 MPH range.
Just my $.02-worth.....
Le Mans Master
Joined: Oct 2004
Posts: 5,269
Likes: 54
From: Orlando Florida
St. Jude Donor '05
When I bought mine it already had the Edelbrock Performer heads and Intake. I added the Performer cam and the Edelbrock 600 cfm carburetor. This combination performs really good and is very 'streetable'.
The bottom end is stock L48, no issues so far... I have not dynoed it but I'm guessing it's well over 300HP at the crank.
The bottom end is stock L48, no issues so far... I have not dynoed it but I'm guessing it's well over 300HP at the crank.
Safety Car
Joined: Oct 2004
Posts: 3,725
Likes: 5
From: Minnesota
RedBad, that sounds close to the combination I'm going with. I've already got the Performer 600 carb and Hooker headers but with an old Torker intake which is designed more for higher RPMs. My cousin who's in the engine business says a rebuild along with a Performer intake and a mild cam will get me to right around 300 HP with the stock heads. 
Race Director
Joined: Jan 2003
Posts: 15,176
Likes: 88
From: State of Confusion
Originally Posted by tabbruzz
I'm also looking for more power. There is just so many choices out there it can get confusing...Good luck...Tony
79 vette, L-48 auto, 3.55s, cherry red metallic, headers, dual exhaust, holley carb, 2101 intake, mild cam
Best ET
13.80 with a 1.91 60' at 97+mph
Best ET
13.80 with a 1.91 60' at 97+mph
With open headers, shifting at 5800 RPM, on straight SUNOCO Ultra 94, it ran 13-teens @ 105 MPH in good air, usually 13.30s:
with an 8" converter and 28" x 10" Dragway Specials, it now runs 12-nineties @ 106 (best of 12.774 @ 109).
I drove this car to the track for 2 seasons, and still occasionally drive it around town (even with a spool...)
Hope this helps.....
Le Mans Master
Joined: Oct 2004
Posts: 5,269
Likes: 54
From: Orlando Florida
St. Jude Donor '05
Originally Posted by jdmick
RedBad, that sounds close to the combination I'm going with. I've already got the Performer 600 carb and Hooker headers but with an old Torker intake which is designed more for higher RPMs. My cousin who's in the engine business says a rebuild along with a Performer intake and a mild cam will get me to right around 300 HP with the stock heads.
Not sure about the stock heads, I think most of the power gain comes from the heads and the cam. I don't have the long tubes yet, these are probably good for 30HP (compared to the stock manifolds).
I do not think that the intake makes a huge difference, the cam is a good idea.
Drifting
Joined: Nov 2004
Posts: 1,971
Likes: 7
From: Longwood Florida
I am thinking 2 really important questions here.
1st are you talking flywheel 300Hp or 300RWHP?
300Hp is only about 260rwhp. 300rwhp is about 350flywheel.
Also HOW much money are you wanting to spend?
And are you installing it yourself?
A good set of heads 1100.00
nice cam kit w/springs 300.00
nice RPM intake 150.00
set of decent headers 150.00
good carb 300.00
That 2K in parts... add about 500-600 labor you are there. Or buy a crate motor for a few hundred more?
1st are you talking flywheel 300Hp or 300RWHP?
300Hp is only about 260rwhp. 300rwhp is about 350flywheel.
Also HOW much money are you wanting to spend?
And are you installing it yourself?
A good set of heads 1100.00
nice cam kit w/springs 300.00
nice RPM intake 150.00
set of decent headers 150.00
good carb 300.00
That 2K in parts... add about 500-600 labor you are there. Or buy a crate motor for a few hundred more?
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
BerniesVette,
Decide on how you want the end product to perfrom: Torque or HP.
For Torque, I suggest a tpi with alum heads with relatively small runners and a short duration cam such as a 268 or 272. Add headers with small primaries, 32" tubes, a 4-2-1- collector, 2.5" tubes with an X crossover and hi flo mufflers and you'll be a happy camper. Later, rebuild the bottom end to 383 and you won't be able to wipe the smile off your face up to 5000 rpm.
For HP, try a miniram with a 58mm throttle body, alum heads with larger runners (200+) and a cam in the 280s. Add headers with larger primaries, shorter tubes, 4-2-1 collectors, 2.5" (or even 3") pipes with X crossover and Edelbrock RPM muffs and you'll be happier at the track. Add the 383 and the correct trans/rear end gear package and you'll compete with anyone.
In either case, I like speed density with a chip from a reputable aftermarket chip burner. If possible, get a curve plot from a dyno, send the results to the chip burner and he can custom burn one for you.
I like tpi over aftermarket EFI since they are plentiful (read - cheap)and since the next owner of your Vette may not be able to tune it himself and may need to take it to GM for service.
Decide on how you want the end product to perfrom: Torque or HP.
For Torque, I suggest a tpi with alum heads with relatively small runners and a short duration cam such as a 268 or 272. Add headers with small primaries, 32" tubes, a 4-2-1- collector, 2.5" tubes with an X crossover and hi flo mufflers and you'll be a happy camper. Later, rebuild the bottom end to 383 and you won't be able to wipe the smile off your face up to 5000 rpm.
For HP, try a miniram with a 58mm throttle body, alum heads with larger runners (200+) and a cam in the 280s. Add headers with larger primaries, shorter tubes, 4-2-1 collectors, 2.5" (or even 3") pipes with X crossover and Edelbrock RPM muffs and you'll be happier at the track. Add the 383 and the correct trans/rear end gear package and you'll compete with anyone.
In either case, I like speed density with a chip from a reputable aftermarket chip burner. If possible, get a curve plot from a dyno, send the results to the chip burner and he can custom burn one for you.
I like tpi over aftermarket EFI since they are plentiful (read - cheap)and since the next owner of your Vette may not be able to tune it himself and may need to take it to GM for service.