[Junkyard Dawg]

I have a stock '78 350 in my '71 Chevelle. The only performance mods it has are headers and a 4.10 rear out back. I've read this engine produced 170 HP but man this thing feels poochy!

I'd like to know of some performance ideas to beef it up some? I don't wanna go too overboard as I may be big blocking this car in the future.

I was thinking maybe a Edelbrock performer RPM intake, a Holley 670 cfm, maybe a cam designed to run in the same powerband as the intake? What else would be good to breathe some power into this smog engine?

 

[MadMarv]

I think you are in a sticky situation.. heads, carb, headers, etc.. all add up, and quick, with machine work, springs, pushrods, etc..
If you are gonna BB it I say wait.
If you are going to keep the SB grab a decent set of heads, know what you are going to use the car for, then call UDHarold for a cam, get an exhaust on there, etc.
Aftermarket heads, decent cam, decent exhuast, etc, you will make good power.
But if you are going to BB it, consider money put into the SB wasted, you won't get it more than 1/2 of it back on resale.

just my .02..

But I'm wrong half the time.. heh.

 

[Junkyard Dawg]

Of course all things considered I may end up putting the sbc in something else.

But then again since it's a 350/TH350 I wouldn't mind finding a 400 sbc and then befing it up and then mating it to the current TH350 after it's beefed up of course. If I go the bbc route I think I'm gonna opt for the TH400.

Oh btw what rpm is the 170 hp '78 350 good up to?

 

[Aaron Kelley]

Nitrous! I've never used it but seems like a easy way to make power. How about a good exhaust system? Shop around the swap meet or ask some friends, you could probably find some good deals. It seems like most everyone has SBC parts intake, headers, roller rockers, carb, ect. in thier garage.

Good luck

 

[Glenn1018]

IMO the 4.10 is too steep for that engine. You could offset this a bit with taller tires, but that'll change the stance/look of your car.

Since you have a TH350, you should have a cam and torque converter that'll work in the rpm range you drive in. The cam will likely want more CR, which means different heads (or pistons).

If you want to go the least expensive route, swapping to a highway gear and a different cam should produce decent results and get your driveline working in a suitable powerband. I'd still hang on to the 4.10.

 

[Texas70]

If you want something with big power, go with a big block . It really depends what power you are looking for. You may want to see about building a 383 stroker out of that 350. Bottom line, to get real HP out of that engine will take some bucks and alot of work.

 

[m71]

if the engine is in good running condition then i think you could see impressive acceleration gains by getting an rpm intake, a cam around 220@.050 .450/.480 lift, and about a 2500-3000 stall. that would probably make as much difference as just adding 125hp nitrous shot to what you have as is. but nothing will be usable if you go big blocking it next year or whatever. if the big block is a long way off, then i'd get some vortec heads to go along with the other parts i mentioned. but the bottomend had better be in great shape if you decide to swap to the closed chambered vortec heads. otherwise the rings probably won't like it.

 

[Junkyard Dawg]

What effect would it have on the rings? And how do I know for sure? Do a compression check? I have no knowledge on how many miles or anything else this engine has.

 

[Bob West]

XE274H and a little help from scoggin dickey ought to have you running mid/low 13's easy enough.

 

[Junkyard Dawg]

So you're recommending a set of Vortech heads/intake as well as that cam? Will they work with most headers? What kind of power gains can I expect?

Originally posted by Glenn1018:
IMO the 4.10 is too steep for that engine. You could offset this a bit with taller tires, but that'll change the stance/look of your car.

What gear ratio would you recommend? Performance is the name of the game here but I want to be able to make this engine work and be able to do it again if I replace it.

 

[Mike Feudo]

I have the same engine in my 79 vette. I put flat top pistons and a mild cam in it. Not really worth the effort it is still a stone. The stock heads are really bad if I didn't have smog problems a set of Vortecs would be on there in about a day.

 

[Junkyard Dawg]

Mike I'm guessing you have 882 heads?

Hhhhmmm....wonder how well vortechs would work with my (I'm guessing) dished pistons?

 

[Bob West]

Vortecs have small chambers...58-62cc's...they will work great with even dish pistons,with flattops they make 10-1 or a little better. Double roller timing chain and gears.

 

[Mike Feudo]

I built a dished piston Vortec for the old Nova. Even with welded subframe connectors it has ripped the radiator mount off the radiator twice from the body twist because of the torque. You will not believe how well the Vortecs make a small block run.

 

[ACLineman]

First you must decide if it's worth dumping $$$$$ into a "78 smog engine"

I'm with TEXAS70, put your money into the BB.....you'll be MUCH Happier.

 

[young gun '71]

I had a '79 350 just like that. the first thing to do would be to take those heads and dump them in the deepest lake around. the engine I had last had a performer intake, demon carb and the best I ever got out of it was a 16.7 with my 2.73s

after a year of me driving it around trying to kill it most of the inner valvesprings were broken. I imaging shifting it around 5500-6000 at the strip and constantly wrapping it out on the street wasn't helping either

I couldn't kill it but after that year it wouldn't wrap more than 4500

 

[m71]

what casting number are the heads? i went 8.30's in the 1/8mi with '78 "smog" heads and dished pistons in a 400sbc. that would be good for high 12's in the 1/4mi. 16.70's in the 1/4mi? there was alot more wrong than just the heads.
this is just an opinion, but if you don't know the ins and outs of a small block like the back of your hand, then you should probably hold off on the big block for awhile, until you get some more experience.

 

[Junkyard Dawg]

I'm pretty sure they're 882's

 

[Junkyard Dawg]

So what rear end ratio would you recommend? 3.73? 3.55? BTW I may even use this combo with my big block so I only wanna have to change gears in the rear once. Also remember gas milage isn't so much important as performance. (quicker acceleration)