81 4spd Scooter

I have an 81 4spd, two tone, very low miles and would like to enhance the H.P. performance of my stock 350 engine. I'm looking at bumping my H.P. to 300-350. I realize there are other modifications needed (intake, exhaust,...), however, being new to this field, I would like to start with some advice on what is the best head/cam combo to purchase.

Thanks

81corvettevortec

I rebuilt my entire engine. with a KB rotating kit. I also went with a set of 2.02 vortec heads and a comp cam 268 grind, with a edelbrock performer intake, and hedman headers. i am very happy with my setup. it should be good for around 330hp. i was still able to pull a 13.7 in my 81 too! i think it is a good street combo! not sure if your wanting something more race prepared tho?

BigBlockk

If this car were mine I would get a set of headers and a complete 2.5" exhaust (with cats) all the way to the rear bumper first. Then I would have a street port job and three angle valve job done.

Now I've probably saved enough by not replacing the heads to get a nice little hydraulic camshaft with 210 to 216 degrees intake duration (at .050" lift) and about 214 to 224 degrees exhaust duration (at .050" lift).

BigBlockk

Later.....

Ironcross

One of the most significant changes you could make is to either install the 1970 LT1 solid tappet cam and springs that would really wake it up or a more milder cam is the hydraulic cam from the mid 60`s 327/350 HP cam.

GrandSportC3

I'd recommend World Product Sportsmen II Heads and a solid flat tapped cam with lift in the low to mid .500's and about 226 - 235 degrees .050 duration...

memLT-1

I agree a set of .202 heads and the 350 hp hydraulic cam

81 4spd Scooter

Thanks for the advice...BTW, with this increase in H.P., will this also require suspension changes? Is your 330 H.P. increase with stock or modified suspension?

Thanks

COMMANDER370

You will be surprised at what just a set of headers and 2-1/2" true duals will do for preformance

81corvettevortec

I am still running stock susp. altho that is the next thing to be changed!!!
Ryan.

1970-Bronze

You might want to check out the Trick Flow packages Summit has....

UKPaul

Made a big improvement in how my '81 ran. Will you still have the CCC system in place, or have you/are you taking it off? If the computer is still running it then it will restrict your choice of cam. I'm running a CompuCam 2040 (210/216 440./.454") which has given better mid & upper end power (though not such a big kick as the exhaust system gave). I'm waiting for some heads to arrive & expect a big improvement as the cam was designed to work with higher CR than the stock 8.2 ish (and new heads are gonna vastly improve it over the stock smoggers). So, the jury is still out on my choice of cam. Dallanex has kept his ECU in place & runs a CompCam (260? 268?) which isn't computer specific. All you need is a cam that keeps a decent manifold vacuum at idle & the ECU should be OK. You won't be able to put in a cam that has lots of overlap & a lopey idle as the ECU will fall flat on it's face, but you shouldn't need a cam like that for the power you're after (I hope not! I'm after about 350hp & everything I've read up/heard/asked points to being able to get that amount of power with the ECU in place).
Heads I'm going for are AFR180's, but I was also looking seriously at TFS 23deg ones (I was going to get some but the exchange rate fell so much that AFR's are now affordable). Other people have had good results with edel perf/perf rpm. It seems that most heads available are going to be an improvement on the stock ones. Vortec are a good bang for the buck (but you'll need a matching manifold & valve covers which pushes the cost up a bit, especially if you've already changed the inlet manifold). If you do change the intake manifold & keep the ECU then you'll need to drill & tap the manifold so that you can fit a coolant temp sensor needed by the ECU. This isn't difficult, but the thread isn't 5/8" UNF (don't ask how I know this!). The tpi is the same (18?) but the hole diameter is slightly larger (NPT???).
I junked the Aircon on mine & the steering feels more responsive/lighter due to the loss of all that dead weight, so ally heads will help even more. Something to check if you go for ally heads is the front ride height, as it may rise due to reduuced weight.
I'll attach my sig for what I've done & I'm certain that the stock heads & low CR are locking away some power.

81 4spd Scooter

If I go with this set up, will it still be emissions and 50 state legal?

81 4spd Scooter

Will this option still be emissions and 50 state legal?

Thanks

redc3

if your new to this i suggest the edelbrock matched sets. all the homework has been done for you. and i cant remember hearing any bad news about them.you can get heads, manifold, and cam all matched to work together. but you still got a 350 under there and simple mods will wake it up. swap in a better carb, and run a dual exhaust setup, and youll feel the difference right away.