The cubes do make a difference! The LT-1 used in the '70 Z/28 is fairly close to the same as the 302 with the major exceptions of different stroke and cam. Torque starts much sooner in the LT-1 than the 302 and it's much more stop light friendly. I think the avg guy will see a quicker 1320 et with the LT-1 but someone that is willing to push the 302 into it's power zone and knows how to drive it there (launch and shift) should be able to run just about side by side. That really means running the risk of more broken parts with the 302.

------------------
...Dennis
"The '69, the '96 our local club"
and the "daily driver"

 

I bet you could get 75HP more out of a 350 with good aftermarket heads than the 302. The extra stroke makes a bunch more TQ and modern heads outflow the old Camel Humps big time.

I'm not knocking the 302, its a legendary engine, but the only reason its a 302 inch motor is because of the Trans Am 305" displacement limit back then.

Just my opinion.

 

Eric is right. The 302 would not have been installed in factory built cars except for SCCA
Trans-American road racing rules. Basicaly an LT-1 is a longer stroke DZ 302 with a better cam, screw in studs and guideplates. The LT-1 was a better cam design for bottom end and almost as good at the top end but it is a little bit RPM limited as compared to the DZ 302 cam. In 1970 the SCCA rules allowed for de-stroking the factory 350 to 302 specs for track use so the need for a street version of the race 302 went away. As was said many times before, there ain't no substitute for cubic inches.

-Mark.

 

The mule 350 engine Chevy used to get the 370hp rating used the 30-30 cam! So it was identical to the little Z engine except of having 48 or so more cubes!!

They dropped the -178, LT-1 cam in it so they could run an automatic b/c it was more streetable with a 240 or so intake duration vs the 254 of the 30-30 cam, imho...pdq67

 

Why stop at a 350? If don't get the 355 you mentioned and you're going to start from scratch and use aluminum heads etc., a 383 wont cost that much more. Then you'll really feel the difference in power

[This message has been edited by Torker (edited 11-24-2002).]

 

I have the TRW piston numbers of forged pistons that'll yeild 10.5:1 compression with 64cc heads, i forget the number off hand though.
I'm sure you'll need it.

Solid cam would be nice, same power as a hydraulic roller without valve float and a lighter valvetrain.

 

more cubes is always a good thing. heck, why stop at 383cu, go with a 406, they look the same (basically) from the outside, and all things even, will make more torque/horsepower than a 383. the only complaint i hear about a 406 is finding the block, which hasn't been a problem around here, yet. when my 406 block is used up, i'm likely going to go w/ a world motown block, those will work safely at 434inches. it's only money, right

 

A couple things to keep in mind. First you'll be a point lower on your compression with the flat tops even if you run the same 64cc heads. Second I would consider aftermarket heads with a larger intake port volume once you get larger than 331 cid or so. Third and most importantly, if you're used to the 302, don't try to run your 350 like it's a 302. You don't need to, it'll be much more streetable. I've spun rods in a number of good 350's trying to run them hard. Keep the rpm below 6500 or better yet below 6000 with this longer stroke motor.

I'd consider the other guys advice and stroke the thing, also run the longest rods you can, this will help you to run more compression.

 

I thought about doing up a 383 but I've gotten the impression that it's kind of a pain in the butt to build one. Sounds like you have to grind things here and there and have to get a small circle base cam so the crank doesn't hit it... Just kind of sounds like a head ache to deal with. The 400 SB sounds good but then you're better going with the longer rods and you have to make sure the heads have steam holes drilled. Just seemed like the 350 would go together smooth with out any hassles. Is the 383 really that much of a hassle to build? I see alot of guys putting them together, but I don't know of anyone personally that's built one...Any info would be great...

 

I've built a few 350's over the years and my current engine is my first 383. There is no comparison - the 383 makes a LOT of extra TQ even over the 350. My previous combo went high 11's with 3.55 gears, a 3000 stall, and a fairly mild solid F/T cam. Don't get me wrong, a properly built 350 will get you down the road in a hurry, it just takes a less radical combo to do the same thing with a 383.

As for grinding and small base circle cams its really no big deal. Just do your research (there's some great info here) and take a little extra time making sure everything clears in the bottom end. Its only a couple extra hours of work IMO.

You mainly have to watch the rod bolts - the shank end comes close to a couple cam lobes and the nut end may shave the sides of the block near the oil pan rails. Nothing a bench grinder and carbide bit can't fix.

Eric

 

yeah, what eric said. it's really not a big deal, in fact i kind of enjoy it, but i enjoy building motors too. and as for the 400, everybody and thier brother makes a rotating assembly for the 400, from stock rod length to 6", and a lot of them are real affordable. i ran a small base circle cam,(same price) and actually nothing hit, but a few of the rods had to be slightly clearanced to achieve .060. again, no bigee, and that was all that was needed. and as far as the steam holes, drilling them is not a big deal, but unless you are going to idle around in traffic all day, regularly, you do not have to drill them. mine, and 4 or 5 of my buddies have or are running 406's, w/o the steam holes, and they run just fine, even if you have to sit in traffic once in awhile. all of our cars are more of a street strip deal, and none of them have overheating problems. but again if it makes you feel better, drilling them isn't a big deal. just my .02, good luck on your decision!

[This message has been edited by 68rs406 (edited 11-25-2002).]

 

383's are not hard to build. Just as the others said. I actually have two and neither one of them have small base circle cams. One is a short rod 5.565 and the other is a long rod 6". The cost is really not an issue, it will cost just about the same these days to build a 350 or 383. It would cost you more to build a 350 that could compare to a 383. Once again there is nothing wrong with 350's they are great engines. 327' and 350's is all I used to build, until the 383's became so easy/cheap to build.

One other thing you said you have a stock/original Z I wouldn't get to carried with HP otherwise you will have to make to many modifications to take advantage of the power. Not to mention what torque and HP does to the chassis. If you have the bug you might want to go out and get something a little less collectable and have fun. It would be a shame to beat up a Z.

Royce

 

You guys have been great at helping me out. camaroman7d, I agree with you, I don't want to beat the car, I just want to make the car a bit quicker. I don't plan on taking it to the strip very often. I would be very happy if I could get it into to the mid to high 12's. So if you guys think a 350 would get me there then I would be happy with that. With the less torque of a 350, might not beat the car up too much. What do you guys think? Again, I'm wanting to go with a flat top engine so that I can run on pump gas.

 

You should have no problem getting into the 12's with a streetable 350. Yes flat tops are the way to go as well. Build a decent short block and put a good set of heads on it and you should be well on your way. Of course you can't forget the exhaust system as it plays a big role. The right cam, intake and heads should get you there, with a decent exhaust. What kind of gears do you have? Being a Z, I take it you have a 4 speed? I would go with a nice solid cam. Of course I didn't give any specifics, just a ballpark idea. Make sure you pick parts that will compliment each other (well matched).

Sorry I didn't re-read your post. You have 4spd and 4.11's 12's should be no problem at all. You will need good tires and bolt on traction bars. I would suggest frame connectors as well. As you can see one thing leads to another. Being a Z I would just use bolt on connectors (weld in are better), but I wouldn't dare. These will help reduce the chance of chassis flex, saggy doors, body cracks etc...

Royce

[This message has been edited by camaroman7d (edited 11-26-2002).]

[This message has been edited by camaroman7d (edited 11-26-2002).]