I recently got a 1986 Trans Am with a carburated 305 and NWC T5 transmission. The car is basic as far as options go except for T-tops. The car has been sitting in a barn for 10-11 years, rats and mice have had their way under the hood but no where else. I am pulling out the 305 and have no ability or desire to try and re-wire the car back to factory specs. The only things that still work from the firewall forward as far as I can tell is the drivers side headlight, horn and 1 side marker light. The plan is to go back with a 350 and that's as far as I have dreamed so far. I need advice because I feel that at this point I have so many options. Anyone willing to share their experiences or knowledge will be greatly appreciated. Small block chevy that will fit under the stock hood, operate on pump gas, be able to be driven to work occasionally (and occasionally smoke the smarta#@ reving his motor next to me at the red light) and not break the bank are the only criteria. I know I can buy a combo set up from Edelbrock, etc and that may be my best option. Any suggestions either way?

 

Welcome aboard thirdgen.org.

Are you willing to build/assemble an engine, or do you want to buy one to bolt in?

As to what will "fit", any Gen I SBC as long as you don't go nuts on the intake manifold. And, with a T5, you don't want an engine that needs a nuts intake manifold.

If you're willing to build/rebuild, get a junkyard '96-'99 light truck 350 engine. It will have "Vortec" heads, which are about the best heads the factory ever produced for Gen I SBCs. They take a specific intake manifold, but that's a minor thing (they are readily available). Your current flywheel/clutch will fit no problem.

When you have the heads in the machine shop for going though, have them cut the tops of the valve stems for positive type seals. This will do 3 things: 1) give you better oil control around the valve stems; 2) allow for more valve lift; 3) allow you to use better valve springs. Have better valve springs installed when they put them back together.

These Vortec engines used roller lifters, which is a good thing. Get a roller lifter cam in the 26x duration range (you can reuse the roller lifters as long as they aren't damaged, like from infrequent oil changes). With a 650 CFM double pumper Holley type carb, HEI vacuum/mechanical advance distributor, good headers (like Hooker 2055HKRs), and a cat-back for the '86-'90 TPI single cat application, this should be an easy 300+ HP engine that is easy to drive on the street and will take care of the occasional reving snotnose in the other lane (as long as you don't do high-RPM clutch dumps or try to speed shift that poor T5).

 

Thanks!!! I am willing and able to put a motor together even though it's been years since I have done it and feel that if will be good for me and my teenage son to do this together. Great information to get me started in the right direction! I have a few friends that have recommended similar set-ups but with a 750 cfm carb. which I questioned. I think with the help of friends and this site it will be a fun project that I will be proud of. Thanks again and I hope that as I go I will receive more input such as yours to help me along.

 

Any thoughts out there about the 650 recommended here and the 750 I have had someone else recommend? Im not taking this car to the track and my initial thought was a 650 as well.

 

Using the old formula: CFM = RPM*CID/3456, at 100% VE, a 650 will support a .030"-over (355) to 6327 RPMs.

Yes, a 650 double pumper will be fine on a mild 350.

 

See, this is the information I need. Once I read the comment with the formula in it I remembered there was a formula! Yeah, It's been that long since I tinkered with anything like this! Thanks again. Another question I have is about alternator mounting brackets, etc. The brackets and such from a motor out of a truck, if I get one from a truck, will probably not allow for clearance under my hood, right? I suppose the brackets from my 305 will fit the Vortec motor if this is the case or will I need to quit being a cheep-o and buy some sho-nuff fancy ones? Over time I plan on doing this anyway, but initally I just want the car to run so I can get it to the body shop under it's own power. Maybe I'm just looking too far ahead because I am a bit excited about the car.

 

The brackets from your 305 will fit. I vaguely recall hearing one bracket mount bolt hole needs to be drilled and tapped, but don't take that to the bank.

 

ive got an l31 block sittin in the garage, ill take a look at it and see if the holes match up to the 305s brakets or if indeed one needs to be drilled.

 

Might be the head. Don't recall, though.

 

Thanks for checking on this. I have spent some time in the classified ads on this site and it looks like a great source for some of the things I will be needing. Very glad I found this site! Seems to be lots of good people here.

 

so the L31 block i have has all the same accessory bolt holes as my 70s 350 block. and the vortec heads had all the necessary accessory bolt holes too. but i got those heads with work already done to them......

 

Thanks for looking. Not a problem if I have to have that done but nice to know that it may not be necessary. Some of the aftermarket serpentine set-ups are pretty expensive so it may be awhile before I get around to something like that.

 

Get a 650 holley or a 600-650 edelbrock for a mild 350/

 

One last carb question for a while: I understand that vacuum secondaries are best for street applications such as mine with an automatic transmission. Since I have the 5 speed should I consider mechanical secondaries or just quit over thinking it and use the vacuum secondaries.

 

as five7kid would say "vacuum secondaries are for towing vehicles"

 

With a T5, you shouldn't consider anything but a mechanical secondary carb (and that means no Edelbrock carb).

 

Why no edelbrock? I have a mechanical secondary edelbrock with my T5 works good.

 

gotcha! thx

 

I have a friend at work that told me he had a set of L82 heads, ported and polished, that I could just have for free. I have not seen the heads nor do I have any casting numbers, etc yet. From what I have heard and read, these heads may not be anything special, but for free I am really considering using them until I save up for the ones I want. Does anyone have an opinion on this or should I just hold off a bit and go for the Vortec setup or whatever else I decide. Really, I figure that if these heads are OK (especially for freebies) then I will be fine until I decide to swap them out, but if I am able to gather some feedback about them and what I need to look out for then I can make a better decision.

 

I think the L82 heads were 624 castings not horrible but I think they have 76cc chambers. You will have to have them milled down for a 305. They also might have 2.02 valves and I am not sure how well they work on a 305.

 

OK, but 305 is trot line weight now. Working on 350.

 

if youre working on a 350, the 76cc heads would be fine with a flat top or domed piston to keep the compression ratio up.

 

Also if I remember right 624 heads hare thin walled and often weaker castings so get them magna fluxed.

 

The Edelbrock secondary throttle blades are mechanically opened, but there is an air valve above them that controls air flow, so, no, you don't have a "mechanical secondary" Edelbrock.

 

Free L82 heads? He should have paid you to take them off his hands.

Unless you have a door that you need to hold open with something heavy.

 

I found a '97 Vortec 350 today at the wrecking yard. It has a bad crank shaft, but they wanted $300 for the long block assy. I didn't have much time to look the motor over so I'm probably going to go back tomorrow and look a little closer if it's still there! He said they don't last long...someone always looking for that motor. This particular motor had water get into the motor and the crank/mains were "gone". I got a friend with a Lunati crank that may work if I can get a price from him I may be good to go.

 

You can probably have that crank ground down and cleaned up, which you probably would have done anyway.

I say get it; you need the heads and a 350 block to start with and there they both are!

Good luck on your build!

 

Yeah 57, that's what I am figuring out about those heads...they are not a big deal. No sense in putting money in to those heads when the vortec set-up (like you suggested) would be so much better for practically the same money. I had to throw the (free heads) idea out there to figure it out though.

 

One common way to get water into the oil is lack of antifreeze and the block cracking in the lifter valley. Ask me how I know. The cracks can be repaired, but it'll cost you more than the $300 you're paying for the engine.

Make sure you can get the engine replaced if the block is cracked. And, have it tanked and checked over carefully before spending any money on it.