Sup all,

I'm starting to get serious with my second car build. I'd figure I can layout my thoughts and goals and have you guys who've done this help me with what parts I'll need.

Goals:
Car will be a DD
25+ mpg on regular 87 pump gas
Max power I can get reliably with fuel eff as main concern (to put it in perspective, I want it fast enough where an import won't pull away from me)
Will need A/C and heat

What I have now:
Stock 4-speed stick
2.73 posi rear
Carb

I know that the carb won't cut it for what I'm looking for. I know that switching to TPI is the way to go. So what I'm basically looking at is finding a short block, cam, heads, complete TPI, etc. Will my fueling need to be changed to support TPI or can I just reuse the mechanical fuel pump and rod?

My budget is not high. I'm aiming for cheapest possible way, using second hand parts where I can. Don't quote me $500 heads and $300 cams lol. I'd like go the 350 route as I'd still have some torque. I don't want to completely sacrifice power for efficiency.

So basically, what am I looking for? What heads and cam? Will flattop pistons with valve reliefs be a good start on a short block?

Let me know if you need more info of what I got or intentions. Looking to have everything drop in ready by this summer.

 

With Tuned Port Injection, you'll need to either drop the fuel tank, swap sending units, and install an internal electric fuel pump, or, add an external electric fuel pump. It then becomes a matter of which Tuned Port Injection you want to go with in terms of overall ECM control, and I would personally target the '7730. With your goals though, I myself would port out the stock heads that are already on the car, then focus my attention on the intake, cam and carb selection, because 25+ mpg can easily be attained with a carburetor, while being extremely efficient to boot, but that is just me. With fuel injection, it is never the matter of slapping it on and running better than a carb, as tuning becomes very critical in terms of running as efficient as possible with fuel injection...

 

For what it is worth my 91 with a 93 truck 350 with TBI and 2.73 gears pulled down 23 mpg at 80 mph average. This was a trip from Kansas City out to Ft. Riley driving around on base and some city driving when I got home. So with that low compression and a seriously wimpy cam and driving fast I got where you want to be. Once I get the Vortec TBI together I may try it again and see if I can improve it with better compression and everything else. Oh and I believe I am still running a stock exhaust and LO3 manifolds so the new headers should help my mileage too. Good luck.

 

25 mpg is totally achievable with a carbed setup.
The basic requirements are the same as for a well built performance engine.
A free flowing exhaust with little to no back pressure. This would include headers and a muffler that has an adequate cfm.
An intake manifold that is smaller in runner cross-section than larger. A performer intake as opposed to RPM Air Gap for example.
A vacuum secondary carb is a must. A spread bore with it's smaller primary venturi will help.
If performance can take a back seat to your fuel effeciency needs, then your stock heads will probably be OK however try to have as much compression ratio as the engine can tolerate. An efficient cylinder head like Vortecs will allow 9:1 static compression and run on regular fuel. That's not quite the case with stock smogger heads (if that's what you have).
If you're going to get a cam, there are plenty of choices that are slanted to fuel economy and will still offer some degree of performance. Be sure to match your cam choice with your compression ratio.
Pay attention to your timing curve and be sure to run a vacuum advance.
Your stick trans and 2.73 rear gear will help considerably.
Here's a link to an excellent article.
http://www.chevyhiperformance.com/ho...075/index.html
For the record, I've knocked down over 22-23 mpg at cruising speeds and still run mid 12's at 108 mph in the quarter.

 

With those thoughts in mind...

What would it take for a carb? I am strictly looking for 25mpg being the lowest highway. City will also need to be as high as possible.

The car is already carbbed. I did not even think about the fueling issue. Changing the intank pump completely changes the game. Don't want to go through the trouble of dropping the rear, have no access to a lift, and I'm not cutting an access hole. Also not dealing with electric pumps. Plus I don't have to swap out my whole harness.

I have the free-er flowing exhaust down. I have headers, true duals, no cats and notyetdecided mufflers.

Lets start talking part numbers for intakes, heads, cams, carbs and what not.

Will an aluminum GM dual plane intake work?

What is wrong with a CCC Quadrajet or CCCs in general that you say a vaccuum secondary is a must? Keep in mind I'm not too keen on carb tuning. Definitely understand the reason for spreadbore. I'd like to have it where I don't have a CEL light.

I believe I have the stock LG4 305 heads on the bad 350 block. I have a pair of 416 heads I brought up before. They will need to be redone, so I don't really want to do that.

I'll need a cam. Are there certain specs I'm looking for? Duration/lift?

The reason I'm asking for part numbers is so I can start figuring out build costs.

I'll take a look at that link.

Thanks for the input so far!

 

A CC Q-jet would be great for getting 25mpg if it is in good functioning condition. Also, if you are looking for MPG a smaller-ish cam would be best for your MPG needs.

If you want 25+mpg AND 400+hp do an LSx swap with a t-56.

It's a give or take, HP or MPG.

 

Yep, I know all about the LS swap and the tradeoff. The swap's out of the cards in this budget build.

 

The Q-Jet is one good gas mileage choice; another would be the Holley 6210, tuned per the "sticky" in the carb forum.

A stock LG4/L69 intake, Edelbrock Performer, or ZZ4 takeoff would be fine.

Keep the CR low, no more than 9:1; and use this cam here http://www.summitracing.com/parts/CCA-12-207-2/ or this one http://www.summitracing.com/parts/CCA-08-407-8/ if it's a roller motor.

Vortec heads are probably the best bet, with the smallest dish pistons you can conveniently find, about like these. http://www.summitracing.com/parts/UEM-KB193-030/

 

^Nice. That's what I'm taking about.

So if I were to put a parts list together, it'd look something like this:

Short block (2piece or 1piece RMS)
Smallest dished pistons (ex. KB193-030)
Vortec heads (906 or 062)
Cam (12-207-2 for flat tappet or 08-407-8 for roller)
Edelbrock Perfomer Intake
Good condition Quadrajet or Holley 6210
Lifters?
Rods?

Gotta start pricing the heads and stuff out.

 

If you haven't already checked out this article, I strongly suggest you should.
http://www.chevyhiperformance.com/ho...075/index.html
There are some insights into what can make an engine perform on regular fuel.
The Vortecs are a great choice because of there efficient design. Combine that with the right cam, a few other building tricks and you can have it both ways (up to a point).

 

well since you wanna start pricing heads. i just so happened to decide to go a diff direction with my motor and need new heads. so im selling off my 906 vortec heads. you can pm for details if you want.

since youre going to not be building a high hp motor, stock crank and rods will be fine, and cheap. and stick with 1.5 stock rocker arms. if youre talking about cam lifters, use whatever kind your motor/cam needs (flat tappet vs roller). if its flat tappet, get new lifters with the new cam. if theyre roller you can reuse the old ones, or buy good used ones.

 

Aboslutely. Won't run without em.

See "lifters".

If I was doing this, first thing I'd do, is obtain a 96-2000 truck motor as my core. I would not fool around with some old 010 block or something. That will take care of, among other things, the heads, lifters, and rods. Can't imagine any way of doing this that would cost any less than that. Might not even have to touch the short block AT ALL if you go that route.

 

i agree. an 96-99 L31 truck pull out would get you pretty much all the parts needed. if you get one in good shape you can leave the long block intact and run a vortec carb intake and a carb. the L31 made as much as 230hp and 330tq, and moved those trucks around pretty well. the L31 pull outs can be found for $500 or less depending on milage and condition.

im starting my stroker project with an L31 short block that i picked up for $100. it spun a couple rod bearing, but that didnt matter to me since ill be replacing the entire rotating assembly anyway.

 

Looked through that website. They use big buck parts, but I get the concept. Thanks!

Thanks for the offer. I'll hold out and look into a L31 pull out that you guys suggest. If they're as cheap as you say, I'd be good to go with money left over for a rebuild.

^ This funny guy... lol. I was asking part suggestions, but I got the point. Reccommended stocker equivalents should do.



I'll start looking around.

Happy New Year Fellas!

One quick Q, the L31 would accept my 4-speed and have the mechanical fuel pump bore right?

 

L31 will accept the 4 speed since it has the same bell housing bolt pattern as every other gen1 SBC. however its a 1pcs rear main seal, so youll need a diff flywheel if the one you have now is a 2pcs rear main seal. ill have to check my block when i get home to see if the hole is there for the fuel pump pushrod, but i think it is.

but it you go FI instead of carbed, youll have to ditch the mech pump for an electric one anyway.

 

Ok, that's what I thought. I have a 1pc rms flywheel hanging around. If the hole isn't there, I can always run a low pressure electric one where the mechanical one would be.
Doubting I'll go FI with need of messing with the in-tank pump. I can reuse a lot of things with carb since I have parts for that, just have to get a good condition carb.

 

[QUOTE=KnightmareCS;5136807]
Doubting I'll go FI with need of messing with the in-tank pump. QUOTE]

You can also run a high pressure pump externally to feed an EFI system. No problem there. All that's required over a carbed application (other than the wiring) is a fuel return line. What I find is that EFI is more expensive to assemble. What's more, anything you build, carbed or injected, will need to be tuned within an inch of it's life if you are to achieve your mileage objectives. It's cheaper to tune a carb. No computers. No programs. Carbs just take knowledge. Of course having a carb with more tuning tuning features, as in replaceable idle air bleeds and high speed air bleeds, etc, will cost more but the results are superior.

 

My L31 had all the provisions for a mechanical fuel pump on the block. However, the cam did not have the stock cam did not have the needed lobe to work the rod.

 

its much easier to remove and replace a gas tank than an engine.

 

the mounting surface for a mech pump is there because the block is the same design as all other gen 1 engines. the question would be if the hole is there or not for the fuel pump pushrod. i think my stock cam had the lobe. its been a couple months since i got it an tore it down.

 

The high pressure electric pump I would think requires removing the stock pump. Also the longetivity of the pumps is another issue. Not sure how long one would last. The cam having no lobe for the pump is no problem, it'd be replaced anyways.

I've done engines, no problem. Gas tanks on the other hand....
Engine's being removed either way. Don't wanna have to drop the rear and then fiddle with the tank.


So far I've found an 01 Express Van engine. From searching, I think I can find one for a good price.

 

ok, so i was wrong. my L31 doesnt have the pushrod hole or the cam lobe.

to run an inline electric as opposed to the intank electric, the mech pump would have to go (for FI) the electric pumps work better and last longer as pushers and not pullers. so the closer they are to the tank, the longer they last and the better they work. a low pressure electric inline pump would be fine for a carb. carbs take 5-7 psi.

 

Correcting previous post: The high pressure electric pump I would think requires removing the stock in-tank pump.

Can I just put a low pressure electric inline pump in the vicinity of where the mechanical pump would have been or would it just be a better idea either way to put it close to the tank?
The problem I see with putting it close to the tank is that it still would have to travel all the way up......., buuuuuuut you mentioned the electrics work better as pushers then pullers.
I may or may not have answered my own question.

 

There is enough room to put almost any kind of high pressure pump near the tank. My 86 TA has a pump just above the rear axle and my 86 Camaro has a Holley Blue pump in the place of the OE in line FI filter. Neither pump is for fuel injection but the physical dimensions are the same.

 

you want the electric pump as close to the tank as possible. if you have a low pressure "helper" pump in the tank then yes, youd have to drop the tank and remove it. and if you were going to do that you could just as easily stick a stock replacement tpi high pressure pump in its place and not have to worry about an external pump if youre going FI. (and get to use all stock parts for the fuel system to boot)