Inliners International Forums General Discussion Hi Performance 250 EFI Conversion Questions

I sent a email to Tom directly but thought this might be a better place to contact him and possibly get some other peoples input that may have experienced this already:

I wanted to see if I could get your opinion and recommendation on some modifications to a 1968 GM 250
· Currently Stock in a 1968 C-10 Pickup
· Upgraded ignition to HEI
· Currently Original and Strong running motor never rebuilt (Estimated 130k)
· All external Gaskets replaced (valve cover / oil pail / rear main / side valleys)
· The transmission is the Saginaw 3-spd on the Column

My Goal: Drivability and Reliability without tearing into a rebuild
· Basically want to get the 250 to be dead reliable so I can drive the truck and enjoy it first while I do other mods
· Hoping to choose to do a rebuild / build up in the future when I choose to (not forced to)
· Just want to ensure it is done right, right now and I won’t be setting myself up for more issues if I do some improvements
· any of your recommendations of Must Do’s or what to look out for since the motor is stock

Improvement thoughts:

· Any of your recommendations of Must Do’s or what to look out for since the motor is stock



· EFI – Wanted to get your thoughts on FAST’s EZ EFI system and if you have had any experience with it on the I6’s

o I have been researching and thinking about going this route for my motor since it “supposedly” handles upgrades easily

o I saw mention of a customer of yours that had you building him a motor and he briefly mentioned using the FAST EFI system

o Wanted to check and see if this was the EZ-EFI system

o The customer has/had a Mid 60’s Chevrolet Truck and he stated this: “I want to stay with the inline 6 cause I just think there cool, so I hired Tom Lowe from Autowerkz & inliners.org to build me a monster. I should be taking delivery of freshly built 250 bored 30 over with a clifford 270 cam & lump heads that have had the works thrown at em including roller rockers towards the end of July Then the thrash begins. Front clip will come off & engine compartment will be sanitized & repainted & rewired. I'll paint the frame rails, A arms 7 anything that needs replacing or repainting will be done. I had planned on running this weber 38 carb but have a F.A.S.T. fuel injection setup that will work killer so I think that's the new plan.”



· Intake: If I was going to use the EZ EFI system which intake is best / recommended

o The Clifford or a Offenhauser

o The EZ EFI accepts a Holley 4150 Flange style

o Also wanted to get your thoughts on a Heated or Non-Heated intake with EFI



· Headers: Custom Made or Aftermarket

o I am going to get a quote from a local shop on producing some custom headers for my application

o If the price was comparable to Aftermarket headers (Fenton etc…)

o Wanted to get your opinion of what is the best option or design to follow


And if you think these are not worthwhile modifications with my setup thats ok too just let me know haha


Thanks for the help

Hey I can answer some questions of yours probably while I don't currently have efi I have researched a lot on it as it's in my plans.

-no info on fast efi I know allot of guys have ran megasquirt so you could probably get someone to give you a tune to start with if you went with that route.

-the manifold won't need to be heated because the fuel is being injected straight into the cylinders so there is no need to heat the manifold like you would for a carb.

-headers while custom from a local shop may be an option there are multiple companies that already make headers. Some cast and some tubular. I really like cliffords headers personally.

He's so nice he answered twice , I've been playing with an EFI system on a Clifford manifold because it had the injector bungs cast into it, but expierienced rough running until I got into higher RPM's, I believe because of the siamesed ports, TLowe has experimented with EFI and solved the low RPM rough running with port dividers that are welded into the ports. A throttle body would give pretty good results ithout too much aditional work.

If reliability is your goal, keep it factory stock. Carburators will run 40+ years with only periodic cleaning maybe once every 10 years. If you don't like adjusting or replacing the ignition points every 10 years or so, you can convert to pointless ignition like pertronix, but then you introduce sensitive electronics into the combo which will fail much sooner.
Honestly, bone stock carburated and old stock distributor is what you want if you ask for reliability. That stone age "junk" ran fine for 40-50 years. and still runs. Not one modern electronic controlled vehicle can get there, not even close.

Headers will never hold up like cast iron exhaust manifolds. If you want reliability but insist on headers then get stainless steel headers built - then follow up with a complete stainless steel exhaust system.

Thanks for the input, currently it has a 1 barrel carb and mainly I want to be able to do some highway cruising and go some distances reliably (say 4 hours trip). Just thinking a better/smoother flowing setup might help this situation out since it won't be short around town trips

Was hoping to see if these motors really accept TBI style efi that well or if they have issues still

I've been trying to read some on 4 barrel option also

A throttle body injection system (TBI) will work on these engines, on this board you'll get people with varied opinions, one will tell you use a carb, another will tell you to swap to a 4200 engine, still another will tell you swap the head. It boils down to do what you can afford that someone else has already had documented success with.

Google "Chevrolet 250 GM TBI" and you will find several sources.

http://67-72chevytrucks.com/vboard/showthread.php?t=320356
http://baizefamily.com/
http://howellefi.com/gm-tbi-products/complete-tbi-kits/universal-tbi-kits.html


One of this days I will make the move to fuel injection.