BritishV8 Forum

Happy New Year everyone.  One of my cars is a '64 Sunbeam V8 (Tiger clone). I am thinking of switching out my Edelbrock 600 cfm carb for a TBI system.  I'm presently running the carb over an Edelbrock F4B medium rise manifold. My engine is a 302 bored .030 over. I'm running a mild Ford Racing street/strip cam.  All this goes through a C4 automatic to the stock Tiger rear-end.  The car is very quick - at least by '64 standards.  I am looking to improve the fuel efficiency, though, as I most often use it as a highway cruiser.  Thoughts?

from sunny, cold, blustery South Dakota

Paul

 -- moved topic --

Paul, I'll chime in based on some personal experience.  TBI fuel injection, because of its constant mixture monitoring will give you better driveability and fuel economy; horsepower wise should be comparable if the throttle body is properly seized.  However, sequential multi-port fuel injection with long/tuned intake runners would be the better choice for economy and power.  

There's lots more factors other than fuel induction that can enhance fuel economy, such as, gearing, tire seize, exhaust improvement, engine timing, choke setting, friction and drag etc., etc.,. What MPG are you getting now?

Jacques

Hi Paul

Here are my thoughts:  

It seems Edelbrock provides carbs with either economy or performance jetting.  Do you know which you A) have, B) would prefer?  

A change in rear end ratios is probably in order, do you know the ratio you now have?  

Why TBI, why not multiport EFI?  Here is a multiport step by step "How To". http://www.therangerstation.com/tech_library/V8EFI.html

See you in September.

Bill

thanks for the replies regarding the pending switch to fuel injection.  I'd prefer to go multi-port but am not sure I have enough room under the bonnet for all the apparatus.  Things are really tight on the Sunbeam.  More research needed on that.

Rear end - 2.88     tough to get anything lower without going to AOD  tranny.  The final ratio on the C4 automatic is 1:1.

A tranny swap is a possibility.  

Current mileage is around 17 when I behave myself on an interstate and stay around 65 mph.  I'd like to boost that a bit, especially considering the rising cost of gas.

Carb is jetted for economy.  

look forward to seeing you Bill.       How's the Duratec project?

Paul

for hwy cruising overdrive is always a good idea.I went from a c4 with 3.55 rear end in my v6 alpine to a t5 with 4.11s and it turns over less RPMs at 70 now than it did before. I got the mustang V6 t5 so i could get the one with the larger overdrive gear. The 5th gear ratio is .68, so at 70 im turning about 2750ish. Much better drivability wth the t5 and fuel economy, plus sports cars should have a manual tranny anyway. Good luck with your V8, im sure thats a fun car.

thanks for the reply.  Yeah, it's a hot rod.  Lots of power, especially from 3500 on up.  I've had the car up to 120 on the interstate and it was still climbing.  If I was 20 I'd probably know what the real top end is!

Paul

The Duratec project is currently in pieces.  Know anything about a Ranger M5 R1 tranny?

Bill

Paul, what is the weight of your car and also the rear tire seize?  IMHO, the car could see 20 MPG.

Jacques

Along the same lines, does anyone know of a factory tbi that can be bolted to a 4bbl manifold that can be megasquirted or something similar that flows 400 cfm or up?

Try the early GM Chevy cars and P/U trucks 305 c.i. and 350 c.i. starting in 1986 up to the mid '90s.  Also, the Dodge trucks (V-8) with 318/360 c.i. from 1987 to 90 something had a throttle body with built in injectors. Some minor modification (adapter plate) to adapt it to a 4 barrel intake may be required.

The car weighs about 2250 lbs.  The tires on the car are 185/70/13's.  The 13 inch tires are standard for both Tigers and Alpines.  Many owners have modified their cars and run 14 inch tires.  Some have even gone to 15 inch.

The Chevy 350 throttle body is often used in the swap between carbs and TBI.  There are a number of different electronic control systems that can be used, including the original GM.  Megasquirt gets good reviews.

If $$$$ was no issue I'd install an AOD tranny, upgrade to 14 inch wheels and install a fuel injection system. At this point I think the least expensive part of this will be the switch to the TBI injection.

later

Paul

"Along the same lines, does anyone know of a factory tbi that can be bolted to a 4bbl manifold that can be megasquirted or something similar that flows 400 cfm or up?"

Um, how about a factory Ford TBI as used on the mid-1980s 302s?

Thanks Joe, I forgot about mentioning the Ford TBI.  Paul, if you could find a 1985 LTD or full size Ford/Mercury car with a 302 that would be another choice although I can't remember if the EGR valve (with position sensor) was part of the TBI or bolted to the plate underneat it?

The thread on Rover with 2  downdraft 2 bbl carbs on this page has a picture of mid 80's Ford TBI. Holley 2 barrel bolt pattern.

Paul, why go to 14" wheels?   I felt the same way, but decided to go whole hog and am going 15".   I think that in a few years the 14" tire market will be as dead as the 13" is now.  

Be aware that 6" wide Saab 9000 wheels are a perfect fit for the Alpine.  Correct bolt pattern and off set.  Most styles are 15", a few are 16".  Add some P195 tires and you would be in business.   Get genuine Saab wheels, I think the aftermarket wheels are "close", but we know that "close" is not always good enough on an Alpine, right?

If interested, check out the listings on Saabnet and car-parts.com.  The used wheels from these sources seem to be very reasonably priced.

Bill

ive read that the gm tbi is around 450-500 cfi, im trying to find the info on the ford. There is a good write up on the gm here.

http://www.diyautotune.com/tech_articles/megasquirt-carb-to-efi-part1-nova.htm
I think i may have hood clearance issues with that, but ill go to the local upullit yard to see if i can get some accurate measurements. Summit sells a plate to mount the gm tbi to a 4 bbl intake.

I have 15 inch vtos, they are 4.4 backspace, look nice. If i have to do it again, id go with 4 inch backspace for the rear, and a little more on the front, to get the wheels more inline. Heres what it looks like. I would probably go to 16 inch if i had it to do over, 1 inch wouldnt make it look that much different, and i think in the future sport tires will be better supported.

http://www.youtube.com/user/socorob?ob=0

Nice youtube Alpine!  The wheels look good on the car.  How much trimming did you have to do, if any, to get lock to lock turning with no rubbing?

The guys at diyautotune are very helpful.  Matt was quick to respond to my questions and helpful.  When it's time for purchase that's where I will go.

I didnt do any trimming, but i think the PO rolled the front valance already. These tires are less than 1/4" taller than the 13 inch tires that i replaced, so not much difference there. If i can find a suitable tbi that will fit under my hood, ill go with diyautotune also, theyve answered every question ive had and have been very helpful. Im having trouble find how much the 302 tbi cfm rating is, and the height of it. I have limited space, 5-3/4 inches from where the carb sits on the manifold to the top of my aircleaner which i think almost touches the hood, so i may not be able to find anything to work and have to stick with a toilet on top of my engine.

Paul, I think you should be getting a bit better with some type of FI either TBI or MPFI. I'm running a much smaller engine of course but my 2.8 with MPFI, a T5 with a final overdrive ratio of .76, a 3.43 rear gear, and 205 60 13s I get around 25mpg on the highway. The effective gear ratio in 5th is 2.60 so your 2.88s should be close. I'd think you would probably get around a 3 to 4 mpg increase with the injection, but an overdrive trans would make far more difference. Increasing the wheel diameter probably won't buy you much as you are effectively limited to overall diameter by the wheel wells anyway.

RE: which i think almost touches the hood

A quick way to find out how much clearance you have is to get some kids playdo or something similar.  Make a ball a little bigger than you think the space is, put it on top of your air cleaner & close the hood.  The hood will flatten the playdo & you can then measure how thick it is to know for sure how much space you have.  Remember to look at the crown of the hood & where any cross braces are to decide where to put the the ball so you'll catch the area with the least clearance.

Ive been looking around a lot, and seems like gm used the same tbi with different injectors for the small blocks and V6s. For a 2.8, with some headwork and a larger cam, should I use a tbi with 4.3 injectors or 350 injectors, since that was only a little over 200 hp in that era? If i get the 350 version, could i just use megasquirt and have it deliver a little less fuel if its too much?

Hi Rob

Like you, I've tried to do some research/study in this area.  Based on what I know about Megasquirt and the GM TBI you could go with the stock 350 injectors and let the computer adjust the fuel flow.  Having said that I found some info showing there are injectors that are a better match for your 2.8. I found the following on another web site:  

These injectors are rated at the pressure used by the factory, about 13 PSI Application Throttle bore size Injector color code Flow rate Part #

2.8l v6 1-3/8" Black/White GM 5235430
4.3L 1-13/16" Yellow/Blue GM 5235203
5.0L 1-13/16" Green/White 40 lb/hr GM 5235279
5.7L pickup 1-13/16" Orange/Black 55 lb/hr GM 5235206
5.7L Cop Car
1-13/16" Yellow/Brown 65 lb/hr 17084327-ACR
Late big block pickup 2" Blue/Black 80 lb/hr GM 1708430 big block pickup 2" Dark Red/Dark Blue 90 lb/hr GM 5235231

later,

Paul

A few places ive read said not  to match the injectors to engine displacement, but to horsepower rating. Get the injectors that are equal to or a little above what your hp is. Ive read so much, its hard to know whats really right or wrong. In a few weeks ill try to get over to the u pull it yard and get some good measurements. Im trying to keep the cost low as possible, so ill get as mch as i can off a donor vehicle. But first, i just got my cam in, and lightened lifters are on the way, had my spare heads magnafluxed, and getting ready to send them off for bigger valves and port/polish/mill. Hopefully at least this part will be complete by summer, then next will be efi. Head work is very expensie these days.

Yesterday I ended up passing a u pull it yard on the interstate and pulled in.. these gm tbi's were missing off most cars. The few V8 cars that had the tbi's on them still were all missing the injectors. Maybe this swap is very common? I finally found one on a 4.3 astro van that just got there a week before after looking in about 40 different cars. In a couple months when i get around to doing this, ill see if these injectors will work, if not ill swap them for 305 injectors. The collar that goes between the tbi body and intake is very tall, but if you find a blazer 1990ish, it had a slightly different looking fi system, i think it said mpi on it or something like that, but it had the same collar as the tbi, but was only about half as tall. The tbi with that collar is about 3-7/16 inches tall to the top of the collar. I also read a lot of people use an econoline van frame mounted fuel pump with the gm tbi. There were only 7 or 8 vans there, and only 1 had the fuel pump in it, all others were taken already. I was also having trouble finding the IAT sensors in the air cleaners, those were all taken too.