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Hagerty
Hagerty Employee

Piston Slap: Adding EFI to a Tri-Five Chevrolet? | Hagerty Media

I have a four-door 1956 Chevy Bel Air with the original 265 V-8, Powerglide transmission, frame-off restored, and cruises nicely. It's perfect for me, I bought it on the day of our 42nd anniversary. The only problem with mine is it's harder to start than I like, and belches too many smelly fumes.
https://www.hagerty.com/media/advice/piston-slap/piston-slap-adding-efi-to-a-tri-five-chevrolet/
10 REPLIES 10
DUB6
Technician

   I think we may be placing the cart way before the horse with a discussion of EFI.  There may be some simpler answers.  An original 265 likely has an old Rochester or Carter 2-bbl., and although the car is "restored", do we even know if the carb has ever been rebuilt?  Even if it has, modern gas and different driving styles and conditions could have put the carb "out-of-tune".  Sounds like it's running rich.  Might even have a sticking choke plate.  Out-of-time motors can also throw smelly fumes.  Or there could be internal engine problems that are causing blow-by, which is making its way out the exhaust.  I would have a competent old-school mechanic look at all the potential issues that could cause emissions and/or mileage problems first before just buying EFI, transmissions, and cat-converters!  Could be that there are other fixes that will allow the car to stay in its more-or-less original configuration and still solve the smelly experiences!

CFH
Intermediate Driver

I have to agree with DUB6. I don't remember '50's and '60's cars being overly gaseous when they (and I) were new. It does sound like the car is either running rich or missing. You might also want to do a compression test and inspect the plugs to see if you have a bad cylinder.
wish
New Driver

Ditto the need for more evaluation -- even timing and points can be out of whack causing the hard starting and the smells. Throwing a catalytic converter on a poorly running engine could cause it to clog up and create more problems.

The TH400 is not an overdrive transmission, the 700R4 would be the overdrive equipped equivalent, though for a factory 265 setup a 200R4 should bolt up, easily handle the power, and be more efficient based on what I've read while researching them.

On the fuel injection side, Holley offers a Sniper system that will bolt on and look like a factory Rochester 2G carb. Remember even the high performance versions of these motors were under 200 horsepower gross.
Sajeev
Community Manager

Oops that was a dumb mistake, I am changing to 700R4 right now.  Thanks for the correction. 

Sajeev
Community Manager

Thank you all for your insight. I grew up in the catalytic converter generation, and my first car (1965 Galaxie) was kinda smelly in my book. Not as smelly as the emissions exempt hot rods i see these days (i.e. it was a stock 352 V8 that was a boat anchor and very little else) but I just assumed he wanted the smell gone entirely when stuck in traffic. 

Swamibob
Instructor

Hey Sajeev;

Good responses so far. What that car really needs is a good tune up and a change to an electronic distributor. Either a drop in unit like a Pertronix or Crane XRi or a different distributor all together like Pertronix or MSD makes. Also the accompanying coil for that electronic ignition. I've used both and the better spark makes an enormous difference in how old engines run. I don't doubt the old two barrel need some cleaning and a little love too. Would an EFI make it even better? Yes, it would. Holley makes excellent kit for that job and their best retailer is the guys at EFY System Pros www.efisystempro.com They have the BEST Sales and more importantly Service anywhere. Holley and EFI System Pro's have a kit to work with the original fuel tank.
I don't work for either company, but I have used a lot of Holley products aincluding their EFI systems and I and several friends have had excellent interactions with EFI System Pros.
DUB6
Technician

   I certainly don't think there is anything WRONG with an EFI setup.  However, the owner makes it a point to tell us that it is "an original" motor and trans, and a "frame-off restoration".  If there are some simpler things to be done to preserve the originality of this very period-correct car, I just think that looking into them FIRST is preferable to switching out lots of stuff - and unless we know exactly what is causing the issues, it's entirely possible that switching that stuff will not solve the problem at all.  If the engine needs a ring job, and Sniper and cat-converter will not be beneficial.

   All I'm trying to do is suggest that the things be looked at that we would have looked at when that car was 10 years old (before HEI distributors and EFI fuel systems and ANY kind of "R4" transmissions) - i.e., the basics of carburation, fuel burning, ignition, compression - the stuff that made them run in 1966, in other words, there may be a very simple answer and then an informed decision can be made as to how to fix it!

strassenmeister
Pit Crew

I agree with many of the other commenters - it's worth looking into the ignition, carburetor, and confirming that the rest of the engine is in tip-top shape before pulling the EFI trigger.
What about a Gear Vendors overdrive for the Powerglide, instead of replacing the whole transmission? Admittedly, a modern transmission with a lockup converter is the most efficient, but this may be the easiest route and keep it more original and reversible if that matters.
Sajeev
Community Manager

The gearvendors is a good option, but they are very expensive. Might be better just to swap transmissions, considering it's not uncommon on a Tri-Five. 

ctaarman
Intermediate Driver

I suggest you search youtube for people who have owned and run these aftermarket EFIs for more than a year versus the warm and fuzzy videos that cover installation and first day performance. Despite their learning curves they are not set and forget. One would be much better off in this car to get a good rebuilt carb and install an aftermarket AFM ( about $160 including Bosch sensor, exhaust bung, cables and digital gauge), then tune the carb and timing. for efficient fuel burn. You will get as consistent performance and econoly as EFI for one tenth the price.