ETW1 carb accelerator pump - Viton

[outpostm37]

Has anyone performed a mod for the leather original Carter Ball & Ball carburetor accelerator pump to address today's oxygenated fuels?
Left to right: 1) original leather accelerator pump seal 2) Viton with viton oring and U cup. 3)Carter Thermoquad Viton accelerator pump.
Been running Carter TQ carbs on most of my Mopar V8 engines. The rebuild kits come with alcohol resistant U cups for the TQs. These accelerator pumps on the Carter TQ carbs seem to last forever. Figured I would try a conversion on the ETW1.

[ashyers]

outpostm37,
Interesting idea!

I thought I'd chime in with my thoughts . I live out in CA which may have the poorest fuel available from the standpoint of older engines. Here's what I've found with some of my older vehicles, including the M37. Run modern rubber fuel lines, anything older than a few years will fail alarmingly quickly, usually near the clamp area. This isn't an issue in the M37 unless you modified it, but the vent lines should be checked. Leather accel pump seals work well as long as the carb is used regularly. If you run the float bowl dry they're done. Watch the switch from Winter to Summer gas. The modern stuff seems to boil pretty easily in the fuel pump and if you have Winter gas in the tank you may see some vapor lock issues as the weather warms. The alcohol in the fuel will "clean" your fuel system. If there's any gunk it won't be there for long, it's headed to your jets. That said my truck runs well on the crappy 87 we have out here and has had no fuel system issues for some years. I do drive it a few times a week, if not daily. This likely helps.

As far as the pump seal watch the tension on the seal. If it drags it's going to effect pump function. I had an issue with a reproduction pump seal that was too tight and effectively disabled the pump.

Andy

[outpostm37]

Andy
Yes, since the pump operation is on vacuum, if it drags too much in the chamber, it will affect the performance.
Have you done the screen under the carb? I made a two piece gasket with titanium screen between the layers to help atomize the fuel droplets.
See my other post in Technical.
Mike

[ashyers]

Mike,
I haven't tried the screen under the carb trick, but I will say that the carb at full throttle, 3000 RPM, and the governor dialed out will generate a couple inches of vacuum. I guess you'll see if better atomization beats out the restriction caused by the screen .

If you loose the oil bath filter it's worth 2HP, unfortunately I kind of like that big clunky thing . A less restrictive filter and cold air would do that engine good. Maybe a "performance" snorkel!

Andy

[Kaegi]

Mike,
I haven't tried the screen under the carb trick, but I will say that the carb at full throttle, 3000 RPM, and the governor dialed out will generate a couple inches of vacuum. I guess you'll see if better atomization beats out the restriction caused by the screen .

If you loose the oil bath filter it's worth 2HP, unfortunately I kind of like that big clunky thing . A less restrictive filter and cold air would do that engine good. Maybe a "performance" snorkel!

Andy

if you read the studies done by the SAE an oil bath flows better than many paper filters. They use a scoring system on flow and ability to filter. paper is better for getting larger particles out and oil bath better at getting the finer particles. they score the same in over all testing for filtering

[ashyers]

Kaegi,
Filtering or not, as fitted on the M37 it sure is restrictive. We did some back to back tests for fun and it killed 2 rwhp, that's a large % when you're only dealing with 50 .

Andy

[Kaegi]

Kaegi,
Filtering or not, as fitted on the M37 it sure is restrictive. We did some back to back tests for fun and it killed 2 rwhp, that's a large % when you're only dealing with 50 .

Andy

that interesting. just go bigger cam and shave the head to get again of 35. ;/)