Inliners International Forums General Discussion Blown and Injected Engine hesitation

I have an AMC 258 bored to 267. Has a turbocharger off a Carburated Buick turbo V6. I fabricated a plenum to bolt to inlet of turbo that takes a 4 bbl carb. I get an engine hesitation under light acceleration. Goes away under heavy acceleration. Cannot tune hesitation away with timing or jetting. I wonder if carb is too big, 500 cfm Edelbrock, or do I need to make a water jacket to heat plenum under carb. A smaller version of this setup with a S&S Harley carb had instant response. With no manifold heat . Any ideas. Mike

it may need more pump shot.

It would help us out to see some pics of your install if possible.

Sounds like a lean hesitation.

MBHD

I agree, it must be a lean condition. I am running the pump rod in nearest hole to carb for the longest stroke has helped a little. I just got back from a 20 mile ride and the intake plenum is dripping with condensation. I guess fuel must be doing same inside. I think maybe my design is flawed as plenum has a low dip before entering turbo to keep carb low. I am going to try and add pictures. Can not figure out how to add post pictures but can e-mail too you. Thanks Mike hschrei@siue.edu

You can change the accelerater (SP) squirter sizes for more fuel.

You should have the carb at least even with the turbo inlet,that would help.

The Buick Regals had used quadrajet carbs & had a plenum that bolted directly to the turbo & was even with the inlet.

I had one but sold it.

You can host pictures @ photobucket.com.
photobucket will almost automatically search for your pics on your computer,but you have to select which pics,hard for me to elaborate but I think you can do it.


MBHD

I agree, my carb sits too low, plenum is about 1 inch below turbo inlet. Engine is in a 27 Ford T roadster, no hood. I wanted to keep carb as low as possible. I now realize it was a mistake. When engine was in my 65 Rambler American I used a S&S Harley Carb mounted directly to turbo inlet. No hesitation at all. Carb was too small but car ran 14.20 at drags. Carb would also empty float bowl in traps and detonate. Broke pistons 4 times and finally I gave up and swapped in an AMC 401. Recently rebuilt the 6 and put in my roadster. Maybe I should go back to the Harley carb but really like the looks of the 4 bbl. Mike [img]http://s37.photobucket.com/albums/e100/Ramblinon6[/img]

You can always install some extra injectors for additional fueling.

Or run a methanol injection kit like I do for some extra fueling & cooling & higher octane.

Also, since you are not intercooling,I would highly recomend a methanol injection kit.

MBHD

Mike:
I like your car, the photos look good.
I think you're right on the money with your idea to put a water jacket to heat the carb plenum. I have read other threads in the Bulletin Board that go into great detail on the subject. These threads are on naturally aspirated manifolds, but i think the principle would be the same, especially if you have condensate on the outside. I didn't look back, but i bet if you do a search on heated intake manifold it won't be hard to find.
What material is it made of? It appears to be steel. I have a similar setup, but with an Eaton M90 supercharger & Edelbrock 600, and my carb plenum (aluminum) drops about 1/2" below the blower inlet. (for the same reason you stated, to keep the carb low) Mine performs well, with no flat spots (after about 5 minutes of warm-up), so maybe the aluminum conducts a little more heat out there than steel would.(?)
But i have considered heating it for cold weather driving.
Anyhow, i hope this "rambling" will help you sort out your Rambler. lol
Good luck!
pappy
p.s: pages 7 & 8 of the link below show my setup

how do you see his photos? i have a spearco carb to turbo plenum that may work better and is water heated. tom

I would think you would have some fuel puddleing w/that set-up & not so great fuel atomization before the turbo ?

The Buick regals ,turbo manifold, the foor of the carb manifold that bolts directly to the turbo, the carb floor is actually higher than the bottom on the compressor wheel. IIRC

With a supercharger Eaton,there, that would have better response & sucks in the air/fuel better from the carb, but w/a turbo, there is lag you have to deal with.

MBHD


http://s37.photobucket.com/albums/e100/Ramblinon6

thanks hank. the carb to turbo adaptor i have is nearly identical to your setup. spearco added to the base of it a place to run water for heating. it is all cast as 1 piece. i bet if you add heat it would work better. it is pooling fuel and starving engine. add heat and it will be a day and night difference. tom

Thanks everyone. I added some pics to my album that show intake better, early mock-up. My plenum is steel and stays cool even though the offy manifold gets hot to touch even without running coolant through manifold. I made a shield to try to direct heat to plenum but did not have much affect yesterday. Plenum no longer was sweating but hesitation still there. I am going to remove plenum and fabricate a water jacket around bottom . Pappy, a friend of mine took pictures of an engine a few weeks ago at a cruise in I think was Padukah. Sure looks like yours. Beautiful car and fabrication. You are a craftsman. Mike

Cool setup ramblinon!

you may not be familliar with inliners.org rules and regulations, its required that you post a video of your car in action, once your issue is resolved.

Just kidding...would be nice though. Good luck

Mike:
yep, we was at Paducah. It's a GOOD show, and only about 60 miles from me.
thanks for the kind words.
pap

Well, I solved my hesitation problems. Before I built a water jacket around intake plenum I decided to try another carb. I had a 500 Edelbrock I had on a Rambler 6 years ago. I had modified the weights on the secondary air valve to make them heavier and slow the secondary opening. I had a notebook of all changes I had made to carb. I rebuilt it putting 35 squirters in instead of stock 28 and converted it to a electric choke. Hesitation is now gone and drivability is great. May still need manifold heat later when it gets cold but great now. Lesson learned, do not assume carb working great on one engine, blown buick nailhead, will also work great on another, turbo rambler 6. It also helps to keep notes on modifications you make. Thanks again for everyones help. Mike