Offenhauser 4 barrel with what carb?
- Thread starter xLURKxDOGx
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RustyPlymouth
Well-Known Member
you would be looking for one of these. if all you have done to the motor is bored it it will work perfectly. just came off of my slant.
http://www.forabodiesonly.com/mopar/showthread.php?t=274565
http://www.forabodiesonly.com/mopar/showthread.php?t=274565
RustyPlymouth
Well-Known Member
now for an unbiased opinion. a 600-650 is just to much for a more or less stock slant. people seem to do pretty well with the edelbrock 500 straight out of the box but the mpg isnt that great. if you dont mind a little initial tuning the holley 390 is the way to go performance/mpg wise. you could even get the 4bbl-2bbl adapter and run a holley 2300 series. ive tried the stock 2bbls that people run with the super six setup, they were ok. the small 4bbl really woke it up higher up in the rpms. the 390 was aslo trouble free (after initial tune) for 8 years. if you arent into messing with carbs find an edelbrock bolt it on and just accept what happens. if you dont mind getting gassy once in a while get a holley and tune it to perfection and reap the benefits.
It depends entirely on which TYPE of carburetor you choose. You can run up to a 650, but it has to be the right kind of carburetor. I would look into one of those new little Street Demons. The 625 three barrel. They have very small primaries and a very large single secondary barrel. Since they are a vacuum secondary carburetor, they will only flow what the engine demands, so all you have to do is tune the primaries and adjust the secondary air door so that it does not open prematurely. I bet one of those would haul *** on a slant properly tuned.
2 Darts
A-body Addicted
Mopar worked up a 225, Offy manifold, and Holley 390 cfm combination. The details of it are in the Mopar Six Cylinder book. What the set-up does not elaborate is the camshaft or exhaust type they used. Also, I'm not sure how old the recommendations are. Do they take into account the ethanol in most pump gas? I don't know.
cam.man67
Well-Known Member
I use a Holley 390 on mine. Works great.
momoparman
MOISMYHOME
What kind of tuning did you have to do to get the 390 to work properly?
I've been into slants for years and had best results with a Edelbrock 500. I too would like to ty the new Demon. I ran a 390 Holley for awhile but went back to the Edelbrock for a set it and forget it combo. Even with a stock cam,but with headers and a full 2 1/2'' single exhaust. Just a thought.
On my current project I have a Edelbrock 600,Head work,mild cam,and headers. It is a bit lazy on the bottom end till is hits about 3200 rpm then comes alive.
On my current project I have a Edelbrock 600,Head work,mild cam,and headers. It is a bit lazy on the bottom end till is hits about 3200 rpm then comes alive.
This 390 has been trouble free for me on my iddybitty 170/6 for 3 years and 15.000 miles of driving and a few passes at the track for fun, I guess I got lucky
Billy (Leanna's man) built it for me.
Billy (Leanna's man) built it for me.
DodgeLad
Skipped the Light Fandango
Can the Edelbrock 500 be tuned for better MPG?
BillGrissom
Well-Known Member
The bore depends on what pistons are available. Most people over-bore to clean up the cylinders, so the minimum required for that is wise. It does raise displacement slightly but if you thin the cylinder walls too much you get problems with distortion under pressure and such. The designers weren't stupid. If you want to push the bore, you should have the wall thicknesses measured w/ ultra-sound first.
Don't over-carb. As mentioned, the critical thing is the size of the primaries, not the max cfm w/ secondaries flowing. The Thermoquad and Quadrajet were the best design, with small primaries and monster secondaries - termed "spread-bore", but I know of nothing similar for smaller engines like the slant. With fuel injection, you can get similar combinations. There is a smaller flow version of the Holley Commander 950 (600 cfm I recall). If still not small enough, you might install smaller injectors. It flows only 2 injectors until you mash the pedal. Haven't heard of anyone trying one on a slant.
Don't over-carb. As mentioned, the critical thing is the size of the primaries, not the max cfm w/ secondaries flowing. The Thermoquad and Quadrajet were the best design, with small primaries and monster secondaries - termed "spread-bore", but I know of nothing similar for smaller engines like the slant. With fuel injection, you can get similar combinations. There is a smaller flow version of the Holley Commander 950 (600 cfm I recall). If still not small enough, you might install smaller injectors. It flows only 2 injectors until you mash the pedal. Haven't heard of anyone trying one on a slant.
RustyPlymouth
Well-Known Member
not a whole lot. idle mix so it still runs happy and doesnt burn your eyes when you are sitting somewhere idling. a couple jet changes to get in the right range. other people may get more into it but thats all i felt i needed to do. ran great, no hesitation and awesome 24 mpg.
momoparman
MOISMYHOME
So your saying it probably runs a bit rich out of the box and I may need to drop a jet size or two. I will be watching my plugs of course....they tell me things.
RustyPlymouth
Well-Known Member
pretty much.
xLURKxDOGx
"An angel fat, at satan's feast"
Thanks for all the info everyone!!!! Im looking into all the options as well speak.
Jake
Jake
TheMoparMan
Modifies everything
I've had the best results with a Edelbrock 500 cfm
This is just what I needed.
GEO
Sarcasm Inc.
There's always running an adapter and a holley 2 barrel .
Either the 350 or 500cfm
Either the 350 or 500cfm
cjh
Well-Known Member
Holley 465 ???
BillGrissom
Well-Known Member
Kind of tedious though. Install a wide-band O2 sensor in the exhaust and you will have total knowledge, not just an average over mostly low-power cruising. Easy in a slant since a single exhaust.
2 Darts
A-body Addicted
Dual Purpose Set-up for 225 w/Offy 4 bbl manifold
Holley 6299
390 cfm Hollley, vacuum secondary *
Primary jet #49
Secondary jet # 52
Power valve 25R-591A-65
Idle Air Bleed .078"
High Speed Bleed .043"
Diaphragm Spring Yellow
* The good thing about a vacuum secondary carburetor regardless of brand is that the secondary does not open until engine demand warrants the extra air/fuel mixture.
Holley 6299
390 cfm Hollley, vacuum secondary *
Primary jet #49
Secondary jet # 52
Power valve 25R-591A-65
Idle Air Bleed .078"
High Speed Bleed .043"
Diaphragm Spring Yellow
* The good thing about a vacuum secondary carburetor regardless of brand is that the secondary does not open until engine demand warrants the extra air/fuel mixture.
DodgeLad
Skipped the Light Fandango
xLURKxDOGx
"An angel fat, at satan's feast"
I ended up going with a Carter/edelbrock 500 and so far its been excellent!! Went with an oldtimer at Carburteors Unlimited in PHX who rebiulds cores and a noticeable amount of power. Thanks again for all the help guys.
Jake
Jake
2 Darts
A-body Addicted
The settings are for Detroit, MI, 581 above sea level.
xLURKxDOGx : Good luck with the carb. It has an air valve secondary, so bog should be minimal if it's set up right. Although advice on this forum has been generally good, IMO, it's hard to beat competent local support.
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