recommendations please

[benno440]

currently have a eddie ch-28 dual quad intake which has been port matched and 2 500cfm edelbrocks which have been ported etc.
i feel this setup is choking my 505 and want some recommendations on a new setup.

something streetable but still have the goods to go hard.

not really interested in the performer rpm or similiar, i am keen on indy intakes etc. would also be cool to keep it a dual quad either inline or crossram, also keen on what size carbs etc. i only have mild ported 440 source heads at the moment

 

[rumblefish360]

What is the rest of the combonation?
There is the Modman intake....

 

[Badvert65]

If you are handy with a hole saw....

 

[Meep-Meep]

You can try two 625 Eddy carbs. Seems to me there is plenty of CFM available to keep that 505 happy, even with the 500's. I believe the CH28 is a divided plenum dual plane and if I recall you have a pretty big cam (meaning high overlap). Cutting a notch in the plenum divider, maybe 3/8" deep all the way across, might help with over all drivability. You can take the divider down even more but leave at least 3/8" off the floor. 426 hemis seem to make good use of the factory divided plenum dual plane intake even with larger than stock cams, but that's perhaps due to the large runners. The CH28 may not be your bottleneck so I'd look elsewhere even as far as a cam change.

The other suggestion would be to get a single plane style dual quad intake (not a divided plenum single plane) but something that resembles a Torker. Though I can't think of any for the RB other than the old STR. A MW style cross ram WILL get the job done and those are available as repo but hood clearance may be an issue in the Charger body. I ran one on my 68 RR and just took the hood off to deal with the clearance issue.

 

[lewtot184]

currently have a eddie ch-28 dual quad intake which has been port matched and 2 500cfm edelbrocks which have been ported etc.
i feel this setup is choking my 505 and want some recommendations on a new setup.

something streetable but still have the goods to go hard.

not really interested in the performer rpm or similiar, i am keen on indy intakes etc. would also be cool to keep it a dual quad either inline or crossram, also keen on what size carbs etc. i only have mild ported 440 source heads at the moment

you need a pair of 750's. forget about the cfm hype. the 750 size carb was used on stage 2 & 3 426 max wedges. the 750 throttle bore and venture area is the same as the ss/b '67 street hemi cheater carbs. the 600's on my 440 aren't big enough. the 500's have to be a miserable option. something to keep in mind is the 750 edelbrock is probably overated. it's closer to 700cfm dry flow, which is probably 600-650cfm wet. the only viable major step up is a victor intake and something like a 1000cfm hp carb.

 

[benno440]

let me explain what i feel when i drive the car and you tell me if it is possibly related.
My cam i s abig 252 @ .50 lunati hydraulic 305/302. (sweetspot 3000-6500)
my gearbox is a upgraded 76 truck 4 speed with an OD gear and a eaton true trac 8 3/4 3:55 gears.

I will sit on about 2000rpm, then take off she will spin for about 5-10 metres then it will grip and i will punch it through the gears but when it gets to around 3500 rpm it still revs but feels like it is making no power and sort of feels to me like it is running out of CFM's.

this is what it feels like to me anyway.

On my setup currently i have 2 x 2" open hole carb spacers to increase plenum size to allow more air, and also running a custom hemi oval air cleaner so i got plenty of room with the 2" reverse cowl

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you need a pair of 750's. forget about the cfm hype. the 750 size carb was used on stage 2 & 3 426 max wedges. the 750 throttle bore and venture area is the same as the ss/b '67 street hemi cheater carbs. the 600's on my 440 aren't big enough. the 500's have to be a miserable option. something to keep in mind is the 750 edelbrock is probably overated. it's closer to 700cfm dry flow, which is probably 600-650cfm wet. the only viable major step up is a victor intake and something like a 1000cfm hp carb.

2 new carbs are alot of money, some people have said to get 600 cfm's i do take your advice highly Lew. But do you definely reckon this could be some of my problem

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You can try two 625 Eddy carbs. Seems to me there is plenty of CFM available to keep that 505 happy, even with the 500's. I believe the CH28 is a divided plenum dual plane and if I recall you have a pretty big cam (meaning high overlap). Cutting a notch in the plenum divider, maybe 3/8" deep all the way across, might help with over all drivability. You can take the divider down even more but leave at least 3/8" off the floor. 426 hemis seem to make good use of the factory divided plenum dual plane intake even with larger than stock cams, but that's perhaps due to the large runners. The CH28 may not be your bottleneck so I'd look elsewhere even as far as a cam change.

The other suggestion would be to get a single plane style dual quad intake (not a divided plenum single plane) but something that resembles a Torker. Though I can't think of any for the RB other than the old STR. A MW style cross ram WILL get the job done and those are available as repo but hood clearance may be an issue in the Charger body. I ran one on my 68 RR and just took the hood off to deal with the clearance issue.

what does cutting the divider actually do?

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What is the rest of the combonation?
There is the Modman intake....

any clue where i can get pricing on a modman intake.

cant find anything useful on google

 

[Meep-Meep]

If you have 2" carb spacers then probably no need to cut the divider. It exposes both sides of the carb to all 8 runners, which will make the signal weaker but can help with a big cam.

I have run big cams with a dual plane intake and never had as good results as I did with a single plane. Putting in a cam that is better matched to that CH28 intake will be my recommendation, because the cam you have now seems to be an upper end cam but your motor architecture is a stroker torque monster. Plus you have 3.55 gears, which are completely up side down for that cam. Sure the big cubes will have a positive effect, but I still think you have a mismatch. You want to create as much average power within the RPM range you spend your time in and having a cam that is on the upper end (varied slightly with the big cube motor) is not working well.

 

[coloradodave]

Benno,
Just for reference, I run two 500 cfm Edelbrock carbs on a factory Max wedge crossram on my 451. The motor pulls strong to 6,500 rpm. I had two 750s on the motor and it made more power on the top end but the drivability and mpg suffered. Try some simple diagnostic tests before buying high dollar stuff you may not need. The 1,000 cfm should work fine for your street car if everything else is spot on.
#1: Verify total timing at full advance (+- 34*)
#2: Do a plug color test. Make a full throttle run and chop the throttle and ignition. Coast to a stop without idle time and pull a couple of plugs to see the coloring of the insulator down inside. A light and magnifying glass helps.
#3: Increase the size of the secondary main jets 3-4 sizes to see if the power picks up.
#4: Try a run without your air filter
#5: Hook up a temporary fuel pressure gauge on the cowl, taking it from the fuel line before it enters one of the carbs. Look for 5-6 lbs. throughout the rpm range.
Good luck and let us know the results if you elect to do these tests.

 

[benno440]

dave my total timing is i think 37* as my initial is 19* , i wll order some custom MSD bushes right now as msd smallest one is 18 advance. double checked fuel pressure all good at 5.5psi. i will give the jet sizes a go, but it seems like my motor runs fairly rich as i start the car in the garage and have to evacuate in a couple mins or i will pass out

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If you have 2" carb spacers then probably no need to cut the divider. It exposes both sides of the carb to all 8 runners, which will make the signal weaker but can help with a big cam.



I have run big cams with a dual plane intake and never had as good results as I did with a single plane. Putting in a cam that is better matched to that CH28 intake will be my recommendation, because the cam you have now seems to be an upper end cam but your motor architecture is a stroker torque monster. Plus you have 3.55 gears, which are completely up side down for that cam. Sure the big cubes will have a positive effect, but I still think you have a mismatch. You want to create as much average power within the RPM range you spend your time in and having a cam that is on the upper end (varied slightly with the big cube motor) is not working well.

thanks Meep, yeh i totally agree my cam is mismatched, i do not really want to change a cam at the moment as busy with a few other things but it will be on the books in a few months. where can i get recommendations on a cam, what do you guys recommend?

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What about if i lock my distributor at say approx 34* and dont worry abour initial and total, due to my big cam to get a better clean idle and better cruising? i have a good battery and mini starter, can this cause problems on a street car?

 

[dvw]

I've run that intake on a 440" with a .557 solid. Both 750's and 600's. Less than .05 difference in the 1/4. This car runs 11.50-11.60. Much better 2x4 intakes out there but most are MW port. I've never run the Indy on the street but on a previous Indy headed 500" it was better than a stock crossram from 3900 rpm and up. Made 650 with the crossram, 710 with the indy. As far as carb size. I run a 572 with the Indy and 2 750 Eddys out of the box. 9.19@148 best. I'm sure your combo would be OK w/the 500's. I'd be looking for a tunnel ram.
Doug

 

[coloradodave]

"dave my total timing is i think 37* as my initial is 19* , i wll order some custom MSD bushes right now as msd smallest one is 18 advance. double checked fuel pressure all good at 5.5psi. i will give the jet sizes a go, but it seems like my motor runs fairly rich as i start the car in the garage and have to evacuate in a couple mins or i will pass out"

Benno; Increasing the secondary jetting will not affect idle or low speed running. Running that rich at idle could be from your idle mixture screws being adjusted too far out, timing issues or the springs under the metering rods being too strong for the vacuum your motor is making. What is your vacuum reading at idle and how far out from seated are your mixture screws?
As far as the locked out distributor, it depends on whether or not your particular combination likes it, and, if so, if your starter/battery will crank the motor when hot. I've never tried to do that on a street car.

 

[benno440]

vac at idle is around 4hg, idle screws are 1.5 turns out, if i can remember i am running the pink springs in the metering rods

 

[coloradodave]

Just concerning the rich idle, the pink step-up springs require 7" of vacuum to hold the rods down. Replacing the pink ones with blue ones (3") may help you to get a cleaner idle. Is the idle stable now or does it surge or wander?

 

[benno440]

idle is pretty good, there is a slight wander of maybe 1-2 rpm once warmed up, have to stay on throttle for a while to keep motor from dieing when cold though. i will try the blue springs, i also currently have my distributor all in at 1800 rpm but i think that total * is a bit high, but i cant go any lower initial the motor really doesnt like anything lower than 19*.

when it comes down to it i do blame my cam selection, but for the time being i am trying to get the best out of what i got

 

[Meep-Meep]

4" hg at idle???? Time to lock out the advance at 34-36. This may not solve all your issues but should be an improvement. And with a stroker you probably have a small dish in the piston, so no chamber obstructions (even better). Low vacuum will require the carbs be completely recalibrated. Idle feed restrictors, main jets, emulsion tubes, etc.. because the signal across the venturi is not the same when the carb was set up new. Might want to call Eddy and see if they have booster clusters for very low vacuum applications.

 

[747mopar]

If you haven't tried bumping up the jets like Dave said I'd try it. I've been tuning mine lately and had a similar feeling (just didn't pull very hard in the upper rpms), I went from the stock 78 jets up to 87s and there was a noticeable difference with every jet change. I'm pretty happy with the primary side now and will be starting on the vac sec next. As far as future recommendations go..........don't ask me, I believe in the KISS method (Keep It Simple Stupid haha). Good Luck Benno

 

[benno440]

4" hg at idle???? Time to lock out the advance at 34-36. This may not solve all your issues but should be an improvement. And with a stroker you probably have a small dish in the piston, so no chamber obstructions (even better). Low vacuum will require the carbs be completely recalibrated. Idle feed restrictors, main jets, emulsion tubes, etc.. because the signal across the venturi is not the same when the carb was set up new. Might want to call Eddy and see if they have booster clusters for very low vacuum applications.

OH OHHH, too much more of this Meep and your going to lose me to the clouds haha. i understand basics etc. but now your scaring me.

 

[lewtot184]

Just concerning the rich idle, the pink step-up springs require 7" of vacuum to hold the rods down. Replacing the pink ones with blue ones (3") may help you to get a cleaner idle. Is the idle stable now or does it surge or wander?

bingo!

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something to think about is the big mech pump. I know your using a regulator but is it compatible with a 14psi pulse pump? most regulators are designed for constant flow/pressure like an electric pump, not a pump whose pressure and capacity will vary with engine rpm. I have a friend that had a fairly nice running gtx, until he changed fuel pumps. the car drove ok but was lazy at WOT. apparently the new pump was pushing thru the needle and seats when he opened the end carbs (6-pak with .110 needle and seats) just enough to kill off power. those 500's have .093 needle/seats and probably wouldn't take much to push thru them; especially with a pump whose capacity can increase with rpm. an over rich condition is a real power robber. it doesn't take much to mess the whole program up.

step-up spring change should cure the idle problems. locked timing will need a start retard. I don't think you need to go there.

the 500's should be easy to change to 600's by swapping out the primary clusters and doing some jet change.

 

[benno440]

what jets should i be aiming for in these 500's.
My main dramas is the higher rpm's where it seems to run out of power when it should still be charging on.
I will change springs limiit timing at 34-36 and bump up intitial a touch. my springs i am currently running the 2 light silvers, i want to be all in for my average cruising rpm of 1800 dont i?

 

[SlinktRR]

vac at idle is around 4hg, idle screws are 1.5 turns out, if i can remember i am running the pink springs in the metering rods

4" is awful low..are you fouling plugs or misfiring? I'd wager your vacuum would be closer to 8-10 when running right even with that cam. If you can't tune it out you may have to clean them both out completely apart with carb cleaner and compressed air to remove any dirt or junk inside. The passages can get plugged pretty easily.