Edelbrock 600 on a 4.6

Eliot · Post by **Eliot** » Sat Jun 02, 2007 7:24 am

Bill Shurvinton on this board sells them.

Sondar · Post by **Sondar** » Sun Jun 03, 2007 11:21 pm

Just to pick up on Minorv8's comments, I had thought about the possibility of crap in the carb, but I would expect that this would cause it to run lean, not rich as it would block fuel flow. I can pretty much guarantee that the rods are a pair as the guys tried several pairs so it's pretty unlikely that they would all have been mis-matched.

Carb size is an interesting one. I'm not going to make any decisions about it until it's been on the dyno but I would say that it's pretty smooth & flexible right from the bottom of the rev range with the 600 on there. Mind you, it's pushing a TR7 so there's only 1100kg to move which will probably mask any flat spots to some degree. How far up the rev range would you expect the air speed problem to show?

minorv8 · Post by **minorv8** » Mon Jun 04, 2007 8:23 am

Sondar, if the dirt is in the air bleeds then it would definitely run rich.

As for drivability, off idle to somewhere around 2000-2500 rpm would be the range where I would expect most problems.

mgbloke · Post by **mgbloke** » Sun Jun 10, 2007 2:26 pm

Did a Track Day at Castle Combe yesterday using the 500 carb.
Runs lovely on the road but on the track it just leans right out.
Ive had this problem for so long now.
Next Trackday Im gonna stick the 600 carb on, jetted the best I can with the Innovate wideband guage (that I havent got yet).
Think at the end of the day it might have to be the 600.

Mark

darren peart · Post by **darren peart** » Sun Jun 10, 2007 9:54 pm

Sounds exactly the problem i had with mine ,like i mentioned previously the only thing that sorted the problem was to scrap the edelbrock and replace it with a holley 600dp hope you have better luck.

Eliot · Post by **Eliot** » Mon Jun 11, 2007 6:54 am

A 600 seems massive, even at 100% ve @ 6k rpm you should only be pulling 487cfm.

Are you sure you are not suffering from surge or the pump just isn't pumping enough fuel.

http://www.4secondsflat.com/Carb_CFM_Calculator.html

mgbloke · Post by **mgbloke** » Mon Jun 11, 2007 8:34 am

[quote="Eliot"]A 600 seems massive, even at 100% ve @ 6k rpm you should only be pulling 487cfm.

Are you sure you are not suffering from surge or the pump just isn't pumping enough fuel.

As I had nearly a full tank of fuel it cant be surge in the tank.
The pump is new and can fill a gallon container in under 1min.
Pressure set to 5psi.

I havent tried the 600 at a track day yet. If the problem remains Ill know to look elsewhere.

Also the wideband will give me much needed info.

Mark

kiwicar · Post by **kiwicar** » Mon Jun 11, 2007 1:50 pm

I agree 487cf/min should be OK if the flow were truley steady state (though I make it 511 cf/m for a 4.6 at 6k revs [capicity in litres times revs over 2 all devided by 27 ?])
However the flow through the manifold and carb will be pulsed, and although probably only varying by 10% to 15% above and below mean flow that still puts peak flow at about 550 to 590 cf/m range, I would also think the 600 is a better carb for this engine, especially if the primarys are smaller than the 500

.
Mike

Eliot · Post by **Eliot** » Mon Jun 11, 2007 6:47 pm

kiwicar wrote:I agree 487cf/min should be OK if the flow were truley steady state (though I make it 511 cf/m for a 4.6 at 6k revs [capicity in litres times revs over 2 all devided by 27 ?])
However the flow through the manifold and carb will be pulsed, and although probably only varying by 10% to 15% above and below mean flow that still puts peak flow at about 550 to 590 cf/m range, I would also think the 600 is a better carb for this engine, especially if the primarys are smaller than the 500 .
Mike

I was using the carb sizer in the link posted before, which also tallies with another tool i have - and that's assuming you have 100% ve - which you never will. A more realistic 85% yields 414CFM.
But as the o/p has pointed out, the actual choke sizes are the same between the 500 and 600 anyway.

Sondar · Post by **Sondar** » Thu Jun 14, 2007 1:32 am

Finally had the 4.6 dyno'd & tweaked yesterday with the Holley 600. It just needed a minor jet change & timing adjustment.

Horses at the rear wheels are up to 190 (best run 193) compared to 186 with the Edelbrock. They're made at the same rpm (approx 5,400), but it hangs on within a gnats whisker of that figure all the way to 6,000 whereas the Edelbrock dropped off pretty quick over peak BHP. I guess that makes sense due to the extra air flow available with a 600. Torque is slightly (2-3% ish) down, mostly at lower revs, which again makes sense due to the effect of the venturi size on air flow.

It seems that my engine has responded differently to mgblokes motor, HP is up slightly, not down & torque is only slightly down. Apart from the engine spec differences, the other obvious difference is that I'm using a Holley rather than the Edelbrock 600. Talking to the dyno guy, he commented that no two engines are the same & that you just have to find what works on the engine in question, which may be exactly right in the case on mine & mgblokes 4.6's. It seems that tuning is a bit of a black art...

Overall, not really much in it between the Edelbrock 500 & the Holley 600 you might say. But as far as driveability goes, it pulls cleanly & strongly from 30 mph in top gear (about 1,100 rpm) & is much happier to rev than it was with the Edelbrock. The idle is much cleaner & the sound is way better. It's just a better car to drive.

I guess the recent problems with the Edelbrock may be down at least in part to dirt inside it, but the driveability (mainly at low revs around town), idle & engine note was always a bit questionable. Just after being run in a couple of years ago, it was producing about 180 BHP at the rear wheels, so if there is dirt in there, it doesn't seem to be affecting peak power.
I sometimes wonder if I got a duff carb, as other people are obviously happy with theirs.

Hopefully that's the end of this saga, at least for me! Best of luck to anyone else who's struggling with this stuff...

Johan Van Wyk · Post by **Johan Van Wyk** » Thu Jun 14, 2007 2:22 pm

Hi! I am keen to hear how the leaning out ended. I tend to agree with the others that 20 should result in damage. When I studied this stuff 14:1 was the point where the balance between power and economy was struck, with anything over 15.5 seen as getting lean- that was in South Africa though, with a high lead content fuel. Optimum power was achieved at 13 - 13.5, and that's how we used to set SU's of the day.

I had a 390 Holley on a stage 2 3.5, and over 14:1 it used to surge ran really well on about 13 at sea-level and 13.5 at 4 000 feet above sea level. With that height diff, we could gain 17% bhp when we went to the coast for a meeting.... It felt soooo unfair that the Durbs geezers always had this extra bit on tap.

I have just accidently come across this site. Its magnificent, and I hope it lives on and on.

Johan

mgbloke · Post by **mgbloke** » Fri Jun 15, 2007 6:02 pm

Just got my Innovate DB-1 guage kit.
Should have it fitted this weekend. Ill test with the same setup as my first rolling road session and see how things compare.
Im going to setup the 500 and 600 carbs the best I can and try them both on the track back to back on 2nd July at Castle Combe.

Mark

mgbloke · Post by **mgbloke** » Sat Jun 16, 2007 8:56 pm

What an amazing tool.
I am very impressed with the LC-1 and DB guage from Innovate motorsport.
The Rolling road figures as we all suspected were way off.
This could have been caused by leaks in the system as some joints were blowing a bit.
Anyway, after some fiddling around Ive found a setup which is very near to Minorv8's with the 500 carb. The 95 secondaries are showing 10.9 to 11.2 WOT which might be a tad rich. Mid range is around 13.9. Cruising is around 13.2
Rods are 68x52 with 86 primary jets.
Will try the 600 tomorrow.

Wondering if my leaning out problem at trackdays is due to G force as it always seems to happen when exiting corners.
Have tried adjusting the float height to allow a bit more fuel in.
Just a thought.

Eliot · Post by **Eliot** » Sun Jun 17, 2007 8:05 am

Widebands are great tools - the fact that you can now change combinations and then see the results right before you eyes is unbeatable.

sidecar · Post by **sidecar** » Sun Jun 17, 2007 9:17 am

Eliot wrote:Widebands are great tools - the fact that you can now change combinations and then see the results right before you eyes is unbeatable.

I'm waiting for a call from Bill then I'll be over there in a shot to collect mine! I can't wait!....I love new toys!

The days of "plug reading" will soon be over

(Total waste of time with unleaded in my opinion).

Regards,

Pete.