Holley 600cfm on 3.5 RV8

[Crazy]

Hey guys, I need to seek some wisdom from y'all!!

I've got a 3.5L RV8 out an SD1 that I'm putting in my Volvo. I've been offered a 600cfm Holley 4bbl carb for next to nothing, and I'm thinking of taking them up on this, and I know that the 600cfm is a bit on the large side for the 3.5, but what would the disadvantages be, or can it be set up to be ok? If it can be set up ok, how would I go about this, or is it just a simple case of jetting it to suit?

It's only going to be used as a daily driver, maybe with a bit of drift fun on occasion, and that's about it. It won't be a racer (not at 2.5 tonnes kerb weight!!!) so I'm not worried about that so much, I just don't want it so that there's no low end torque (as I hear that this can be a problem with the 600cfms on the 3.5)


Cheers guys!!

[sidecar]

I think your login name says it all if you stick a 600 CFM on a 3.5 lump!

No really I do think that you will have problems setting the carb up due to a lack of 'signal' You will probably end up with bad flat spots and a bogging issue.

The Eddy 500 carb does work on the 3.5 basically for two reasons, it has small primaries and an air flow valve. (Not that this helps because you've not been offered one on those!).

Just my humble of course!

[katanaman]

Far too big a carb for a 3.5, you will get poor low end power and there will be nothing that you can do about it. Your engine simply wont flow enough air to make it work properly at lower revs. 600's are cheap because there are millions of them on 5.0 and 5.7 American engines. Either get a 390 Holley or a 500 Webber/Edel. The 500 has smaller primaries than the 390 so you will probably get better low end running although a 3.5 will never need the full 500 unless its a bit special.

[Crazy]

There anything that can be done to them to make them work cos this is like a tenner so I don't mind trying stuff out. If it cocks up, it's only a tenner gone. If it works, then sweet

[sidecar]

There anything that can be done to them to make them work cos this is like a tenner so I don't mind trying stuff out. If it cocks up, it's only a tenner gone. If it works, then sweet

If its only a tenner then that's good but how much time are you going to throw at this carb? What's that worth? (Plus you will end up buying jets and springs etc).

Really in my humble unless someone else can give you the calibration settings for this carb and a RV8 3.5 then you are either going to have to spend several hours on a rolling road or buy something like an Innovate LC1 so that you can analyse that exhaust gas yourself.

I can give you a good base setting for the Eddy 500, I'm sure that others can do that same for a more suitable Holley.

I do see your predicament, suitable 4 barrel carbs are all several 100 quid!

(Ask yourself why. )

[kiwicar]

Hi
Can't you get a pair of SUs on a standard manifold? they are ideal for the 3.5 rover, far easier to set up, will give far better economy and part throttle use and will make for a far more drivable and as a result quicker car.
best regards
Mike

[Crazy]

I already have a set of twin SU's, are they really a better set up for a daily driver?

[Denis247]

I already have a set of twin SU's, are they really a better set up for a daily driver?

If it's a std engine, yes. SU's are very underrated.

[Ian Anderson]

a bloke I know ran a Rover 3.5 in a MGB on a Holly 600 double pumper and it ran very well (his words)
But is was a fully developed race car and trick engine running about 300hp

Also back then emissions would not have been a problem!

Ian

[CastleMGBV8]

Stick with the SU's they have potential for 230BHP so unlesss you are radically modifying the 3.5 they should be fine/

A decent upgrade is a set of Peter burgess econotune heads for an extra 30+ BHP on a otherwise standard engine if in good condition and assumung the cam is not seriously worn.

You can do the work yourself if you have the tools and a bit of skill and patience.

Kevin.

[kiwicar]

Hi
the SU is a very good carb in good condition, it is a pretty good carb in worn condition and that really only starts to be an issue on 200K mile+ carbs, a 4 barrel will be in a pretty poor state by about 60K. If you want more from your SUs (and under about 210 bhp on a 3.5 it isnt necessary) they can be modified for more flow and slightly more consistant metering at wide open throttle but not really necessary for most aplications.
Best regards
Mike

[Crazy]

That's cool then. I'll stick with the SUs then cheers guys

I'll have a look at those heads too, as the engine has only 75k or something around that on it so it's in really good condition. No wear in the block at all. The carbs are quite good too, nice and tidy and came on the inlet manifold too. Only issue was the thermostat not working but I have a spare Manila n thermostat n that works so should be all good when the engine goes for the first time


Cheers for the advice guys.



Ouch, just had a look at the heads, £600 for them new n none on eBay anyone know a good place for some or is it just a case of keep my eyes open?

[mgbv8]

Crazy!!
I need a 600 for my second 4.6 project. You wanna buy it for a tenner and sell it for £45 + postage cost??

Regards
Perry

[Crazy]

Ah man, I told him when you guys said about it being so boggy n bad for the 3.5 that I didn't need it so he's sold it to someone else now shame I didn't know you wanted it bud. I thought of getting it n selling on but when I was told they're common I didn't bother. Dammit!

[mgbv8]

Bugger!!
Never mind. Worth a shot eh?

Regards
Pel