Cam help

[V8luke]

Hi guys, could you help me out, I have about £150 to spend on a cam for my carb 3.5, thinking real steel as they seem good value. I'm looking for good low end torque to get me off the line but also a really rough idle as I love that noise, any advice please[/img]

[DaveEFI]

Think anything which gives you a good bottom end will also give a good idle.

[V8luke]

I was thinking stump puller from real steel I can afford that

[sidecar]

Think anything which gives you a good bottom end will also give a good idle.

Also anything that gives you a rough idle will have a long duration, long duration cams allow the valves to get close to the pistons during the 'on the rock' period, this could mean that the the pistons need cut outs to avoid valve contact.

Don't forget that you will need new cam followers.

[V8luke]

That's great guys thanks, appreciate the help, is the stump puller a decent long duration cam though?

[sidecar]

That's great guys thanks, appreciate the help, is the stump puller a decent long duration cam though?

Its name would suggest that it is not a long duration cam, however one chap I know as looked at the actual cam spec and it apparently has a longer duration than what most people consider to be Real Steels 'hot cam'...The Typhoon. Like I said, this is just what I've been told.

Basically you ain't going to get a cam which is setup for torque and low end BHP which sounds and runs like a rough idle long duration cam!

[kiwicar]

Hi
No the stump puller is a high lift moderate duration medium overlap cam, it really is aimed at giving a big "hit in the back" as it gets to the mid range For the asociated changes to get the extra lift to work you gain quite a bit across the rev range but it will roll off quite quickly after peak torque (the duration of the exhaust lobe being the same as the inlet does this and the 110 LSA). What are you using this engine in? is it a manual or an auto, what use will it be put to? Installing the Reasl steel Blower cam will give very slightly less peak torque and slightly higher top end output but a little more bottom end and a few more revs at the top for very similar changes to valve springs, spring seats, caps and guides needed for the stump puller. Basicly for the turbo cam you get less of a hit in the back but a wider power band. My only other comment is that with a 3.5 it is quite a lot of cam timing, I would think a set of "stage 1/2" or maybe "stage 1" heads but don't get the ports opened up anywhere appart from the push rod area. Long tube headers would also be essential. Don't fit big valve heads and I would use SUs 40 dcoe webers or injection with it as I think getting a 4 barrel set up on that cam and capacity combination would be a challange. One last thing, with either cam you will need a decent compression ratio, 10:1 as a minimum probably 10.75:1 or even 11:1 is better as you do not have a lot of capacity to keep the velocity up in the inlet tract so a head skim and tin gaskets, and check valve clearance.
Best regards
Mike

[cammmy]

If all you are doing is changing the cam, going for rough idle will essentially be a trade of power/torque for noise. You have to do work to get more mixture in the cylinders higher in the rev range to see any benefit.

As sidecar said. If you are changing the cam, factor in new lifters or you absolutely will trash it within a few thousand miles.

Unfortunately the two things you are looking for are somewhat mutually exclusive.

[V8luke]

It's going in my little wild bunch 23t bucket altered drag car, I'm a nostalgia drag racer.[/img]

[kiwicar]

Ah Hi
is this the purple chassis with yellow body panels?
As it is a rece car I take back some of what I said before, the real steel tormnado would be a good choice, with long tube headers and a mechanical secondaty 4 barrel (you aren't worrying about the transition from cruse so set up is easy) on an open plenum manifold start with Stage 1 heads but add bigger valves when you can.
If you already have the heads then the 234 would also work.
Are you at the pod on saturday?
Best regards
Mike

[DaveEFI]

Hi guys, could you help me out, I have about £150 to spend on a cam for my carb 3.5, thinking real steel as they seem good value. I'm looking for good low end torque to get me off the line but also a really rough idle as I love that noise, any advice please[/img]

In many ways, if the engine is otherwise standard, the stock 3.9 cam is pretty good. Most old RV8s have worn cams anyway, so it's likely to produce a big improvement over what you have.

[V8luke]

Hi, no not at pod at the weekend, alton towers with kids, I'm building the car at the moment, but it's called tee total and runs number w/b 89, I can't afford a tornado cam or I would go for it, my budget is £150 so I have to chose in that area

[SimpleSimon]

Hi guys, could you help me out, I have about £150 to spend on a cam for my carb 3.5, thinking real steel as they seem good value. I'm looking for good low end torque to get me off the line but also a really rough idle as I love that noise, any advice please[/img]

In many ways, if the engine is otherwise standard, the stock 3.9 cam is pretty good. Most old RV8s have worn cams anyway, so it's likely to produce a big improvement over what you have.

A valid point there Dave