What to do?

Stu E · Post by **Stu E** » Tue Aug 14, 2012 4:57 pm

Hi all.
I'm after some opinions as to which is my best way forward.
Currently I have a 3.5 with an Offy manifold and Edddy carb, EFI heads that have had a little porting work on the intake side so the manifold matches the heads, but a standard cam.
I'm considering fitting a mild cam (probably something from Real Steel) or would I be better off getting a 3.9 and swapping the bits over. Not to bothered about how long it takes as it will be a winter project. Just wondered if I would notice the difference between a 3.5 and 3.9.
Just to add to the mix would retro-fitting EFI make any dfference?
Cheers Stu.

teamidris · Post by **teamidris** » Thu Aug 16, 2012 3:15 pm

I'm still not convinced by the 3.9 ? Definately more power, but it's still a re-bored 3.5 and an over-bored anything never seems a good idea, no matter what the engine. (even closer bores for head gasket to seal) So I wouldn't blame you either way, unless you took out a good 3.5 and put in a bad 3.9

No idea how good your carb is, but the hot wire efi is supposed to knock the socks off anything (as opposed to flapper system). But there again, I recon a good carb is better than a worn efi.
I'm pleased with my piper torque max. I'd be fibbing if I said I knew exactly how it compared to a standard cam, but it came down to a mental choice of bottom end power or top end power. I wanted Grunt

mgbloke · Post by **mgbloke** » Thu Aug 16, 2012 4:27 pm

What vehicle?
I have an MGB that I have been fiddling with for quite a few years.
I started with a 3.5 Rover SD1 bog standard on twin Su carbs then changed for a 4.0L with Econotune heads an Edelbrock with JWR manifold and a piper 270/2 cam. This made a considerable difference and transformed it into a very fast car. next I went 4.6 and a Piper 285 cam. Which made an even bigger difference not so much to the top end but pickup and driveability were amazing in such a light car. next i fitted merlin heads from real steel which made the engine really come to life right through the rev range especially top end with a solid 238 cam. Now it is 4.8 and stunningly fast.

My advice would be to go for a 4.6 and you will have a big smile on your face.
Mark

Stu E · Post by **Stu E** » Thu Aug 16, 2012 5:17 pm

Thanks for the reply.
The 3.5 had new rings, main,big end & cam bearings & cam 6000 miles ago. The eddy carb has probably done 5K. The heads were replaced 1000 miles ago. Good point about replacing it with a bad'n. Don't want to end up having to fit liners.
Cheers Stu

Stu E · Post by **Stu E** » Fri Aug 17, 2012 6:39 pm

It's in a Pilgrim Sumo.
Wasn't thinking about a 4.6 as then I guess I would have to change the box and uprate the brakes as well. If I was going to do that, I think I would sell the car and start again.
Just want a little more power, and wondered if anyone had done the 3.5 to 3.9 and noticed nuch of a difference.
Stu

Cobratone · Post by **Cobratone** » Sat Aug 18, 2012 1:39 am

Stu E wrote:It's in a Pilgrim Sumo.
Wasn't thinking about a 4.6 as then I guess I would have to change the box and uprate the brakes as well. If I was going to do that, I think I would sell the car and start again.
Just want a little more power, and wondered if anyone had done the 3.5 to 3.9 and noticed nuch of a difference.
Stu

I went from a standard 3.5 in a Sumo to a 4.8 putting out over 300 bhp and didn't need to uprate the brakes. The 'box lasted fine until I put it on a rolling road, I changed to a R380 after that. Pete (sidecarbod) also puts 300+ bhp through his sumo with std brakes. HTH

Stu E · Post by **Stu E** » Sat Aug 18, 2012 7:03 am

Cobratone wrote:
Stu E wrote:It's in a Pilgrim Sumo.
Wasn't thinking about a 4.6 as then I guess I would have to change the box and uprate the brakes as well. If I was going to do that, I think I would sell the car and start again.
Just want a little more power, and wondered if anyone had done the 3.5 to 3.9 and noticed nuch of a difference.
Stu
I went from a standard 3.5 in a Sumo to a 4.8 putting out over 300 bhp and didn't need to uprate the brakes. The 'box lasted fine until I put it on a rolling road, I changed to a R380 after that. Pete (sidecarbod) also puts 300+ bhp through his sumo with std brakes. HTH

High Tone,
I appreciate the reply

I have read about both yours and Petes upgrades over the years. My car is a MKII and although Den states the chassis is capable of handling 300+BHP, I wonder how the Cortina front brakes would like it?
Thinking about it did Robin ( Pocket Rocket) put a 4.6 in his MKII.

Perhaps a little more research is needed.

Thanks Stu.

Pocket rocket · Post by **Pocket rocket** » Tue Aug 21, 2012 1:12 pm

Not yet

- the 4.6 is in bits all over the garage and house - just waiting to be built.

Don't think I will worry about the Cortina brakes (or the rear drums

) but I'm not sure about the gearbox. Nice to hear Tony's experience - maybe I will just have to avoid rolling roads

sidecar · Post by **sidecar** » Tue Aug 21, 2012 4:01 pm

Dunno how good my LT77 was before I swapped my engine over but it did not last long after the swap. (I don't think it had been on the rollers at that point but I can't remember). I've just seen an R380 go for 100 quid on ebay, now it could have been knackered but equally it could have been OK. Other people have stated that the LT77 is OK behind a 4.6, I can't comment on their driving style but I will say I 'boot' my car otherwise what's the point.

I don't know what the Sumo MKII brakes are like but the 'Granny' ones on the MKIII are more than good enough. I bet if the ones one the MKII are in good condition, bled properly and have quality shoes, pads and disks they will be fine.

sidecar · Post by **sidecar** » Tue Aug 21, 2012 4:13 pm

Stu E wrote:It's in a Pilgrim Sumo.
Wasn't thinking about a 4.6 as then I guess I would have to change the box and uprate the brakes as well. If I was going to do that, I think I would sell the car and start again.
Just want a little more power, and wondered if anyone had done the 3.5 to 3.9 and noticed nuch of a difference.
Stu

With regards to going from a 3.5 to a 3.9 well Muscle Manta and I built one to replace a 3.5 lump and the guys was over the moon. BUT, and its a big BUT his 3.5 was totally knackered!

I think that it would cost a bit more to go to a 4.6 lump as the short engines for for more money but it is worth it over a 3.9. (But then there is the gearbox???)

One thing I will say is that building a decent spec Rover engine ain't cheap, really you want stage III heads with a 4.6 so that they flow well under the bigger 'lungs'. If you stick with low spec heads the rev range will be compressed because the engine won't want to rev.

You then weigh all this up and some people will say sell your car and buy another, the thing is it ain't always about the money, if you like your car, know your car, or built your car you might just 'want' to keep it anyway even if it isn't the 'right' thing to do.

Oh your manifold is not much good either!

Stu E · Post by **Stu E** » Tue Aug 21, 2012 4:19 pm

Dave in Plymouth has an LT77 behind his 4.6 in his SR and hasn't had any problems. Had a measure up yesterday as was thinking about changing the cam, looks like it would be easiest to take the engine out to do. Will keep an eye out for bigger engine.
Busy driving it at the minute.
Thanks for the replies Stu