Engine Rebuild Spec advise needed.

[mr scoops]

Right then.
I've just bought a 1641 engine that I intend to split and rebuild for Superdry.
I want some extra ponies and also some extra torques so I can run the 1303s gearbox I have ready to go on there too.
 
So the plan is, and I already have these parts, but I'm now being advised not to use them (apart from the IDF's).
 
Strip the engine.
 
Fit a 78.4mm Stroker Crank.
 
Fit a Scat C25 Cam
 
Fit 1.25:1 Ratio Rockers
 
Fit CB Los Bandito's head (041's with 37.5mm and 40mm valves fitted)
 
Fit In/Out oil pump to use an external filter and mount an oil cooler.
 
Buy and Fit 40IDF Carbs.
 
I've since been advised
a)  The 1641 barrels are too thin and will give me overheating issues. If this is the case I have a brand new set of 1584 pistons and barrels so will fit these to give myself 1801cc.
 
b)  The cam is the wrong grind for what I want (more focussed on torque increase than hp increase)
 
c)  The CB Bandito's heads will need major porting and the slightly enlarged valves are not going to work with my build.
 
d)  The In/Out Oil Pumps are woefully inadequate and will not be up to the job.
 
e)  The ICT's I'm currently running are not man enough for an 1855cc (even with enlarged jets) and I need the IDF's. This kind of makes sense but I thought I'd include the comment here whilst I'm at it.
 
I would appreciate any assistance from anyone with engine building experience as this will be my first build and I don't want to bugger it up!

 

[67panel]

dont agree about the 1641 p&bs ,if you where thinking of 1679s then yes to thin ,just need to make sure your cooling system is up to scratch.full flow oiling yes .cant say about cam and heads cos not seen them or used them but would say if your building a torque engine then smaller valves /ports will help.you also need to think about compresion ratio 8.5 -1 ?you say valves to small but peeps build 1776s with stock heads and they work ok.what sort of hp you after?with the stroker cranck you will need cb rods for clearance as well as cam with clearance.phone James at Stateside he will help and he keeps cranks and rods in stock.

 

[Trikky2]

For torque an fk7 or fk8 with ratio rockers, wide mouth tubes and stock valves will work well - dont forget you will need to semi hemi cut the stock heads to get the cc up for the right deck height - I dont recommend going the cheapskate shims route for deck height.

 

[mr scoops]

Are you saying to ditch the CB Banditos then?
I was going to do a mild port and polish job on them.

 

[Trikky2]

Well if you already have them then use them. It just means slightly less torque at low revs and slightly more power at higher rpms :mrgreen:

 

[alex4057]

Right then.
I've just bought a 1641 engine that I intend to split and rebuild for Superdry.
I want some extra ponies and also some extra torques so I can run the 1303s gearbox I have ready to go on there too.
 
So the plan is, and I already have these parts, but I'm now being advised not to use them (apart from the IDF's).
 
Strip the engine.
 
Fit a 78.4mm Stroker Crank.
 
Fit a Scat C25 Cam
 
Fit 1.25:1 Ratio Rockers
 
Fit CB Los Bandito's head (041's with 37.5mm and 40mm valves fitted)
 
Fit In/Out oil pump to use an external filter and mount an oil cooler.
 
Buy and Fit 40IDF Carbs.
 
I've since been advised
a)  The 1641 barrels are too thin and will give me overheating issues. If this is the case I have a brand new set of 1584 pistons and barrels so will fit these to give myself 1801cc.


PIFUL, they will be fine,


 
b)  The cam is the wrong grind for what I want (more focussed on torque increase than hp increase)

cam choice is a difficult one, you would be best off looking for a engle120 or C35


 
c)  The CB Bandito's heads will need major porting and the slightly enlarged valves are not going to work with my build.

They will need hand p[orting and polishing btu this is were the most HP gain can be had, my advise is to spend the time and efforrt here, they are great heads when worked properly.

 
d)  The In/Out Oil Pumps are woefully inadequate and will not be up to the job.

Yes these are twong and not worth it, get the case proper tapped for a return and then use a shadek pump with an output on the pump cover.

 
e)  The ICT's I'm currently running are not man enough for an 1855cc (even with enlarged jets) and I need the IDF's. This kind of makes sense but I thought I'd include the comment here whilst I'm at it.

Again kinda agree, dellorto DRLA 36's or weber IDF 40's are the way to go, much more tunable and will be better all round.


 
I would appreciate any assistance from anyone with engine building experience as this will be my first build and I don't want to bugger it up!

Cheers

Alex

 

[mr scoops]

Thanks.
I was under the impression the C25 was similiar to an Engle 100.
Isn't a 100 (& C25) a mild cam that's going to help with more tourque?
The engine won't be revving higher than 4000rpm and the redline as far as I'm concerned will be 4300rpm.
I want a tourquey cruiser engine so I can sit at 65mph on the motorway without revving the tits off the van.
With a stock box I'm currently at 4000rpm doing 60mph

 

[K@rlos]

Would it be worth going to 90.5 barrels & pistons? The valve sizes should be fine IMO for torque, although I would say some delicate porting & polishing coupled with a decent cam would go a long way. IDF's or DRLA's too and you'd be on for a 'stump puller' as the yanks say

 

[mr scoops]

I initially intended to change the crank but stick with the 1600 barrels.
I've bought a good strong 1641 so intend to stick with that.
I agree, I think IDF's are the way to go.

 

[alex4057]

torque will be created by going for bigger cc,

the engle 100 and c25 are similar and will be fine if all you want is 4300rpm.

 

[mr scoops]

I'm new to engine building so appreciate the advice.
I'd read that as a rule of thumb an increase in barrel dia leads predominantly to an increase in bhp and an increase in stroke lead to an increase in torque.
Hence I'd decided to stick with the 1641 pots and stroke them with a 78.4mm c/w crank.

So, at the moment (further to this thread) I'm going to port and polish the heads, balance the bottom end and look for a pair of IDF's.

Subject of course to any additional advice which anyone would like to give.

 

[ZedBed]

I'm new to engine building so appreciate the advice.
I'd read that as a rule of thumb an increase in barrel dia leads predominantly to an increase in bhp and an increase in stroke lead to an increase in torque.
Hence I'd decided to stick with the 1641 pots and stroke them with a 78.4mm c/w crank.

So, at the moment (further to this thread) I'm going to port and polish the heads, balance the bottom end and look for a pair of IDF's.

Subject of course to any additional advice which anyone would like to give.

I thought this too, but then I drove a 90.5 1776 which had plenty of torque. And on the subject of carbs, it had a single std solex carb. I was very impressed.

 

[sparkywig]

Would that be one of Laurie's, Steve?

 

[ZedBed]

Would that be one of Laurie's, Steve?

It belongs to someone on here, I doubt it's an LP one, but I don't know. Having had a 1700 T4 engined bus and driven lots of 2L ones, I didn't think a std stroke 1776 T1 would be worth the effort. Now I know better, this had far more go than a std T4 engine. I was very jealous and seething with said jealousy, ordered what I hope will be an even better one - an LP 1955 wasserboxer crank special. :lol: Can't wait. 8) Leave it to the experts I say.

 

[mr scoops]

torque will be created by going for bigger cc,

the engle 100 and c25 are similar and will be fine if all you want is 4300rpm.

Perfect. Ditch the pump, tap the case, IDF's instead of ICT's and a port and polish on the Banditos!

Sorted, thanks!

Alan