would stage 4 require a block rebuild?
Discussion
ok, so i've got some huge engine work lined up, this consisted of basically large carbs and a spikey cam to couple my gas-flowed head on a standard block...
but now i've seen an even better head which is tuned to a Stage 4 specification...
this includes twin 45DCOE carbs, Kent fast road/race cam, oversized valves and some porting work to boot!
i was wondering if this would bolt on my standard block quite happily or whether it would never mate properly as the standard pistons/crank are gonna have trouble "keeping up" with the trick top end...
so will i need my block rebuilt with slightly "racier" pistons? if i don't, would it be adviseable to do it anyway as my block's done 72,000 miles!?!
my engine's pretty standard anyway being the Vauxhall/Opel 1979cc cam-in-head 8v iron lump
anyone in the know or with experience i'd be interested to hear your thoughts!!!
cheers,
Gareth.
but now i've seen an even better head which is tuned to a Stage 4 specification...
this includes twin 45DCOE carbs, Kent fast road/race cam, oversized valves and some porting work to boot!
i was wondering if this would bolt on my standard block quite happily or whether it would never mate properly as the standard pistons/crank are gonna have trouble "keeping up" with the trick top end...
so will i need my block rebuilt with slightly "racier" pistons? if i don't, would it be adviseable to do it anyway as my block's done 72,000 miles!?!
my engine's pretty standard anyway being the Vauxhall/Opel 1979cc cam-in-head 8v iron lump
anyone in the know or with experience i'd be interested to hear your thoughts!!!
cheers,
Gareth.
I have a stage 4 head on my Golf and at the time it was done the pistons were bored out and replaced. I'm not sure if it is entirely necessary (somebody with more experience will likely tell you soon) but if your going to do it on a car with that mileage, then surely it's best to at least recondition the pistons, and if your doing that, then boring them out is only a small step away 
Gareth,
Just a quick question: When was the last time you completely stripped and rebuilt the brake-system on that Cav? It's now more than 20 years old, and you're moving onto engine mods
Obviously if you've already done the brakes, then you can tell me where to go, and I'll buy you a drink on Monday!
Sheepy
Just a quick question: When was the last time you completely stripped and rebuilt the brake-system on that Cav? It's now more than 20 years old, and you're moving onto engine mods
Obviously if you've already done the brakes, then you can tell me where to go, and I'll buy you a drink on Monday! Sheepy
If the bottom end's in good condition then it won't be necessary, but to make the most of all those top end mods it would be advisable.
Should the bottom end be verging on becoming 'worn out' then subjecting it to a large power increase and lots of revs will finish it off pretty quickly.
Best rebuild it with new bearings and rings (with rebore and crank regrind too if things look iffy) so you know you don't have to worry about it.
Even better to have the entire bottom end (crank, pistons, con rods and flywheel) lightened and balanced while you're at it. Won't give you any more power, but will improve throttle response and acceleration.
Should the bottom end be verging on becoming 'worn out' then subjecting it to a large power increase and lots of revs will finish it off pretty quickly.
Best rebuild it with new bearings and rings (with rebore and crank regrind too if things look iffy) so you know you don't have to worry about it.
Even better to have the entire bottom end (crank, pistons, con rods and flywheel) lightened and balanced while you're at it. Won't give you any more power, but will improve throttle response and acceleration.
Sheepy said:
Gareth,
Just a quick question: When was the last time you completely stripped and rebuilt the brake-system on that Cav? It's now more than 20 years old, and you're moving onto engine mods
Sheepy
fear not, about 18 months ago i had *BRAND* new discs, calipers, master cylinder and lines...
brake pads were new before Le Mans (still plenty left at service 2 weeks ago), and drums were tightened and new shoes at same service...
plus i've recently got some Ford RS Turbo vented discs that'll fit on my standard calipers (with spacers) that'll be bunged on either before/with engine mods...
whats more worrying is i'm likely to get the engine top notch *THEN* stiffen the suspension to cope!!!
want the power, then worry about the handling...
Depend on 3 things:-
1) Are the bearings etc you have in good condition. If not you may shorten their life quickly if you are using all that extra power.
2) Are your pistons split skirt type? If so they will not be able to take the stick.
3) Will the valves touch the pistons? You may need to pocket the pistons.
In all honesty don't bother. Stick with what you have, tune it properly and improve the grip of the car to put the power down earlier.
1) Are the bearings etc you have in good condition. If not you may shorten their life quickly if you are using all that extra power.
2) Are your pistons split skirt type? If so they will not be able to take the stick.
3) Will the valves touch the pistons? You may need to pocket the pistons.
In all honesty don't bother. Stick with what you have, tune it properly and improve the grip of the car to put the power down earlier.
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