have a read of below from this page http://www.racingheadservice.com/rhs...ner-volume-faq
Although Racing Head Service® offers many different intake runner volumes in its cylinder heads, chances are that only one or two of them are appropriate for your application. When it comes to deciding which cylinder heads to order, it is important that you make a realistic judgment of your intended use for your vehicle.
Remember that velocity produces low rpm torque, and flow produces high rpm horsepower. So that 170cc cylinder head that you’ve been looking at -with its smaller, higher-velocity runners and valves, is going to accelerate well from a stop, produce lots of low speed torque, and be a great performer below 6000 RPM (which covers about 97% of all street-performance scenarios), but it may not reach the peak RPM you’d want in say, a drag race engine. Conversely, that high–flowing 235cc Small Block Chevy cylinder head that your friends tell you is all the rage at the local track is going to help your engine to rev like crazy and produce a ton of upper rpm horsepower, but it won’t build power below 3500 RPM -making it virtually unusable on the street.
Which is the correct way to go? Most experts will tell you that the answer is not “bigger is better”, but rather that you should run the correct heads for your application with components (cam, intake, exhaust system, etc.) that are designed to work with them. So if you’re looking to build an all-out race car that will never see street duty, that 235cc head with compression, cam, induction, and drivetrain to match will have you winning races in no time. If you just want to get an extra 20 or 30 horsepower out of your street vehicle, and you aren’t planning on performing 4000 RPM launches anytime soon, then that 170cc head is probably the best choice.
Just a little side note
Did you find out the cause of the 2 lobes wearing out
I think its slightly amusing that a bunch of a strangers on the internet who know nothing about this work other than what OP has written but seem to think the mechanic has done wrong and assumed he is the one who has messed up...
Last edited by 35kid; 14-10-2017 at 08:50.
Ok, my 2 cents before I do me hoovering.
I compared cams and like you say quite close etc, presume it is timed up and carb tweaked.
I have a wideband doofah and is invaluable.
Despite your concerns over builder I thought that even a possibly mismatched combo with now lower compression but high volume flow sucking the ******** out of low end performance should still spin the wheels up on such a lightweight car!?
Can a new issue with the gearbox cause this!? Can't see the fella pinching ya converter lol
Carb and kickdown cables opening fully? Pedal to the mat are butterflies fully open?
Try horsing it with 2 selected not D (don't use 1).
I have rudimentary knowledge so I just go for basics ;-)
Last edited by Kustom Jim; 14-10-2017 at 09:30.
"I'm not going to take this defeatist attitude and listen to all this crap any more from all these people who have nothing except doomsday to predict."
I think until someone can dissect all the relevant info and look at this objectively it's all supposition, I am a Ford 460 guy, have built lots of motors some of them gave me grief i.e. For instance Trashed lifters/wiped cam possibly caused by spring pressures, everyone appears to be trying to help but it becomes a bun fight, there are well documented engine combos on the Ford sites that will give you a proven combination notwithstanding all relevant procedures such as timing, fuelling, valve train etc done correctly, we all know an engine is basically an air pump, and the ability to shift this air/fuel efficiently will dictate the outcome, I think there is a lot of learning to be had out of this situation for all, so hopefully in due course we will find out, hope it works out. Dave
Last edited by TheWebDesignCompany; 14-10-2017 at 09:52.
It seems possible that the whole thing has just been really badly set up, as I adjusted the timing (retarded it by quite a lot) and it has made a huge difference.
I think it was sparking mid stroke or something, as it is now spinning the wheels again and driving with way more power.
It still doesnt have quite as much low end torque but this cam has 110 lobe separation and the last one had 109 with lower start on the power band and running to a higher rpm too, so I guess I just had a better cam before...
Do you know what initial timing you have now?
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