How much power could these heads support?

topcatcustom · Post by **topcatcustom** » Wed Jun 30, 2010 9:48 pm

As title http://cgi.ebay.co.uk/CHEVROLET-BIG-BLO ... 23083cc870

Ally heads would obviously have a very nice weight advantage- but how good would these be on a 454-500ci lump, NA, meth?

kiwicar · Post by **kiwicar** » Thu Jul 01, 2010 9:29 am

Hi Tom
probably 550-650 or so depending on porting but I'll look it up tonight TBH I would be a little weary, he is not showing you the ports in any of the Photos, as they are the thing you really want to see that is a bit strange

If he knows his stuff then there is probably a reason for not showing you, ie they are pretty much standard. Also the valves are not very big so I would recon on the lower end of this estimate. With Iron heads it is the devil's own job to get someone to port them in the UK, it is hard work for the porter and generally they only want to port Ally heads. Personally I would save your cash and buy Ally ones. Realistically those heads are worth about £75. unless he is throwing in the rockers in which case buy them, strip off the rockers and flog the heads on Ebay for £75!
Best regards
Mike

topcatcustom · Post by **topcatcustom** » Thu Jul 01, 2010 10:22 am

Looks like the rockers are on there after re-reading the listing, Just wasn't sure how they would make for a starting point. If I actually got a blower then port size wouldn't matter so much until things got serious, however bigger valves would be nice- like I said though- starting point...

kiwicar · Post by **kiwicar** » Thu Jul 01, 2010 11:11 am

As you say a starting point, and again stick a blower on there and you should be able to blow up a gearbox of two (did you say methanol earlier

). No big block head is going to be very restrictive and there is a view that square port heads are too much for anything below about 520 Ci and big revs. looking at it again 600 ish BHP NA plus a blower, you will be over 1000bhp before you know it

Mike

kev_the_mole · Post by **kev_the_mole** » Thu Jul 01, 2010 11:25 am

Tom,

Go Methanol

When I was in Jersey last month (report coming Mike!) I was talking to a very nice man with a 1935 ERA 4D. This 2 litre supercharged hooligan ran on a mixture of

80% methanol
10% benzol
10% petrol
and two thimbles of acetone per gallon

His feet were on fire from the engine and exhaust, his nads were frozen from the supercharger between his legs and he stuffed everyone in the sprint and 1st hillclimb.

You know it makes sense

Cheers,

Ian

topcatcustom · Post by **topcatcustom** » Thu Jul 01, 2010 11:57 am

Sounds fun!!! It's all just thinking at the mo but now I've got a blown motor I want a bigger one!

CastleMGBV8 · Post by **CastleMGBV8** » Thu Jul 01, 2010 1:44 pm

Ian,

Look forward to the Jersey report, I have rather a soft spot for ERA's I think you have to be brave or mad to drive one in anger, back in the day of course there was nothing safer to compare it with.

Have a tape somewhere of the exhaust note of an ERA and the V16 BRM doing solo runs around Goodwood.

I think they were both Nick Masons cars, the BRM makes the most incredible sound.

Methanol has to be flushed out by running the engine on petrol afterwards otherwise the Methanol will seriously corrode an engine.

Kevin.

kev_the_mole · Post by **kev_the_mole** » Thu Jul 01, 2010 2:47 pm

Kevin,

This one was definitely driven in anger! I sidled up to him in the paddock after the first run and asked him if he had any children. It took him a couple of seconds to work out I was asking him to adopt me. He laughed and told me that the car was his wife's retirement fund but she'd be bloody old before she got it (They're both in their 70's). He was an old school gentleman racer and it was an honour to trail in his wake.

Driving a £1million+ car at 10/10ths all the time, talk to anyone and had time for everybody. Contrast this with the Jersey 'millionaire' squad with their 'man' to close car doors, polish the paintwork and hand round the smoked salmon sandwiches.

Next year it's back to the dual carriageway along the bay and I won't have the clearance problems with the Toyo's and I hope to stuff both Mr. ERA and the Jersey Champion

Cheers,

Ian

kiwicar · Post by **kiwicar** » Thu Jul 01, 2010 3:17 pm

On a similar line (but still meandering off topic) I have it on good authority that Nick Mason, caught in the right mood, is well worth chatting to if you see him (and he can often be found at sprints and owners club track dys). A mate was admiring a nice shiney red P4 ferrari in the pits at Thruxton some years ago and started chatting to the middle aged owner, next thing he knows he is in the passenger seat with the owner taking him for a very enthusiastic blat around the circute, it was only when he got back to the pit did his Dad (who he was there with) told him who the gentleman was and what the car was worth!
Best regards
Mike

Edited to correct the name of the Mason, makes a little more sense now (but no more interesting clearly)

JJMclure · Post by **JJMclure** » Thu Jul 01, 2010 4:16 pm

what's the big block going in TC? not going to shoe horn that bad boy into the mazda?!?!?!!

topcatcustom · Post by **topcatcustom** » Thu Jul 01, 2010 5:03 pm

No, its a "possible" plan for the near future, thinking about doing a drag motor, and really fancy an xjs body on it! Would prefer a BBF but there are half as many bits for them than chevys and they are twice the price

kiwicar · Post by **kiwicar** » Thu Jul 01, 2010 6:47 pm

Hi Tom
what blower are you thinking of? 10/71 or a big fancy screw type charger? or a pair of eatons from a Jag?
Mike

topcatcustom · Post by **topcatcustom** » Thu Jul 01, 2010 8:39 pm

I'd like to stick with a roots tbh, simple, inefficient but proven race history and the only blowers allowed on top fuelers. I think a screw type big enough would cost an absolute fortune, centrifugal not normally big enough, eatons are too small and cant be used wet. I was thinking an 8-71, most big block blower kits still use 6-71's which seem a bit small for a bb race motor.

bigaldart · Post by **bigaldart** » Thu Jul 01, 2010 10:31 pm

Tom,

Forget the pressure, just think of it as heavy air and you realise its even harder to turn the corners, hence porting is worth even more with a blower. Forget those heads, by the time they are done on Ebay they will be way too expensive for what they are, even the cheapest ali BBC heads are a much better option. S/H they can be had for around £6-700 a pair.

Alan

topcatcustom · Post by **topcatcustom** » Sat Jul 03, 2010 6:05 pm

Al- I was hoping they wouldn't get bid on at all

Also was thinking the roller rockers would be worth a few quid, I asked him to put more pics up which he has- look standard ports, not sure what make the rockers are though

I guess if I buy a standard bbc to start on then apart from the rockers the heads may be no different- are the valves standard size too?