18 replies to this topic

[lawn bowls]

a friend raced the vr ute at the drags for the first time 355 750 double pumper harrop manifold the cam is a crane h286 its got a turbo 400 3000 hi stall convertor 4.11 borg warner 28/10/16 slicks it only revs to 5500-5600 the car ran out of cam about 30 metres before the finish line went 11.9 at 111 mph,with this cam and 28 inch tall tyres 4.11 should it be at max revs about 30 metres before the finish line

[Shiney005]

I don't know, but I would have thought the 286 Crane would rev past five and a half grand. I had a Crane 292 in a 308 once and it used to rev all the way to valve float.

[Redslur]

Agree you need a bigger cam with 4:11's to power over the line. I had a 355 pulling 7k over the line with 4:11s.

[RedTaxi]

A stock 308 revs that far. Single or dual plane Harrop? Compression, Head work? 11.9 is still pretty good for those revs.

[UC308Hatch]

Your rpm & speed match the calculations for your tyre size

But according to the advertised cam specs, you should have more rpm up you sleeve


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[UC308Hatch]

Sorry that’s not real clear - it says 6200rpm

[UC308Hatch]

Being a 355 it probably drops the rpm down by 500rpm to 6700, maybe that’s all you get with that cam......

[UC308Hatch]

Sorry wish I knew how to edit, 5700rpm

[yel327]

Just look at a similar grind for a SBC and compare the rev range for a 302 and a 350 and you’ll get the answer. 4” bore with 3.48” stroke (350) or 3.75” stroke (377) don’t want or need to rev as hard as a 3” (or thereabouts) stroke.

[Shiney005]

I never thought of that, but makes perfect sense.

[lawn bowls]

it has about .490 lift it sounds resonbly healthy cam with open exhaust 

[Shiney005]

Timing?

[gtrboyy]

I'd be expecting it to atleast go 6-6500rpm with that cam/manifold/carb also be wondering if it's starving fuel up top or hei ignition not up to snuff...2 things found quickly holding back my vh sle with f280/355 4500 stally 4.5 gears etc

[Redslur]

It might rev to 6-6500 but would not have any power there. The H286 at best powers to about 5800rpm with my dyno experiences. I swapped out the 286 for a 304.  A much better cam and good performance up to around 6000rpm.

 

If your car isn't revving past 5500-5600rpm you have other problems like fuel starvation or spark issues. A 286 will go well over 6000rpm but as stated, rolls over powerwise well before then,

[gtrboyy]

Also check voltage 85amp alternator is enough for streetcar but something bigger like 120a or ls 140a alternators

[lawn bowls]

It might rev to 6-6500 but would not have any power there. The H286 at best powers to about 5800rpm with my dyno experiences. I swapped out the 286 for a 304. A much better cam and good performance up to around 6000rpm.

If your car isn't revving past 5500-5600rpm you have other problems like fuel starvation or spark issues. A 286 will go well over 6000rpm but as stated, rolls over powerwise well before then,

crane cams say I think it will rev to 6000 rpm with 308 but rev to 5500 with 355


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[yel327]

I think they mean make power until 5500rpm, not rev to 5500rpm.

[lawn bowls]

I think they mean make power until 5500rpm, not rev to 5500rpm.

most probably


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I think they mean make power until 5500rpm, not rev to 5500rpm.

getting a aspirated v8 to run 11s and reving to 5500 rpm is good


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[ozyozyozy]

Good no’s at the drags.
With those cam specs i would be surprised if it reved much harder in a 355.
Could try 3.9 gears, to give it more legs.