My 347 Demo.

Duke · Jul 10, 2011

Currently running a Holley 600 DP. Working on a 700 to swap out with the 600.

So..with only 416 HP, my demo - http://www.youtube.com/watch?v=suEoGJJ5faA http://www.youtube.com/watch?v=aKpwmMufiOI

MikeH · Jul 10, 2011

And a BIG thumbs up!

Duke · Jul 10, 2011

Thanks -

The first video shows a 0 to 109 MPH in ~11 seconds. Thats with wheel spin in 1st and 2nd. Need more rubber.

64beam · Jul 15, 2011

Hi Duke,

That is some impressive acceleration considering your Hp and limited tyre size. Are you experiencing fuel starvation? Why the need to go to the larger Holley?

Regards, Robin.

Duke · Jul 15, 2011

64beam said:
Are you experiencing fuel starvation? Why the need to go to the larger Holley?

No, just replace all of the fuel line with 3/8 and installed a high performance pump.

Checking the internet of similar engine builds as mine that have posted dyno results. Five different engines with the same heads produced between 475 and 530 HP. They all are running carbs bigger than 750 CFM. I know that the 600 CFM is holding back my engine. The 700 CFM should produce much more than the current 416 HP.

64beam · Jul 15, 2011

Duke said:
No, just replace all of the fuel line with 3/8 and installed a high performance pump.

Checking the intent of similar engine builds as mine that have posted dyno results. Five different engines with the same heads produced between 475 and 530 HP. They all are running carbs bigger than 750 CFM. I know that the 600 CFM is holding back my engine. The 700 CFM should produce much more than the current 416 HP.

What Hp are you looking for? 530 Hp would be absolutely stark raving mad in a Tiger

. Did you look at the Holley HP range for your 347?

Duke · Jul 15, 2011

64beam said:
What Hp are you looking for? 530 Hp would be absolutely stark raving mad in a Tiger . Did you look at the Holley HP range for your 347?

500 would be awesome. Mad....YES, that is the point. Remember, it is right pedal dependent.

I am not aware of a Holley HP range. Most carb calculators for the 347 call for a 600-750 carb dependent on VE.

64beam · Jul 15, 2011

Duke said:
500 would be awesome. Mad....YES, that is the point. Remember, it is right pedal dependent.

I am not aware of a Holley HP range. Most carb calculators for the347 call for a 600-750 carb.

The Hp series are either a race (mechanical secondaries) or the street Hp (vacuum secondaries). The later are for light competition and street use. Check out the Holley site for the finer details. If you are spinning the motor up to 7K, they recommend the 750.

Duke · Jul 15, 2011

64beam said:
The Hp series are either a race (mechanical secondaries) or the street Hp (vacuum secondaries). The later are for light competition and street use. Check out the Holley site for the finer details. If you are spinning the motor up to 7K, they recommend the 750.

OK, got it. Both the 600 and 700 I am building have mechanical secondaries and choke. The 700 CFM has the 50cc secondary acc pump. Not spinning it over 6500, limitied to 6200 right now.

Jeff Scoville · Jul 22, 2011

Curious

Getting ready to finally start the restoration on the Tiger.
Not sure what condition the block is in (factory original 260)
My question is a little of your subject line, but as I was looking into upping the CI's, is it possible to turn the 260 block into a 347?
Will start a new post if you'd like but just thought you might "Be in the know"!
Awesome project by the way!

alpine_64 · Jul 22, 2011

Jeff Scoville said:
Getting ready to finally start the restoration on the Tiger.
Not sure what condition the block is in (factory original 260)
My question is a little of your subject line, but as I was looking into upping the CI's, is it possible to turn the 260 block into a 347?
Will start a new post if you'd like but just thought you might "Be in the know"!
Awesome project by the way!

Jeff,

Welcome back.. been ages since i have seen you on the board. As for your SBF question, i dont think it would be advisable to turn a 260 into a 347. The 260 doesnt apparently like overboring to go to 289 (they will run hot due to the different bore centres apparently) You can turn a 289 into a 347 and of course a 302 is an obvious and easy call.. but boring and stroking the 260 is probably asking for more trouble than you want.

If you have the orignal 260 and want to use it with more grunt look into a set of alloy heads and better manifold intake/exhaust and a roller cam setup with a good ingnition setup.

Duke IIRC at one point warmed over his original 260 by flowing the heads and putting in bigger chev valaves and hotter cam along with intake and bigger carb, that was using the orignial iron heads.

If you want a 347.. you are better off starting with a 289 (if you can get the rarer 5 bolt block that will save you bell housing hunting) or the 6 bolt 302, get a mexican block with the 4 bolt mains if you can, then get the appropriate bell housing and throwout/fork setups to adapt your original narrow ear 'box to it.

MikeH · Jul 24, 2011

I thought the 289 was a bored 260. And the 302 was a stroked 289.

alpine_64 · Jul 24, 2011

MikeH said:
I thought the 289 was a bored 260. And the 302 was a stroked 289.

While the 260's bore and stroke indicated that it would just be a larger bore, i believe the actual bore centres are different, so if you bore a 260 to a 289 many people have found they overheat due to issues with the water passages.

A 289 and 302 are basically the same apart from the stroke, you can make a 289 into a 302 by switching out the crank/rods without any worry. You can also stroke the 289s out to 331's and 347 etc.. apparently this was not originaly advisable on 289s due to the way they were cast at the bottom of the bores (shallower than on the 302 IIRC), but the new stroker kits use shorter pistons so the skirts wont cause issues on the 289s as they did on the original stroker kits.