347 build

[Coupe66]

Hi guys,
I have decided to build a 347 bottom end to replace the 302  existing motor in my 66 coupe.

The current set up has AFR165 heads(58cc), weiand stealth intake, 1 5/8"extractors, MSD, 650 DP Holley. All of this I want to use on the new short 347. I realize this is not the best set up for maximum gain, but I am still keen to use them and see how it goes.
The existing engine goes fairly well, considering it has 9.2 to 1 compression and a 2500rpm stall with a small cam which I am unsure of the specs. Diff is 9" with 3.9 gears.
Recently I raced at willowbank and it ran 13.21 @104.7mph, with a very slow 1.9sec 60 ft time.
I would love to get a mid to low 12 with the extra cubes and more compression.
I will also be changing the converter to a 3500rpm and am wondering what sort and size of cam would be recommended with this set up?
Any feedback appreciated.
Cheers.

[GLENN 70]

A Hyd roller is the go if you are willing to go down that track . Let us know if you want a roller on just a flat tappet cam 1st . A 3.9 ratio is very low so I hope you are running 15 tyres .  Going to a 3500 stall will cause wheel spin with normal street tyres but good at the track with ET street radials . 13.9 is ok but 104.7 is good for a much better time like maybe a 12.9 to 13.1 range depending on traction .

[Coupe66]

Am happy to go whatever cam is required.
I ran a 13.2 and had good traction with E/T street radials. Just slow 60 ft with I think too small converter.

[shaunp]

Are the head 165 Renegades? . A 347 really wants 185 heads, but you can make do. I'd run about 10.5 comp and  you want something like an xtreme energy 274, but a 282 HR cam will help with those heads. Boofhead on here has some 347 stuff for sale at the moment such as a Scat rotating assembly, custom cam and some Canfield heads, probably put a 750 on it. Id suggest you get a 282XE ground on 110 centres rather than 112 this will wake it up

[GLENN 70]

Sorry I meant 13.2 not 13.9 .  With a 347 and an extra say 60 HP that means extra mph and that will be around 110 mph with more converter slip with a bigger hi stall . With 3.9 ratio gears with 26 inch tall tyres ? Will be around 5900 rpm and it might run out of puff before that with that combo . Hey what does your car look like as I go to Willowbank watching now and then .

[Coupe66]

Thanks for that Glenn.
Yes the heads are the new renegades and I am keen on going at least 10.5 compression. I will check out those cams you suggested.

My 66 coupe is red with white interior and I was up at Willowbank on the all ford day and saw you and 69ish, but got there late and did not get a chance to come up and introduce myself. As you know the little bit of rain cancelled the racing and I headed off shortly after.
I like my drag racing so hopefully a consistent mid to low 12 will be achievable with a new 347 combo.

[GLENN 70]

Yep it shouldn't be to hard . Get the 60 foot down to a 1.7 and an extra 6 or 7 mph and it will do low 12s    . Rodney and I will be at the track on the 3 sept

[shaunp]

The 282XE roller will also need some springs you'll want about 140+ on the seat, the cheapest way to buy these is via trickflow they are actually a PAC racing springs but cheaper to buy them From trick flow, I'll get you the number. I cant see why you wont get to low 12s with a 347 but it will need drag radials, I'v got a 2/3 finished 347 here if you want to have a look before I put the sump on. If your block is a pre roller buy some Howards link bar lifters they are the best Value and made by Morell, you'll also need to buy push rods the correct lenght, and fit a steel gear to the disy to suit the cam.

[shaunp]

[shaunp]

This one but get it custom ground on 110 centres if you can afford it

https://www.summitracing.com/int/parts/cca-35-522-8/overview/make/ford

Im using this one which is one grind smaller but with 1.7 rockers not 1.6 which gives it 600 thou lift. I had it ground on a steel billet and @ 110 centres. I'm running 195 comp AFR heads & and Airgap- 750 DP, but will be putting port injection on it down the track at some stage.

https://www.summitracing.com/int/parts/cca-35-518-8/overview/make/ford

The XE lobes are fairly aggressive in the ramps XFI more so.

[shaunp]

Here's your springs assuming 1.25 caps 150 on the seat 450 rate

https://www.summitracing.com/int/parts/tfs-16306-16/overview/

[shaunp]

Here's the lifters if you have an early block

https://www.summitracing.com/int/parts/hrs-91168/overview/make/ford

[Coupe66]

Thanks shaunp.
I will probably build a new short motor and not use my block as it is already 40 thou over. That way I will just transfer all the top gear over to the 347.
Will the afr165 springs not be adequate for the suggested cam?

[Coupe66]

Are the head 165 Renegades? . A 347 really wants 185 heads, but you can make do. I'd run about 10.5 comp and  you want something like an xtreme energy 274, but a 282 HR cam will help with those heads. Boofhead on here has some 347 stuff for sale at the moment such as a Scat rotating assembly, custom cam and some Canfield heads, probably put a 750 on it. Id suggest you get a 282XE ground on 110 centres rather than 112 this will wake it up

The 282XE looks good on the specs. Can you explain the 110 centres and how this will be beneficial?
I am still learning a lot about cams and how differences can affect performance.
Cheers

[shaunp]

So by bringing the center tighter you increase the overlap which is what you want on a carby engine. They grind them on 112 so that they work with factory injection better as there is less gas reversion on overlap. A tighter lobe center will make it more lumpy at idle and not some Vacuum out of it but but 110 centers are still fine in a street car. But it also increase the power and torque in the mid range. In real terms and even tighter centre of say 108 is great but this is more of a track cam then a street cam then. So to a forced induction engine is better with a wider center so you dont blow the fuel charge out the exhaust on over lap

With respect to your current springs you'll need to find out what they and test them, but generally if you dont have the AFR comp option package they are a flat tappet spring. With a roller cam the lift acceleration is so great you cant control the valves at around 6k without a good spring, the springs I listed are similar to what AFR use on the 195cc comp package which will hold a decent HR cam to 7k plus

You'll find a HR cam will make power similar to the next size up flat tappet but with a nicer idle.

[Coupe66]

Thanks for that shaunp.
Makes more sense now. Will keep that in mind when choosing the cam.
Cheers.

[shaunp]

Comp will do a custom grind cost about $150 more you just tell them to want, but on 110 centres. If you get a custom grind get it on a -9 steel billet

[GLENN 70]

Yep that's why nitros,blown,and turbo cars run a 114 lobe centre .

[boofhead]

Do it once and do it properly.
Sell all your gear and buy a better top end combination and cam set up.

The 165s are great for a 302 but not so much for a 347/351 - will they work - yep but you leave a lot on the table. When you have smaller heads you need to run larger cams to get the air into the engine that it needs. The problem is the ports go sonic which restricts them so a longer duration cam is needed -  you need more overlap to pull as much air as possible which makes it very peaky - now you have no bottom end and sonic affects top end so overall the risk is it becomes a dog. Only fix is the top end kit which you should have purchased at the start and then you more to a small camshaft to make it fun to drive again.

A generic formula for a 347 is 195cc + head, 225-230 deg at 50 cam, approach 600 thou lift,  110 centers on good lobes, VicJrn intake with a 750 double pumper. 1 3/4 headers. Follow this basic formula it will be reasonable cost - have approximate 450hp at 6000+rpm and be a bag of fun.

Note: You have the gearing and stall so that is a great start.

[boofhead]

Yep that's why nitros,blown,and turbo cars run a 114 lobe centre .

True but there is more to it. Simply as the heads are more efficient you can reduce the overlap and change the intake opening event. If you ran say a 240 High port on a 347 (contrived example) then I would expect wider centers would work far better (aka much wider power band) than a tighter center cam.

[shaunp]

Agreed Boof I've been down this exact path as you know, and I sold the 165 heads and started fresh, in this case I'd just sell the whole engine as a package

[boofhead]

Come and talk to me I might just have some gear that will definitely reach your goals

[GLENN 70]

With your combo on a 347 that's why I said it might run out of puff . The heads ,intake manifold and carby will be too small for good HP . Your combo seems to work quite well now with a 105 nearly mph . Get the 60 foot down to a 1.6 or 1.7 and you will be in the 12s  . Do you run a spacer under the carby ? . Nothing wrong with a 302 .

[Dwayne]

Bookmarking this one, thanks guys.

[GLENN 70]

Going faster isn't cheap . A different package will put you down into the high 11s or very low 12s ,and that's still keeping it mild . My combo is mild and good for high 11s .