Carb Or Carbs

[Jon Green]

Hi all,

 

Planning a bit of a tune up in the next week or so. I have ready an unleaded head to replace my old 4* head on my 2.1 pinto.

 

I've also got a FR34 cam to go in at the same time and a DGAS carb.

 

I've not done any work on the head.. Its an injection one.

 

Will this all work? does the FR34 profile require an uprated flowed head with bigger valves and will it work ok with the DGAS carb? I have dellorto 40's fitted at the moment but they are too thirsty!

 

Any one else running a similar set-up?

 

Cheers,

 

Jon

[Longboarder]

It will all work fine together and doesn't have to have big valves. The least you could do is tidy up the inlet ports at the last 1/2 inch before the valve seats and unshroud the valves by grinding off the lip around the valves in the combustion chambers.

 

If fitting a new cam make sure that all the other components are OK so it will start first go and run at 2000rpm or whatever the manufacturer advises for the first 20 mins. i.e. get the current setup running well with the DGAS before fitting the new head and cam or use the 40's on the new head till the cam is run in.

 

Nigel

[Jon Green]

Cheers Nigel,

 

Do you think I may get better fuel economy by dropping the dellorto's even with going to a hotter cam?

[geoff shep]

Am in the process of removing the head to fit a better cam on an old, and I assume leaded, head - is it easy enough to find and fit an unleaded head? How do I identify one and/or where can I get one?

[Guest docter fox]

identify? yes, they have egg shaped inlet ports (space for injectors)

 

get hold of? try your local scrappy

[Longboarder]

All injection heads with the cam shaped inlet ports are unleaded and flow better than carb heads straight out of the box. There is (should be) a letter/s stamped on the machined exhaust face of the head by number 4 port to show if a carb head is unleaded. The letters are P, PP, R, RR and L. (1.6 are M, MM, N, NN. 1.8 is S, SS).

 

Changing to DGAS from twin 40's even with the new cam should improve fuel consumption although I used to get an easy 30mpg on my dellortos.

 

Nigel

[Guest salty_monk]

Changing to a hotter Cam moves the power band up the rev range, twin carbs allow you to make the most of this...

 

One is not a compensation for the other... The 34 is the 310 isn't it? Probably be better on the 40's. The FR32. the 285 is probably best with the Dgas.

 

Any combination will work though, it's just how much benefit you'll see.... worth having a modded dizzy & also a vernier pulley with a hot cam.

 

I got less than 20 MPG most of the time on my DGAS on previous car, maybe about 22 - 25 on the new one if I'm lucky. Nigel's figures might suggest you'll get no improvement in mpg whilst compromising potential performance...

 

Dan

[Big Jim]

Now I'll agree with nigel and Salty on some of the above, but not all!

 

The "hotter" the cam, the more up the rev range goes your power band, as Salty says, but that means that it also goes crap at the bottom end on the rev range, ie. around town, etc. as you need to keep the "pot boiling" to make use of the cam.

now that's fine if you're a Stockcar driver or such, reving the nads off it, but not for cruising around the normal roads, so be very careful how "hot" you go.

 

Nigel says that he got 30mpg out of twin webers, well he's the only one!

Salty says that his drank fuel on the DGAS, but he never had it set up properly.

 

I had twin 40's once on my Pinto, had them set up on a rolling road, and the average consumption was 20mpg. They lasted a month, then they got sold at a loss, I went back to the DGVA and got over 35mpg when the fuel crisis was on, mind you I didn't press the pedal an awful amount! Average was around 30mpg with "normal driving" ie thrashing it from time to time.

When I put the FR32 cam in, I went to the 38DGAS, and it ran like a bag of spanners! (so don't think you can just plug & play) but once our Mr Carb wizz had looked at it, it went like sh1t of a shovel, and returned 25 -28mpg.

The only time a properly set up DGAS will loose out to twin Webers is at top revs, were the webers can give more fuel (obviously)

 

Ask your self one question; Why do you see such an awfull lot of "twin webers complete with Pinto manifold" on E-bay?

Because they drink bloody fuel like it's going out of fashion!

[Jon Green]

Ummm......

 

so what your all saying is that my hot cam will run on a DGAS but its not going to get the full potential and by fittig a hot cam im going to be reving it loads to keep the it 'on cam' so my fuel economy will be rubbish still.

 

Im thinking i may be best selling my FR34 and going for a milder cam like an FR32. The original cam is badly worn so needs replacing with something else anyway. Put the DGAS on and have it rolling roaded.

[Guest docter fox]

I've got an fr32 cam in the spare head and it was good for when I was using it, fine around town and a bit more top end, I'm rebuilding an injection head when I manage to get hold of one and I was thinking of trying something "hotter" than the fr32 as I don't do much around town etc what duration is the fr34?

 

salty did have his set up on a rolling road, and I think he got 121 bhp IIRC he just drives it like he stole it

[Longboarder]

FR34 is the sports injection cam, 265 duration but lots of lift. Very tractable.

FR32 is a 285 with slightly less lift but more duration and less tractable. More power at the top end.

I would say you should both stick to what you've got and Jon don't worry about economy unless the hood is intended as your daily driver. Fuel consumption is very much related to how you drive it. It will be fine on either carb but I loved the dellortos. Just lucky with the fuel economy.

 

Nigel

[Guest docter fox]

been driving around with dad lately and have been quite impressed with the fuel consumption, I normally manage about 25 mpg at best but driving steady does make more difference than I thought... not as much fun though

[Jon Green]

Nigel,

 

After I read that the FR34 was a sports injection cam I thought I'd better check the box again!

 

Im feeling a bit silly now as my cam (which has been under my bed for a long time) is not an FR34 it's an FR33 Fast road/rally.

 

Does that change everything? :boohoo: :boohoo: :boohoo:

 

Jon

[Guest trevor hooley]

fr33, is same cam as i gave eric. he has his on a dgas and is fine, but a properly setup set of twin dellortos would be better, we run them as yopu know and get around 25mpg, slightly less at full chat. it did the tresure hunt last weekend, and used exactly ( to within 5p ) the same ammount of fuel as adrian used on his dgas, and less than big kev..........

 

and im not gentle on it

 

karl

[Guest salty_monk]

Foxy is right;

 

I had a Piper 285 (FR32 eq) & the Dgas. It was RR by Sanspeed (a webber agent) to 121bhp or 99bhp at the wheels up from 89bhp on first run. Unleaded head. Standard 2l, no vernier pulley.

 

Yes I did drive it like I stole it... Best I ever got out of it was 160 miles on a full tank (RH 30 ltr) when I filled it up I got 28 litres back in.. comes out somewhere in the mid twenties I guess... Can't be arsed to work it out. I should say though that I was following (read slipstreaming) Drewsus most of the way to Llandow when I achieved that at 70 - 80mph.

 

Worst MPG ever was on Barkston heath, around 14mpg I think from memory.

 

Mine was definitely lovingly abused plus my dizzy had no vac advance. The new one I have has same setup but has vac advance which is the main reason the new one gets better mpg in my opinion...