Carburettor Conversions - Distributor Info

NZGTRA17 · #1 10-08-2008, 07:51 PM

I have converted my engine over to a carb and in the process had to fit another distributor. Initially I purchased a Pro-Comp HEI distributor to get the car up and running.

Worked OK for first dyno runs but spark became erratic on multiple cylinders (timing light showed this up on several cylinders). Engine would still run but it was impossible to time. Other issues were size of HEI requiring mandatory fitment of 1" carb spacer so that aircleaner would fit and lack of adjustment ability for centrifugal advance.

I have just fitted an MSD Pro Billet dizzy (pt no 8579) and a 6AL2. Absolutely magic as car is far easier to start, can now remove spacer if required and advance curve is fully adjustable.

I highly recommend the MSD combination if you are converting to carburettor.

Cobra4B · #2 10-08-2008, 08:55 PM

^ That's what Ed Curtis spec'd out for our top end and carb conversion setup.

NZGTRA17 · #3 10-08-2008, 09:14 PM

Brian,
yes not surprised he recommended the MSD gear. I had a similar setup on my last race car. Tried to slum it for a start on this engine but to no avail !!

I was interested to see that Ed recommended AFR 165's for your engine. I agree that they would be absolutely the best runner size head for solely a 302 application, but I thought you were thinking of stretching the 302 out to 347 in the future? If so, then perhaps fitting bigger 185 runner heads would be worth looking at to ensure that you get the best from the bigger engine later on without having to buy another set of heads. Thats why I went for 185 cc runners on the Brodix' CNC's that I have fitted, as I will go to around 347 - 358 in the near future.

There are some interesting dyno numbers on the AFR website where you can compare output of 165's and 185's on a 302. That really helped me with my selection (as the compromise is not to much of an issue). I also found the Ford Muscle website reasonably useful for engine combination stuff.

Also interested in the duration (.050" lift numbers) and lift of the cam that Ed recomended for you?

Kel.

Cobra4B · #4 10-08-2008, 09:58 PM

Ed said that for a medium effort 302 or even 347 the 165s would be fine... to run NASA ST2 we can only make about 315 rwhp for our car weight so that's what we're working around.

The car will only be an HPDE car for at least the next year so we wanted reliability. I think Ed's cam specs are secret, but after lots of research etc. I trust his expertice when it comes to making a 5.0 perform. We told him we wanted around 300-320 rwhp and that reliability was our top concern and he recommended a setup from there.

AIMidwest27 · #5 10-09-2008, 01:30 PM

Quote:

Originally Posted by Cobra4B

Ed said that for a medium effort 302 or even 347 the 165s would be fine... to run NASA ST2 we can only make about 315 rwhp for our car weight so that's what we're working around.

The car will only be an HPDE car for at least the next year so we wanted reliability. I think Ed's cam specs are secret, but after lots of research etc. I trust his expertice when it comes to making a 5.0 perform. We told him we wanted around 300-320 rwhp and that reliability was our top concern and he recommended a setup from there.

What are you using for a "competition" weight and what modification factors are you using to come up with 315 rwhp ?

Cobra4B · #6 10-09-2008, 04:00 PM

I figured it out awhile ago and I'm not even 100% sure I'm right, but I used 2900 w/ driver. It helped me to figure out if I wanted to build the 302 or do something larger or do a LSX swap.

FYI I got the cam today and got the cam specs. It's a 218/228 .570/.536 111 cam. States, "This camshaft is designed for naturally aspirated, open track applications. Other uses will not be optimized if this cam design is used. Powerband is roughly between 2500 to 6250 rpm with 302-310 cubic inches, gear vehicle accordingly."

NZGTRA17 · #7 10-09-2008, 06:11 PM

Brian, your cam is similar to what I selected. I am using a custom ground Comp Cams billet with 224 / 232 degs at .050" and .560"/.570" lift. Required piston notching with valves I am using (2.02"s) but this was no biggie and I did myself using an Isky tool.

AIMidwest27 · #8 10-09-2008, 06:37 PM

Quote:

Originally Posted by Cobra4B

I figured it out awhile ago and I'm not even 100% sure I'm right, but I used 2900 w/ driver. It helped me to figure out if I wanted to build the 302 or do something larger or do a LSX swap.

FYI I got the cam today and got the cam specs. It's a 218/228 .570/.536 111 cam. States, "This camshaft is designed for naturally aspirated, open track applications. Other uses will not be optimized if this cam design is used. Powerband is roughly between 2500 to 6250 rpm with 302-310 cubic inches, gear vehicle accordingly."

I have the same cam, stock bottom balanced and good ARP fastners. I did AFR 165's/cam/intake from Ed. 650 holley DP. 300 rwhp/300 torque and it all done at 5,400 rpm. Wish I had done a Stroked 351, because even using 2900 lb competition weight (and that is going to be almost dead empty on gas), you can still make up to around 350 to 370 rwhp for ST2 (depending on modification factors).

Cobra4B · #9 10-09-2008, 08:23 PM

^ Well shoot... sounds like the same motor we're building, but we're not going to touch the bottom-end this go around. I'll let you guys know how ours comes out. We're hoping for at least 300 rwhp, more like 320, but anything's better than an anemic 250 crank HP.

panozracing · #10 10-09-2008, 08:33 PM

I own 2 GTS's with the ABS bodywork and with the gas tanks pumped dry the cars weigh 2778 and 2773.

AIMidwest27 · #11 10-09-2008, 08:48 PM

Careful, rod bolts in a stock bottom end are a real week spot, not likely to take "race" (or hard OT) conditions. Also, you should consider good push rods, the stock ones are very low quality (I assume you did the valve spring and roller rocker upgrade Ed recommended).

Cobra4B · #12 10-10-2008, 09:51 AM

Quote:

Originally Posted by AIMidwest27

Careful, rod bolts in a stock bottom end are a real week spot, not likely to take "race" (or hard OT) conditions. Also, you should consider good push rods, the stock ones are very low quality (I assume you did the valve spring and roller rocker upgrade Ed recommended).

So I've heard... the motor will get spun to about 6000 rpms max w/ a 6200 rpm limiter. Most have said if we want to spin to 6500 or 7000 then we need to replace the rod bolts. Yes, we've got hardened pushrods, new lifters, roller-rockers and new springs on the AFR 165s.

If this motor takes a crap we'll build a new one from scratch... I figure it's lasted this long w/ a bunch of bozos driving it

Blue Streak 21 · #13 10-11-2008, 09:09 AM

Quote:

Originally Posted by Cobra4B

If this motor takes a crap we'll build a new one from scratch... I figure it's lasted this long w/ a bunch of bozos driving it

These 302's are pretty stout. My stock bottom end motor survived two over rev conditions while up at Miller. This Bozo hit 3rd while attempting to up shifting to 5th at 5700 rpm on the front straight. Sever bummer. I have no idea how high the revs were, but they were way over 8000 before I got the clutch back in. The engine never missed a beat. Although my heart did on both occations. I was very surprised that no valves hitting pistons, and no broken connecting rods. I was amazed.

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