camshaft help

[1990turbo]

Last week my stock bottom end split in two. Sucks but i am going to put a 331 dart shp in it now. It has a 76mm turbo and im not sure what would be a good cam for this. it had a ford racing B303 should i stick with this? I will drive the car on the street mostly but will race it some also.

 

[FastDriver]

If you're looking for an OTS cam, you can't go wrong with the F303 in a boosted application.

In any case, without more info about the combination (heads, intake, etc...) I don't think anyone can give you a good answer.

I'm no cam pro. I always go custom. I have a 331 with AFR205s, and a TFS-R with box upper. My cam is a 600 lift cam with 228/224 duration at .050" lift. It runs great, has good manners on the street, and peaks at around 6300 rpm. I'm actually wondering if I'm getting valve float somewhere because it drops off pretty quickly after 6300. Anyway, the F303 is probably a better choice for a boosted application than the B. Still, you'll be leaving power on the table. Investing in a dart block is not a budget decision so do it right and get in touch with someone who does this for a living. just my $.02

When comparing cams for a turbo motor, take into account that turbo motors prefer minimal overlap. You'll also note looking at the latest turbo custom cams, that the grinds typically have a duration bias in favor of the intake - something you don't see in nitrous, blower, or na cams.

Chris

 

[FastDriver]

How much power were you making with your stock block? What was your timing and AFR under high-load throughout the RPM band?

Thanks,

Chris

 

[1990turbo]

i just bought the car in january spent an s load of money on it so i wouldnt have to work on it. it was shiny fast and i had to have it. i didnt really get much info on it no recepits etc. it does have a laptop fuel management not sure what brand ported cobra intake msd 7al-2 box. i did get a dyno sheet with it was 410 hp 485 torque at 9psi. heads are aluminum no name on them just a serial number 3686-3. so far im quoted about 4000 for a dart shp 331 with forged internals.

 

[90stang5speed]

I have the F303 in my 308 but its still up jack stands for now. Like Fastdriver said, a custom would probably be best but for off the shelf, the F303 is what I picked. Im no expert on this though.

 

[FastDriver]

i just bought the car in january spent an s load of money on it so i wouldnt have to work on it. it was shiny fast and i had to have it. i didnt really get much info on it no recepits etc. it does have a laptop fuel management not sure what brand ported cobra intake msd 7al-2 box. i did get a dyno sheet with it was 410 hp 485 torque at 9psi. heads are aluminum no name on them just a serial number 3686-3. so far im quoted about 4000 for a dart shp 331 with forged internals.

Wow, it's surprising that you split the block at that power level. Did it actually crack the block down the lifter valley, or did you just destroy internals? Did you get a boost spike, or was it still at 9 psi?

Which internals did you go with?

I think you need to pull those heads off and take a look all the way around them. Take pictures and post them. Guys on here might be able to help you identify the heads. Then you can decide whether to reuse them on your new stroker or sell them off and buy some bigger ones.

Do you have an idea on what kind of budget you're on?

I'd love to see pics of your ride too. Sorry for playing 20 questions. Getting another turbo guy on Stangnet is nice to see.

 

[90lxcoupe]

I'd go custom on that combo, or call comp and see what OTS cam will work. I used an NX282hr with decent results, that cam is good all around and really like nitrous and boost. but the custom is the way to go, just make sure the valvetrain is right.

If
I'm no cam pro. I always go custom. I have a 331 with AFR205s, and a TFS-R with box upper. My cam is a 600 lift cam with 228/224 duration at .050" lift. It runs great, has good manners on the street, and peaks at around 6300 rpm. I'm actually wondering if I'm getting valve float somewhere because it drops off pretty quickly after 6300.

What height were the springs installed at? We just did the cam in my motor and i was really suprised at how much spring heights affected what the actual spring pressures were. Im talking like 15-20 lbs of pressure difference with only .020 difference in spring height. There is much more that goes into the cam and springs than i would have expected. My motor went to the shop and was supposed to be a simple job, now its sitting there with the bare shortblock and finally ready to be re-assmebled.

 

[FastDriver]

I'd have to go back and look at the cam card. I don't recall.

 

[1990turbo]

It split right down the lifter valley through the main journals. Chunks fell out when i took out the crank. As far as engine specs go i have never built a motor so i am getting an education right now. I have only had the car a few months and dont really know how it was driven before i got it. I got on it a few times when it was dry so not many times here in Oregon this year. I was told the car went 10.9 at 9psi. not bad for a grocery getter I have been quoted right around 4000 for the short block with all forged scat internals. so im hoping to have a reliable motor to drive on the street because i really cant drive it very hard with the street tires gets a little hairy. i had slicks on it when i bought it now it has saleen sc chrome knock offs. I think with the good bottom end it should be pretty quick.

 

[clement]

I'm no cam pro. I always go custom. I have a 331 with AFR205s, and a TFS-R with box upper. My cam is a 600 lift cam with 228/224 duration at .050" lift. It runs great, has good manners on the street, and peaks at around 6300 rpm. I'm actually wondering if I'm getting valve float somewhere because it drops off pretty quickly after 6300.

it drops off because its a reverse split.

 

[Rick 91GT]

it drops off because its a reverse split.

For the original poster, why not step up to a Sportsman Block? I assume the new assembly would be "o" internal balance so youll need to plan on buying a new balancer, flywheel or flexplate, and the Dart block will need an aftermarket oil pan. The block also requires 1/2" headstuds, so if your heads are only 7/16" you will need to machine them out.

Can you take some pics, maybe we can ID the heads for you.

 

[FastDriver]

it drops off because its a reverse split.

Didn't know that was characteristic of reverse split cams. Can you explain why that is the case?

 

[clement]

because their comes a point where the exhaust doesnt evacuate as efficiently as the intake can fill the cylinder.