Roller cam in flat tappet motor

[vertex]

I am in the process of gathering all the parts for an EFI conversion, most of the parts are coming off of a 1993 Thunderbird. I don't want to swap the whole motor becasue it has 125,000 plus miles on it. Since it is the 5.0 HO motor it sounds like I am going to need to swap the cam for the one in my motor.

I know roller cams have different lobe profiles than flat tappet cams so am I going to need to get roller rockers or is there another trick? I assume if I swap the cam and use the distributer from the same motor I will not need to change the distributer gear.

Thanks for the help

 

[RajinCajun]

Don't believe it will work for a couple reasons.. The roller cam lobes are not designed to make the standard lifters rotate as they provide lift, and I think the lobes ramp up to quick for standard lifters..

 

[trailpsycho]

What you can do is swap a 351W flat tappet cam in to achieve the correct firing order. Converting your block to a roller requires some machining and milling, I believe, so not probably what you are looking to do. Several folks have run the EFi with the older firing order with only minor idle problems. A 351W cam would slide right in and it would also provide what you are looking for firing order wise and you could increase the bottom end of your power band as there are soem great truck cams for the 351W. Best of luck.

 

[vertex]

That was going to be my next question about the 351 cam. I think I am going to go that route. I am sure everyone will have a different answer but is there any 351 cam you would recommend?

Thanks for the help

 

[vertex]

I have one more question. Can you run a flat hydraulic lifter cam in a motor with solid flat lifters? If not you have to replace the lifters and push rods but is there anything else?

I guess I am assuming my stock 302 will accept hydraulic lifters.

 

[bmc69]

I have one more question. Can you run a flat hydraulic lifter cam in a motor with solid flat lifters? If not you have to replace the lifters and push rods but is there anything else?

I guess I am assuming my stock 302 will accept hydraulic lifters.

All 302s are hydraulic lifter motors, whether roller or flat tappet. You can take the cam, lifters and lifter retainer from a roller motor and install in a non-roller block..you simply have to tap two holes in the center of the valley for the 'spider' that holds the lifter retaining clips in place. However, that's not something you want to do if yr not dealing with a bare block that can be properly cleaned of chips and such afterwards.

Roller ROCKERS are a different animal altogether and are not required for either the flat tappet or the roller tappet configuration.

Considering the age of the components in question..I would take the advice offered up on using a 351W cam that has similar lift and duration numbers to the 5.0 cam it replaces and new lifters..a fairly cheap kit.

 

[COBlu77]

On my first EFI conversion on my old 302, I used a Summit 351W cam that has the same profile as an Edelbrock Performer and many others. It always ran a little on the lean side and just didn't have the low end torque I was hoping for. After doing a lot of research especially over at www.corral.net, I figured out that I probably wasn't going to get the perfect cam unless I had one custom made. The Mustang computers were designed for the roller cams with more lobe separation than most after market cams. I think that the lobe separation is probably the most critical issue. Most stock EFI cams have about 116 degrees and most aftermarket cams designed for carburated engines have 110-112. I believe it throws the valve timing off from what the computer timing is. Having the MAF helps, but doesn't overcome all the timing differences anything but the stock cam creates. Other non stock Mustang things like headers, fan wash, no EGR, etc only confuse and compound the issue

Aftermarket cams run "OK", and better than an older carb, but not perfect. On my 351w conversion, I used the stock cam from a 93 Bronco/F150 5.8L with EFI. It doesn't work perfectly with my Mustang computer, but better than the Summit cam. I haven't done it yet, but the ultimate solution would be to get a custom tune done by a dyno shop or master a Tweecer.

 

[SaddleUp]

FWIW. The minor idle issues are very very minor. So minor that I couldn't tell a difference when I ran that way and on the two other 302 conversions I've done for others it was the same way. (We didn't swap the cam on any of them) A 302 with the Mustang EFI and the older 302 firing order will still have a great idle (Probably better than ever before) even though the injectors are out of sync. (The injectors still fire multiple times per revolution so the fuel will still be there) On the same note the stock Truck EFI fires an entire bank at a time and it still works out fine. Personally I would only go to the trouble of swapping the cam if the motor will already be apart. Otherwise I would leave it.

 

[eb66to77]

SaddleUp, That is a nugget right there. I love it when people post stuff that I would have to search for or possibly not know. Makes it so much easier.

 

[Broncobowsher]

On the cam swap issues, I have seen some glaring misinformation posted above and want future people to understand what can and can't be properly swapped, so...
Roller cam must use roller lifters, flat cam must use flat lifters. No exceptions.
Old block (pre '85 5.0 and pre '94 5.8) are not set up to accept factory roller lifters. If you want to run a roller cam in these blocks there are 2 options. Either use the stock late model lifters, dog bones and spider but you MUST use a special cam with a reduced base circle. This is because the lifter bores are shorter in the pre-roller blocks.
The other option is to use a standard roler cam, but you must use special retrofit lifters. These are linked and don't require the spider or dog bones of the stock ford parts. This is the only way to use the mustang cam in an early block using all off the shelf parts.

 

[Ed74]

I would like to perform an engine upgrade in the near future. Currently, I am running a stock 302 with 160k and terrific compression. Unfortunately, all my seals are leaking due to there age.

After reading this thread and others like it, it seems that it is efficacious to simply pull a roller HO engine, with EFI and serpentine components, from a mustang GT or comparable donor and have it rebuilt. Versus rebuilding my non-roller stock block, in addition to replacing the cam to match the firing order. I can only assume that a roller assembly is much more efficient than its predecessor. Are my thoughts correct? If so, what is a good price to pay for a complete 93 HO EFI, with the intentions of rebuilding the block?

Also, which route would you guys choose if you are building a highway driven daily driver, with a good balance of low cost, reliability, gas mileage, horsepower, and torque. (ALL WITHIN REASON OF COURSE)

a. Stock 302 rebuild
b. mustang efi rebuild, as mentioned above
c. complete HD 5.8L/351-4V ford racing crate engine, with intentions of adding efi in the future

I am leaning towards choice b, though c is very enticing. However, I do not want to cut my hood, add a body lift, or search and/or pay for expensive intakes.


Thanks for the info!! ;D

 

[Ed74]

Sorry for changing the emphasis of this thread. If necessary, I can start a new one. I thought it would be somewhat relevant.

Once again thanks guys

 

[natureboy300]

That was going to be my next question about the 351 cam. I think I am going to go that route. I am sure everyone will have a different answer but is there any 351 cam you would recommend?

Thanks for the help

Take a look at comp cams, they have their extreme 4x4 cams that are designed for low end power and are in the 351w firing order. I have the 250H which was the smallest they offered, I went that route because I wanted as much torque as possible from idle up. If I were to do it again id probably go to the next step up, it has great throttle response and great power from idle but with the 347 I think a step up wouldnt have hurt low end power. And although the specs on the cam say idle to 5500 seems as though it starts to drop off at about 4500 ish.

NB