Scat stroker and Stipe cam - is there an issue?

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modernbeat
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Scat stroker and Stipe cam - is there an issue?

Post by modernbeat » Sat Mar 02, 2019 4:16 pm

Trying to read up on, and head off any issues with a stroker build, I read about a possible interference issue with the Scat stroker cranks and new Stipe cams where the counterbalance or rod would touch the cam. Apparently didn't happen with reground cams.

Is this happening? Or did someone just linebore the block too close to the cam? If it is happening, what is the solution without screwing up the timing gear mesh?

I looked for the post that noted the issue on the old forum, but couldn't find it even after multiple searches.
Jason McDaniel


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Re: Scat stroker and Stipe cam - is there an issue?

Post by Scottio » Sat Mar 02, 2019 6:01 pm

I did the stroked scat crank and 280 stripe cam 4 years ago. I had to relieve the engine block and form the oil return line so they crank didn’t hit but no problem with the cam. BTW I wouldn’t do the stroker crank again. I don’t like grinding away at the engine and that ugly pan spacer. I don’t feel much performance increase. I would have been way happier with a stock stroke scat.

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GrandpaFord
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Re: Scat stroker and Stipe cam - is there an issue?

Post by GrandpaFord » Sat Mar 02, 2019 6:55 pm

Jason,

What are you trying to do? Are you after more torque or higher rpm? Are you going to put this engine in a standard car or speedster?

Several people on the forum have reported that they wished they did not put in a crankshaft with longer stroke. That is required modification to the engine and did not give as much power increase as they had expected. (Search Model A crank.) If you are after ultimate performance you will need overhead valves. The stock cam only lifts the valves about 1/4 inch and the path for the intake air and exhaust is torturous which limits the rpm and horsepower but not the torque at low rpm. A Stripe 290 cam is probably the best choice as it will increase the valve lift and also advance the intake timing. Top that off with a high compression head and you will not need the stroked crank. This will be more than enough power for average cruising. Buy the Scat crank with the standard stroke and counter balance weights for far less vibration.


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modernbeat
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Re: Scat stroker and Stipe cam - is there an issue?

Post by modernbeat » Sun Mar 03, 2019 2:28 am

This engine is being built to haul a heavy load of camping gear, and two large guys, up steep grades. I'm looking for torque, and larger, stronger journals. I'm really after the larger journal size than the extra stroke. And I'm aware of the work required to stroke the engine, but there was a mention of the new cams being just large enough that they interfered with the stroker crank in an old post, and if it's true, that would require relieving the crank counterweight or rod. And if I had to do that, I'd want to know it before the first dry fit.

FWIW, I've built a few full pressure, inserted, hot-rod Model A engines. I'm familiar with the work it takes, and the (skimpy) results obtained. I see guys on the forum admonishing others that they shouldn't build their T's so they can go 60mph without noting that having the power makes it easier to accelerate in slower speed ranges, requires less shifting and less lugging (which is hell on engines). I doubt our truck will ever see much over 45mph. It's just not built for that.
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Re: Scat stroker and Stipe cam - is there an issue?

Post by Scott_Conger » Sun Mar 03, 2019 11:34 am

Jason

if you're looking for torque, you may wish to investigate Dan McEachen's 7.5 degree advanced timing gear. A high lift Stipe cam and Dan's gear get very good reviews for the increase in torque at bottom end with only minimal loss at top end.
Scott Conger

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Re: Scat stroker and Stipe cam - is there an issue?

Post by Kevin Pharis » Sun Mar 03, 2019 4:55 pm

Here is a pic of a Stipe .280 cam up against a shortened model A crank. There is about .100” clearance between the top of the rod and the root diameter of the cam. And about .300” clearance between the crank and the cam lobes. If there is a clearance issue, I would assume it is with the rods
AEB5BB37-DFF3-4343-B484-A0CF666732A3.jpeg

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GrandpaFord
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Re: Scat stroker and Stipe cam - is there an issue?

Post by GrandpaFord » Mon Mar 04, 2019 9:31 pm

Jason,

I don't think you have to worry about a broken crank with a new Scat crank, even with the stock size journals. The cranks that are breaking are old with lots of miles on them or have been ground wrong. I have a shaved low head on my car and a new Stripe 280 cam. Although I am not trying to carry lots of camping gear, my touring car goes up hills in high at about 30 to 35 mph and will run 50 on the flats, even with 5 passengers. (I don't usually drive that fast and it would probably go faster.) The only thing I would do differently is to use the Stripe 290 cam which has the advanced intake timing while retaining the normal exhaust timing, which would give you more torque at lower rpm. The biggest change comes about with increased compression ratio. I should note that I have 3 to 1 gearing in my differential. I think a Stripe 290 cam, a Scat crank, and a high compression head with give you the most bang for the buck without a lot of work. I should also note that I have a distributor. The car did not come with a mag or magnets. I also have a straight through NH carburetor. I am very happy with the performance of my engine.

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