#1  
Old 07-22-2022, 09:34 AM
bb400ho bb400ho is offline
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Default need a little help with timing?

hello i recently installed a rebuilt 250 sprint engine in a 67 tempest sprint that i bought on this forum. I finally got everything together and running . it runs decent but doesn't seem to have the power that it should. here are a few details, its a zh engine, and it has a bossbird pulley . i used the distributor and the carb (7026261) from the 230 engine that was in the car originally. its hooked to a 200r4 with 355 gears i also installed a pertronix module. i ran an additional wire that supplies 12 volts to the coil. I have played with the timing some and it is much better that before but i dont think its where it should be power wise. im wondering if the distributor would have a different timing curve and also if the carb would have different jets and idle tubes.any help is greatly appreciated
thanks Bryan

  #2  
Old 07-22-2022, 10:50 AM
sprintbird sprintbird is offline
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What is your ignition timing set at?

  #3  
Old 07-22-2022, 10:58 AM
bb400ho bb400ho is offline
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Default timing

i started wit 5 btdc and im at 12 btdc now and that seems much better. i also have tried ported and manifold vacuum and the manifold seems better.

  #4  
Old 08-01-2022, 09:42 AM
bb400ho bb400ho is offline
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Default anybody have any ideas?

I've been playing with the timing /carb adjustment and the car starts pretty good cold, idles great when warmed up but it just has no lower end power. mid range and top end are pretty good. could this have anything to do with the adjustable cam pulley?

  #5  
Old 08-03-2022, 09:39 AM
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camerjeff camerjeff is offline
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Default

Yes if it has an adjustable cam pulley it can cause the issue. If your cam in "retarded" it will drop the low end torque, and in theory increase high end HP, You can try advancing the cam timing and see if it increases your engines low end torque.
On my stroker I retarded the cam timing 2 degrees and that seemed to be the sweet spot for that engine. But on a stock OHC-6 I did not find changing the cam timing to have any benificial effect.
That being said, if your engine has had the block or head milled during the rebuilding process, that will result in increasing the cam timing slightly compared to stock. And could be your issue. I have used offset dowel pins in the past to make up for this issue.

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  #6  
Old 08-03-2022, 01:31 PM
sprintbird sprintbird is offline
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Agree with Jeff. Another thing to consider is that these engines aren’t torque monsters by any means. The 230 was designed to rev more so than the 250 Sprint. So once you have tuned it as far as you can go, then the only option is to add more rear gearing. (3.90s or more) You May want to try a little more initial timing. I usually tell people to add 7 to 10 degrees on top of the factory setting. So 5 + 7 to 10. You can go to 15 BTDC. Also try putting in one step down/ lighter spring in the distributor to get it to advance a bit quicker. Somethings to try.

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