Another timing question
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Lead Driver
Joined: Aug 2003
Posts: 6,305
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From: Boulder Creek, Ca
Another timing question
Yesterday, took 65 F100 for a test drive after installing a fresh rebuilt 70 302, seems to be running fine. Have the Dura spark electronic ign. With respect to dwell, manual refers to 'manufacturers decal' which is not a lot of help. Hooked up vac. guage and while moving the distributor and adjusting the idle mixture could only obtain max. of 16" of vac. but it was stable. Believe normal ranges is between 18-22". Have not used vac. gauge in past to set dwell but thought may help give point of referrence. Timing light indicates it's at 14 degress BTC with vac. advance disconnected. Using the back yard machanics timing ear, it starts right up, do not detect any mis-firing, and so far sounds good. Did the 1800 rpm for 15 min 'run in' per rebuild shop instruction then checked compression, all cylinders 110 psi. Should I be concerned with the low vac. reading and start looking for a problem, or will it improve as engine breaks in? Any suggestions, input appreciated.
dave
dave
Last edited by daveengelson; Jul 7, 2006 at 11:23 AM.
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Lead Driver
Joined: Aug 2003
Posts: 6,305
Likes: 18
From: Boulder Creek, Ca
Not sure if can answer your question. Went with low budget rebuild after the 302 it replaced cracked a cylinder wall within 12,000 after having it rebuilt. Expensive shop, as it would have cost more to sleeve the 1 cylinder than to purchase low end long block. Very little info from salesperson, but from casting # found it's a 68 289 block .040 over with stock 69 302 heads. All parts claim to be new, but imagine at $1300 they do not replace with high quality replacement parts. Have a Holley 4bl and requested slight upgrade on the cam. According to paperwork 'cam lift' is .281 int., and .296 exh. The 'valve lift' is .450 int. and .474 exh. Finally, the lobe ctrs are 108 int. and 116 exh. Misspoke mentioning dwell, should have referred to timing. Went with 76 spec's for Mustang ll with a 302. Not sure what to expect with this replacement engine, needed a quick fix.
dave
dave
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
Sounds like an RV cam. Only thing about the engine that I can think of is they don't have the cam timing right and/or it's got the Grand Canyon sized dished pistons the 72-77 302 had and you've got an 8 to 1 comp ratio. In that case you may very well have too much cam(overlap) for the ratio. It may very well need time to loosen up too. If nothing sounds out of whack, give it a few hundred to a thousand miles to break in.
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Lead Driver
Joined: Aug 2003
Posts: 6,305
Likes: 18
From: Boulder Creek, Ca
Dittled with it somemore. Set where most bang for the buck at 16" of vac. and readjusted timing, now at 12 degrees, and idle adjusted at 650 rpm. Only other thing can think of is perhaps carb to riser gasket replacement. Seems to run and sound okay. Will take your advise and check at 500 and 1000 miles. Appreciate the input.
dave
dave
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