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283350 conversion

S

steve_j

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"I built a 350 chev engine fro

"I built a 350 chev engine from a seized CC 283. Then I built a skiboat, from scratch, to put it into. I used most of the 283 parts, including the intake manifold and carburetor (Rochester 4 jet, not quadrajet). I repaced the old ignition with a GM HEI ignition. The engine runs very cold with no thermostat. I have a terrible flat spot when I accelrate hard, from an idle. The accelerator pump, appears to be giving an ample shot of gas. So, what's the problem? Temperature? ...or maybe Jetting? Any thoughts would be greatly appreciated."
 
Could it be the advance of you

Could it be the advance of your distributor? Why are you running without a thermostat?
 
"Eddie I never had good luck

"Eddie I never had good luck with automotive HEI conversions to marine applications. The safety concerns aside, I would install a true marine distributor kit such as the kit from Pertronics. (Perfect timing curve) It comes with a complete distributor, coil and a quality set of marine wires. I run 10 degrees advance on a 350 chevy Chris Craft, AC MR43T plugs gapped @.040 and a Rochester quadrajet. The set up runs great.
Joe"
 
"Joe, Steve had the question.

"Joe, Steve had the question. Anyway, I'm not a big fan of electronic conversions to begin with and I dang sure would not risk any possible safety hazards to do it."
 
"Eddie The safety concern I w

"Eddie The safety concern I was refering to was Steve currently having an automotive HEI distributor in there, not a true marine (sealed, protected) ignition system like the Pertronics. Usually the advance curve is wrong on the automotive distributors. The marine ones are strictly mechanical advance (no vacuum) and are set up to deliver the proper ignition curve for maximum torque that a boat needs to get out of the hole.Thats why I thinks he's getting that hesitation. I am no expert, I simply let him know what worked for me on my Chris Craft."
 
"First of all, put a t-stat in

"First of all, put a t-stat in there! That motor is probably running so cold it's building acid in the oil that will eat the bearings and generate sludge. I'd be willing to bet it's also responsible for that flat spot.

Jeff"
 
"Joe, I hear you on both accou

"Joe, I hear you on both accounts. I think our friend Steve needs to reconsider the distributor situation."
 
"It sounds to me, like some of

"It sounds to me, like some of you are not familiar with the old Chris Craft configuration. These old 283's have no provision for a thermostat. They draw in fresh water, circulate it thru the jackets in the exhaust manifold (each side completely seperate), then through the head (not the intake manifold, it does not have any provision for cooling). The heads are drilled on the end, to allow the water out of the head and back to the exhaust manifolds to exit with the exhaust. The flow is restricted, by the fact taht the holes in the end of the heads are only about 1/2" diameter. This configuration has no re-circulation of water. I understand that there was a conversion kit to include a thermostat for these engines but some die-hard Chris Craft guys say that it isn't worth trouble and that there is a risk of premature engine failure, caused by some form of malfunction in this conversion."
 
"i have two 283-f in my 67cc a

"i have two 283-f in my 67cc and they both have thermostats [147-f], my overheating problem was caused by exhaust manifold that were 75%clogged had to remove them and rod them out since then alls been fine"
 
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