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Sam
01-05-2002, 07:28 AM
Well I finshed the engine compartment last night, fresh paint, hoses, and a little rearranging. It will be nice to have my garage back. I have two questions regarding exhaust and ignition.


1. At what point does a motor need to have the stock ThunderBolt ignition changed. My engine builder says based on our planed upgrades the
stock ignition will be fine.
2. Basicly the same question as above only it applies to the exhaust system. In this case
also the builder said that the stock system will be fine. (straight 4" exhust, no mufflers)

Thanks
Sam

turbo2256
01-05-2002, 12:36 PM
Change out the ignition as soon as possible. The Merc ign only burns about 75 percent of the fuel to begin with stock. Put a Jaccobs on mine and it did all or more than it clamed (1 sec reduction in plainig time better economy and like 20 more hp). My 12 year old son even said when i fired it up at the launch "it doesnt sound the same". The MSD works great too and is a bit cheeper. Either way if you dont upgrad you will be loosing alot.

turbo2256
01-05-2002, 12:52 PM
Sam,
A lot depends on mod's to your engine. Headers help a lot Lightning Mfg makes a good set up for the small block and price isn't bad. They are SS
inner tubes and steel outer tubes. I wouldn't recomend them for salt water use, upon occasion would be ok. The stock stuff wont flow all that well I can give you figures on BB stuff. If you figure the cross section area of the manifold outlet and compare it to your 4 inch pipe. On a BB its like 4 sq in compared to 13 sq in for headers. My current BB 7.4 stock with ported edelbrock oval ports, headers would give me about 80 more fish power.

Sam
01-05-2002, 01:54 PM
Turbo, of the two which do think is more important exhaust or ignition. At first blush I would think ignition but that's just my uneducated guess.

Sam

BigGrizzly
01-06-2002, 01:38 AM
I have found in your case you need both. the ignition is margional at best and the stock is a waste. I like the tainless Marine, the actually rival the tube type on you application. Of the expensive tube type I use the CMI hedders. I have used the sport tube ones not the Elbow tops.

Randy

turbo2256
01-06-2002, 03:36 AM
The green flowing a bit short after going thru the motor. Been there and am there myself. Still dont know how radical the engine is and its a Chevy with the center exhaust ports which run hot
and is one of the weak points of the small block Chevy. I might go with the headers first there about 1200 for the Lightnigs. Thinking it would give you the most HP increase lower the back pressure and keep those 4 exhaut valves cooler. Griz the CMIs are great if it was a salt water boat they are great lightning has full pollished or satin full SS and many racers use either. The complete MSD system is less than half that with dist and box(6A Marine unit)but might cause those valves to even get hotter with out headers. The Jacobs unit is about 350 to 400 and uses your dist and is good for a few more HP than the MSD but it has a brain in it that measures the resistance it takes to fire each cylinder and sends each cyl just the proper amount to fire it( each cyl fires a bit different in any engine and changes with conditions driver, weather, etc....
If the Jacobs unit senses a miss fire it sends a jolt MSD could only dream about to fire it. Jacobs
also uses less energy to run. Now thatyour brain is spining a bit. The jist of this. I would go with the headers or Jacobs first choice or go MSD
and take it a bit easy untill you got the headers on. Just getting on plane is were the engine sees the most load and is most likely to detonate and heat up and can be more dangerous than top speed. Now you got some knowlege. Ok now one more thing we need to get togeather on your advance curve which will depend on what you have done to your motor for this season andwhich Merc ignition your running.

Sam
01-06-2002, 05:26 PM
Turbo, your right my head is spinning, the problem is that my knowledge only takes me so far. From that point I have to depend on questions and answers leading to a decision. With each question there might be several correct answers depending on who's speaking. I know my engine builder is trying to stick to the paln of building reliable HP within a given budget. The money part of it really isn't the big issue. We both agreed that there is a line you can cross. Once you cross that line you are better off starting from scratch ie: bare block. I am not interested in being the fastest out there just one of them. If you can give me a shout at work tomorrow I would love to talk to you.(248-335-4440 ext 25 I'll email you my home #)

Thanks
Sam

Sam
01-06-2002, 05:36 PM
Turbo, is there a problem with your AOL e-mail, my message keeps being rejected.

Sam