Guest johnny1913 Posted March 3, 2003 Share Posted March 3, 2003 What is this I hear about something that will let you set up lots of timing until boost comes on and then timing is retarded? It sounds good for off-boost response. -Nate Quote Link to comment Share on other sites More sharing options...
Mudge Posted March 4, 2003 Share Posted March 4, 2003 Accel has a box that will do this, thier high voltage ignition has an optional $200 box that allows use of a MAP sensor and retard. http://www.hybridz.org/phpBB2/viewtopic.php?t=15245 That thread has the box in question. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted March 4, 2003 Share Posted March 4, 2003 The latest Summit catalog had more timing retard boxes than I could count. Quote Link to comment Share on other sites More sharing options...
Mudge Posted March 4, 2003 Share Posted March 4, 2003 There are cheapie boxes too, that just have a rheostat that work with MSD and other brand boxes too. MSD has kind of a bad name sometimes, some of thier stuff likes to spontaneously die, other times people have no problems. I haven't heard anything bad about the Accel boxes yet, nor thier coils. I really would like to have a fully programable timing map becuase I'm used to "having it all," but it gets more expensive that way. Quote Link to comment Share on other sites More sharing options...
Guest DaneL24 Posted March 5, 2003 Share Posted March 5, 2003 Why not modify a distributor to have less total advance, and then advance the initial timing. Then the peak advance will be the same, only you will have more off-boost response with the advanced initial timing. There are quite a few ways that you could do this. You could disconnect the vacuum advance, plug up all the vacuum lines, and just use the centrifugal advance. Since total advance is a product of both vac. and cent. advance, this will limit limit the total advance. You could also install slightly stronger springs in the advance mechanisms, or shave a little material off the cent. advance weights (just make sure they are balanced). This won't be as precise as an electronically controlled system, but it should work with some experimenting and a few adjustments. A lot cheaper too. Quote Link to comment Share on other sites More sharing options...
Guest DaneL24 Posted March 5, 2003 Share Posted March 5, 2003 Actually, disconnecting the vacuum advance on a distributor won't help to reduce the total advance. Since a turbocharged motor produces positive manifold pressure, the vacuum advance wouldn't work anyways. Another cheap idea I had was to remove the vacuum advance and build a boost diaphram with a pushrod to shift the breaker plate toward retard as boost increases. You could build the boost diaphram with some pipe for a cylinder, a small cylindrical object for a piston (wrap with tape and lube with grease for sealing), a spring to regulate the piston position by resisting the PSI, some pins as retainers for the spring and piston, a flexible pushrod leading to the breaker plate, and a hose to the intake to deliver boost to the diaphram. I'm not sure if this would require any kind of breaker plate modifications. Then you would just mount the diaphram to something, the valve cover would probably be a good place to mount this. It might be a little tricky, but maybe you could even use the boost diaphram to shift the whole distributor housing. For example, you could weld an arm onto the distributor housing or mounting brackets, and using some extra nuts, washers, lock washers on the dizzy mounting bolts, not to mention some grease, you could make it so the whole dizzy housing would shift without the risk of the distributor riding up and disengaging the shaft. Probably would be a good idea to have a return spring on the dizzy housing, and maybe an adjustable bolt to press againt the bracket so the initial timing isn't messed up (kind of like an adjustable throttle stop screw, only it stops the dizzy housing from rotating the wrong way). Then you could make the pushrod and the bracket that it connects to adjustable, so you could have a little bit of tuning ability as you adjust the boost. This would take quite a bit of fabrication, but it is possible to do, and would still be a lot less expensive than an electronic system. It would be a good idea to get a guinea pig distributor to try this on, no point messing up a perfectly good distributor if the experiment fails. Quote Link to comment Share on other sites More sharing options...
Guest Phil1934 Posted March 5, 2003 Share Posted March 5, 2003 If old style Chevy dist., use a dual vacuum advance can off a '68 Pontiac. It will retard under boost if you hook your manifold to the outer inlet and leave the inner open. Quote Link to comment Share on other sites More sharing options...
fl327 Posted March 6, 2003 Share Posted March 6, 2003 if you are running stock turbo efi, no box needed unless you are running a whole buttload of power, then why are you still running stock efi? turbo setup only allows for like 26 degrees advance, adn with 7.4-1cr you have a lot of room to play. msd 6btm will do the do for you, but not neccessary. Quote Link to comment Share on other sites More sharing options...
Clifton Posted March 8, 2003 Share Posted March 8, 2003 I'm using the MSD boost retard. They make one for use with the 6AL and one with stock ignition. I have the one for stock ign. You can adjust it between 0-3 degrees per psi. I have used the Jacobs one in the past. It is crap compared to the MSD's adjustablity. It was worth the $179 I paid. I run mine close to the edge of knock. If I hear anything I just turn the little knob a little more. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted March 9, 2003 Share Posted March 9, 2003 I'm using MSD BTM too, but I'm going to go with J&S Safeguard It's does both ignition retarf by boost and knock. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.