383 Install update - 700R4 issues and vacuum brake issue

[rhdowns]

Well my 383 from skip white performance is installed and sounds great. I have a TV cable from bowtie overdrives installed that was installed when I had the 305 in it.

The original 700R4 that has about 90k miles on it is very unhappy about the new motor. It slips if you give it more than about a quarter throttle. It shifted fine with the 305 but very unhappy now with all the extra power. I am torn as to what to do next. Do have the transmission rebuilt or buy a new one? Bowtie overdrive has one for about $1395 rated to handle the horsepower\torque this engine puts out.

Second issue - vacuum for the brakes. Under most conditions they work fine but in parking lots where you use them once and then use them again the second time they are like manual brakes and you have to really step hard on the puzzle to stop. I'm told that it is the camshaft and that I either have to swap out the cam or buy some vacuum boost\storage thing to fix this issue.

Third issue is we thought the truck had a posi rear and it does not so putting it in first will light one side up for as long as your foot is in it. Is it very involved to swap out rear ends for a posi trac rear?

Thanks for all your help.

I will hopefully post some pics and vids when I get back from cold Boston Thursday. The engine sounds great and looks good.

Oh one more issue the bracket for the air conditioner - when trying to bolt up the ac unit the valve covers are too high and interfere so I either have to have lower profile valve covers or have the valve cover mashed down on the corner.

http://67-72chevytrucks.com/vboard/s....php?p=4299016 Original post that has some pics.

[INSIDIOUS '86]

Your throttle valve cable may be misadjusted it should be pulled all the way out at full throttle so disconnect it pull the throttle back till full and adjust the cable so it's at the end of it's runout next to the stud. As for the slipping my trans did that just before it blew if you don't have the money for a trans the best thing to do is to get either a Fairbanks or sonnax servo to hold the clutches down harder it will let that stock trans hang in there for some slightly agressive street driving but no burnouts you will burn the clutches up. Look up patc transmissions online the have alot of info
Posted via Mobile Device

[codydubb]

If worst comes to worst try some Risoline trans stop slip, they sell it at checker or autozone i think, my 700 started doin the same thing when i put my new engine in it works magic guaranteed to stop the slip so they say but it worked for me for a few months till i decided to go with a different trans

[INSIDIOUS '86]

Also I found that if you put a spring on the throttle valve cable in front of the plastic clip that attaches to the stud it will pull the cable out farther at part throttle an keep line pressure up to compensate for high of idle torque, and when you hit full throttle it will compress so as not to pull the cable to tight
Posted via Mobile Device

[billnorman]

Sounds like you are getting some great advice from Insiduous. You may wish to see how much vacuum you have at idle. If the cam is causing it to be way down at idle, you may wish to add a check valve and a large vacuum storage can in series with your booster. If you ran over somebody with your performance engine and lousy brakes, it would make a great lawsuit for the plaintiff.

[piecesparts]

I updated my vacuum brake booster with one from Tuff Stuff, on my truck. That made a serious amount of difference in operation with my 383 engine's vacuum. The booster responds better and does not seem to run out of vacuum as quick as the factory unit did. You may want to go into your 700 tranny with some updates to make it align with your cam and drivning style. I rebuilt mine to use the heavier clutches, planetary and sun housings. I don't have that slip issue now. I also did the valve body with heavier springs and a hardened seperator plate.

[spudz]

install hydroboost brakes.