Need rotary guru help

IH8DSM · 01-10-2010, 11:58 PM

Ok the truck is a 74 repu with a 13b, as of right now its got a holley carb, a header and a rebuilt motor. The motor is street ported and made with atkins springs/seals and fel pro gaskets except for the oil control rings.

Heres the problem, it starts, runs, drives, idles with no problems but once its warmed up and you turn it off or stall it, then thats the end of it. it wont start up again till its cooled down. After its cooled down it will start and run again till its warmed up again. We're clueless at this point we've tried three different carbs ( niki, side draft, and now the holley) two completely different motors (had a fresh rebuilt one in there previously did the same thing) 3 different starters, different distributor, different igniters. Battery is good, alt is good. Used seperate parts for both motors similar problem. New fuel pump, good fuel pressure. Maybe 200 miles since rebuild, everything in side checked out fine.

So at this point getting really frustrated, So any ideas would be helpful.

Rogue_Wulff · 01-11-2010, 02:28 AM

Not enough miles on the engine. It takes a while for a fresh engine to build enough compression for a hot start.

IH8DSM · 01-11-2010, 12:50 PM

Think that could be the case? Never had that problem on any of the other rebuilds/

dudemaaan · 01-11-2010, 02:04 PM

check the compression just to see what it is, if used housings and such were used then compression won't be as high and it can take longer for everything to seal up. Hot start problems is usually a sign of weak compression, too much fuel in these situations can also make it harder to start.

Rogue_Wulff · 01-11-2010, 02:09 PM

As stated above, new seals and used housings tend to need 1000-1500 miles in order to fully seat in together. I've seen many rebuilds that were nearly impossible to start hot, but started fine cold. The issue usually went away after 1000-1500 miles.
Even minor carb issues can greatly increase the difficulty in hot starting a rebuild.

Kentetsu · 01-12-2010, 03:58 PM

Any chance that timing could be the issue? That's all I can think of that hasn't already been mentioned. Good luck!

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91GSL-SE · 01-14-2010, 02:41 AM

Any fuel lines getting hot? Could be vapor lock?...
Also is your fuel system vented?

01-10-2010, 11:58 PM	#1
IH8DSM RCC Contributor Join Date: Mar 2008 Posts: 610 Rep Power: 18	Need rotary guru help Ok the truck is a 74 repu with a 13b, as of right now its got a holley carb, a header and a rebuilt motor. The motor is street ported and made with atkins springs/seals and fel pro gaskets except for the oil control rings. Heres the problem, it starts, runs, drives, idles with no problems but once its warmed up and you turn it off or stall it, then thats the end of it. it wont start up again till its cooled down. After its cooled down it will start and run again till its warmed up again. We're clueless at this point we've tried three different carbs ( niki, side draft, and now the holley) two completely different motors (had a fresh rebuilt one in there previously did the same thing) 3 different starters, different distributor, different igniters. Battery is good, alt is good. Used seperate parts for both motors similar problem. New fuel pump, good fuel pressure. Maybe 200 miles since rebuild, everything in side checked out fine. So at this point getting really frustrated, So any ideas would be helpful. __________________ 85 rx7 gsl-se - AA tags/ never ending project will never run

01-11-2010, 12:50 PM	#3
IH8DSM RCC Contributor Join Date: Mar 2008 Posts: 610 Rep Power: 18	Think that could be the case? Never had that problem on any of the other rebuilds/ __________________ 85 rx7 gsl-se - AA tags/ never ending project will never run

01-11-2010, 02:04 PM	#4
dudemaaan Rotary Fanatic Join Date: Mar 2008 Location: Brenham, TX Posts: 335 Rep Power: 18	check the compression just to see what it is, if used housings and such were used then compression won't be as high and it can take longer for everything to seal up. Hot start problems is usually a sign of weak compression, too much fuel in these situations can also make it harder to start. __________________ 500+ HP thanks to: Fast reacting IAT sensor thread! Mechanical Pre-turbo Water Injection Thread Dual Stock fuel pumps Thread T2 differential swap!

01-12-2010, 03:58 PM	#6
Kentetsu RCC Contributor Join Date: Feb 2008 Location: Grand Rapids, Michigan Posts: 530 Rep Power: 18	Any chance that timing could be the issue? That's all I can think of that hasn't already been mentioned. Good luck! . __________________ "Learn from the past, or it will become your future...." '85 GS 12a + LSD/Sterling carb/Respeed coilovers/Respeed front swaybar/Respeed adj. rear spring perches/Illuminas/Bilsteins on rear AutoX vids @ http://www.youtube.com/user/Kentetsu1

01-14-2010, 02:41 AM	#7
91GSL-SE At the dirt track. Join Date: Jan 2010 Location: Willamette Valley, OR Posts: 89 Rep Power: 16	Any fuel lines getting hot? Could be vapor lock?... Also is your fuel system vented? __________________ Rollin like a reuleaux. Unstoppable.

01-11-2010, 02:28 AM	#2
Rogue_Wulff Non Member Join Date: Jun 2008 Posts: 310 Rep Power: 18	Not enough miles on the engine. It takes a while for a fresh engine to build enough compression for a hot start.

01-11-2010, 02:09 PM	#5
Rogue_Wulff Non Member Join Date: Jun 2008 Posts: 310 Rep Power: 18	As stated above, new seals and used housings tend to need 1000-1500 miles in order to fully seat in together. I've seen many rebuilds that were nearly impossible to start hot, but started fine cold. The issue usually went away after 1000-1500 miles. Even minor carb issues can greatly increase the difficulty in hot starting a rebuild.