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Discussion Starter #1
Well , looks like I will get my chance to build the fastest Jalpa . On my way to the car wash yesterday , I heard a screech , rattle and some very sick sounds coming from the engine compartment. I nursed it home knowing I was screwed already. I pulled all the plugs and number 8 looked like someone took a hammer to it. It had been making a strange miss ever since I bought the car. Even after the rebuild it had this weird miss. When the dyno results came in , I had expected much better numbers given the mods done. I am pulling the engine this weekend. I probably broke a valve spring or dropped a valve. I may have even broken a rod. It is hard to tell . I am going to rebuild with custom heads, custom cams 11 to 1 Je pistons and carillo rods. That should reach the 400 Hp I am looking for. The head guy says he can make a set that will flow 250 plus. Stock is about 140. I plan to raise the redline to 9K . Have power 4500 to 8k. I will update all through the progression. I plan to keep it normally aspirated. Just lots of old school HP. Lee
 

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Discussion Starter #3
I had been thinking about upgrading all the internals anyway. I guess I should be careful what I wish for. I think it was probably a valve problem. When the head guys assembled my heads they bent two valves not knowing how the crazy valve assembly worked on the Jalpa. They probably slightly bent several others just enough to barely seal. I have had weird vacuum readings ever since run in on the rebuilt engine. There has been a lot of flutter on the gauge up to about 4 k rpm. Seemed very abnormal to me, however since I had never driven or heard another Japla, I had no frame of reference. Do jalpas rev smoothly or sound like there is a popping in the engine all the way up. I assumed I had a valve problem but with new valves I discounted that. (Probably should have listened to my instinct)The funny thing is that I bought a leakdown tester about a week before the meltdown and was planning a leakdown test on all the cylinders. The cylinder where It hammered the plug was also one of the ones one giving odd vacuum readings. A completely new set of heads CNC machined will resolve any potential problems. The odd thing is that the regular compression test was pretty good on all cylinders. I had assumed that the Jalpa motor would rev smoothly and quickly to redline. It is very possible I was making 275 HP on 7 cylinders. That would be more in line with the math on the head flows, exhaust etc. It would have put me at 315 or 320 on 8. With the increase in head flow, that is what it should have been making. I am really looking forward to opening it up this weekend to see what happened. I will post pics and analysis. Lee
 

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My jalpa had a lot of decel popping and erratic vacuum up to 2200 rpm. The two other Jalpa’s in the area I am familiar with did not suffer from those symptoms. I attributed my problem to a combination of compression variance (110psi-165psi), chain tension, and the rather peculiar OEM architecture of distributor driven off the alternator belt driven off one cam driven off chains and gear to the crank. Odd that your compression tests were equal.
 

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Lee,

REALLY sorry to hear about this!!! :(

Sure you're Jalpa will be back though and even more impressive!!!
Hang in there and keep us in the loop!!

FWIW, my Urraco pulled very smoothly, but a different setup of course ...

Regards,

Bryan
'74 P250S S/N 15622
Indianapolis Indiana USA
 

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Lee, I will have to stick the Go Pro to my car and zoom around a bit for you. Mine runs smooth, quiet and only pops a bit when I let the engine slow the car.

It ran completely different before and after various services. When it is happy, it doesn't sound like anything all that out of the ordinary unless you are giving it a lot of gas.
 

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Discussion Starter #7
Thanks Chris. That is why I really wanted to see your car. I have no frame of reference. I am dropping the motor and should have the head off by the end of the day. I already spoke with the custom head guys. I wonder if a Jalpa could turn 10K?
 

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Discussion Starter #8
Thanks for the support Bliss. I think the misfire has something to do with the cams and valves. My compression was all 185 to 195 so had to be something else. Also .carb jetting never made a difference. There was always kinda like a stuck valve on the engine reving. May have actually been or possibly a broken spring. Running static compression did not show it. I am really looking forward to finding the problem. Plus I always wanted to build a screamer.
 

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Thanks for the support Bliss. I think the misfire has something to do with the cams and valves. My compression was all 185 to 195 so had to be something else. Also .carb jetting never made a difference. There was always kinda like a stuck valve on the engine reving. May have actually been or possibly a broken spring. Running static compression did not show it. I am really looking forward to finding the problem. Plus I always wanted to build a screamer.
Hmmm ... Jetting should have made a difference ... The P250 at least needs it with today's gas ...

Now's your chance to build that screamer!! Then come up North and we'll play with my car ;)

Looking forward to hearing the ideas and the progress Lee!! :)

Bryan
'74 P250S S/N 15622
Indianapolis Indiana USA
 

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Discussion Starter #10
Thanks . I found the problem. Somehow a nut got sucked into the cylinder. The only thing I can think is that it went through the carb and down the velocity stack. It was not making the sound until 5 minutes after I started it so unlikely that it was dropped in while I had the carbs off. It would have started rattling right away. It is possible that a stray nut fell in right as I removed the carbs and manifolds before I stuffed rags into all the holes. Attached are pics of the damage. All repairable except the piston which needs replacing. Since I am this far I might as well move forward with the formula one (10 K rpm)Jalpa project. After studying the cam drive setup, I see no reason it will not turn 10 k without problem. Here are some pics
 

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Oh my!! Lee, do you run the stock air cleaner setup?

I know it's very much a tangent, but curious ... What's your setup for dropping the sub-frame?

Regards,

Bryan
'74 P250S S/N 15622
Indianapolis Indiana USA

Thanks . I found the problem. Somehow a nut got sucked into the cylinder. The only thing I can think is that it went through the carb and down the velocity stack. It was not making the sound until 5 minutes after I started it so unlikely that it was dropped in while I had the carbs off. It would have started rattling right away. It is possible that a stray nut fell in right as I removed the carbs and manifolds before I stuffed rags into all the holes. Attached are pics of the damage. All repairable except the piston which needs replacing. Since I am this far I might as well move forward with the formula one (10 K rpm)Jalpa project. After studying the cam drive setup, I see no reason it will not turn 10 k without problem. Here are some pics
 

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Discussion Starter #12
I use the stock covers for the carbs but mine are euro. I have a car lift and just raise the car up off the engine. I made the cradle as a test stand and to move it around.
 

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I use the stock covers for the carbs but mine are euro. I have a car lift and just raise the car up off the engine. I made the cradle as a test stand and to move it around.
Thanks Lee!!

I like the stand, I need to re-make mine ...

Euro airboxes are definitely better for the Jalpa - IMO :)
With the boxes on, I wonder where the nut came from?
Water under the bridge ...

Merry Christmas/Happy Holidays to all!! :)

Bryan
'74 P250S S/N 15622
Indianapolis Indiana USA
 
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