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FE Technical Forum / 396 truck FE
« on: August 19, 2015, 06:53:59 AM »
I posted this on the old forum, but wanted to make sure people saw it. Basically, somewhat mismatched 396FE turned out pretty well. The back story is that this one was through two shops and nobody could get it to run. Poor guy was forced to buy 3 carbs and pay out the nose for labor and they never got it running. When I came in, I found a set of heads with loose and sunk seats, multiple broken guides, springs installed at the wrong installed height, and horrible intake leak and needless to say, no tuning whatsoever.
Initially, we found the heads and intake from a buddy, bought a set of headers to replace the log manifolds, then dove in knowing the cam may not be ideal. Later I found the pistons were 1.66 CH, but at this point the smartest move was to get him through the season with a fun cruiser and then do something better over the winter or next winter, he needed to get on the road or the project would have likely died both from his motivation and his wife's impatience of the money flow
The resulting engine is a truck 390 (low compression) with Edel heads, RPM intake, Accel dist, 650 Thunder series Edelbrock carb, FPAs, 3.50 gears and a CR 4 speed, cam was the smallest thumper, 226 intake, 241 exhaust, low 500s on lift, 107 LSA on 102.
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1484&sb=2
Needless to say it was a little down on torque, good sized cam, lots of overlap, big intake, big heads, but it was not nearly as bad as you'd think. To tune it, I put a set of pink enrichment springs in the carb (was supposed to come with them stock, but didn't) to keep them from cycling at idle. (7 inches of vacuum). Recurved the distributor to allow 38 total at 2800 with 20 initial and put a 4 hole Transdapt phenolic spacer on.
I put the spacer on initially to help keep the carb cool, but looking for issues with stalling when he hit a bump backing out of his driveway, I found that the carb also had very high float levels, so likely the boiling issue was not only a temp issue, but the float level was high enough to let the gas go where it wanted with heat as well. In the end, those four things really helped drivability.
I was surprised at the end results, this engine runs really well in a short box 2WD pickup, even with a deep breathing intake and not much compression. The next step will be a 3.98 crank in it to get the pistons up where they should be, potentially rock the cam back a couple of degrees and then tune again as 416. It should be a lot stronger then, but for now it's a real nice driver and it sounds awesome.
I can't say I would pick a Thumpr cam on my own, but it certainly wasn't nearly the enemy we generally make them out to be. The truck runs as well as any low compression 390 could with any other reasonable cam and could easily be used as a daily driver.
Initially, we found the heads and intake from a buddy, bought a set of headers to replace the log manifolds, then dove in knowing the cam may not be ideal. Later I found the pistons were 1.66 CH, but at this point the smartest move was to get him through the season with a fun cruiser and then do something better over the winter or next winter, he needed to get on the road or the project would have likely died both from his motivation and his wife's impatience of the money flow
The resulting engine is a truck 390 (low compression) with Edel heads, RPM intake, Accel dist, 650 Thunder series Edelbrock carb, FPAs, 3.50 gears and a CR 4 speed, cam was the smallest thumper, 226 intake, 241 exhaust, low 500s on lift, 107 LSA on 102.
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1484&sb=2
Needless to say it was a little down on torque, good sized cam, lots of overlap, big intake, big heads, but it was not nearly as bad as you'd think. To tune it, I put a set of pink enrichment springs in the carb (was supposed to come with them stock, but didn't) to keep them from cycling at idle. (7 inches of vacuum). Recurved the distributor to allow 38 total at 2800 with 20 initial and put a 4 hole Transdapt phenolic spacer on.
I put the spacer on initially to help keep the carb cool, but looking for issues with stalling when he hit a bump backing out of his driveway, I found that the carb also had very high float levels, so likely the boiling issue was not only a temp issue, but the float level was high enough to let the gas go where it wanted with heat as well. In the end, those four things really helped drivability.
I was surprised at the end results, this engine runs really well in a short box 2WD pickup, even with a deep breathing intake and not much compression. The next step will be a 3.98 crank in it to get the pistons up where they should be, potentially rock the cam back a couple of degrees and then tune again as 416. It should be a lot stronger then, but for now it's a real nice driver and it sounds awesome.
I can't say I would pick a Thumpr cam on my own, but it certainly wasn't nearly the enemy we generally make them out to be. The truck runs as well as any low compression 390 could with any other reasonable cam and could easily be used as a daily driver.
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