Big mutha thumpr cam 350
![big mutha thumpr cam 350 big mutha thumpr cam 350](https://i.ytimg.com/vi/ulQBXMnmT4c/maxresdefault.jpg)
GM gradually added roller camshafts to 305's and 350's from the mid 80's forward. Does not fit LT1/LT4, or factory roller Small Blocks built from 1985 and newer. Now back to my original question.Street/strip, needs 9.5:1 compression, 2800+ stall, intake, gears and headers, very rough idle.įits Chevrolet GEN 1 Small Blocks including the 262, 265, 267, 283, 302, 305, 307, 327, 350 and 400. I've got a light set of springs in mine and all of the timing is in by around 23-2500 rpm. The weights and bushings in the distributor also rust and seize up and that can cause problems too. Another problem is that they might have had stiff springs in the distributor causing it to advance too late. My motor likes the extra initial timing and is pretty snappy when I roll into it. I've also read where people aren't putting much initial timing in their combos that run this cam and I think that might be part of the problem. I spent a few hours playing with these and a few other carb settings on my 'Cuda and it honestly felt like I gained 75 hp and the drivability went from challenging to super easy.
![big mutha thumpr cam 350 big mutha thumpr cam 350](https://i.ytimg.com/vi/YinMkHW0Lqk/hqdefault.jpg)
You'll be amazed at what a power valve and opening those secondary butterflies can do for idle quality and the transition from the idle to main circuits. The only issue I have which I think the converter will fix is the high idle in park and lunging forward when in drive. I'm leery of pushing the stock 350 much farther than that but it was still pulling strong then. The cam comes on right at 2,000 rpm as advertised by comp and pulls strong to 5,000. The smaller ports of the performer intake will help with the vacuum signal at the carb. I'll leave the super victor and 750 mech sec street HP for my 406. It has a Edelbrock Performer intake with a 600 CFM single line vac sec holley. Now that your red in the face, tell us what you really got You will probably need something in the 3000-3600stall rating, to get 2200-2400 stall because of the lack of low end torque. Sorry but with the long legs of those 3.08 gears, (assumed) a low conpression 350 with a 'thumper' cam, most likekly overcarburated with a 'Deamon' and a intake designed for 7000rpm. You obviously know solid performance with the other vehicles listed in your signature, if you ever achieve results that are on par with the rest of the stable, please post them up for the other 9,999,999 that have been unable to get there. I wish you luck accomplishing "performs well when tuned". The cam makes for extremely poor carb signal in favor of a wanna-be sound. Sorry, hope this doesn't rub the wrong way, I have known 2 people that tried the 'thunper', I know 2 people that gave up trying to get the motor tuned and took the Thumper out and put it in the scrap heap. I'm sure I'll have to adjust the secondary butterflies, accelerator pump cam, squirter size and the spring for the vacuum secondaries too. I've already bought 3.5 and 4.5 power valves for my holley and I'll be tuning on it next. I haven't checked idle vacuum yet, however I'm sure it will be about 8-9" based upon research.
#BIG MUTHA THUMPR CAM 350 INSTALL#
Basically I wrapped up the install today, broke the cam in and drove it around the block. I'm sure the tight stock converter is keeping it from idling the way I want when it's in gear. I've got about 18-20 degrees of initial timing in it(w/vacuum advance hooked up) and 33 degrees total by about 2300 rpm. The cams perform well when tuned and I'm starting that next. The 350 in the truck is stock and I primarily wanted a cam that had that big cam sound but wasn't super aggressive on lift.
![big mutha thumpr cam 350 big mutha thumpr cam 350](https://www.compcams.com/media/catalog/product/cache/6f0688fdd61495c799d0d38b4490ff42/k/1/k12-239-3_1100_1_55.jpg)
Oh and have you measured vacuum? What is it at idle? Are you sure you have no intake leaks? Did you try playing with the timing to see if you can get better idle performance? Last time I helped someone with a Thumpr, we had to dial in quite a bit of initial timing to prevent it from stalling all the time. If you get too aggressive with the stall without knowing the gearing, that creates problems of their own too.
![big mutha thumpr cam 350 big mutha thumpr cam 350](https://i.ebayimg.com/images/g/lz8AAOSwcONegTiy/s-l300.jpg)
2300-2500 should be OK, but tell us what rear gears you have and tire size. Yes, you will need a high stall to reign it in a bit. They tend to be all show, and no go, and hard as heck to tune properly for good street manners. I don't know anybody who really likes the Thumpr cam. A little too late, but perhaps you should have asked us what cam/converter combo would work together BEFORE you bought that cam.