[chvy285]

I have a 355 with lunati 285 [email protected] 510 lift 108degree lobe sep edelbrock performer eps intake 305 heads runnin very sluggish cant figure out why it seems to take very long time to get any speed at all edelbrock 600 carb could this be my problem is not enough carb??? LOST if anyone could give me any ideas would greatly appreciate it i know the 308 gear isnt helping but truck was alot quicker before cam intake and headets thanks for the help

 

[tudlums]

sounds like the ignition timing is slow or if you have vacuum advance it may not be responding properly...you will loose vacuum sometimes when you change cams..and if this all checks out ok you will need to put the cam in at a 106 lobe center...

 

[BogiesAnnex1]

I have a 355 with lunati 285 [email protected] 510 lift 108degree lobe sep edelbrock performer eps intake 305 heads runnin very sluggish cant figure out why it seems to take very long time to get any speed at all edelbrock 600 carb could this be my problem is not enough carb??? LOST if anyone could give me any ideas would greatly appreciate it i know the 308 gear isnt helping but truck was alot quicker before cam intake and headets thanks for the help

This can be a lead in to a lot of tuning issues but this is a pretty big cam that has moved the power band way up the rev range. For sure the 3.08 gearing isn't helping because the engine's power band and the gearing to get up to it no longer match. The 305 heads unless you put in 350 valves and did some porting aren't helping either as about the time the engine revs to the cam's power band unmolested 305 heads are out of breath. You may also be looking at detonation with these small chamber heads, they have the spark plug way off to one side with a lot of compression on a 350, the plug location brings the slow burn of large chamber heads with a lot of compression. This will put the point of maximum pressure late in the power cycle where it isn't effectively pushing the piston and creats a situation where the piston has moved so far down the bore that the quench function is no longer a viable method of damping the excess temperatures that cause detonation of the unburnt mixture ahead of the flame front. More advance that comes in quickly will help getting the peak cylinder pressure earlier but will increase any detonation tendency. There are some cures for that of which richening the mixture is the quickest without backing down the advance. The 600 cfm carb won't be the best at feeding the engine where it has to go for max power on this cam, but that's probably the last issue to chase as it will do well enough to at least tickle your fancy for power but won't satisfy it.

Bogie

 

[vinniekq2]

with all the parts you have in the engine,its the cam thats a little big.The carb could be a little bigger.The heads could use some work. Im sure with some tuning it will improve.Is that a hydraulic flat tappet cam. when the engine reaches 2500 rpm does it get a lot better?

 

[chvy285]

355 slow

Thanks to everyone who answered it seems the cam is to big for the stock 305 headsand my 308 gear it seems a head swap to maybe a good set of double humps and a lot more gear would be a huge help as i am really new to all this i never realized u could overcam one that easily this is in a 1983white gmc swb also runnin a 10/31/50 tire also seems to be killin it what would be a good tire size lookin for at least a 410white gear now

 

[chvy285]

It starts pullin around 2700 pretty hard but nothin like it shouldat the top if first gear its pullin hard if u hold it to around 5500 before shiftin when u shift it barks tires just takes forever to get it there was just very disapointed in the petformance but i am new at this and learning some things i am learning are turning out to be expensive lessons lol

 

[E.Furgal]

if it's an 67-72 p/u they are not heavy by p/u standards my long bed is 3890. lb

 

[chvy285]

I installed a cloyce heavy duty double roller timing chain and gear at first had it all out of whack and had to tear it all down and reset it i had it set on wrong timing mark and wouldnt hit a lick